失活V_2O_5-WO_3/TiO_2 SCR脱硝催化剂的再生方法
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摘要
针对模拟钙中毒的商业V_2O_5-WO_3/TiO_2选择性催化还原(SCR)脱硝催化剂,选用络合剂乙二胺四乙酸(EDTA)、表面活性剂十二烷基苯磺酸(LAS)两种清洗剂配合超声波震荡方法对其进行清洗再生,并结合活性测试以及多种表征手段,研究清洗剂浓度及组配方式和清洗时间对钙中毒催化剂的活性恢复及物化性能变化的影响。结果表明:0.01 mol/L的EDTA水溶液辅助超声波震荡清洗30 min取得较好的再生效果,清洗再生后的催化剂脱硝活性在400℃达到85%以上,恢复到新鲜催化剂活性的近90%,并且CaSO_4的去除率达到92%以上,钒和钨的残余率分别为99.4%和98.3%。此外,增加少量的LAS可以微弱地提升CaSO_4的去除率和催化剂的脱硝活性。清洗再生机理研究表明,EDTA可以较好地恢复催化剂的微孔结构、去除表面条带状硫酸钙涂覆层、恢复催化剂表面Lewis酸位以及1 680 cm~(-1)处的Br?nsted酸位。EDTA和LAS均可以有效提高催化剂的氧化还原能力。
For commercial V_2O_5-WO_3/TiO_2 selective catalytic reduction(SCR) denitration catalyst for simulating calcium poisoning,two complexing agents, i.e., ethylenediaminetetraacetic acid(EDTA) and surfactant Dodecylbenzenesulfonic acid(LAS), were selected to clean and regenerate the calcium-poisoned samples with the assistance of ultrasonic oscillation. The effects of concentration of cleaning agent, the combined ratio of cleaning agents and cleaning time on the catalytic performance and physio-chemical properties of the poisoned catalysts were investigated. The results show that aqueous solution of 0.01 mol/L EDTA is assisted by ultrasonic cleaning for 30 min to obtain the effective regeneration. The NOx conversion of Ca-poisoned catalyst can reach r 85% at 400 ℃, the recovery of the fresh counterpart can be 90%, the removal rate of CaSO_4 is over 92% and the residual rates of vanadium and tungsten are 99.4% and 98.3%, respectively. The addition of a small amount of LAS can improve the removal rate of CaSO_4 and the denitration activity of the catalyst. In addition, the cleaning and regeneration mechanism was also analyzed. It is indicated that EDTA can restore the microporous structure of the catalyst, remove the surface banded calcium sulfate coating layer and recover the Lewis acid sites and the Br?nsted acid sites at 1 680 cm~(–1). EDTA and LAS both can effectively improve the redox ability of the catalyst.
For commercial V_2O_5-WO_3/TiO_2 selective catalytic reduction(SCR) denitration catalyst for simulating calcium poisoning,two complexing agents, i.e., ethylenediaminetetraacetic acid(EDTA) and surfactant Dodecylbenzenesulfonic acid(LAS), were selected to clean and regenerate the calcium-poisoned samples with the assistance of ultrasonic oscillation. The effects of concentration of cleaning agent, the combined ratio of cleaning agents and cleaning time on the catalytic performance and physio-chemical properties of the poisoned catalysts were investigated. The results show that aqueous solution of 0.01 mol/L EDTA is assisted by ultrasonic cleaning for 30 min to obtain the effective regeneration. The NOx conversion of Ca-poisoned catalyst can reach r 85% at 400 ℃, the recovery of the fresh counterpart can be 90%, the removal rate of CaSO_4 is over 92% and the residual rates of vanadium and tungsten are 99.4% and 98.3%, respectively. The addition of a small amount of LAS can improve the removal rate of CaSO_4 and the denitration activity of the catalyst. In addition, the cleaning and regeneration mechanism was also analyzed. It is indicated that EDTA can restore the microporous structure of the catalyst, remove the surface banded calcium sulfate coating layer and recover the Lewis acid sites and the Br?nsted acid sites at 1 680 cm~(–1). EDTA and LAS both can effectively improve the redox ability of the catalyst.
引文
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[3]CHEN F,HUANG B C,YANG Y X,et al.Synthesis,characterization and NH3-SCR activity of MnSAPO-34 molecular sieves[J].Acta Phys Chim Sin,2015,31(12):2375-2385.
[4]XIONG S C,XIAO X,LIAO Y,et al.Global kinetic study of NOreduction by NH3 over V2O5-WO3/Ti O2:Relationship between the SCR performance and the key factors[J].Ind Eng Chem Res,2015,54:11011-11023.
[5]BOSCH F J H.Formation and control of nitrogen oxide[J].Catal Today,1988,2(4):369-379.
[6]张强,张发捷,程广文,等.一种离线清洗钙中毒SCR脱硝催化剂的清洗剂及清洗方法[P].CN Patent,103599816 A.2014-04-26.ZHANG Qiang,ZHANG Fajie,CHENG Guangwen,et al.Cleaning agent and cleaning method for offline leaning calcium poisoning SCRdenitration catalyst(in Chinese).CN Patent,103599816A.2014-04-26.
[7]张发捷,张强,程广文,等.SCR脱硝催化剂再生技术试验研究[J].热力发电,2015,3(44):34-41.ZHANG Fajie,ZHANG Qiang,CHENG Guangwen,et al.Therm Power Gen(in Chinese),2015,3(44):34-41.
[8]杨震,魏冬雪.某电厂湿法烟气脱硫系统的除垢阻垢研究[J].硅酸盐学报,2015,34(6):1705-1709.YANG Zhen,WEI Dongxue.J Chin Ceram Soc,2015,34(6):1705-1709.
[9]王静,沈伯雄,刘亭,等.钒钛基SCR催化剂中毒及再生研究进展[J].环境科学与技术,2010,33(9):97-101.WANG Jing,SHEN Boxiong,LIU Ting,et al.Environ Sci Technol(in Chinese),2010,33(9):97-101.
[10]温继伟,王孝强,董长青,等.失活SCR脱硝催化剂再生技术试验研究[J].电力科技与环保,2018,34(3):23-26.WEN Jiwei,WANG Xiaoqiang,DONG Changqing,et al.Electric Power Technol Environ Protect(in Chinese),2018,34(3):23-26.
[11]刘平,陶政修.醋酸钙溶液吸收二氧化硫烟气的试验研究[J].环境科学导刊,2007,26(1):4-6.LIU Ping,TAO Zhengxiu.Environ Sci Surv(in Chinese),2007,26(1):4-6.
[12]白伟,赵冬梅,肖雨亭.失活SCR脱硝催化剂化学清洗再生技术研究[J].中国电力,2015,48(4):6-10.BAI Wei,ZHAO Dongmei,XIAO Yuting.Electric Power(in Chinese),2015,48(4):6-10.
[13]BENSON S A,LAUMB J D,CROCKER C R,et al.SCR catalyst performance in flue gases derived from subbituminous and lignite coals[J].Fuel Process Technol,2005,86(5):577-613.
[14]RAMOS-LUNA M A,CEDENO-CAERO L.Effect of sulfates and reduced-vanadium species on oxidative desulfurization(ODS)with V2O5/TiO2 catalysts[J].Ind Eng Chem Res,2010,50(5):2641-2649.
[15]SCHUTTE R W,AMOCO PRODUCTION C.根据EDTA化学特性选择硫酸钙垢清洗的最佳条件[J].清洗世界,1992,8(4):25-31.SCHUTTE R W,AMOCO PRODUCTION C.Clean World(in Chinese),1992,8(4):25-31.