Ag/BiOI光催化剂湿法脱除烟气中气态单质汞性能及机理

doi:10.16085/j.issn.1000-6613.2017-1314

摘要/Abstract

摘要： 采用沉淀-光还原法制备了不同Ag含量的Ag/BiOI可见光催化剂，利用XRD、N₂吸附-脱附、SEM、TEM、XPS、DRS、光电流和ESR对其物化结构进行表征，在湿法鼓泡反应器脱汞装置上考察了Ag负载量、光照、SO₂和NO对气态单质汞（Hg⁰）脱除性能的影响。结果表明，与BiOI相比，Ag添加后光催化剂的脱汞效率大幅提高。当Ag负载质量分数为2%时，Ag/BiOI催化剂的脱汞效率高达98%。荧光灯辐照对Ag（2%）/BiOI催化剂的高效脱汞至关重要。与NO相比，SO₂对脱汞效率的影响颇为明显。与BiOI相比，Ag（2%）/BiOI中BiOI的边缘出现较多的Ag微颗粒，且Ag颗粒分散度较好；Ag的添加可以提高BiOI表面的化学吸附态氧含量和增强BiOI在可见光波段的吸收能力，有利于其高效脱汞。机理分析表明，超氧阴离子自由基（^•O₂^-）和空穴（h⁺）在光催化脱汞过程中起主要作用。

关键词: 鼓泡反应器, 催化剂, 银/碘氧化铋, 单质汞脱除, 烟气

Abstract: A series of Ag/BiOI visible-light-driven photocatalysts were successfully synthesized by the precipitation-photoreduction method. The physical-chemical structures of the composites were characterized by X-ray diffraction(XRD), N₂ adsorption-desorption, scanning electron microscope(SEM), transmission electron microscope(TEM), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectroscopy(DRS), photocurrent test and electron spin resonance (ESR). The effects of Ag content, fluorescent lamp (FSL) irradiation, SO₂ and NO on the removal of gaseous elemental mercury(Hg⁰) were investigated in a wet bubbling reactor. The results showed that in comparison to BiOI, the mercury removal efficiency of Ag/BiOI was greatly improved when silver microparticles were added. In particular, with Ag content of 2% in Ag/BiOI, the mercury removal efficiency reached as high as 98%. The presence of FSL irradiation was very essential for keeping high Hg⁰ removal efficiency. Compared to NO, SO₂ showed a dramatic inhibition on Hg⁰ removal. The characterization results showed that some Ag microparticles were highly dispersed onto the surface of BiOI. The content of chemisorbed oxygen and absorption ability in visible light range were significantlyenhanced when Ag microparticles were doped onto the surface of BiOI, which could be beneficial for its high activity of mercury removal. The mechanism analysis indicated that superoxide radicals(^•O₂^-) and photoinduced holes(h⁺) were the primary active substances in the photocatalytic removal of Hg⁰.

Key words: bubbling reactor, catalyst, Ag/BiOI, elemental mercury removal, flue gas

中图分类号:

X511

李成伟, 张安超, 宋军, 张立享, 张丹, 刘志超. Ag/BiOI光催化剂湿法脱除烟气中气态单质汞性能及机理[J]. 化工进展, 2018, 37(04): 1442-1450.

LI Chengwei, ZHANG Anchao, SONG Jun, ZHANG Lixiang, ZHANG Dan, LIU Zhichao. Mechanism and performance of wet process to remove gaseous elemental mercury from flue gas using Ag/BiOI photocatalyst[J]. Chemical Industry and Engineering Progress, 2018, 37(04): 1442-1450.

