The rotating packed bed (RPB) reactor can significantly enhance mass transfer efficiency between multiphase flows and reduce reaction time with the cutting and crushing effect of the filler on the liquid. However, the internal structure and hydrodynamics of a RPB reactor are extremely complex, making it difficult to accurately describe the flow and mass transfer behaviors within the packing even using high-speed cameras. Computational fluid dynamics (CFD) has been used by many researchers to simulate the flow and reaction characteristics in RPB reactors in recent years due to its unique advantages in effectively simulating the flow and mass transfer behaviors in multiphase flow processes. This article summarizes the research progress of scholars using CFD technology to simulate rotating packed bed reactors, and focuses on the selection of multiphase flow models, determination of boundary conditions, and packed bed calculations, which were key parts of CFD calculation.

The helical coiled tube heat exchanger based on liquid metal has the characteristics of compactness and strong heat exchange capacity. It is valuable in energy and chemical systems such as thermochemical hydrogen production, fourth-generation nuclear energy, high-temperature solar thermal power generation, and waste heat recovery. The convective heat transfer issues of liquid metal flowing across tube bundles are getting more and more attention. However, turbulent heat transfer flowing across tube bundles is complicated, and the experimental and numerical simulation is chanllenging. At present, there is no reliable and relevant literature review, hindering the design and technical development of this type of heat exchanger. This paper reviewed convective heat transfer researches on liquid metal flowing across tube bundles. Firstly, it was pointed out the similarities and differences between liquid metal and other fluids in convective heat transfer characteristics. Then, it was summarized and compared flow and heat transfer empirical relations of liquid metal. It was recommended empirical formulas for the design of this type of heat exchanger. Subsequently, by applying the recommended empirical relations, the flow and heat transfer performance of different working fluid was compared with flowing across tube bundles, and the liquid metal flowing through different flow channels was also compared. The turbulent heat transfer of liquid metal has the potential to strengthen. The flow resistance caused by tube bundles is considerable, so it is recommended to take measures to reduce the resistance. This paper provided a reference for the subsequent design of heat exchangers involving liquid metal flowing across tube bundles.

The process systems engineering(PSE) study to reaction system of preparing propylene oxide by hydrogen peroxide method, which meets the requirements of environmental friendliness, atomic economy and sustainable development, can achieve good technical and economic results. The technological process PSE study in the 100—400kt/a HPPO plant can reduce the feedstock consumption of 149—720t/a hydrogen peroxide and 184—889t/a propylene. Under the conditions of reaction pressure 1.5—4.5MPa and reaction temperature 39—95℃, the automatic control PSE study in the 400kt/a HPPO plant can reduce the feedstock consumption of 509—757t/a hydrogen peroxide and 629—935t/a propylene. The PSE study in reaction system of HPPO plant with different process parameters and different production scale can increase the total heat transfer coefficient of the reactor to 2400—2800 W/(m²·K) and prolong the service life of the catalyst to 4.8—5.0a. Thus Sinopec completed Chinese first 100kt/a industrial-scale HPPO plant in 2014, with 100% high-grade product rate, becoming the world's third industrial-scale HPPO full-set technology licensor, with feedstock consumption in HPPO plant at international leading level. The part of PSE study results are being or will be applied to 4 HPPO industrial-scale production plants, with the total production capacity of 1.00 Mt/a and the number of HPPO plants and PO production scale ranking first in the world.

At present, the heat dissipation demand for high efficiency and high temperature uniformity is increasing in various fields. Pulsating heat pipe has become a suitable and effective heat dissipation element due to its excellent heat transfer efficiency, flexible heating mode, simple structure and other advantages. In this paper, a cylindrical annular pulsating heat pipe was proposed and designed, and the drying characteristics of the cylindrical annular pulsating heat pipe were studied experimentally. In the experiment, anhydrous ethanol and HFE-7200 were used as working medium. Under the condition of 90° dip angle, the heating power of 100—200W was tested for the pulsating heat pipe with 30% and 70% liquid filling rate. Under the condition of 30% liquid filling rate, the heating power of the pulsating heat pipe at 30°, 45° and 70° was measured at 20—100W. The drying characteristics of cylindrical annular pulsating heat pipe at different elbows were studied. The results showed that the higher the dip angle, the higher the drying power of the cylindrical annular pulsating heat pipe. When the working medium was HFE-7200 and the dip angles were 30°, 45° and 70°, respectively, the powers of the four elbows of the cylindrical annular pulsating heat pipe were all 100W.

Methanol is an ideal hydrogen carrier because it keeps liquid state at normal temperature and pressure and has a very high hydrogen-carrying density. The design of methanol reforming reactors is important for the methanol online reforming system. For methanol reforming reactors, the CO concentration in reformate is high at high reaction temperatures that is not conducive to subsequent deep CO removal. But at low temperature, the low methanol conversion and liquid hourly space velocity (LHSV) s results in low catalyst utilization and large reactor volumes. Hence, a two-stage reforming process with the first isothermal section operating at 300℃ and the adiabatic second section working from 300℃ to 220℃, was proposed. A simulation study on Aspen Plus proved that the reactor was theoretically feasible. The experimental study was then carried out in a fixed bed reactor and the results showed that under conditions of complete methanol conversion, the methanol LHSV for this two-stage process was 4.08h^-1, the CO concentration in reformate was 0.56% and the reforming hydrogen production efficiency was 108.98mL/(min·mL catalyst). The isothermal reforming process at 220℃ had a methanol LHSV of 1.5h^-1, a CO concentration of 0.40% in reformate and a reforming hydrogen production efficiency of 44.89 mL/(min·mL catalyst). The two-stage process achieved higher reforming hydrogen production efficiency at higher LHSV, lower catalyst usage and a more compact reformer structure. At the same time, the CO concentration of this two-stage process was much lower than that of the isothermal reforming process at 300℃ (1.77% at 300℃) at the same LHSV. Therefore, the two-stage process proposed in this paper was of great importance to obtain high hydrogen production efficiency and low CO concentration.

As a heat exchanger is an important energy transfer equipment in chemical and nuclear power, the fluid induced vibration (FIV) of the tube bundle becomes an important factor to induce the tube bundle rupture. So the safety and reliability of the tube bundle becomes especially important. In order to study the flow induced vibration response of C-tube in the passive residual heat removal heat exchanger (PRHR HX), the in-containment refueling water storage tank (IRWST) and C-tube were simplified, and the numerical simulation of the flow field and vibration response were carried out. Simulation results showed that the intersection of natural and forced convection in the temperature field caused by the velocity disruption, due to the loss of flow velocity, vapor bubbles can not be flushed, combined and wrapped with tube, resulting in transition boiling, the boiling reduces the heat flux to produce the phenomenon of thermal stratification. According to the fluid flow characteristics, the flow field can be divided into three regions:gas-liquid two-phase hot flow region, hot flow region, cold flow region. Among them, there was high turbulence energy in the gas-liquid two-phase hot flow region, and the steam volume fraction reaches 50%, which made the rapid growth and collapse of steam to provide the disturbance, and the damping ratio of C-shaped tube structure was reduced, so the upper bend at the end away from the solid support became the region with the largest induced vibration. Based on the vibration results, the vibration direction is the C-tube plane, and the position of the upper bend vibrates were most strongly impacted by the gas-liquid two-phase hot flow. Therefore, the tube bundle at this position in PRHR HX was prone to wear with the support and anti-vibration components, and there was a potential risk of tube bundle rupture.

Two processes, conventional reactive distillation (RD) processes combining reaction and separation unit, and the distillation column coupled with side reactors (SRC) processes, were explored for the reactive distillation process for the synthesis of methyl methacrylate, by the equal mole ratio of methacrylic acid and methanol, in this study. At the MAA mole flow of 10 kmol/h and the conversion efficiency of 98.6%, the optimal operating conditions for minimizing the total annual cost (TAC) were determined via the Aspen Plus sequential iterative optimization procedure. The above two techniques were simulated and optimized in terms of the minimization of the total annual cost and the CO₂ emission. The results showed that SRC process had significant advantages, and comparing with RD process, TAC can be reduced by 8.5%, CO₂ emission can be reduced by 16.3%. The minimum TAC was 115.23 million yuan per year under the optimal operating conditions, which included SRC column stages of 26, reactors of 3, side reactors (R1/R2/R3) feed location at the 6th, 11th, and 14th trays respectively, the SRC tower side line that entered the side reactors (R2/R3) feed locations at the 23rd and 24th trays, respectively, and the MeOH distribution ratio of the three side reactors (R1/R2/R3) was at 0.58︰0.22︰0.2.

