钒钛基SCR脱硝催化剂碱土金属中毒
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摘要
分别制备了钒钨体系和钒钼体系的新鲜催化剂,并通过浸渍法、固态扩散法与干混法分别制备了碱土金属中毒的催化剂,比较了中毒方法、碱土金属以及催化助剂种类等因素对催化剂脱硝活性的影响,并利用程序升温脱附(NH_3-TPD)、程序升温还原(H_2-TPR)和X射线光电子能谱分析(XPS)等表征手段进行分析。结果表明,3种中毒方法中,浸渍法碱土金属中毒对催化剂毒害作用最大;Ca对催化剂的毒性大于Mg,且钒钼体系催化剂比钒钨体系催化剂具有更强的抗碱土金属中毒性能。碱土金属的存在会降低催化剂表面的总酸量与酸位点的强度,提高催化剂的还原温度,改变活性组分的价态并降低催化剂上表面活性氧的比例。
Fresh V-W and V-Mo based SCR catalysts were prepared, and then poisoned by alkaline earth metals through three methods, i.e., impregnation, solid phase diffusion and dry mixing. Experiments were performed to investigate the denitrification activity of the catalysts affected by the poisoning method,alkaline earth metal type, catalyst promoter type and other factors. In addition, the catalysts were characterized by temperature programmed desorption(NH_3-TPD), temperature programmed reduction(H_2-TPR) and X-ray photoelectron spectroscopy(XPS). The results showed that among the three poisoning methods, impregnation exhibited the most significant poisoning effect on the catalysts. Ca was more toxic to the catalyst than Mg. V-Mo based catalyst possessed better anti-poisoning performance than V-W based catalyst. The presence of alkaline earth metal had many significant effects on the catalysts, including reducing the total acid sites and the acidity intensity on the catalyst surface,increasing the catalyst reduction temperature, altering the valence of the active component, and decreasing the proportion of surface active oxygen.
Fresh V-W and V-Mo based SCR catalysts were prepared, and then poisoned by alkaline earth metals through three methods, i.e., impregnation, solid phase diffusion and dry mixing. Experiments were performed to investigate the denitrification activity of the catalysts affected by the poisoning method,alkaline earth metal type, catalyst promoter type and other factors. In addition, the catalysts were characterized by temperature programmed desorption(NH_3-TPD), temperature programmed reduction(H_2-TPR) and X-ray photoelectron spectroscopy(XPS). The results showed that among the three poisoning methods, impregnation exhibited the most significant poisoning effect on the catalysts. Ca was more toxic to the catalyst than Mg. V-Mo based catalyst possessed better anti-poisoning performance than V-W based catalyst. The presence of alkaline earth metal had many significant effects on the catalysts, including reducing the total acid sites and the acidity intensity on the catalyst surface,increasing the catalyst reduction temperature, altering the valence of the active component, and decreasing the proportion of surface active oxygen.
引文
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[18]TOPSOE N,TOPSOE H,DUMESIC J.Vanadia/titania catalysts for selective catalytic reduction(SCR)of nitric-oxide by ammonia:Ⅰ.Combined temperature-programmed in-situ FTIR and on-line massspectroscopy studies[J].Journal of Catalysis,1995,151(1):226-240.
[19]TOPSOE N,DUMESIC J,TOPSOE H.Vanadia-titania catalysts for selective catalytic reduction of nitric-oxide by ammonia:ⅡStudies of active sites and formulation of catalytic cycles[J].Journal of Catalysis,1995,151(1):241-252.
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[22]KIETVKA M,DIAS A P S,KUBICZEK H,et al.The influence of poisoning on the deactivation of deNOx catalysts[J].Comptes RendusChimie,2015,18(10):1036-1048.
[2]顾卫荣,周明吉,马薇,等.选择性催化还原脱硝催化剂的研究进展[J].化工进展,2012,31(7):1493-1500.GU W R,ZHOU M J,MA W,et al.Research progress on selective catalytic reduction de-NOx catalysts[J].Chemical Industry and Engineering Progress,2012,31(7):1493-1500.
[3]陈晨,陆强,蔺卓玮,等.燃煤电厂废弃SCR脱硝催化剂元素回收研究进展[J].化工进展,2016,35(10):3306-3312.CHEN C,LU Q,LIN Z W,et al.Research progress of element recovery of waste de-NOx SCR catalyst from coal-fired power plants[J].Chemical Industry and Engineering Progress,2016,35(10):3306-3312.
[4]牟洋,杨娟,余剑,等.金属硫酸盐与氧化物助剂对SCR脱硝催化剂性能的影响[J].化工学报,2013,64(9):3220-3227.MOU Y,YANG J,YU J,et al.Effect of metal sulfate and oxide additives on performance of SCR denitration catalyst[J].Chemistry,2013,64(9):3220-3227.