参考文献

[1] WANG S B,WU H W. Environmental-benign utilisation of fly ash as low-cost adsorbents[J]. Journal of Hazardous Materials,2006,136(3):482-501.
[2] PACYNA E G,PACYNA J M,SUNDSETH K,et al. Global emission of mercury to the atmosphere from anthropogenic sources in 2005 and projections to 2020[J]. Atmospheric Environment,2010,44(20):2487-2499.
[3] GALBREATH K C,ZYGARLICKE C J. Mercury transformations in coal combustion flue gas[J]. Fuel Processing Technology,2000,65:289-310.
[4] 李洋,陈敏东,薛志钢,等. 燃煤电厂协同脱汞研究进展及强化措施[J]. 化工进展,2014,33(8):2187-2191. LI Y,CHEN M D,XUE Z G,et al. Research on synergistic mercury removal of coal-fired power plants[J]. Chemical Industry and Engineering Progress,2014,33(8):2187-2191.
[5] 张君,李志超,段钰锋,等. 燃煤电厂汞迁移排放及脱除[J]. 燃烧科学与技术,2015,21(5):415-420. ZHANG J,LI Z C,DUAN Y F,et al. Migrate emission and removal of mercury in coal-fired power plant[J]. Journal of Combustion Science and Technology,2015,21(5):415-420.
[6] 睢辉,张梦泽,董勇,等. 燃煤烟气中单质汞吸附与氧化机理研究进展[J]. 化工进展,2014,33(6):1582-1588. SUI H,ZHANG M Z,DONG Y,et al. Research progress of adsorption and oxidation mechanism of elemental mercury from coal-fired flue gas[J]. Chemical Industry and Engineering Progress,2014,33(6):1582-1588.
[7] ZHAN F M,LI C T,ZENG G M,et al. Experimental study on oxidation of elemental mercury by UV/Fenton system[J]. Chemical Engineering Journal,2013,232(9):81-88.
[8] 苑鹏, 卢凤菊, 梅雪,等. 高级氧化法在烟气脱硫脱硝脱汞中的应用研究进展[J]. 化工进展,2016,35(10):3313-3322. WAN P,LU F J,MEI X,et al. Recent progress on application of advanced oxidation processes(AOPs)to remove SO₂,NO_x and Hg⁰ from flue gas[J]. Chemical Industry and Engineering Progress,2016,35(10):3313-3322.
[9] 王伶俐,方艳芬,顾彦,等. 模板法制备BiOI及其可见光降解有机污染物[J]. 太阳能学报,2014,35(5):918-924. WANG L L,FANG Y F,GU Y,et al. BiOI synthetized by template and its degradation of organic pollutants under visible light[J]. Acta Energiae Solaris Sinica,2014,35(5):918-924.
[10] 毛茂乔,单国强,夏佳慧,等. 水热法合成BiOI及在模拟太阳光下对双酚A的降解[J]. 科学通报,2014,59(31):3072-3079. MAO M Q,SHAN G Q,XIA J H,et al. Preparation of BiOI by a hydrothermal method and photodegradation of bisphenol A under simulated solar light irradiation[J]. Chinese Science Bulletin,2014,59(31):3072-3079.
[11] ZHANG X,AI Z H,JIA F L,et al. Generalized one-pot synthesis, characterization, and photocatalytic activity of hierarchical BiOX (X=Cl, Br, I)nanoplate microspheres[J]. J. Phys. Chem. C,2008,112(3):747-753.
[12] 刘思瑶,王永强,赵东风,等. BiOI/BiVO₄异质结光催化剂的合成及其催化活性的研究[J]. 人工晶体学报,2016,45(1):15-20. LIU S Y,WANG Y Q,ZHAO D F,et al. Synthesis and photoactivity of BiOI/BiVO₄heterojunction composite photocatalyst[J]. Journal of Synthetic Crystals,2016,45(1):15-20.
[13] 邵先坤,郝勇敢,刘同宣,等. 基于表面等离子体共振效应的Ag(Au)/半导体纳米复合光催化剂的研究进展[J]. 化工进展,2016,35(1):131-137. SHAO X K,HAO Y G,LIU T X,et al. Research progress of Ag(Au) semiconductor nanohybrid photocatalysts based on surface plasmon resonance[J]. Chemical Industry and Engineering Progress,2016,35(1):131-137.