Pressure swing adsorption (PSA) is a multi-step coupled periodic cycle dynamic process, and the effect of the flow state of the fluid in the adsorption bed on the separation efficiency has not been clarified yet. It is of great guiding significance to deeply explore the concentration field distribution of the fluid in the adsorption bed under different flow conditions through numerical simulation, in order to enhance separation efficiency. In this work, based on Aspen Adsorption V12 a four-bed, nine-step PSA model was established to simulate the separation of dimethyl sulfide /nitrogen, and the effect of the degree of turbulence on the separation efficiency was investigated during the transition process of the mobile phase from layer to turbulence in the adsorption bed. The results showed that when the Reynolds number was in the range of 800—1200, enhanced mobile phase turbulence could effectively improve the separation performance. When the mobile phase changed from transition flow to complete turbulence during PSA adsorption, the dimethyl sulfide was removed from 20μL/L to 8μL/L with the dimethyl sulfide content of 2000μL/L as raw material, and the nitrogen yield decreased from 93.3% to 86.9%. The research results indicated that enhancing turbulence within a certain range should be beneficial to improving the separation efficiency, but excessive flow rates could cause the adsorbent to fluidize, thereby losing effective adsorption and separation capabilities. Therefore, regarding the practical application of PSA process, the turbulence impact on the system should be comprehensively accounted to enhance the separation efficiency.

The burner used in cracking furnace is the key equipment of ethylene plant. It must meet the specific technological requirements and the increasingly strict environmental requirements while keeping the combustion stable. In recent years, the rise of porous medium combustion technology has brought new changes to the burner of ethylene cracking furnace. A new porous medium burner for ethylene cracking furnace was designed and developed by CFD technology and hot experimental method. The combustion state in the double-layer porous media structure was studied by numerical analysis. The upstream of the porous media region was 30 PPI Al₂O₃ foam ceramics, and the downstream was 10 PPI SiC foam ceramics. It was found that the combustion atmosphere in the cracking furnace was more consistent with the equivalent ratio of φ=0.8 and the inlet flow rate u₀=0.8m/s. The joint simulation of the traditional bottom burner and the porous medium side-wall burner in the cracking furnace was carried out. The simulation results showed that the temperature distribution in the furnace was uniform and met the requirements of process and environmental protection. Two porous media burners were prepared and combined with bottom burners for test firing in hot state test furnace. The flame stability was mainly observed. The experimental results showed that the combustion state was good and the NO _x emission was lower.

The corrugated channel can be used to break the accumulation of non-condensable gas (NCG) layers and reduce the resistance to mass transfer in the cryogenic removal of volatile organic compounds (VOCs). In this study, a two-dimensional model for the cryogenic removal of low concentration R134a from nitrogen on a sawtooth corrugated plate channel was established, and the impact of the sawtooth bottom angle on the removal performance of R134a were revealed. The results showed that the isosceles triangular sawtooth corrugated plate can significantly improve the removal efficiency of R134a on the cold wall surface per unit area compared with the flat plate channel. The spatio-temporal average phase change rate (α) of R134a on the sawtooth plate under the conditions of present study was 0.1268g/(m²·s), which increased by 144.6% compared with flat surface. The NCG flow near the cold wall surface will convert from the flowing adjacent to the wall, to off-wall mixing with the bulk flow, and finally to forming the flow blocking zone with stable vortex with the increase in the bottom angle (θ) of the sawtooth corrugated plate. Significant off-wall mixing with the bulk flow of the NCG layer occurred when θ was 13.30°—35.45°, with α ranged from 0.082—0.1268g/(m²·s). The α reached the maximum value of 0.1268g/(m²·s) when θ was 17.46°. The effect of the off-wall mixing with the bulk flow of the NCG layer will decay and the α will keep at a lower level when θ deviated the aforementioned range. The present study can provide a reference for the design of sawtooth corrugated plate structure for cryogenic condensation-freeze removal of low concentration VOCs.

Walnut shell has high yield, high fixed carbon content and low ash content. In this paper, the walnut shell was selected as the research object, the comprehensive pyrolysis characteristic index was proposed, the thermal dynamics analysis was carried out on it, and the carbonization process and principle were studied. Finally, the best carbonization process was obtained through experiments and response surface simulation analysis. It was found that the comprehensive characteristic index of pyrolysis first increased and then decreased with the increase of heating rate, and reached the peak at about 10℃/min^{since the pyrolysis reaction was more intense at this heating rate. The carbonization process of walnut shell was a multi-stage complex reaction process, which decomposed hemicellulose, cellulose and lignin in stages, and the activation energy of this process increased gradually. Finally, through simulation and experimental analysis, the optimal process was obtained as follows: heating time was 14.8min, final temperature was 324.7℃, soaking time was 60min, material particle size was about 5 mm and the optimal carbonization rate was 69.4%.}

Absorption refrigeration can be used for the recovery and utilization of industrial and building waste heat. However, the low performance of absorption refrigeration systems hampers their engineering applications. To develop absorption refrigeration technology suitable for waste heat recovery, this study established a mathematical model of an absorption refrigeration system using 55% lithium bromide (LiBr) solution and 35% lithium chloride (LiCl) solution as working fluids. The effects of different cooling water, chilled water, and heat source parameters on the thermodynamic performance, system efficiency, and exergy efficiency of a single-effect absorption refrigeration system were analyzed. The results indicated that the inlet temperature and flow rate of the cooling water, inlet temperature of the chilled water, and inlet temperature of the heat source were the main influencing factors on the thermodynamic performance and exergy efficiency of the absorption refrigeration system. The system coefficient of performance (COP) increased with the increase in cooling water flow rate and inlet temperature of the chilled water, while it decreased with the increase in cooling water inlet temperature. Within a certain temperature range, the COP increased with the increase in heat source temperature. The effective coefficient of performance (ECOP) increased with the increase in cooling water inlet temperature, cooling water flow rate, and chilled water inlet temperature, while it decreased with the increase in heat source temperature. The highest COP values for the LiBr and LiCl solution single-effect absorption refrigeration systems were 0.789 and 0.779, respectively, while the highest ECOP values were 0.694 and 0.684, respectively.

Polyvinyl alcohol (PVA) is a polymer material with excellent performance. The main purpose of the recycling section is to recycle the alcoholysis waste liquor rich in methyl acetate (MeOAC), methanol (MeOH) and other chemical materials generated upstream. The main separation task of the third and fourth distillation columns of the recycling section (TQ-603 and TQ-604) is to simultaneously process the column kettle liquor from the second column (TQ-602), the column kettle liquor from the first column (TQ-601) and the column kettle liquor from the third column of the polymerization section TQ-302. Their main composition is a mixture of methanol and water. In this article, Aspen Plus chemical process simulation software was used to simulate and optimize the 100kt/a PVA recovery section in the third and fourth towers. The thermodynamic method was selected, and the parameter regression was conducted for the main MeOH-H₂O system. The optimal operating parameters of the single tower were obtained after optimization. On this basis, the double-effect distillation technology was implemented for the energy-saving renovation of the original process. A multi-tower heating process was developed through simulation and optimization to achieve deep energy saving.

A rigorous dynamic mechanism model was established using Unisim for a complex heat exchange system (water cooled cascade refrigeration system) coupled with an ethylene propylene cascade refrigeration system and a circulating water cooling system in a certain device. Real time acquisition of on-site data was achieved using OPC technology, resulting in the establishment of an online dynamic simulation system. Through online dynamic simulation, synchronous tracking between the model and the on-site device was achieved. The online dynamic model can reflect the current operating status of the on-site device, thus obtaining a high-precision digital twin model. In addition, to address the issue of high system energy consumption, a global simulation optimization was conducted with the objective function of minimizing total system power consumption and the decision variable of circulating water temperature. Among them, for the calculation of fan power, a prediction model for fan power was obtained through regression using one year's historical data of the factory, thus solving the problem of power calculation in the optimization process. Finally, the optimization results were validated and calculated online in the digital twin model, and the optimization effect was predicted. After optimization, the system saved a total of 772.69MW in power consumption, with a total annual cost savings of 564000CNY, bringing significant economic benefits to the enterprise.

