Liquid hydrogen has high energy density, and it has cost advantage in long-distance transportation. Under the guidance of carbon reduction policies, the global liquid hydrogen market will be further expanded. However, the liquid hydrogen market is restricted by the high energy consumption of hydrogen liquefier. This study focused on the industrialization status of hydrogen liquefier. First, domestic and foreign liquid hydrogen production capacity and liquefier providers are investigated. Then, the construction status, thermodynamic process and key performance parameters of two typical hydrogen liquefiers are reviewed. Further, the pre-cooling methods, liquid hydrogen production capacity and energy consumption of hydrogen liquefaction processes published in recent years are summarized, and the hydrogen liquefaction processes of WE-NET project and IDEALHY project are introduced in detail. In addition, the technical difficulties of hydrogen liquefier are described. The analysis showes that improving the efficiency and reliability of core equipment and developing the dynamic control strategy of liquefaction process are the keys to promote the industrialization of hydrogen liquefier. Large-scale hydrogen liquefier to achieve scale effect and small-scale hydrogen liquefier to improve the start-stop speed are two important development directions.

The research progress of high-pressure hydrogen leakage and jet flow was described. The aspects of real state of equation of hydrogen, the structure and model of high pressure under-expanded jet, the hydrogen concentration distribution of jet flow region, and the numerical simulation based on the computational fluid dynamics are concluded, summarized, and reviewed. The research direction in the future is raised. The existing research shows that there are several real gas state equations for high pressure hydrogen. The state equations of Peng-Robinson, Abel-Noble etc. are convenient and accurate. Highly under-expanded jet flow is formed during high pressure hydrogen releases, and Molkov model can be used to predict the characteristics of under-expanded jet flow. The jet flow region is controlled by momentum or the combination of momentum and buoyancy. The concentration of hydrogen in jet flow region is quantitatively related by the dimensionless parameter formed by release diameter, distance from release orifice, and medium densities. The common computational fluid dynamic software such as ANSYS-Fluent, FLACS etc. used in high pressure hydrogen release have been verified to have good precision. The future directions include large scale experiments, irregular release orifices, engineering applications of research results, and high efficient numerical methods.

The vapor compression refrigeration/heat pump systems realize heat transfer by using vapor-liquid phase change. The application of vapor-liquid separation technology has always been a research focus, in order to control the degree of dryness and mass flow distribution of the two-phase refrigerant to ensure the stability and improve the performance of the systems. In this paper, the research status of vapor-liquid separation technology in vapor compression refrigeration/heat pump systems is reviewed. The application modes of vapor-liquid separation technology are summarized, the main functions and working mechanisms of different application modes are discussed. Finally, the key research directions are prospected. It is found that the main functions of vapor-liquid separation technology included ensuring the reliability of systems, improving the performance of heat exchangers, separating components of zeotropic mixture refrigerant, and improving the circulation process. However, the existing research is not paid enough attention to the performance improvement of vapor-liquid separators. CFD simulation technology is an effective method to study the internal separation mechanism and optimize the structure of vapor-liquid separators. The development of application modes of vapor-liquid separation technology, the optimization research of phase separation heat exchangers and the design optimization of vapor-liquid separators will become the key research directions in the future.

The thermal control technology based on phase change has the advantages of reliable equipment performance, light weight, and low energy consumption, which receives widespread attention in industry and academia. Using the characteristics of solid-liquid phase change constant temperature endothermic and gas-liquid phase change ultra-high thermal conductivity, a multiphase coupled high-efficiency heat storage and heat transfer process can be realized. This paper proposes the concept of multiphase coupling for the solid-liquid/gas-liquid multiphase coupling thermal control technology. Taking the typical phase change material and heat pipe coupling system as the starting point, the working principle of phase change and multiphase coupling method are firstly introduced, and the typical coupling methods are summarized: the phase change material is placed in the evaporation section, condensation section, and adiabatic section of the heat pipe, or the heat pipe is embedded in the phase change material as a thermal conduction skeleton. Then, the research progress of multiphase coupling thermal control technology used in the field of electronic device cooling and battery thermal management are reviewed. In addition, the application in other fields (such as thermal/cold storage) are also summarized. Finally, the current problems and future development are proposed from the perspective of material modification, device coupling and system coordination.

The variation of hydrate growth behaviors can affect the growth rate and formation amount of hydrates in water-oil emulsions, posing challenges to the safe operation of multiphase pipelines and the development of flow assurance strategies. In this work, the experimental methods for hydrate formation and the quantitative indexes of hydrate growth rate are systematically reviewed. The influence of key factors (e.g., composition of oil phase and water cut) on hydrate growth behavior is summarized. In addition, the research progress on the growth mechanisms and the quantitative models of hydrate formation are deeply analyzed. Overall, the experimental methodology and quantitative indexes of hydrate growth have been well-developed, and a deeper understanding of the influencing factors and growth mechanism has been gained. In future studies, the hydrate growth behaviors under multi-component complex systems should be further explored. The understanding of hydrate shell structure and growth mechanism in water-in-oil emulsions should be deepened from the microscopic perspective. Based on all these studies, the hydrate growth rate model for actual multiphase pipelines could be established.

The oscillating heat pipe (OHP) with 11 bends was employed to the heat dissipation system of the lithium-ion battery. Different proportions of hybrid fluids (H₂O and HFE-7100) were introduced into the oscillating heat pipe, and the heat transfer experiment was carried out at different heating loads to simulate a lithium-ion battery. The experimental results showed that micro-emulsion can effectively avoid the occurrences of partial drying at high heating loads and prevent thermal control due to the high temperature of the battery surface. Best heat transfer performance was obtained at oil in water (O/W) type micro-emulsion (0.048%SDBS∶HFE-7100=1∶1) and could ensure the normal operation of lithium-ion monomer battery (20—30W), and the temperature did not exceed 40℃ and the surface temperature difference was less than 1.8℃. With the high heating loads of the monomer battery (40—50W), the local temperature of the battery was below 56℃ and the average temperature of the battery surface was below 55℃.

Pulsating heat pipe (PHP), as an effective heat transfer unit, has been widely applied in thermal management, due to its merit of flexible structure. The performance of PHP is critical for efficiency and safety in operation. Operation conditions are influential on the improvement of heat transfer performance of PHP. The operating characteristics of PHP with low heat flux were experimentally studied with deionized water as working medium. The filling ratio was designated as 30%—40%, balancing the availability of start-up at low heat flux and the endurance of operation at high heat flux. The results showed that the thermal resistance had a reverse law in the processes of rising and falling heat flux, because of the differences of the status of working media and the mode of heat transfer before and after start-up. At the same heat input, the thermal resistance of falling section was significantly lower than that of rising section. Close to the start-up region, the reverse trend of resistance became more significant. The thermal resistance of the PHP with 40% decreased by 0.777K/W and 0.546K/W in the falling heat flux section (11.7W) compared with the rising heat flux section under natural cooling or forced cooling. The thermal resistance of PHP with 30% decreased by 0.259K/W in the descending section (7W) under natural cooling, and 0.093K/W in the descending section (10W) under forced cooling. The results offered a preliminarily verified proposal to performance improvement for OHP operating under low heat flux and in weak cooling mode.

In order to study the vertical pipe seepage falling film evaporative condenser, the heat transfer characteristics of the single condenser tube under different external temperature, air Reynolds number and liquid Reynolds number were explored by using the combination of simulation and experiment method. Combined with the problems in previous research, the physical model and boundary conditions were selected reasonably, the axial distribution of temperature and heat flux density of the falling film process were obtained, and the radial position was analyzed in time series. The results showed that the heat transfer effect of reverse ventilation was better than that of co-directional ventilation, but it was easy to aggravate the instability of the liquid film in the lower part of the pipe section and even cause dry wall. It was found that the dry wall area would be covered by the liquid film immediately through time series analysis. Therefore, the effect of short-term dry wall on the overall heat transfer would not very obvious. It was still necessary to pay attention to the great influence of the high reverse ventilation intensity on the stability of the lower liquid film. It was recommended that the single-pipe air Reynolds number should not exceed 3500 under the working conditions of this paper. In addition, the test results showed that the heat transfer of a single tube in this paper was about 2200W, which was 6.7% different from the simulation results, and the comprehensive heat transfer coefficient of the single tube was about 1400W/(m²·K).