[14] YU C L,YU J C,FAN C F,et al. Synthesis and characterization of Pt/BiOI nanoplate catalyst with enhanced activity under visible light irradiation[J]. Materials Science and Engineering B,2010,166:213-219.
[15] 王欢,崔文权,韩炳旭,等. Ag/AgX(X=Cl,Br,I)等离子共振光催化剂的研究进展[J]. 化工进展,2013,32(2):346-351. WANG H,CUI W Q,HAN B X,et al. Research progress of plasmonic Ag/AgX(X=Cl,Br,I) photocatalysts[J]. Chemical Industry and Engineering Progress,2013,32(2):346-351.
[16] ZHU L F,HE C,HUANG Y L,et al. Enhanced photocatalytic disinfection of E. coli 8099 using Ag/BiOI composite under visible light irradiation[J]. Separation and Purification Technology,2012,91:59-66.
[17] ZHANG A C,XING W B,ZHANG D,et al. A novel low-cost method for Hg⁰ removal from flue gas by visible-light-driven BiOX (X=Cl,Br,I) photocatalysts[J]. Catalysis Communications,2016,87:57-61.
[18] ZHANG A C,ZHANG L X,LU H,et al. Facile synthesis of ternary Ag/AgBr-Ag₂CO₃ hybrids with enhanced photocatalytic removal of elemental mercury driven by visible light[J]. Journal of Hazardous Materials,2016,314:78-87.
[19] 余长林,操芳芳,舒庆,等. Ag/BiOX(X=Cl,Br,I)复合光催化剂的制备、表征及其光催化性能[J]. 物理化学学报,2012,28(3):647-653. YU C L,CAO F F,SHU Q,et al. Preparation,Characterization and photocatalytic performance of Ag/BiOX(X=Cl,Br,I)composite potocatalysts[J]. Acta Physico-Chimica Sinica,2012,28(3):647-653.
[20] 陈鹏,刘红婧,董帆,等. 可见光诱导Ag/AgX等离子体光催化净化NO的性能与机理[J]. 科学通报,2016,61(32):3482-3489. CHEN P,LIU H J,DONG F,et al. Performance and mechanism of visible-light-induced plasmonic photocatalytic purification of NO with Ag/AgX[J]. Chinese Science Bulletin,2016,61(32):3482-3489.
[21] LI G T,WONG K H,ZHANG X W,et al. Degradation of acid orange 7 using magnetic AgBr under visible light:the roles of oxidizing species[J]. Chemosphere,2009,76(9):1185-1191.
[22] LIU Y X,ZHANG J,PAN J F,et al. Investigation on removal of NO from SO₂-containing simulated flue gas by UV/Fenton-like reaction[J]. Energy Fuels, 2012,26:5430-5436.
[23] CHENG H,HUANG B,DAI Y,et al. One-step synthesis of the nanostructured AgI/BiOI composites with highly enhanced visible-light photocatalytic performances[J]. Langmuir,2010,26:6618-6624.
[24] ZHANG X C,LU B Q,LI R,et al. Simple hydrolysis-photodeposition route to synthesize Ag/BiOCl_0.5Br_0.5 composites with highly enhanced visible-light photocatalytic properties[J]. Separation and Purification Technology,2015,154:68-75.
[25] ZHOU C C,CAO J,LIN H L,et al. Controllable synthesis and photocatalytic activity of Ag/BiOI based on the morphology effect of BiOI substrate[J]. Surface and Coatings Technology,2015,272:213-220.
[26] LIU H,CAO W R,SU Y,et al. Synthesis,characterization and photocatalytic performance of novel visible-light-induced Ag/BiOI[J]. Applied Catalysis B:Environmental,2012,112:271-279.
[27] HAN L,WANG P,ZHU C,et al. Facile solvothermal synthesis of cube-like Ag@AgCl:a highly efficient visible light photocatalyst[J]. Nanoscale,2011,3(7):2931-2935.
[28] LIN L,HUANG M H,LONG L P,et al. Fabrication of a three-dimensional BiOBr/BiOI photocatalyst with enhanced visible light photocatalytic performance[J]. Ceramics International,2014,40:11493-11501.