Investigations on the bubble dynamics under the influence of electric fields are beneficial to have a deeper understanding of the mechanism of electrohydrodynamics (EHD) enhancing boiling heat transfer. In view of this, the dynamic behavior of single bubble attached to the solid upper-wall under the effect of uniform AC (Alternating Current) electric field was simulated by the VOSET (Volume-of-Fluid and Level Set) method coupled with electric field force model. And, the effect of voltage frequency, electric field intensity and liquid permittivity was investigated. The numerical results showed that the electric field force acted on the gas-liquid interface and points to the interior of the bubble. The periodical variation of the voltage U led to the periodical variation of the electric field force. Under the extrusion action of electric field force, the bubble had the periodical deformation. The frequency of bubble deformation had a close relationship with voltage frequency. When the voltage frequency was small, bubble deformation had good following with the voltage. But the following performance gradually became weak as the increasing of the voltage frequency. Electric field intensity and liquid permittivity were important factors affecting electric field force. With the increasing in electric field intensity and liquid permittivity, the effect of the extrusion action of electric field force was obviously enhanced, which resulted in larger bubble deformation. But the changes of the electric field intensity and liquid permittivity had no obvious influence on the frequency of bubble deformation. It can also be found that the distortion degree of the electric potential and electric field line was more obvious with the increasing in liquid permittivity, which led to the decrease in the density of electric field line inside the bubble.

Sinopec Engineering (Group) Company Luoyang R&D Center of Technology developed a microbubble and microdroplet dual-enhanced desulfurization reactor. The desulfurization reactor adopted microbubble and microdroplet enhanced absorption method, which changed the large millimeter bubbles in the desulfurization tower into microbubbles below 200µm, and changed the liquid flow mode from overflow to spray. The gas-liquid mass transfer efficiency was improved by this method, and the complexity of the desulfurization tower was simplified by using new internal components instead of the plates, and the reactor had a lower height than the plate tower. The effects of solvent height, absorption temperature and solvent circulation on purification efficiency were studied. The pressure drop at different solvent heights was also measured. The experimental results showed that the desulfurization reactor had low pressure drop and high desulfurization efficiency, and made the mass concentration of H₂S≤50mg/m³. When the flow rate of feed gas was 50m³/h, the best operating conditions could be: the solvent height was 800 mm, the absorption temperature was 40℃, and the solvent circulation was 0.8m³/h.

The increasing demand for efficient and compact methods of heat transfer has generated interest in the utilization of a narrow channel with a significant velocity gradient along its height, thus presenting substantial potential. This research study focused on investigating the heat transfer phenomena in a flow boiling system that employs a narrow slot channel made of titanium under negative pressure conditions. The experimental analysis employed a designated working fluid, namely an ethylene glycol aqueous solution with a mass concentration of 55%. The experimentation was conducted under specific operational parameters, encompassing a mass flow rate spanning from 750kg/(m²·s) to 2000kg/(m²·s), a saturation temperature within the range of 80℃ to 90℃, and an inlet temperature ranging from 60℃ to 70℃. The findings of the study revealed that the activation of a substantial quantity of nucleation sites in titanium necessitated an elevated heat flux. Consequently, this phenomenon maintained the average heat transfer coefficient (h) in a state of relative constancy both prior to and subsequent to the onset of nucleate boiling (ONB). The heat flux required to start of ONB and the mean heat transfer coefficient during the phase of fully developed boiling were subject to influence from alterations in the mass flow rate. Notably, in instances where a considerable degree of subcooling was present, the thermal performance within the confines of a titanium narrow-slit channel displayed reduced sensitivity to variations in inlet temperature during the fully developed boiling stage. Elevating the inlet temperature while concurrently reducing the subcooling degree markedly enhanced the average heat transfer coefficient by as much as 65%. The perturbation of back pressure on heat transfer performance manifested primarily during the fully developed boiling stage, wherein diminished back pressure corresponds to augmented average heat transfer coefficients.

During the transportation process of liquefied natural gas, the low-temperature state will be transmitted to the pipe wall, causing displacement stress in the pipeline due to cold shrinkage. Compensation platforms need to be installed on the trestle to solve such problems. Building a compensation platform requires a large amount of resources with an investment of at least ten million yuan. Currently, there is no systematic analysis results on the span of compensation platforms in China. This article used theoretical analysis and finite element software simulation to divide the bridge into multiple design schemes for large span compensation platforms, and compared and analyzed the feasibility of obtaining the maximum span of the compensation platform. This research achievement would to some extent fill the gap in the field of large span compensation platform implementation and provide reference for the subsequent design of LNG long trestle transportation.

Aiming at the problem of seal failure of the metal O-ring with internal holes of a pressure vessel flange under high pressure conditions, which was caused by excessive deformation of the O-ring due to unreasonable design of the flange structure, a three-dimensional cyclic nonlinear elastoplastic model was established to analyze the effects of flange side wall gap and compression ratio on the circumferential distribution of contact stress and O-ring deformation. The leakage rate of O-ring under different flange side wall gap and compression ratio was tested, the deformation characteristics of O-ring were analyzed, and the deformation failure mechanism of O-ring under high pressure and big side wall gap was discussed. The research results showed that the established finite element model can accurately simulate the mechanical behavior and deformation of O-ring, and the calculated curve had a good agreement with the experimental curve. The contact stress of O-ring was more sensitive to the flange side wall gap, reducing the flange side wall gap and increasing the compression ratio can improve the reliability of O-ring seal. O-ring was prone to necking deformation under high pressure conditions, resulting in circumferential discontinuity of contact stress and leakage. Controlling the preload clearance of O-ring and playing the restraint effect of flange side wall can improve this kind of deformation. The research results can provide a reference for the flange structure design of high pressure metal O-ring sealing with internal holes.

The hydrodynamics and mass transfer characteristics of a three-stage internal loop airlift reactor were investigated experimentally. The gas hold-up, mixing time, residence time, and volumetric mass transfer coefficient were measured in the cold mode experiment under different superficial gas velocities (0.015—0.1m/s) and internals. Experimental results showed that as the superficial gas velocity increased, the gas hold-up increased, mixing time decreased, and mean residence time decreased. Meanwhile, the volumetric mass transfer coefficient increased as the superficial gas velocity increased. The effect of internals on the reactor performance was discussed based on the flow pattern observation. It was found that the mixing effect of the reactor was better when the diameter of the upper cross-section of the internal is relative large (3^# internal), whereas the reactor inhibited the liquid backmixing effectively when the upper cross-section of the internal was relative small (1^# internal).

At present, the understanding of the mechanism of liquid sulfur solidification molding is not very complete, and it is difficult to observe the internal particles and the distribution of cooling water flow field under experimental methods. To solve this problem, based on experimental research, computational fluid dynamics (CFD) simulation method was used to numerically simulate the wet granulation process of sulfur, and mathematical modeling was conducted on the cooling molding equipment. Different drop heights were compared and analyzed, the optimal parameter combination for sulfur wet granulation process was obtained by adjusting the particle size distribution and morphology of sulfur particles under the temperature of cooling water and the inlet flow rate of cooling water. The law of sulfur wet granulation was analyzed in depth. Based on the experimental results, the forming tank model and simulation process parameters were further validated and improved. The research results indicated that as the falling height increases, the proportion of fine sulfur powder increases, but the adhesion of sulfur particles decreases. The optimal parameter combination for sulfur wet granulation process was a falling height of 30mm, a cooling water temperature of 55℃, and a cooling water inlet flow rate of 2.5m/s.