The heat exchanger network is the key energy-saving equipment for chemical process systems. During the operation of the heat exchanger network, the production requirements and operating conditions often change, especially the phenomenon of fouling resistance in heat exchangers, which make the operation parameters of the heat exchanger network deviate from the set value and difficult to satisfy the operation requirements. The certain area margin is usually set in the design stage, and the bypass control is an important method to adjust the margin online. During the full cycle of heat exchange network operation, continuous energy conservation was taken as the optimization objective and an optimal control method of slow-release margin was presented. Firstly, according to the whole operation cycle of heat exchange network, combined with sliding window algorithm, the relationship between the fouling resistance and the optimal control was analyzed, and a control strategy of continuous energy saving in the whole cycle of heat exchange network was obtained. Then, the online optimal control of the heat exchanger network was realized with improving the control performance in each sliding window. Considering the sustainable energy saving of the whole operation cycle of heat exchange network, the slow-release margin optimization method was proposed, the optimal solution of the available margin in each sliding window was obtained. Finally, a slow-release margin optimization control method for the heat exchanger network was proposed with the optimization of the continuous controllability target in the whole cycle. Results showed that the proposed method not only can realize the continuous controllability in the whole cycle but also considers the dynamic control performance of each sliding window.

The dynamic pressure mechanical seal stator needs the ability of axial sliding and angular swing. The O-ring in the sliding interface plays the role of sealing and compensation. The quality of its design is very important to the stable operation of the seal. Therefore, the finite element model of the fretting compensation structure was established, and the pre-compression amount of the two typical compensation structures of the O-ring integral groove and the split groove in the smooth micro compensation condition and the vibration disturbance micro compensation condition were analyzed respectively. The effects of medium pressure and wire diameter on the sealing performance and compensation characteristics of O-rings were tested and verified. The analysis results showed that the most important factors affecting the compensation performance of the static ring were the compression amount of the O-ring and the interface friction coefficient. The split groove compensation structure had better followability in the compensation process, more suitable for high-speed, and stronger vibration conditions. The friction force and the degree of fluctuation was smaller. The analysis results were verified by experiments, and the optimal compensation structure parameters of the O-ring were obtained. During the start-up stage of the dynamic pressure mechanical seal, the friction of the O-ring was the largest. Reducing the compression amount and improving the lubrication state of the compensation interface can effectively reduce the fluctuation of the friction force. To improve the compensation performance, good lubrication can effectively reduce the frictional force fluctuation by more than 20%. The research results provide a reference for the design of the micro compensation structure of the high-speed dynamic pressure mechanical seal.

A new heat pump technology for fuel driven non-electric heat pump system (NEHP) was proposed. NEHP uses one system to meet the demand for cooling in summer, heating in winter, providing domestic hot water throughout the whole year, and supplying a certain amount of domestic electricity as necessary. It is a distributed energy system that can combine cooling, heating and power (CCHP). In this paper, a novel technology of NEHP was described in detail based on the principle and design idea. The energy saving performance of the NEHP technology application was simulated and calculated, and the operation economic analysis was comprehensively analyzed. NEHP technology was suitable for use in areas lacking or without electricity, which had the incomparable applicability advantages compared with electric heat pumps (EHP). It can be used in areas where both gas and electricity were abundant as well, and had a wide range of application scenarios. For the NEHP-G system by using natural gas, it will have lower operating costs than that of EHP in the modes of heating or cooling if the ratio of natural gas price to electricity price (r_ge) was less than a fixed value. The fixed values of r_ge were 4.17 at rated heating mode, 5.62 at rated cooling mode with waste heat recovery, and 3.06 at rated cooling mode without waste heat recovery, respectively. Taking the prices of commercial gas and electricity in Chongqing in 2021 as an example, compared with EHP, the operating cost of NEHP-G can save 42.17%—47.49% in the heating season, 48.22% in the cooling season with waste heat recovery, and 32.26% in the cooling season without waste heat recovery, respectively. The cost saving of NEHP-G was significant, and it had huge market application potential.

In order to explore the influence of mass flow rates on boiling starting point in microchannels with different walls, three kinds of microchannels with different corrugated walls were made by computer numerical control technology. R141b was used as the experimental working medium, and the power of the heating plate was adjusted at the inlet temperature of 33℃ and the pressure of 60kPa. The boiling curves of three different corrugated walls were measured under the conditions of mass flow rates of 203.75kg/(m²·s), 255.68kg/(m²·s), 307.61kg/(m²·s), 358.59 kg/(m²·s) and 409.57kg/(m²·s), respectively. By analyzing the boiling curves of each wall microchannel under different mass flow rates, the change rules of superheat and heat flux at ONB point were summarized. Furthermore, the boiling curves of different wall microchannels under the same mass flow rate were compared, and the reason for the decrease of superheat at the boiling starting point of corrugated wall was analyzed. Finally, compared with the existing typical ONB prediction model, the parameters related to mass flow rate are introduced based on the correlation of Hsu model for correction. The results showed that with the increase of mass flow rate, the measured wall superheat of ONB point decreased for the same kind of wall microchannel. At the same mass flow rate, the superheat of ONB point of ordinary microchannel was the highest, followed by sinusoidal microchannel, and the superheat of ONB point of triangular microchannel was the lowest. Compared with six typical ONB forecasting models, it was found that the overall forecasting effect of Hsu model was good, especially the average absolute error of triangular microchannel was 7.56%. Based on the correlation of Hsu model, the average absolute error of ordinary, sinusoidal and triangular microchannels was 0.77%, 1.91% and 2.08%, respectively, which improved the forecasting accuracy of ONB superheat of corrugated microchannels.

In this paper, based on the fixed-bed tubular pyrolysis furnace, the properties of waste tire pyrolysis products were studied and analyzed in detail. A series of modification and upgrading methods were proposed according to the characteristics of the pyrolysis products. Based on the methods, a set of step spiral pilot-scale pyrolysis reactor suitable for efficient energy resource utilization of waste tires was independently designed and developed to obtain pyrolysis products with high-quality. The light transmittance of the toluene extract and the flash point were the bottleneck issues that limited the efficient and safe application of pyrolysis carbon black and pyrolysis oil, respectively. The pilot-scale pyrolysis system developed in this research adopted the step pyrolysis technology and multi-stage condensation technology, which could effectively improve the quality of pyrolysis products. The light transmittance of the toluene extract of the obtained pyrolysis carbon black reached 100% and the flash point of the obtained pyrolysis oil reached 76.5℃, both of which met the corresponding standards. At the same time, the pilot-plant adopted the scheme of circulating pyrolysis gases for energy supply, which could realize the thermal self-sustaining of the system and significantly reduce the energy consumption of the pyrolysis process. In this research, the bottleneck problem of high-value utilization of waste tire pyrolysis products had been solved based on the self-developed pilot-scale step pyrolysis system. This study laid a foundation for the large-scale promotion and application of waste tire pyrolysis technology.