[5]李想,李俊华,何煦,等.烟气脱硝催化剂中毒机制与再生技术[J].化工进展,2015,34(12):4129-4138.LI X,LI J H,HE X,et al.Poisoning mechanism and regeneration process of the denitration catalyst[J].Chemical Industry and Engineering Progress,2015,34(12):4129-4138.
[6]苗强.脱硝技术的现状及展望[J].洁净煤技术,2017,23(2):12-19.MIAO Q.Progress and prospects of denitration technology[J].Clean Coal Technology,2017,23(2):12-19.
[7]LIETTIL L,NOVA I,FORZATTI P.Selective catalytic reduction(SCR)of NO by NH3over TiO2-supported V2O5-WO3and V2O5-MoO3catalysts[J].Topics in Catalysis,2000,11(1/2/3/4):111-122.
[8]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 Processing Technology,2005,86(5):577-613.
[9]KERN P,KLIMCZAK M,HEINZELMANN T,et al.High-throughput study of the effects of inorganic additives and poisons on NH3-SCRcatalysts.PartⅡ:Fe-zeolite catalysts[J].Applied Catalysis B:Environmental,2010,95(1):48-56.
[10]NICOSIA D,CZEKAJ O,KROCHER O.Chemical deactivation of V2O5-WO3/TiO2SCR catalysts by additives and impurities from fuels,lubrication oils and urea solution PartⅡ:characterization study of the effect of alkali and alkaline earth metals[J].Applied Catalysis B:Environmental,2008,77(3/4):228-236.
[11]LI X,LI X S,RALPH T,et al.The poisoning effects of calcium on V2O5-WO3/TiO2catalyst for the SCR reaction:comparison of different forms of calcium[J].Molecular Catalysis,2017,434:16-24.
[12]沈伯雄,卢凤菊,高兰君,等.中温商业SCR催化剂碱和碱土中毒特性研究[J].燃料化学学报,2016,44(4):500-506.SHEN B X,LU F J,GAO L J,et al.Study on alkali and alkaline earths poisoning characteristics for a commercial SCR catalyst[J].Journal of Fuel Chemistry and Technology,2016,44(4):500-506.
[13]沈伯雄,陈建宏,姚燕,等.碱土金属对MnOx-CeO2/ZrO2-PILC催化剂SCR活性影响研究[J].燃料化学学报,2012,40(12):1487-1491.SHEN B X,CHEN J H,YAO Y,et al.Effects of alkali metals on catalyst of MnOx-CeO2/ZrO2-PILC in the low-temperature selective catalytic reduction[J].Journal of Fuel Chemistry and Technology,2012,40(12):1487-1491.
[14]LI X,LI X S,LI J H,et al.High calcium resistance of CeO2-WO3SCRcatalysts:structure investigation and deactivation analysis[J].Chemical Engineering Journal,2017,317(1):70-79.
[15]LI X S,LIU C D,LI X,et al.A neutral and coordination regeneration method of Ca-poisoned V2O5-WO3/TiO2SCR catalyst[J].Catalysis Communications,2017,100:112-116.
[16]REICHE M A.Characterization by temperature programmed reduction[J].Catalysis Today,2000,56(4):347-355.
[17]LI X,LI X S,CHEN J J,et al.An efficient novel regeneration method forCa-poisoningV2O5-WO3/TiO2catalyst[J].CatalysisCommunications,2016,87(5):45-48.
[18]TOPSOE N,TOPSOE H,DUMESIC J.Vanadia/titania catalysts for selective catalytic reduction(SCR)of nitric-oxide by ammonia:Ⅰ.Combined temperature-programmed in-situ FTIR and on-line massspectroscopy studies[J].Journal of Catalysis,1995,151(1):226-240.
[19]TOPSOE N,DUMESIC J,TOPSOE H.Vanadia-titania catalysts for selective catalytic reduction of nitric-oxide by ammonia:ⅡStudies of active sites and formulation of catalytic cycles[J].Journal of Catalysis,1995,151(1):241-252.
[20]CHEN L,LI J H,GE M F.The poisoning effect of alkali metals doping over nano V2O5-WO3/TiO2catalysts on selective catalytic reduction of NOx by NH3[J].Chemical Engineering Journal,2010,170(2/3):531-537.
[21]蔺卓玮,陆强,唐昊,等.平板式V2O5-MoO3/TiO2型SCR催化剂的中低温脱硝和抗中毒性能研究[J].燃料化学学报,2017,45(1):113-122.LIN Z W,LU Q,TANG H,et al.Research on the middle-low temperature denitration and anti-poisoning properties of plate V2O5-MoO3/TiO2SCR catalysts[J].Journal of Fuel Chemistry and Technology,2017,45(1):113-122.
[22]KIETVKA M,DIAS A P S,KUBICZEK H,et al.The influence of poisoning on the deactivation of deNOx catalysts[J].Comptes RendusChimie,2015,18(10):1036-1048.