The micro bubble downflow tubular gas-liquid contactor is a kind of downward co-current gas-liquid contact mass transfer equipment. It enhances mass transfer by absorbing high-density micro bubbles generated by the high-speed liquid jet of the jet bubble generator, which has the advantages of compact structure, large gas-liquid contact area, and high mass transfer efficiency. Based on the performance experimental testing platform of a micro bubble downflow tubular gas-liquid contactor and the CO₂-N₂ mixed gas system, the effects of pump liquid volume on pressure drop and maximum natural suction capacity were first investigated. On this basis, the effects of different operational and structural parameters on its decarbonization performance were explored. The results showed that the micro bubble downflow tubular gas-liquid contactor adopted high-speed liquid jet negative pressure suction, the pressure drop and maximum natural suction capacity increased with the increase of liquid volume. When the liquid volume was 14L/min, the maximum natural suction capacity fluctuated within the range of 12.5—14L/min with the increase of column length; during the process of increasing the liquid volume from 4L/min to 14L/min, the pressure drop increased from 20kPa to 300kPa. The change in the length of the mass transfer section had a relatively small impact on the CO₂ removal rate, while the liquid to gas ratio and the inlet gas volume had a greater impact. The CO₂ removal rate increased with the increase of MDEA solution concentration, and the MDEA solution concentration decreased with the increase of cycle times. After three cycles of use, the absorption capacity significantly decreased. The self-designed micro bubble downflow tubular gas-liquid contactor had good decarbonization performance, with a maximum CO₂ removal rate of over 99%.

Chemical reaction selection and design plays a key role in the field of drug synthesis and material synthesis. The selection of a proper chemical reaction could greatly optimize the synthesis reaction conditions, reduce time and improve synthesis yield of the product. In order to better distinguish the advantage degree of chemical reactions, a graphical neural network model was proposed to distinguish reaction superiority by using a reaction graph descriptor based on reaction atomic mapping relationships. Firstly, a reaction dataset for distinguishing the superiority of chemical reactions was established by using USPTO data. Then, the graphical neural network modeling method was used to establish the mapping relationship between the chemical reactions molecular and atomic features and the reaction superiority probability values. Finally, the aspirin different chemical synthesis reactions were taken as examples to prove and verify the feasibility and superiority of the reaction indicator by using the relevant experimental information.

For the four-stage series reaction section of the 300kt/a propylene epoxidation to propylene oxide, the sensitivity analysis of the effect of operating conditions on hydrogen peroxide conversion and propylene oxide selectivity was conducted by Aspen Plus software. The hydrogen peroxide conversion rate was 97.39% and propylene oxide selectivity rate was 96.69% under suitable conditions of reaction pressure 1.8MPa, reaction temperature 55℃, propylene mass space velocity 0.6h^-1, and mass concentration of hydrogen peroxide 20%, and the consumption of propylene and hydrogen peroxide was reduced by 89.84t/a and 73.28 t/a, respectively, which translated to reduction of 820.20t/a in carbon dioxide emissions by altering the switching mode between reactors. The research results have guiding significance for the industrial operation of propylene epoxidation to propylene oxide.

In the context of “carbon peaking and carbon neutrality goals”, the number of new energy vehicles in China has begun to surge, but after the large-scale application of lithium-ion batteries, the problems brought by their scrapping can not be underestimated, such as the waste of strategic metal resources, the impact on the environment and human health. Therefore, the reuse of waste lithium-ion battery resources is very necessary, especially the recovery of cathode materials. At present, the recovery methods of cathode materials mainly include fire metallurgy, hydrometallurgy, microbial metallurgy and deep eutectic solvent leaching, etc. This study focuses on the emerging deep eutectic solvent leaching methods, according to the difference of hydrogen bond donor and acceptor and whether there is external field assistance, the deep eutectic solvent leaching method is divided into 5 categories, the latest progress of deep eutectic solvent leaching method is summarized, the reduction effect of DES leaching cathode materials is overviewed, and the chemical reaction kinetic principle and mechanism of DES leaching are explained by shrinking core model. At the same time, the problems facing the development of recycling waste batteries with low eutectic solvents are put forward and the prospect is made. This work provides a feasible guidance and reference for further research and large-scale application of eutectic solvent leaching of cathode materials.

The carbon capture based on electric swing adsorption (ESA) could achieve a swing cycle through on/off mode of power. Meanwhile, it employs Joule heating effect of electrical energy to generate heat and hence to drive the continuous adsorption and regeneration of the adsorbent. With the input of electrical energy in high-grade, an enrichment for a significant concentration difference between carbon source and sink could be achieved, leading to its recent widespread attention. However, the main challenges currently limiting the application of ESA for carbon capture are high energy consumption and low generation efficiency. This paper provided a literature review on research progress on ESA for carbon capture. Firstly, the fundamental principles of carbon capture technology using ESA were presented. Secondly, the research progress and development trends of adsorbents and cyclic construction of ESA for carbon capture over the past decade were reviewed. The performance evaluation of ESA for carbon capture was conducted through the second law of thermodynamics efficiency. Finally, the future development trends of carbon capture technology using ESA were discussed. The key to competitive scalability of such technology lied in improving the conductivity and capture performance of the adsorbent. The preparation technology of adsorbent should be improved. Attention should be given to the heating form of the adsorbent and the resistance distribution in the adsorption chamber. Additionally, coupling with other carbon capture technologies for hierarchical capture should be considered and integration with renewable energy sources should be explored.

Gas diffusion layer (GDL) plays an important role in supporting the catalytic layer and providing the transmission access of gas and water in proton exchange membrane fuel cell (PEMFC). Designing and optimizing the structure of GDL significantly influence the performance of fuel cell. In this paper, the application prospect of hydrogen fuel cell and the structure and working principle of PEMFC are briefly introduced. The problem of insufficient gas-liquid transmission capacity of GDL is pointed out and the effects of pore structure, carbon material, and microstructure of microporous layer, wettability and durability on the performance of GDL are analyzed. This review also summarizes the current research progress of GDL including the modeling studies. Finally, various factors affecting the performance of GDL are summarized, and the development of PEMFC is prospected. It is pointed out that novel metal foam materials could replace the traditional carbon materials to construct the GDL-BP integrated structure with shorter transmission path and smaller mass transfer resistance. It is also proposed to use the emerging 3D printing technology to construct GDL with high precision and complex structure. This review has certain guiding significance for future work in optimizing the gas diffusion layer structure and improving the fuel cell performance.

The development of advanced separation technology is of great significance for improving production efficiency, preparing high-end products, and reducing carbon emission. This paper summarizes the feed phase state, basic principles, application scenarios, advantages and existing problems of common separation technologies in the refining field, such as distillation, adsorption, membrane separation, extraction, and crystallization. Due to unclear understanding of the essential composition of crude oil, the separation process consumes energy and is inefficient. In response to the current situation, it is of great significance to propose a molecular level understanding of crude oil and secondary processing raw materials, leverage the role of advanced separation technologies, and develop new separation process technologies. Based on this, the development and application of molecular management concepts are described, focusing on the application of molecular management in the separation technology. The article also summarizes some of the latest separation technologies, including molecular distillation, molecular imprinting, membrane distillation, touch extraction, aqueous two-phase extraction, melt crystallization, etc. The development trend of separation technology based on the molecular management will be intelligent, green and integrated in the future.

Via experimental validation with a 1.3MW industrial burner, the commercial CFD software in calculating natural gas turbulent diffusion flame length was verified. A coaxial jet diffusion flame in a cylindrical combustion chamber (diameter of 300mm and length of 1200mm) with a diameter of 2mm gas nozzle was studied, using the natural gas containing 95%CH₄ and 5%N₂. The influences of gas flow, nozzle diameter, and combustion air characteristics on the flame length were studied by numerical simulation. The results indicated that in the natural gas turbulent diffusion flame when the gas flow rate was doubled with the gas nozzle diameter unchanged, the flame length increases from 652mm to 782mm, with an increase of 19.9%. When the gas flow rate was unchanged with the nozzle diameter doubled, the flame length increases from 652 mm to 1012 mm, an increase of 55.2%. Changing the gas nozzle diameter was an effective means to control the length of turbulent diffusion flame. Within a specific range of oxygen concentration, the turbulent flame length was more sensitive to the velocity than the oxygen concentration of combustion air. The analysis had important application value for evaluating the performance of natural gas combustion equipment and optimizing the combustion chamber design.