With the development of the seeker towards miniaturization, lightweight, intelligence and multi-mode composite, the electronic devices of the seeker are facing the demand of short-term high-power heat dissipation. The heat storage device of phase change heat sink has the advantages of high energy storage density, light weight and passive no energy consumption, but its phase change material has low heat transfer efficiency and complex melting process, which increases the difficulty of heat dissipation design. The heat dissipation calculation model and phase change heat transfer mathematical model of missile borne heating components were established. The numerical simulation and heat transfer characteristics of phase change heat transfer were studied based on Fluent software. The optimization design of phase change heat transfer was carried out by using vapor chamber and adding reinforced heat conducting rib. The results showed that the maximum temperature and high-low temperature difference of the calculation model can be effectively reduced and the working time of the electronic devices can be prolonged by using vapor chamber and adding reinforced heat conducting rib. When the heat transfer plate adopted vapor chamber instead of aluminum alloy, the high-low temperature difference of the calculation model can be reduced from 98.8K to 50.3K. Three reinforced heat conducting ribs were added inside the heat sink, which can further reduce the temperature difference to 17.9K. The continued increase of reinforced heat conducting ribs would have less obvious impact on the heat transfer effect.

Power-to-Methane (PtM) technology refers to process of converting renewable power into a synthetic natural gas by combining water electrolysis to green hydrogen with CO₂ methanation. PtM process is a crucial energy system technology that integrates renewable natural gas, grid balancing, long-term energy storage and decarbonization. In this paper, the progress of typical PtM demonstration projects worldwide is reviewed, and CO₂ methanation technologies are comprehensively analyzed, including the projects and progress, technology route, operation conditions and reaction characteristics. Finally, the characteristics of chemical and biological methanation routes are compared, including reactor volume, contaminants resistance, dynamic response, etc., which would provide valuable references for the development and demonstration of PtM technology in China.

Molten metal methane pyrolysis is an emerging hydrogen production technology in recent years. Compared with conventional methane pyrolysis and catalytic pyrolysis, it effectively overcomes the problems of high energy consumption, low conversion and catalyst deactivation, and also avoids the high carbon emission as in steam methane reforming technology. The ability to produce value-added solid carbon products along with hydrogen has attracted extensive attention. This article summarizes the latest research and development of methane pyrolysis based on molten metal technology, focusing on the process flow, reaction mechanism, selection of molten medium and rector design etc. We also propose two types of potential reaction mechanisms for elucidating whether the liquid medium plays a catalytic role in methane pyrolysis. Moreover, the selection principle, trends in the development, benefits and drawbacks of different types of molten media are comprehensively elaborated. And the technical economy and greenhouse gas emission reduction also have been discussed, which further demonstrates the feasibility and potential benefits of the process. Finally, suggestions for future technological improvements are presented, and we points out morphology regulation of carbon materials to facilitate transformation into high-value-added products should inevitably become one of the key development directions in the future.

Under our country’s strategic goal of carbon peaking and carbon neutrality, wind power and fossil energy hydrogen production technologies are constantly developing. Use offshore wind power resources or natural gas to produce hydrogen and send it to the hydrogen energy market through storage and transportation technology, which provides a feasible idea for solving the problems of offshore wind power grid integration and consumption and promotes the low-carbon development of deep-sea natural gas resources. Therefore, it is of great significance to study the offshore adaptability of the spiral wound heat exchanger applied in the floating hydrogen liquefaction process system. Based on the multi-degree-of-freedom sloshing platform, an experimental device for pressure drop testing in floating porous media channels was built. Based on the porous media model, the theoretical model of normal-parahydrogen conversion and hydrogen flow heat transfer, a numerical model of flow heat transfer coupled with normal-parahydrogen conversion in porous media channels was established. The performance changes of porous media heat exchange channels under sea and horizontal conditions were analyzed by a combination of experiments and numerical simulations. The research results showed that the pressure drop in the porous medium channel of the spiral wound heat exchanger filled with catalyst was obvious, the temperature drop was not obvious, and the parahydrogen content in the tube increased. With the increase of hydrogen flow, the heat transfer coefficient increased gradually, while the content of parahydrogen in the outlet decreased gradually. Sea conditions had little effect on the pressure drop and heat transfer characteristics of offshore porous media heat exchange channels.

In recent years, more and more attentions are paid to hydrogen utilization. China will have a greater demand for hydrogen energy due to “carbon neutrality”, while Norway has rich natural gas resources and renewable energy, which can supply a large amount of blue hydrogen through natural gas hydrogen production combined with carbon capture and storage technology. However, how to overcome the difficulties of long-distance and large-scale transport is an urgent problem. Taking Norway to China and to Europe as examples, energy efficiency and carbon emission intensity as research parameters, and liquid hydrogen and ammonia as research objects,this study compared the two transport modes by selecting reasonable data for theoretical calculation, building the transport chain and drawing the energy flow diagram of each transport chain. The results showed that the energy efficiency of ammonia (no cracking) transport chain to Europe and China was 41.6% and 33.6%, respectively,which was higher than that of liquid hydrogen transport chain (37.65% and 33.38%) and ammonia (cracking) transport chain (30.39% and 24.83%). In terms of carbon emissions, ammonia (no cracking) transport chain had lower carbon emissions [135.87kg/(MW·h) and 110.76kg/(MW·h)] than liquid hydrogen transport chain [241.27kg/(MW·h) and 214.8kg/(MW·h)] and ammonia (cracking) transport chain [216.94kg/(MW·h) and 183.33kg/(MW·h)].

Low-temperature environment seriously affects the battery discharge performance. Considering the influence of various preheating methods on the temperature field distribution of the battery, this paper used insulating oil immersion to heat the NCM811 battery. The temperature rise rate of the battery and the temperature difference in the battery surface during the preheating process in different low-temperature environments and the discharge parameters of the battery under distinctive SOC during 1C discharge were tested. The results showed that the NCM811 battery had good low-temperature performance, and preheating was very important for low SOC discharge. When SOC was lower than 33.3%, it was almost impossible to discharge without preheating at -20℃. Preheating could significantly improve the battery discharge performance at low-temperature and reduce the internal resistance. The rising rate of battery temperature could reach 0.31℃/s when the internal temperature of battery was preheated to 0℃ in a low-temperature environment of -20℃. For the initial battery states of 100% SOC and 33.3% SOC, the corresponding ohmic internal resistance of the battery decreased to 39.5% and 37.9% after preheating, respectively, and the polarization internal resistance decreased to 15.4% and 21.1% after preheating. Even in the initial state of 33.3% SOC, the released capacity at the 1C discharge rate could reach 81.68% of the charged.

Selective catalytic reduction of hydrocarbons (HC-SCR) is an effective denitrification technology, but the Cu-based molecular sieve catalysts used for catalytic reduction of NO _x by HC-SCR have problems of low catalytic activity and narrow active temperature windows at low temperatures. This work reviews the progress of selective catalytic reduction of NO _x by Cu/zeolite catalysts. In addition, the reaction mechanism of supported Cu-based zeolite catalysts in the application of HC-SCR and the effects of support, supported Cu content, preparation process, reducing agent, H₂O, and SO₂ on the catalytic activity are systematically presented. It is found that doping metal additives that worked synergistically with copper could improve the low-temperature catalytic activity. Finally, the preparation strategy of Cu-based zeolite catalysts with excellent low-temperature catalytic activity and future research directions for developing high-efficiency catalysts, such as appropriately increasing the Cu loading, controlling the Si/Al ratio, and further improving the dispersion of active metal components, are proposed, which could provide a theoretical basis and guide for the optimization and development of novel Cu-based zeolite catalysts with high efficiency at low temperature.

As an effective method of eliminating NO _x, NH₃ selective catalytic reduction (NH₃-SCR) has been employed in the deNO _x process of diesel vehicle exhaust. NH₃-SCR technology often uses copper-based zeolite as catalysts in vehicle aftertreatment system, and nitrogen oxides in the exhaust can be converted into N₂ with the catalysts and NH₃. However, in actual applications, the existence of SO₂ and N₂O and hydrothermal aging frequently affect the deNO _x performance of copper-based Zeolite. Therefore, based on the research trends of isolated Cu²⁺ in Cu-SSZ-13 zeolite catalysts, this paper summarizes the effects of two isolated Cu²⁺ on NH₃-SCR reaction and N₂O generation, including those on hydrothermal aging and SO₂ response; and summed up the methods of inducing Cu-2Z generation. Finally, taking the research status of Cu-LTA zeolite catalysts as an example, we briefly reviewed the research progress of isolated Cu²⁺ in Cu-LTA catalysts, and gave the research trends and future application prospects of Cu-LTA catalysts. This paper can provide ideas for the research of other types of copper-based zeolite catalysts for the deNO _x of diesel vehicle exhaust gases. Specifically, the related properties of the two isolated Cu²⁺ of zeolite should be clarified, and the isolated Cu²⁺ should be rationally controlled in the catalyst design to maintain high catalytic activity and further enhance the hydrothermal stability and SO₂ resistance.

Four kinds of metalloporphyrin/multi-walled carbon nanotube catalysts (FeTPPCl-π-π-c-MWCNTs,FeTPPCl-π-π-MWCNTs, SnTPP-π-π-c-MWCNTs and SnTPP-π-π-MWCNTs) were successfully prepared by utilizing the π-π stacking effect between the π electrons on the metalloporphyrin ring and on the wall of the multi-walled carbon nanotube. The experiments showed that the prepared products can be used as biomimetic catalyst for the Baeyer-Villiger(B-V) oxidation of ketones. The conversion of cyclohexanone to ε-caprolactone could reach 96%, and the yield of ε-caprolactone was 96% with FeTPPCl-π-π-c-MWCNTs as catalyst and 1,2-dichloroethane as solvent at 50℃ under the optimized conditions. In addition, the as-prepared catalysts also showed good catalytic activity for the B-V oxidation of other ketones. The process of B-V oxidation of cyclohexanone was further systematically studied by in situ electron paramagnetic resonance spectroscopy and in situ ultraviolet spectroscopy. It is found that the metalloporphyrin/carbon nanotube biomimetic catalysts can simultaneously improve the stability of free radicals and metalloporphyrin high-valent active species, which is beneficial to enhance the biomimetic activity of metalloporphyrin in the B-V oxidation of ketone compounds.

Using Cu(NO₃)₂·3H₂O and Zn(NO₃)₂·6H₂O as the precursors, we prepared a series of Cu-Zn catalysts by co-precipitation method. The physicochemical properties of the as-prepared Cu-Zn catalysts were characterized through inductively coupled plasma optical emission spectrometers (ICP-OES), X-ray diffraction (XRD), N₂-adsorption/desorption, scanning electron microscopy (SEM), NH₃-temperature programmed desorption (NH₃-TPD), H₂-temperature programmed reduction (H₂-TPR), X-ray photoelectron spectroscopy (XPS), and thermogravimetric/differential thermal analysis (TG/DTA), etc. The introduction of Zn prompted the formation of mesoporous structure and certain amounts of acid sites. The experimental results showed that the synthesized Cu-Zn catalysts exhibited excellent catalytic performance for methanol reforming and furfural hydrogenation, among which CZ-0.60 with Cu/Zn molar ratio of 0.6 gave the highest catalytic performance. The yield of furfuryl alcohol reached 89.7% with 100% furfural conversion at 160℃ for 4h, while that of 2-methylfuran reached 26.3% with complete furfural conversion at 240℃ for 8h. Moreover, CZ-0.60 still maintained good activity in recycling experiments, and showed good thermal stability below 750℃. Furthermore, the possible pathway for furfural hydrogenation using methanol as hydrogen donor over Cu-Zn was proposed.

The effect of acidity and texture properties of M-P/HZSM-5 zeolite on the catalytic biomass pyrolysis to produce hydrocarbon-rich bio-oil derived was investigated. Metals (Zn, Co, Ce, Cu, Mg, Ga) were incorporated into the P/HZ zeolite that was prepared via wet impregnation and systematic physicochemical characterization techniques, such as XRD, BET, NH₃-TPD and FTIR were used to obtain the acidity and textural properties. At the same time, the composition, deoxygenation characteristics and conjugate structure of the upgrading bio-oil were analyzed by GC/MS, UV-fluorescence spectrum and element analyzer. The deactivated catalyst was evaluated by TGA, Raman spectrum and SEM to explore catalytic deactivation mechanism. The results showed that, phosphorus modification significantly reduced the concentration of acid sites, especially the strong ones. This suppressed hydrogen transfer reactions and enhanced the selectivity to olefin, while promoted the stability of the catalyst. The metal loading did not change the framework structure of the catalyst, but formed new metal sites, changed the acid distribution of the catalyst, decreased the specific surface area and pore volume by coverage of the catalyst surface with metal species, and increased the average pore size. The synergistic effect of metal and acid sites significantly promoted the deoxygenation of bio-oil and increased the conversion of monocyclic aromatic hydrocarbons. The deoxygenation degree order was Zn>Mg>Co>Ce>HZSM-5>Ga>P>Cu. The yield of aromatics is positively correlated with the total acid content. High acidity, large average pore size and appropriate specific surface area are conducive to the formation of aromatics. However, low acidity and small pore size promote the conversion of olefin compounds. In addition, the best mass-transfer efficiency and conjugate effect was obtained by using the Zn-P/HZ catalyst, which led to the highest hydrocarbon and monocyclic aromatic hydrocarbons content (86.46% and 78.29%, respectively) among all the investigated metal-modified P/HZ catalysts. Zn promoted the formation of benzene, toluene and alkylbenzene, Mg promoted the conversion of xylene, while Cu and Ga promoted the formation of light olefins. The addition of metal significantly reduced the degree of graphitization and improved the coking resistance.

In recent years, propane dehydrogenation to propylene (PDH) has become the most promising and attractive propylene production technology because the successful large-scale exploitation of shale gas can provide a large amount of cheap propane. Currently, supported PtSn/Al₂O₃ catalysts are mainly used for propane dehydrogenation in industry. In the high temperature reaction of propane dehydrogenation, PtSn nanoparticles are prone to sintering and coke deposition, which causes severe catalyst deactivation. To solve the above problems, we synthesized PtSn/MgAl₂O₄-Sheet catalyst by using MgAl₂O₄-Sheet spinel as support. The catalyst had a large pore size, which was favorable for the adsorption of reactants and the desorption of products in the PDH reaction, and thus improves the activity of the catalyst and reduced the content of coke. Meanwhile, the (111) plane of the MgAl₂O₄ spinel support had a strong interaction with the PtSn nanoparticles, which prevented the sintering of PtSn nanoparticles in the high temperature reaction. In the propane dehydrogenation reaction with the prepared catalyst, the conversion of propane reached 43.2%, the selectivity of propylene reached 95.0%, and the deactivation rate was only 0.008h^-1, which was superior to that with the commercial PtSn/Al₂O₃ catalyst.

Cu-SAPO-44 catalysts were synthesized by three preparation methods: copper sulfate as copper source and cyclohexylamine as single template; copper sulfate as copper source, cyclohexylamine as template and polyethylene glycol (PEG2000) as synergistic template; and Cu-TEPA (tetraethylenepentamine) and cyclohexylamine as co-templates. These catalysts were used for selective catalytic reduction of nitric oxide with propylene (C₃H₆-SCR) under diesel engine exhaust. These zeolites were characterized by X-ray diffraction (XRD), N₂ adsorption-desorption, scanning electron microscopy (SEM), UV-vis spectroscopy (UV-vis), H₂ temperature-programmed reduction (H₂-TPR) and NH₃ temperature-programmed desorption (NH₃-TPD). The results showed that Cu-TEPA template not only acted as structure directing agent, but also provided active copper species. Then, Cu-SAPO-44 catalyst prepared with Cu-TEPA template had high crystallinity, large copper loading, more active Cu²⁺ ions and rich surface acidity, which provided a large number of active sites for C₃H₆-SCR reaction. Therefore, it had the best de-NO _x performance, which could obtain more than 90% NO _x conversion and about 90% N₂ yield at 300—350℃ under lean burning condition containing 10% O₂ and 5% H₂O. However, the introduction of surfactant PEG2000 had little effect on improving the activity of Cu-SAPO-44 catalyst. The Cu-SAPO-44(T) catalyst indicated appropriate reaction stability in long term test of 50hours.