The slow kinetics of oxygen reduction reaction (ORR) and oxygen reduction reaction (OER) at air cathode restricts the further development of zinc-air battery. Precious metal catalysts have high catalytic activity, but the high cost and poor stability limit their further application. These challenges can be effectively overcome by developing highly active, low-cost non-precious metal bifunctional catalysts. After the introduction of the structure and properties of Zn-air batteries, this review systematically introduces the research progress of different types of non-precious metal catalysts in Zn-air batteries, such as MOF-derived bifunctional catalysts, non-metallic bifunctional catalysts and transition metal bifunctional catalysts. The advantages and disadvantages of different types of catalysts are introduced, and the catalytic activity centers and electrochemical properties of the catalysts are explained. Finally, the addition of metal active sites and the modulation of the morphological structure of specific catalysts are pointed out as research priorities in this field, and measures to be taken in the characterization, performance modulation and cell optimization of zinc-air batteries are suggested.

The study of carbon dioxide hydrogenation to methanol reaction holds significant importance in addressing energy shortages and environmental issues. Copper-based catalysts, such as Cu/ZnO/Al₂O₃, have attracted great attention due to their high reactivity and low cost. However, limited by the electronic structure diversity of the Cu species in the catalysts and insufficient characterization techniques, the true active sites and reaction mechanisms of the Cu-based catalysts are still unclear. This paper reviews the research progress on the active sites of copper-based catalysts for the hydrogenation of carbon dioxide to methanol, and the reaction mechanism in conjunction with the research progress of in-situ characterization techniques. By combining various advanced characterization techniques, researchers determined the structure and composition of the active sites, as well as reveals the effects of different catalyst structures on the reaction performance. Through the application of in-situ characterization techniques, the structural changes of catalysts during the reaction process can be observed in real-time, revealing the key steps of the reaction and the action mode of catalysts. In the future, more in-situ characterization techniques and computational simulation methods can be combined to explore the catalyst microstructure and reaction mechanism to prepare green methanol with better reaction performance.

The research progress of platinum-based SO₂ depolarized electrolysis (SDE) anode catalysts is reviewed in this paper. Because of the outstanding electrical conductivity, corrosion resistance, and effective resistance to H₂S and other sulfur-containing poisonings, platinum-based catalysts are considered as the best choice for SDE anode. By introducing non-precious metal such as Al, Cr and Ni, the performance of platinum-based catalysts can be effectively improved and the amount of Pt can be reduced. In terms of the support, the effects of activated carbon, graphite, carbon black, graphene and SiC/TiC on the properties were reviewed and discussed. In addition, the effects of catalyst preparation technology on the structural parameters and performance of catalysts were also discussed. Although many research results have been achieved, there are still insufficient studies on the long-term stability of platinum-based SDE anode catalysts and the interactions among metal elements in polymetallic catalysts. Further optimization of catalyst design and carrier screening/modification, development of new preparation processes, improvement of Pt utilization and catalyst activity and stability, are the keys of future research.

MIL-101(Fe) was coated on the surface of fused iron catalyst by hydrothermal synthesis method. Fused iron catalysts with different active phase compositions (θ-Fe₃C and χ-Fe₅C₂) were prepared by adjusting the carbonization temperature and atmosphere. The catalytic performance of Fischer-Tropsch synthesis was evaluated at 340℃, 1MPa and GHSV=12000h^-1, and the catalysts were characterized by XRD, SEM, CO-TPD, and N₂-physisorption. The results showed that the catalysts with θ-Fe₃C had higher C₅₊ selectivity. Active phases produced by the catalyst were different under different carbonization atmospheres. With the increase of carbonization temperature, the active phases produced by the two atmospheres could be converted to each other, but the difference in catalyst activity was significant. When θ-Fe₃C was partially converted to χ-Fe₅C₂ in CO, the synergistic effect of θ-Fe₃C and χ-Fe₅C₂ was more conducive to the dissociation and adsorption of CO, which improves the activity of the catalyst. When χ-Fe₅C₂ was partially converted to θ-Fe₃C in the syngas, the lattice distortion of χ-Fe₅C₂ occurs, which inhibits the dissociation adsorption of CO and leads to a significant decrease in the catalyst activity. The catalyst carbonized at 700℃ in CO had the best catalytic activity, which provided an CO conversion of 74.4%, and a C₅₊ selectivity of 65.6%.

ZrO₂ catalysts with different Ce contents were synthesized by sol-gel method and used for carrying out to achieve the photothermal catalytic direct synthesis of dimethyl carbonate (DMC) from CO₂ and methanol. Experimental results revealed that the DMC yield via photothermal catalysis was obviously higher than single thermal catalysis, and Ce_0.25Zr_0.75O₂ had the best effect with the DMC yield of 3.084mmol/g, which was 1.9 times that of pure ZrO₂. XRD and TEM analysis results showed that Ce atoms were doped into the crystal lattice of ZrO₂, which led to the formation of cerium-zirconium solid solution and the increasing concentration of surface oxygen vacancies, improving the CO₂ adsorption capacity. The solid solution had smaller nano size and larger specific surface area, and its formation of mesoporous structure was more conducive to CO₂ diffusion. The energy band structure and optical absorption spectra confirmed that the photoresponse of solid solution was widened and the light utilization efficiency was raised. Besides, with the assistance of oxygen vacancy in the narrow band gap prompts, the efficient separation of photo-generated carriers would provide more photo-generated electrons and held for activating methanol and CO₂, and combine with acid-base sites on the surface of solid solution, realizing the highly efficient synthesis and selectivity of DMC. Finally, the reaction mechanism of photothermal catalysis synthesis of DMC from CO₂ and methanol over Ce_0.25Zr_0.75O₂ solid solution was proposed, which should provide excellent theoretical basis and experimental data for the research and development on the photothermal catalytic synthesis of DMC.

The recycling of waste tires and their use as cement concrete aggregate can effectively reduce the environmental hazards and the exploitation of natural resources. To address the problem of weak interfacial properties between rubber aggregate and cement stone, more than ten kinds of interfacial modification methods were analyzed, and the influence of different physical and chemical modification methods on the interface performance, mechanical properties, and durability of rubber concrete was summarized. Through the fiber toughening path to further improve the performance of rubber concrete materials, the effect of steel fiber, basalt fiber, polypropylene fiber and polyvinyl alcohol fiber and other commonly used engineering fiber materials on rubber concrete mechanical properties and anti-cracking characteristics was analyzed. The research found that the interface modification can significantly improve the fragile interface of rubber-cement stone and enhance the interfacial bonding performance. The introduction of fibers can effectively improve the anti-cracking characteristics of rubber concrete materials, among which the mechanical strength of steel fiber composite rubber concrete material was significantly improved. The modified rubber aggregate and fiber composite technology can play a “toughening, anti-cracking” synergistic enhancement of cement concrete materials. The existing interface modification technology still had more disadvantages. The problems of environmental secondary pollution and low efficiency of modification needed to be solved by further optimization of the modification technology. The toughening and anti-cracking characteristics of fiber composite rubber concrete materials still should be explored in more depth, and the research on the synergistic mechanism of the two would clarify the performance advantages of fiber composite rubber concrete materials, which can provide an effective scientific basis for practical engineering applications and further expand the“high value”utilization of waste tire solid waste in cement concrete materials. This study would further expand the scale of the utilization of waste tire solids in cement concrete materials.

Tungsten disulfide (WS₂), as a typical two-dimensional transition metal sulfide with a wide layer spacing (6.2Å，1Å=0.1nm) and a multi-electron conversion reaction sodium storage mechanism, is a sodium ion battery anode material with high theoretical specific capacity and fast sodium ion reaction kinetics. However, in its actual sodium storage process, the electronic conductivity inherent in the 2H phase structure of WS₂ is poor, and the large phase structure transformation and volume change are brought about by the conversion reaction, as well as the dissolution and shuttle effect of the reduced intermediate product polysulfide (NaS _x, 0<x<2) and the low conductivity of the reduced product sodium sulfide (NaS₂) during the charging and discharging process, leading to the less than ideal actual electrochemical performance of WS₂. To address the above problems, this paper introduced the basic structural features of WS₂, briefly described the main synthetic methods and modifications that existed, and researchers has used hydrothermal/solvent thermal and high-temperature sulfidation methods for nanostructure design, compounding with carbon materials, and introducing a second phase to build a heterogeneous structure to enhance the electrochemical performance of WS₂. Finally, the main modification methods of WS₂ materials and the achieved results are summarized. In the future research direction of WS₂ sodium storage materials, the combination of various modification strategies such as nanostructure design, compounding with carbon materials, constructing heterojunctions, doping with heterophase atoms and increasing active sites to fabricate high magnification performance WS₂ materials that can achieve fast charging and discharging with stable structure is the focus of research.