Tar removal from syngas is key for solid waste gasification. Conventional metal-based catalysts, despite their high cracking capabilities, easily deactivate during gasification in tar- and water vapor-laden environments. In this study, a biochar catalyst with a large specific surface area of 1384.2m²/g was prepared and its kinetics of in-situ tar removal were examined in an organic solid waste gasification reactor. The generated biochar could directly be incorporated into the gasification process without regeneration, enabling efficient tar removal at a considerably lower cost. In addition, the deactivation kinetic model of the char catalyst was constructed by measuring its surface properties and evaluating the activity of toluene cracking reaction. On this basis, the tar removal process under the conditions of the demonstration engineering process was simulated using the multi-field coupling software COMSOL. The effects of residence time, catalyst loading amount, and reactor shape on the cracking process were investigated. The results showed that, in a reactor with a height-to-diameter ratio 1.0 and full catalyst loading, the tar concentration at the outlet was reduced to zero within 4—6s, and the H₂ and CO concentrations in the syngas were 0.032kg/m³ and 0.50kg/m³, respectively.

Zinc ion batteries (ZIBs) offer the advantages of environmental friendliness, high safety and low cost. However, the inherent challenges of dendrite growth in zinc cathodes and aqueous electrolytes (such as hydrolysis reactions, water evaporation and electrolyte leakage) make them less stable in practice in terms of cycling. Polymer electrolytes with their low water content and high modulus of elasticity can effectively overcome these challenges. In this paper, the basic principles of polymer electrolytes and their research progress in ZIBs are reviewed, various strategies used to improve the electrochemical and mechanical properties of solid polymer electrolytes in recent years are introduced, and the mechanism of action and application progress of different strategies are analyzed and compared. The application of gel polymer electrolytes in ZIBs and the research status of functional gel electrolytes are expounded, and the prospects for their application in flexible smart electronic devices are demonstrated. Finally, this paper presented challenges in developing high-performance ZIBs based on polymer electrolytes, such as deficiencies in ionic conductivity and mechanical strength, interfacial problems and functional singularity. The prospects for overcoming these challenges are pointed out to provide references and lessons for research on polymer electrolytes in ZIBs.

Phosphobase geopolymer is a new class of geopolymer material formed by the reaction between aluminosilicate precursor and phosphoric acid (salt) solution. Raw materials, amount of activator, amount of water and curing conditions are the main factors that affect the composition and structure of phosphobase geopolymer, and further determine their performance. In this paper, the formation mechanism and network structure development of phosphobase geopolymer are reviewed. The influence of different raw materials, curing systems, types and amounts of activators on phosphobase geopolymer are summarized. The effects of various preparation conditions on the mechanical properties of phosphobase geopolymer are discussed in detail, and a sketch of the heat resistance, corrosion resistance and dielectric properties of phosphobase geopolymer is introduced. In addition, the paper pointed out the insufficient understanding of network structure in the research on formation mechanism and the problems existing in the preparation process of phosphobase geopolymer. It is proposed that the reaction mechanism of phosphobase geopolymer should be further clarified and a systematic performance testing standard should be established. Finally, the high value-added application of phosphobase geopolymer and its development prospect in the direction of solid waste recycling are prospected.

Porous aromatic framework materials are an emerging class of organic porous nanomaterials with high stability, large specific surface area and easy modification, which can meet the needs of various adsorption material designs. In recent years, many scholars have applied the modified porous aromatic framework materials in uranium extraction from seawater and found that they have large uranium adsorption capacity, excellent uranium selectivity and good recyclability. This paper reviews the recent research progress of porous aromatic framework materials based on uranium extraction from seawater. The synthetic reactions and synthesis techniques of porous aromatic framework materials are firstly briefly introduced, and then their interaction mechanisms with uranium are categorically discussed. The adsorption performance of various modified porous aromatic framework materials on uranium are evaluated, and the reasons for the high selectivity and high adsorption efficiency on uranium are analyzed. Finally, the paper provid some suggestions for the future design of low-cost and high-performance porous aromatic framework adsorbents in view of the current limitations of porous aromatic framework materials for uranium extraction from seawater (synthesis of porous aromatic framework materials, improvement of adsorption performance, cost reduction and in-depth study of the mechanism, etc.).

Pervaporation (PV) possesses advantages such as the low requirement for feed water, high rejection and water recovery rate, and strong fouling resistance. Therefore, PV desalination can be competitive with other desalination technologies, especially for high-salinity brine. Current applications of PV desalination however are limited due to its relatively low separation efficiency, stability and fouling resistance. The introduction of novel membrane materials such as two-dimensional (2D) nanomaterials is considered to be an effective means to improve both the material properties and performance of PV desalination membranes. In this paper, a brief introduction to PV desalination technology is initially given. Then, the research status of two-dimensional nanomaterials in the field of PV desalination is reviewed from three perspectives: the properties and synthesis methods of nanomaterials, the preparation and modification strategies of nanocomposite membranes, and the influence of 2D nanomaterials on the properties and desalination performance of PV membranes. It is pointed out that the existing PV mass transfer model had great limitations and the synthesis of new two-dimensional nanomaterials faced great difficulty. To further improve the performance of PV compositemembranes and reduce the preparation cost, it is necessary to clarify the mass transfer mechanism of PV composite membrane and optimize the fabrication method of two-dimensional nanomaterials. In general, two-dimensional PV nanocomposite membranes with excellent separation performance and physicochemical properties will play an important role in the field of desalination.

Polyaniline has the advantages of good redox properties, environmental stability and excellent electrical conductivity, and thus polyaniline is a good gas-sensing material. However, the conjugated delocalized structure of polyaniline restricts its application in neutral and alkaline environments. Carbon nanotubes have the characteristics of large specific surface area and can show good adsorption capacity for different gases at room temperature, but simple carbon nanotubes have poor adsorption selectivity to gases. This paper mainly introduces the gas-sensing properties and gas-sensing mechanism of polyaniline, carbon nanotubes and polyaniline/carbon nanotube composites modified by different means such as metal, metal oxide or polymer doping as gas-sensing materials. The research progress shows that the modified polyaniline/carbon nanotube composite material has better gas-sensing properties, but it is also pointed out that the synergistic mechanism of each part of the composite material is not clear, and there are few studies on the gas-sensing reaction of other gases except ammonia gas. It is proposed that in the future the gas-sensing reaction mechanism of the composite material and the synergistic mechanism of each part of the composite material should be further explored, the molecular structure of the required material should be designed, and then the function of polyaniline and carbon nanotubes should be targeted with chemical doping to synthesize excellent composite gas-sensing materials.

The use of a large number of traditional organic foam materials using petrochemical resources as raw materials has aggravated the depletion of such resources and their wastes are difficult to degrade in the natural environment, which seriously pollutes the environment. In contrast, biodegradable foam is biocompatible, biodegradable and renewable, and is an environmentally friendly material that has received extensive attention. This paper compares foaming technologies, principles, applications, advantages and disadvantages of extrusion foaming, molding foaming and freeze-drying foaming, and introduced the influence of foaming process on material properties and application, and thus it has great development potential to prepare high-performance biodegradable foam by using natural polymer compounds or other renewable resources to simulate the microscopic and chemical network structure of natural foam. Then, this review summarizes the related research status on natural foam, bionic green foam and biomass foam, and focused on discussing research progress of plants and wood, non-isocyanate and lignocellulosic foams. Furthermore, the typical foaming formula compositions and functions are analyzed. It is pointed out that the further exploration of green medium, plasticity improving and formula is the future development and research direction of biodegradable foaming materials.

Direct air capture (DAC) technology is a negative carbon technology, which is an effective supplement to the carbon capture, utilization and storage (CCUS) technology and one of the important technologies to help achieve the carbon peaking and carbon neutrality goals. Solid porous materials have irreplaceable advantages in reducing the economic cost and operating energy consumption of DAC due to their strong adsorption capacity, low regeneration energy consumption, flexible application scenarios and adjustable structure. Starting from the principles of DAC of solid porous materials, this paper focused on reviewing DAC adsorbents, such as zeolite adsorbents, silica-based adsorbents, carbon-based adsorbents, nano-alumina adsorbents, MOF adsorbents and porous resin adsorbents. The advantages and disadvantages on adsorption capacity, adsorption selectivity, hydrothermal stability, regeneration energy consumption and cycle stability of solid porous materials are introduced and compared. The effects of amine functionalization modification and carrier pore structure on the adsorption performance of CO₂ are emphatically analyzed, and specific optimization directions for the challenges faced by various solid porous materials in the application of DAC are prospected. It is pointed out that the design and development of solid porous adsorbents in the future should take both economy and efficiency into account, and further pilot-scale DAC experiments should be carried out.

With the merits of high theoretical specific capacitance and abundant reserves, copper oxides have become next-generation electrode materials for supercapacitors, but their applications are still limited to the poor electron conductivity and inferior cyclic stability. In this work, the sandwich-like Cu₃₀Mn₇₀/Cu/Cu₃₀Mn₇₀ foil was used as mother-alloy. A highly conductive and flexible nano-porous CuMn-core and multicomponent oxide-shell electrode with different Mn residues was prepared by the combination of dealloying and self-propagating oxidation. The effect of Mn residues on the morphology, structure and electrochemical properties of the electrode under different dealloying conditions was investigated. The experimental results showed that the residual amount of Mn would gradually decrease along with extension of corrosion time. The multicomponent oxides obtained under different corrosion conditions were composed of CuO, Cu₂O, Cu _x Mn_1-x O and CuMn₂O₄ phases. In three electrode system, the NP-TMO5 sample indicated the highest area capacitance of 1045.7mF/cm² at current density of 5mA/cm² and maintained 97.9% capacitance after 12000 cycles. The symmetric device composed by NP-TMO5 delivered high area capacitance and energy density of 419.83mF/cm² and 0.084mWh/cm² at current density of 3mA/cm², respectively. Even after 10000 cycles at a scanning rate of 100mV/s, the specific capacitance retention was still 97.9%. The excellent performance of the sample was attributed to the core-shell structure of the porous electrode and the synergistic effect between multi-component oxides, which can optimize the electronic structure and buffer the volume expansion, providing a theoretical basis for the design of highly loaded composite porous structures.

Bismuth oxychloride semiconductor has attracted tremendous attention in the field of photocatalysis for solving environmental and energy issues due to its unique layered structure and adjustable electronic structure. The researchers have made much efforts that in order to improving the utilization rate of BiOCl for sunlight, overcoming the drawback of the high recombination rates of photogenerated electron-hole pairs, enhancing the reduction ability of photoelectrons and so on. Among them the construction of heterojunction is one of the most effective ways to reduce these drawbacks. In this article, the charge transfer mechanism in 4 junction systems, Z-scheme, Ⅱ-type, p-n junction and S-scheme, are summarized. Meanwhile, they are highlighted some BiOCl heterojunctions of excellently photocatalytic performance. At the same time, the photocatalytic degradation performance is compared and analyzed for some heterojunctions. The S-scheme heterojunctions achieved high-effectively charge separation and strong photo-redox ability which resulted in exhibited excellently photocatalytic performance. In addition, the application of BiOCl heterojunctions in the degradation of organic pollutants, reduction of CO₂, reduction of heavy metals and splitting water etc. are introduced. Some problems of BiOCl heterojunction are summed up. Finally, in view of the BiOCl heterojunctions of structure-function relationship and complex synthesis etc., the development trend in computer simulation, carrier load and development of new technology is put forward.

Co-deposition of biomimetic adhesive polydopamine (PDA) and polyethyleneimine (PEI) has emerged as an effective approach for building monovalent perm-selectivity functional coatings. In this experiment, Fe³⁺ ions were introduced into the cation exchange membrane by immersion pretreatment, and the PDA-PEI was deposited on the membrane surface by using the electric field effect and Fe³⁺ ions induction. The results showed that the method greatly shortened the modification time and prepared the monovalent selective cation exchange membrane. Scanning electron microscope, UV-visible spectrophotometer, infrared spectrometer and zeta potential were used to analyze the surface properties and structure of the modified membrane, and the effects of concentration of Fe³⁺ ions of the separation performance were investigated. With the increase of the concentration of Fe³⁺ ions, the membrane resistance of the modified films indicated an upward trend, while the surface positivity charge and perm-selectivity both increased first and then decreased. When the concentration of Fe³⁺ ions was 0.001mol/L, the surface of the modified membrane showed remarkably enhanced Na⁺/Mg²⁺ selectivity of 12.8, low electrical resistance and excellent stability due to the combined effect of the electric field and Fe³⁺ ions on the dopamine (DA) polymerization process.

In this study, polyethylene oxide (PEO) was added to poly (vinylidene fluoride)/styrene maleic anhydride copolymer (PVDF/SMA) membrane system, and PVDF/SMA blend membranes with different PEO contents were prepared by nonsolvent induced phase separation (NIPS). The results showed that the blend ultrafiltration membrane with PEO mass fraction of 2% had the best performance. Water flux was 531.1L/(m²·h), BSA rejection rate was 65.8%, water contact angle was 63.6° and the peel strength was 0.2756kN/m. Then, PVDF/SMA membrane was used as the main research object to test the influence of coagulation bath temperature on pure water flux and BSA rejection rate. The results indicated that temperature had no obvious effect on membrane performance. Therefore, the effects of different coagulation bath components on the properties of blend films were tested at room temperature. The changes of membrane properties in coagulation bath with N,N-dimethylacetamide (DMAc) (mass fraction of 3%, 6%, 9%), sodium chloride (0.05mol/L, 0.1mol/L, 0.2mol/L) and ethanol (mass fraction of 3%, 6%, 9%) were investigated, and the membrane samples were characterized by scanning electron microscopy (SEM). The results showed that with the increase of DMAc content, the pores on the membrane surface decreased and the thickness of the cortex increased, resulting in the decrease of water flux and the increase of BSA rejection rate. However, with the increase of NaCl concentration, the number of macropores on the membrane surface increased and the number of finger shaped pores in the membrane became narrower, leading to the gradual increase of membrane flux and the decrease of BSA rejection. Similarly, with the increase of ethanol content in the coagulation bath, the number of pores on the membrane surface increased, the finger like pores narrowed and the pore wall thickened, the water flux of the blend membrane increased, and the BSA rejection decreased. In short, the use of appropriate coagulation bath ingredients and appropriate concentration can significantly improve the partial properties of the blended film. In addition, the experimental results of the long-term operation stability of the membrane showed that the blended membrane had good anti-fouling property and long-term operation stability, and had a good application prospect in practical sewage treatment.

Walnut shell-based activated carbon PBC was prepared using walnut shell as raw material and phosphoric acid (H₃PO₄) as activator, and its adsorption performance on hexavalent chromium was studied. The physical and chemical properties of PBC were measured using SEM, TEM, BET, FTIR, Raman, XPS and other characterizations, respectively. The effects of solution pH, activated carbon dosage and initial concentration on the performance of Cr(Ⅵ) adsorption were investigated. The kinetic behavior of Cr(Ⅵ) adsorption by PBC were examined and the adsorption mechanism was analyzed. The results showed that the prepared walnut shell-based activated carbon had good adsorption performance at a phosphoric acid impregnation ratio of 1∶1 and pyrolysis temperature of 400℃. The adsorption rate reached 100% for the lower concentration of Cr(Ⅵ) solution (≤50mg/L). The adsorption kinetics and isotherms were in accordance with the proposed secondary kinetic model and Langmuir model, respectively, and the chemisorption dominated the adsorption process. The thermodynamic analysis indicated that the adsorption process was a spontaneous heat absorption process.