The pore structure of adsorbent plays an important role in the process of CO₂ capture. In order to improve the adsorption performance of biochar, the pore structure of biochar was modified by impregnation method using lignin as precursor, and the adsorption properties of CO₂ were studied. The results showed that the specific surface area, micropore volume and alkalinity of biochar after lignin impregnation were increased by 3.7 times, 8.3 times and 1.6 times, respectively, and the CO₂ adsorption capacity was increased from 43.15mg/g to 47.36mg/g. The linear correlation analysis showed that specific surface area, micropore volume and alkalinity were the key factors to determine the adsorption capacity of CO₂. The Avrami model and Langmuir model could well fit the adsorption process of CO₂ by biochar, which indicates that the adsorption was mainly monolayer adsorption with the combined action of physical and chemical mechanisms. When the adsorption temperature increased from 0℃ to 25℃, the adsorption capacity decreases by 46.5%—52.7%, and the adsorption of CO₂ on biochar is an exothermic process. After 10 adsorption/desorption cycles, the biochar had a high reuse rate of 97.3%—99.3%, indicating that the impregnated biochar had good reusability and was a potential CO₂ adsorbent.

Thin-film nanocomposite polyamide mixed matrix reverse osmosis (MMRO) membranes were prepared from secondary interface polymerization between m-phenylenediamine (MPD) and the residual acyl chloride groups of trimethylene chloride (TMC) from the PA layers of TFC-PA membranes while imidazole ligand was counter diffused through the PA layer to react with the Zn(Ⅱ) cations pre-loaded on the polysulfone ultrafiltration substrates to form ZIF-8 nano-particles (NPs). None-selective defects between the in situ grown ZIF-8 NPs and the PA layers were eliminated by the MPD linkage between Zn(Ⅱ) and ZIF-8 PA polymers while additional selective water permeating channels were built inside the formed ZIF-8 NPs, resulting in improved water flux without trading off salt rejection rates. The effects of pre-loaded zinc ion, secondary polymerization, imidazole ligand and amine monomer concentration on the reverse osmosis performance of the formed PA²/ZIF-8 MMRO membranes were discussed. The water flux of PA²/ZIF-8 MMRO membranes reached 63.9L/(m²·h), almost doubled from the pristine PA membranes, keeping the same NaCl rejection above 98%, good long term operating and chemical stability, as well as anti-fouling capability.

In order to improve the peel strength of electrolytic copper foil after roughening treatment, the additive PEG and the composite additive of PEG and sodium tungstate were selected to electroplate the 12μm electrolytic copper foil. SEM, roughness detection, electrochemical analysis, XRD analysis, anti-peeling strength and conductivity test were used to analyze the effect of additives on the surface morphology and properties of copper foil and the mechanism of additives. With the addition of PEG to the basic plating solution, the surface morphology of the post-treated copper foil gradually changed from coarse dendrites to short granular grains, and the roughness of the post-treated copper foil showed an upward trend. When the concentration of PEG was 0.09g/L, compared with the plating liquid system without additives, the anti-peeling strength of the post-treatment copper foil was increased by 103%, and the roughness was increased. The addition of PEG played a dual role in promoting copper nucleation and inhibiting deposition. After the composite additive of PEG and sodium tungstate was added to the basic plating solution, the peel strength of the copper foil was about 21.35% higher than that of the single PEG system and the roughness was reduced by about 20.34% when the PEG concentration was 0.005g/L. Because the composite additive inhibited the deposition and nucleation of copper ions and promoted the deposition of (200) crystal plane, the grain deposition on the surface of copper foil was uniform, but the grain was coarse. The addition of PEG alone can greatly improve the peel strength of copper foil with improvement of the roughness. The composite additive of PEG and sodium tungstate further improved the peel strength and decreased the roughness decreases, and thus the deep plating ability was greatly improved.

The effects of adsorption and separation of O₂/He mixture by two metal-organic frame (MOFs) materials, HKUST-1 and UiO66, were studied by using the Monte Carlo method in molecular simulation. The adsorption isotherms of He and O₂ pure gas were calculated at different temperatures of 150K, 200K and 298K, and the corresponding adsorption heat and adsorption potential energy distribution were also calculated, and then the Idea Adsorbed Solution Theory (IAST) was used to calculate the adsorption selectivity of O₂/He mixture with different helium content in the two MOFs materials. The results showed that both materials exhibited a clear preferential adsorption characteristic of O₂. For three types of O₂/He mixed gases with He volume fraction of 20%, 50% and 80% , the selective adsorption coefficient of HKUST-1 for O₂ relative to He was generally higher than UiO66 at all three temperatures. Both materials indicated more significant selective adsorption at lower temperatures and their selective adsorption coefficients for O₂ relative to He decreased with increasing pressure. At the same time, this coefficient also increased with increasing helium content in the mixed gas. In response to these phenomena, the calculated adsorption heat and adsorption potential energy distribution curves were analyzed.

Traditional methods of increasing transportation needed high costs and complicated constructions, and old pipeline in service could not realize. Also, corrosion existed in pipeline. In order to fulfill no-pressurized increasing transportation at low cost and reducing corrosion for nature gas pipeline, bis-2-dibutylamino-4-N-morpholine-6-N-ethylenediamine-1,3,5-triazine (BDMET) was synthesized using cyanuric chloride and organic amine by nucleophilic substitution reaction. The structure of BDMET was characterized with ¹H nuclear magnetic resonance (¹H NMR) spectroscopy and elemental analysis (EA). As corrosion inhibitor and drag reducing agent, BDMET of methanol solution was infused into nature gas pipeline in field, and drag reducing rate and transmission increasing rate were assayed by field experiment. The results of ¹H NMR and EA tests indicated that the product was the target compound. After infusing into five nature gas pipelines by atomization, the drag reducing rate and transmission increasing rate of the product were 8%—13% and 6%—11%, respectively. Meanwhile, the corrosion inhibition of BDMET reached 85%—86% and the valid time was over 20 days. In addition, the field experiment lasted over 360 days. BDMET synthesized possessed excellent corrosion inhibition property and drag reduction property, and avoided continuous infusing for common corrosion inhibitors. Then, gas inspection proved that the quality of the nature gas was unaffected when BDMET was infused into the pipeline.

Gemini surfactant decyne diol (S104), namely 2,4,7,9-tetramethyl-5-decyne-4,7-diol, is a widely used alkyne diol surfactant. S104 is synthesized by ethynylation of methyl isobutyl ketone with acetylene in the presence of alkali catalyst. Currently, there are two types of synthesis processes: solid KOH catalytic ethynylation and liquid ammonia-KOH catalytic ethynylation, but both have serious environmental problems and other shortcomings. In this paper, the synthesis of S104 from acetylene and methyl isobutyl ketone by solid potassium isobutoxide catalyst suspended in solvent xylene was studied. The effects of various process conditions on the conversion of methyl isobutyl ketone and the yield of S104 were investigated by using single factor experiments. Based on this, a response surface experiment was applied for optimization. Under optimized reaction conditions (reaction temperature 35℃, reaction time 9h, molar ratio of potassium isobutoxide to methyl isobutyl ketone 1.5∶1, mass ratio of solvent xylene to methyl isobutyl ketone 4.5∶1), the yield of S104 was 86.52% ± 2.02%. The KOH solution obtained by hydrolysis after the reaction was returned to the potassium isobutoxide preparation step for recycling, and no significant changes in the conversion of methyl isobutyl ketone and the yield of S104 were observed. The process was carried out under atmospheric pressure and the waste alkali liquor was recycled, avoiding wastewater discharge. It was safe, environmentally friendly, and had high green value.