In view of the significant demand for reducing the cost of carbon capture and the key problem of developing high-performance adsorbents, a new carbon supported potassium-based CO₂ adsorbent was prepared from a polymer precursor derived from Friedel Crafts alkylation between benzene and dimethyl acetal. By means of solid nuclear magnetic resonance, infrared spectroscopy, electron microscopy, X-ray powder diffraction, N₂ physical adsorption and other characterization methods, it was found that the synthesized polymer precursor had a hyper-crosslinked porous structure, and the modification of a variety of oxygen-containing functional groups could be achieved by surface oxidation modification. These oxygen-containing functional groups had the function of anchoring potassium ions, and thus the surface potassium modification can be achieved by ion exchange. After further high-temperature carbonization, a new carbon supported potassium-based CO₂ adsorbent can be obtained. The potassium sites on the adsorbent had good dispersibility and could react reversibly with CO₂. The CO₂ adsorption capacity of the adsorbent under the simulated flue gas reached 1.63mmol/g with good cyclic stability, which endowed the adsorbent with promising application potential.

In order to investigate the wave transmission performance of zirconium aluminum silicate fiberboard (ZAF), a commonly used thermal insulation material in microwave metallurgical reactor under temperature gradient, the complex permittivity of ZAF at 25—1000℃ was measured by cavity perturbation method. Secondly, the thermal conductivity of ZAF in the range of 100—500℃ was measured by laser flash method. Finally, based on the electromagnetic transmission line theory and heat transfer theory, the wave transmission performance of ZAF under the influence of frequency, polarization mode, incident angle and material thickness were studied. The results showed that the dielectric constant of ZAF changed slightly with rising temperature and the dielectric loss factor increased exponentially after 900℃. The thermal conductivity of ZAF increased with the increase of temperature, and the increase rate was about 39.65%. At 2450MHz, the fraction of the ZAF greater than 0.9 power transmission coefficient was higher than at 915MHz, and at the same frequency, the wave transmission performance of the transverse magnetic polarization mode (TM) was superior to the transverse electric polarization mode (TE). Multiple transmission peaks developed in the power transmission coefficient curve as ZAF thickness increased, and there were more wave transmission peaks at 2450MHz frequency than at 915MHz frequency. When the microwave incidence angle was between 0°—30° in the TE polarization mode, the material exhibited good wave transmission performance. When the microwave incident angle was between 0°—60° in the TM polarization mode, the material exhibited good wave transmission performance, and there was a Brewster’s angle where the microwave can transmit entirely. For the study of wave transmission performance of thermal insulation materials under temperature gradient, this study offered a crucial reference value.

Viscosity-temperature characteristics is a key index of lubricating oil. Viscosity-temperature characteristics of lubricating oil were improved by added viscosity index improvers so that lubricating oil have a low enough viscosity at low temperatures to flow and thicken viscosity at high temperatures to get a useful viscosity. With the increasingly international stringent regulations and requirements for energy conservation and emission reduction, low-viscosity and energy-saving lubricating oil have begun to attract the attention of lube oil manufacturer. Polymethacrylate polymers (PMA) are rejuvenated and have attracted people’s attention. The demand for PMA viscosity index improvers in lubricating oil formulations is increasing. Although PMA have low viscosity, high viscosity index and excellent low temperature performance, they have poor thermal stability, and shear stability. In order to improve the performance of PMA, it is necessary to introduce different olefin monomers to copolymerize with alkyl methacrylate. This article introduced the research status of PMA viscosity index improvers by domestic and foreign researchers, and summarized them based on the classification of different functional olefin monomers. The effects of different olefin monomers on the properties of PMA viscosity index improvers were analyzed. By introducing monomers contained polar functional group, alkyl olefin monomers, aryl olefin monomers and plant-based olefin monomers, PMA were endowed with dispersion, shear stability, wear resistance, friction reduction and biodegradability. This article provided guidance and reference for the development of new multifunctional viscosity index improvers.

The global warming caused by the greenhouse effect has affected the survival and development of human beings, and it is urgent to mitigate CO₂. CO₂ mineral carbonation is receiving more and more attention as a CO₂ reduction technology. Alkaline industrial solid waste for CO₂ carbonation has faster reaction rate, higher carbonation rate and lower energy consumption than traditional natural mineralized raw materials, and can also produce high value-added products for chemical and construction applications. This paper reviewed the carbonation mechanism of alkaline industrial solid wastes, the progress of CO₂ mineral carbonation using alkaline industrial solid wastes (fly ash, steel slag, calcium carbide slag) and the integrated absorption-mineralization (IAM) technology. Using alkaline industrial solid waste as feedstock, the carbonation technology mechanism and life cycle impact assessment should be further studied and the process should be optimized in the future. Highly efficient, economical absorbents and mineral raw materials with better mineralization capacity should be developed for the IAM process in the future and the reaction mechanism of the IAM process should be studied.

Reverse water gas conversion (RWGS) reaction is a key step in the catalytic hydrogenation of carbon dioxide (CO₂) to high value-added chemicals and fuels such as methanol, light olefins, aromatics and gasoline, which is of great significance for the utilization of CO₂. This review summarizes the research progress of RWGS reaction in recent years, including thermodynamic analysis of RWGS reaction, catalytic mechanisms, selective catalysts and strategies to improve the performance of catalysts. From the perspective of thermodynamics, RWGS reaction is favorable at high temperature, as methanation reaction emerges at low temperature. The mechanisms of RWGS reaction mainly consist of redox mechanism and association mechanism, and the latter further contains a formate route and/or carboxylate route. Compared with other catalyst system, supported metal catalysts commonly exhibit a superior RWGS reaction performance. In addition, the rational design of RWGS reaction catalysts with high reactivity and durability could be realized by adding alkali metal additives, forming bimetallic alloy as well as modulating the metal-support interaction via selecting a good support or reducing the metal particle size.

Anaerobic digestion (AD) is an important technology for the resource utilization of organic wastes. However, the fluctuations in the waste characteristics and operating parameters during the actual engineering operation might cause the accumulation of volatile fatty acid (VFAs), thereupon, resulting in the depression of biogas production and even the failure of AD due to over acidification. Based on the review of research progress both at home and abroad, this study describes the mischiefs of VFAs accumulation briefly, dissects the major causes of acid accumulation, and summarizes the counter measures from the two aspects of early-warning monitoring and regulation means required before and after acidification, respectively. Hereon, the authors suggest further strengthening the perfection of early-warning index system for the acidification during AD process, breaking through the bottlenecks of acclimation technology to obtain environment-tolerant type microbial flora, and researching the method based on endogenous acid-alkaline buffering system to reinforce the shock resistance of the AD reactor, attempting to provide some reference for enhancing the efficiency and stability of AD reactors in practice.

Anaerobic ammonium oxidation (Anammox) process is considered as an efficient, economical and environmentally friendly biological nitrogen removal technology, which is an ideal alternative to the conventional biological nitrogen removal process. However, anaerobic ammonia oxidizing bacteria (AnAOB), as the functional microbes in Anammox process, has slow growth rate, resulting in a long reactor start-up time, which hinders the practical application and promotion of the process. Therefore, it is urgent to enhance the AnAOB activity and further reduce the reactor start-up time. Redox mediators (RMs), as electron carriers, can enhance the activity and metabolic performance of AnAOB nitrogen-converting enzymes by accelerating the electron transfer process, thus improving the overall nitrogen removal effect. This paper discussed the role of RMs in enhancing the Anammox performance, introduced the characteristics and types of RMs, as well as their basic principles, reviewed the effects of RMs on the Anammox process in terms of Anammox performance, extracellular polymeric substances production, nitrogen-converting enzymes activity and functional bacterial abundance, as well as analyzed and summarized the potential mechanism, with a view to providing theoretical basis and reference value for future practical applications.

In this study, the waste heat recovery was concentrated from the hot stripped gas in CO₂ chemical absorption process. A heat exchanger could be added on the top of CO₂ stripper in the CO₂ chemical absorption system to reduce the CO₂ regeneration energy consumption, which was fulfilled by recovering the waste heat from the stripped gas (i.e., the mixture of water vapor and CO₂) using the bypassed cold CO₂-rich solvent in the heat exchanger. Generally, a better waste heat recovery performance leaded to a low CO₂ regeneration energy consumption. The waste heat recovery performance could be enhanced by adopting the novel membrane heat exchanger to replace the traditional steel heat exchanger because of the coupled heat and condensate transfer in the membrane heat exchanger. A PVDF/BN-OH flat composite membrane was prepared through the blend modification method using polyvinylidene fluoride (PVDF) and hydroxylated boron nitride (BN-OH). In this composite membrane, the polyester fiber (PET) non-woven fabrics was used as the support layer. The waste heat recovery performance was experimented by using the prepared composite membrane in the monoethanolamine (MEA)-based rich-split process. Additionally, the commercial PVDF membrane was also adopted as the control. Compared with the prepared composite membrane without adding BN-OH (i.e., M1 membrane), the membrane adding 1% BN-OH (i.e., M3 membrane) achieved a higher average pore size by about 11.32%, a relatively lower porosity by about 7.14% and a higher conductivity by about 52.25%. Notably, M3 membrane still maintained the hydrophilicity with a water contact angle of 77.1°. Therefore, M3 membrane may have the potential to enhance the coupled mass and heat transfer performance. Under the same operation conditions, M3 membrane could obtain a waste heat recovery flux up to 95.5% higher than M1, and a heat recovery ratio up to 31.6% higher than those of M1 membrane. Compared to the commercial PVDF membrane with a smaller thickness, M3 membrane still had a maximum 54.8% higher waste heat recovery flux and 9.6% higher heat recovery ratio, suggesting the better waste heat recovery performance of M3 membrane. Finally, the empirical correlations between the waste heat recovery ratio and key operation parameters were proposed, which showed a high accuracy.

At present, the degassing and sterilization treatment of geothermal tail water is mainly carried out by degassing tanks and bactericides. This paper proposed an ultrasonic-ultraviolet coupling degassing and sterilization treatment technology. Ultrasonic-ultraviolet coupling technology was used to degas and sterilize water containing microbubbles and bacteria. The ultrasonic degassing efficiency under different flow conditions, the sterilization efficiency under different flow rates and different ultraviolet irradiation intensity, and the degassing and sterilization efficiency after ultrasonic-ultraviolet coupling were investigated respectively. The results showed that part of the gas can be removed under small flow rate; with the increase of the water flow rate, the gas holdup in the water was basically unchanged and the degassing effect does not increase significantly. Under a certain ultraviolet irradiation intensity, when the water flow was small, the sterilization efficiency was 60%—80%;when the water flow was large, the sterilization efficiency was more than 90%, which was considered to be due to the relatively high turbulence degree and short residence time at large flow rates. Compared with the ultrasonic degassing alone, the degassing efficiency of ultrasonic-ultraviolet coupling was basically unchanged, and the sterilization efficiency was about 90%. The optimal experimental operating parameters are finally determined to be 20kHz, 0.15m³/h and 2000μW/cm².

To understand the mechanism of mercury removal by oxygen carriers during in-situ gasification and chemical-looping combustion of coal, we used CaSO₄ as oxygen carrier and CO₂ and water vapor as gasification medium in a reduction reactor working at 900℃. Results showed that the CaSO₄ oxygen carrier itself promoted the oxidation of Hg⁰, but the SO₂ produced by the decomposition of CaSO₄ inhibited the oxidation of Hg⁰. CaSO₄ promoted the chemical-looping combustion of coal to produce element S, which would further react with Hg⁰ to generate a variety of complex HgS _n . This, reduced the Hg⁰ content in the flue gas and improved the mercury removal efficiency. In addition, the CaSO₄ oxygen carrier has good cycle characteristics in the reduction-oxidation cyclic reactions, indicating an excellent chemical-looping oxygen carrier.

Zinc ferrite (ZnFe₂O₄) produced in the roasting stage of zinc concentrate is a group of complex oxides with spinel structure, stable in nature and insoluble in dilute acids and bases. Under conventional leaching conditions, 20% of zinc still exists in zinc leaching residue in the form of zinc ferrite, resulting in low zinc leaching rate of zinc concentrate roasting products, generally about 80%. Mechanical activation has the advantage of creating defects in the mineral lattice and reducing the dependence of reaction conditions such as temperature and acid concentration. Therefore, Mechanical activation was used to pretreat zinc calcine using sulfuric acid as the leaching agent. The effects of mechanical activation time, ball-to-material ratio, sulfuric acid concentration, liquid-to-solid ratio and temperature on zinc leaching efficiency and other impurity ions were investigated. The results showed that zinc leaching efficiency increased with increasing mechanical activation time. The leaching results using the mechanical activation (3.60% mass ratio of H₂C₂O₄·2H₂O to zinc calcine, 2∶1 ball-to-material ratio, 10min ball milling time)-acid leaching process indicated that the zinc leaching rate reached 87.61% with 70g/L H₂SO₄ and 10∶1 liquid to solid ratio at 35°C, which was 5% higher compared to that without mechanical activation (82.59%). Mechanistic analysis showed that mechanical activation reduced zinc calcine particle size, resulting in lattice distortion and localized damage. After mechanical activation, the crystallinity of zinc ferrite in zinc calcine decreased from 47.90% to 34.50%, thus the leaching agent penetrate into the zinc calcine particles more easily, promoting zinc leaching. The findings of this paper would provide a new approach to the green and low-carbon development of the electro-zinc industry.

The effect of the heavy rare earth element erbium [Er(\mathrm{Ⅲ})] on the short-term and long-term nitrogen removal efficiency of the short-cut nitrification process was studied, and the related kinetic analysis was carried out. Short-term experiments showed that Er(Ⅲ) at the concentration of 0—10mg/L promoted the activity of AOB bacteria, 20—60mg/L Er(Ⅲ) slightly inhibited the activity of AOB bacteria, and 80—120mg/L Er(Ⅲ) showed severe inhibition on the activity of AOB bacteria. AOB bacteria would adsorb a large amount of Er(Ⅲ), and the Er(Ⅲ) removal rate was greater than 90% when the influent Er(Ⅲ) concentration was lower than 60mg/L. However,the Er(Ⅲ) removal rate gradually decreased when the influent Er(Ⅲ) concentration was higher than 60mg/L. The results of ICP-MS and EDS analysis showed that Er(Ⅲ) could be adsorbed extracellularly and uptaked intracellularly by AOB bacteria, and the extracellular adsorption was the main one. The experimental results were fitted by Vadivelu model, Hellinga model, Michaelis-Menten model and Hill model, respectively. The results showed that the inhibition kinetics process of Er (Ⅲ) on AOB bacteria can be better described by subsection fitting (0—60mg/L and 60—120mg/L) using Hill model, the R² obtained by fitting are 0.9909 and 0.9999, respectively, and the maximum matrix removal rate q_max (ΔSNPR) was 2.59mg/(g·h) and 7.15mg/(g·h), respectively. Long-term experiments showed that the performance of the short-cut nitrification system will gradually disappear with the addition of 10mg/L Er(Ⅲ), and the performance of the reaction system could not recover after the addition of Er(Ⅲ) was stopped.