Solid phase adsorption is expected to significantly reduce the cost of CO₂ capture, and thereby promote the wide deployment of carbon capture, utilization and storage, which is of vital importance for high quality achievement of carbon neutrality. High performance adsorbent is the current research hotspot in this field, which has received extensive attention from both academia and industrial aspects. This paper focused on zeolite-based CO₂ adsorbents. Following the research and development trend of the materials, the recent progresses were reviewed from the aspects of pure silicon aluminum molecular sieve, ion exchange modification, amination function modification, hydrophobic modification and new adsorption mechanism of“Trapdoor”. The design strategy, synthesis method, mechanism of enhancing CO₂ adsorption and related contents were summarized, and their pros and cons were compared. Based on this, the influence of temperature, pressure and composition of flue gas was discussed in the context of potential scenarios of CO₂ capture. Moreover, by taking considerations on possible issues of large-scale application, suggestions for further work were proposed.

With the rapid development of economy and the continuous advancement of modernization and industrialization, environmental protection and sustainable development have become the necessary conditions for resource development and industrial production. In the process of resource development and industrial production, a large amount of heavy metal wastewater and organic wastewater will be produced. Electrodialysis technology has low energy consumption, low sensitivity to water quality, simple operation, and excellent concentration and separation performance, so it is widely used in the separation and extraction of metals and organics in industrial wastewater. This paper summarized the basic principle and research progress of metal and organic recovery in industrial wastewater, introduced the recovery cases of various metals in different systems and organic recovery cases, analyzed the influence and mechanism of different process parameters such as pH, operating voltage and current, solution flow and ion concentration on the electrodialysis effect, and looked forward to the development direction of electrodialysis technology for separation and extraction of metal and organic matter. It provides a theoretical basis for electrodialysis technology to treat heavy metal wastewater and organic wastewater, and realize the separation and extraction of heavy metal and organic matter.

Advanced oxidation has developed rapidly as an effective technology for the treatment of refractory pollutants and sewage upgrading. Heterogeneous catalytic ozone oxidation has attracted wide attention due to its advantages of high oxidation efficiency and convenient use. The current research mainly focuses on the preparation of highly efficient catalyst and its degradation efficiency, while the exploration and summary of the mechanism of heterogeneous catalytic ozone oxidation are not perfect. In this paper, the important adsorption mechanism and the catalytic oxidation mechanism in the catalytic ozone oxidation system were summarized according to the type difference of heterogeneous catalysts. The effects of surface hydroxyl group, Lewis active site and redox coupling of metal oxide materials, electronic source differences and surface functional groups of non-metallic materials, and composite characteristics of composite materials on the adsorption of ozone and reactive oxygen species production were discussed. At the same time, the generation, transformation and identification among reactive oxygen species and the detailed interconversion process of hydroxyl radicals and superoxide radicals in the heterogeneous catalytic oxidation process were also summarized to provide a reference for the subsequent development of heterogeneous catalytic ozone oxidation technology.

In recent years, the frequent outbreaks of large-scale viral infectious diseases have attracted worldwide attention of airborne pathogenic microorganisms, especially the production and emission of different anthropogenic virus aerosols. By reviewing the emission concentrations, main populations, and point sources of virus aerosols in urban wastewater treatment plants (UWTPs), the correlation between the emission of virus aerosols and bioaerosols are analyzed, the factors of virus aerosols are discussed, the key problems existing in the current research are issued, and the future research trends and directions are also prospected. It is found that the main components of virus aerosols are Norovirus (NoV) and Adenovirus (AdV), and significant differences exist in their concentrations over process units and seasons. Wastewater and sludge, the treatment scale, operation status, and environmental conditions of the UWTPs are the main factors influencing the emission of virus aerosols. Meanwhile, the review of existing studies also reveales that in-depth research lack on the generation mechanisms, dispersion patterns, and potential risk assessment of virus aerosols in UWTPs, as well as the effective control measures for the practical application, which shall receive increased attention in the future.

The reduction of sulfur hexafluoride (SF₆) emissions is a key link in the power industry's efforts to serve the “carbon peak and carbon neutrality”. This article summarizes the current status and main sources of greenhouse gas SF₆ emissions in the power industry, and from the perspectives of open source, cost reduction, upgrades, and degradation, summarizes four SF₆ emission reduction measures: source replacement, recycling purification, equipment upgrading, and harmless treatment. It also reviewes the problems and countermeasures of various technologies. Through a selective analysis of SF₆ emission reduction technologies, this article proposes a two-step strategy for reducing SF₆ emissions, providing reference for building a green, low-carbon new power system and achieving the “net zero” goal. It suggestes strengthening policy constraints on non-CO₂ greenhouse gases such as SF₆, further formulating SF₆ emission reduction targets for the power industry, accelerating the application process of SF₆ emission reduction technologies, establishing a sound SF₆ life cycle management approach, and promoting China's SF₆ gas control to a new level.

Covalent organic frameworks (COFs) are an emerging class of porous crystalline polymeric materials with excellent structural regularity, highly ordered pore size, inherent porosity, huge specific surface area, and abundant active functional groups, which make them ideal materials for adsorption of various pollutants in waste water. From the perspective of topological and pore structure design of COFs, this paper sorted out the key points of COFs structural design. Then, the COFs functional strategy such as side group functionalization, functional group conversion and skeleton functionalization was analyzed, focusing on the impact of active functional groups such as N, S, O, Fe(0), Ag(0), and metal/non-metal nodes on the porosity, water stability and adsorption properties of COFs. Then, the research progress of COFs in the removal of heavy metal ions was introduced, the adsorption performance of COFs on typical heavy metal ions Hg(Ⅱ) and Cr(Ⅵ) in water was analyzed and the mechanism of COFs to remove heavy metal ions in water was explained in combination with density functional theory. Finally, the functionalization strategy of COFs and the technical advantages of functionalized COFs as high-performance adsorbents were summarized, the existing problems were analyzed, and the future development direction was expected to provide reference for the preparation and application of COFs.

Aluminum coagulant is widely used in the field of coagulation because of its large and dense flocs, good turbidity and decolorization performance. However, there is a problem of residual aluminum in water treatment. In order to better promote the application of aluminum salt coagulant in the field of water treatment, the toxic effects of aluminum salt hydrolysate on human body, and the influence on water distribution network system and advanced drinking water treatment process were introduced in detail. The formation mechanism and the morphology analysis methods of residual aluminum were summarized. The hydrolysis process of the dominant species belonged to Al₁₃ and Al₃₀, and the reasons for taking the role advantage in the coagulation were expounded. The effects of raw water quality conditions, chemical conditions, hydraulic conditions and pre-treatment on residual aluminum concentration were analyzed. Finally, the strategies and technologies for controlling residual aluminum in the future were pointed out. It was pointed out that nano-scale new coagulants should be synthesized in combination with artificial intelligence in the future. The influence of hydraulic conditions on residual aluminum during the coagulation process should be paid more attention. It should develop and make an accurate measurement and analysis methods which aimed at various forms of aluminum in water, innovate continuously and strengthen the water purification process, further improve the control measures of residual aluminum, and ensure the safety of effluent water quality.

Three kinds of waste catalyst powder M1-M3 were used as raw materials to prepare the catalysts. These catalysts had different waste catalyst powder mixing ratios. The denitration performance of these catalysts was tested and evaluated at the initial and after 16000 hours. At the same mass addition ratio, the initial performance of the new catalyst prepared by adding waste catalyst powder M1 and M2 was about 30% lower than that of the catalyst M0-0 without adding waste catalyst powder, and the activity degradation rate was obviously faster. It also indicated that the higher the proportion of waste catalyst powder, the greater the negative impact. It was recommended that the proportion of high-quality powder should be controlled. The physical and chemical analysis of the waste catalyst powder and the prepared catalyst were carried out by means of laser particle size analyzer, surface acid adsorption analyzer (NH₃-TPD) and X-ray fluorescence spectrometer (XRF). The microscopic characteristics of the waste catalyst powder could not be fully restored. The effective active components were low and the impurity content was high. These resulted in poor specific microscopic characteristics and low surface acidity of the catalysts, which were the main reason for the poor denitrification performance of the catalysts. In order to achieve the quality of waste catalyst powder close to the original titanium tungsten powder and effectively used for the preparation of new catalysts, it was necessary to further improve the particle size, micro-pores, impurity content and surface acidity of the waste catalyst powder.

In order to clearly describe the whole process of Hg⁰ adsorption by HBr-modified fly ash (HBr-FA), an adsorption kinetic model was established including diffusion and surface adsorption and oxidation based on the dynamic adsorption experiment on a fixed-bed column. The key influence factor of the adsorption and oxidation process of Hg⁰ was discussed, and the dynamic behavior of Hg⁰ in the diffusion region and surface active site was investigated. The model takes into account the processes of axial backmixing, internal and external diffusion, and intrinsic kinetics, which hence can fit well with the experimental breakthrough results with the corresponding kinetic parameters. The sensitivity analyses indicate that axial dispersion, gas film diffusion, and inner efficiency diffusion have dominant impacts on Hg⁰ adsorption, and the model is more sensitive to the gas film diffusivity. Furthermore, the increasing of initial Hg⁰ concentration is beneficial to decreasing the diffusion resistance and promoting the Hg⁰ adsorption-oxidation due to the improvement of mass transfer driving force. The external diffusion resistance can be reduced with the increase of inlet flow rate and bed thickness. In addition, the Hg⁰ concentration profiles inside the particle can be obtained from the model, which shows the external diffusion resistance has greater influence at the initial stage of Hg⁰ adsorption and oxidation by HBr-FA.

The valence state of chromium in the production process of traditional chromium salt industry needs to go through the transformation of trivalent to hexavalent and then to trivalent. The high toxicity of hexavalent chromium has led to chromium becoming a key heavy metal for national prevention and control. The sustainable development of chromium salt industry urgently requires the development of new technologies to avoid hexavalent chromium generation, and acid leaching of chromium-containing raw materials is a feasible way. In this paper, we proposed a new process for the preparation of trivalent chromium salts by acid leaching using high-carbon ferrochrome alloy as raw material and hydrochloric acid as leaching agent. The leached chromium chloride and ferrous chloride could be prepared as trivalent chromium salt products, which can be used as electrolyte for ferrochrome liquid flow battery. In this paper, the effect of reaction temperature, hydrochloric acid concentration, stirring rate and reaction time on the leaching rate of chromium and iron was systematically studied based on the analysis of elemental content, physical phase composition and morphology of high-carbon ferrochrome. The results showed that the chromium leaching rate was 92% and the iron leaching rate was 95% at a reaction temperature of 100℃, a hydrochloric acid concentration of 9mol/L, a stirring rate of 250r/min and a reaction time of 6h. The kinetics of the leaching of high-carbon ferrochrome in hydrochloric acid was further investigated. The leaching process of high-carbon ferric chromium was consistent with the unreacted contraction nucleation model, and the chromium leaching process was controlled by the chemical reaction with apparent activation energy E_a=65.95kJ/mol. The iron leaching process was controlled by the chemical reaction with apparent activation energy E_a=63.85kJ/mol.

As an essential part of refinery, sweetening process has gradually changed from impurity driven to resource driven with the enrichment of H₂S processing technology. Through improving the purity of H₂S in acid gas, the added value of products can be increased, which becomes an important direction to increase profit. Based on this, a sweetening process with amine solution absorption and multiple desorption was proposed to obtain part of high purity acid gas. The rate based distillation method was used to simulate the process, and the process was studied by system engineering methodology. A design strategy of hierarchical design and desorber pressure and feed temperature as main and secondary adjustment means was proposed. An economic evaluation framework based on equipment purchase curve was established for comparative analysis of process. The results showed that compared with the traditional process, the annual fixed investment cost and annual operating cost increased by 30.86% and 40.82%, respectively. The profit increased by 65.45% due to the increase of the added value of the product. In addition, with the increase of the number of desorbers, energy consumption will increase more and more, and the economic benefits will decrease.

The studies on the effects of surfactants on electrodialysis systems are limited. The effect of surfactant type on the reduction of industrial saline wastewater by electrodialysis was examined. Anionic and cationic surfactants, typified by sodium dodecylbenzene sulfonate (SDBS) and dodecyl dimethyl benzyl ammonium chloride (DDBAC), caused an inhibitory effect on the electrodialysis system by forming a contamination layer on the membrane surface. Membrane resistance increased from 4.72Ω•cm² to 30.46Ω•cm² and 15.23Ω•cm². In addition, compared to the pure sodium chloride system, desalination rate decreased 4.54% and 4.75%, and flux of NaCl decreased to 0.19mol/(m²·h) and 0.2mol/(m²·h), respectively. Moreover, transfer rate of SDBS and DDBAC were as high as 58.55% and 90.45%. Octyl phenol (OP-10) and thiobetaine (SB-12), typical non-ionic and amphoteric surfactants, had no significant effect on the electrodialysis system, and the membrane resistance, desalination rate and ion flux remained at the same level compared to the pure NaCl system. The experimental results revealed the influence mechanism of surfactant on electrodialysis performance, and laid the foundation on the wide application of electrodialysis in the field of reduction of industrial saline wastewater.

Panzhihua Iron and Steel Co. releases 3 million tons of blast furnace slag containing 20% to 25% TiO₂ annually, resulting in a large amount of blast furnace slag occupying land, causing dust pollution and posing a threat. To solve the utilization problem of titanium containing blast furnace slag, this article adopted the “selective precipitation technology”, which involved adding insulation measures after the blast furnace slag was discharged to slowly cool the slag. The titanium component was enriched in the perovskite phase, and the grains grow. Further beneficiation and separation can obtain a concentrate of 35% to 50% TiO₂. In the paper, experimental study was conducted on sulfuric acid acidolysis of the perovskite concentrate. The research showed that the optimal conditions for acid acidolysis of the concentrate were: the mass ratio of ore to acid was 1 to 1.21, the reaction temperature was 180℃, the concentration of H₂SO₄ was 90%, the concentrate size was less than 76μm, and the reaction time was 4h. An acidolysis rate of 94.62% can be achieved under the optimal conditions. The acidolysis kinetics experiment indicated that in the initial stage (x=0—0.3), chemical reaction kinetics were the principal characteristic. In the intermediate stage (x=0.5—0.7), a mixture of chemical reactions and internal diffusion controlled the rate. In the later stage (x>0.7), the internal diffusion dominanted the rate.

We loaded a variety of non-noble metal(Ce、Cu、Mn、Fe) on vanadium and titanium based catalysts, and studied the performance of the modified catalysts for the selective catalytic reduction (SCR) denitrification and the catalytic oxidation of volatile organic compounds (VOCs). The Ce modified catalyst showed good SCR denitrification activity and VOCs catalytic oxidation performance in the low temperature section, indicating its good cooperative catalytic potential. As for the Ce doping modified catalyst, the NO conversion rate and VOCs conversion rate over 3V-5Ce/Ti catalyst could reach 100% within the temperature range of 275—300℃. We compared the selectivity of N₂ and CO₂ between SCR-VOC and SCR alone, and found that the introduction of toluene significantly reduced N₂ selectivity, which however was restored to the level without toluene after temperature rise. It was also found that a significant decrease in the selectivity of CO₂ during the synergistic reaction. The SEM, XRD, XPS, NH₃-TPD characterization of 3V-5Ce/Ti catalyst showed that the introduction of Ce provided more surface oxygen vacancies and more weak acid sites as reaction sites on the catalyst without changing the carrier morphology, and thus improved the redox performance of the catalyst. The resistance to water and stability tests showed that 3V-5Ce/Ti catalyst has good sulfur resistance, water resistance and stability.

Volatile organic compounds (VOCs) emission inventory is the basis for promoting VOCs deep governance and formulating effective air pollution control countermeasures. Chemical industry park, as a key emission unit, is an important target for VOCs emission reduction in our country, but currently a mature and standardized compilation method has not been formed based on the micro-scale VOCs emission inventory of chemical parks. Combined with the current research, work experience and ArcGIS technology, this paper discussed the construction method of VOCs emission inventory and emission factor database from the perspective of chemical industry park, optimized the four dimensions of precision, localization, dynamic and visualization, and proposed the technical path of “pollution source identification-pollutant data acquisition-emission inventory compilation-emission factor database construction”, and obtained the emission inventory and factor database with time, space and chemical species distribution. Taking a salt and chemical industry park in Hebei Province as a case, the workflow of VOCs emission inventory compilation in the park was established. The research can provide technical support for effectively promoting regional VOCs comprehensive treatment and fine treatment of air pollutants.