Ce改性钒磷氧催化剂的制备及其脱硝性能研究
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摘要
采用Ce调控负载型钒磷氧(VPO/TiO_2)催化剂的表面酸性并与之形成密切相关的微观结构,研究催化剂VPO-Ce/TiO_2的脱硝性能.结果表明,当P/V为1/3、Ce/V为1/4、活性组分负载量10%、催化剂焙烧温度为400℃时,催化剂的脱硝活性最好,反应温度250～350℃范围内的脱硝率高于96.0%.BET测试结果表明,催化剂0.1VP(0.33)O-Ce(0.25)/TiO_2的比表面积为10.74m~2/g,较0.1VP(0.33)O/TiO2提高了约58.6%.0.1VP(0.33)O/TiO_2表面化学吸附氧(O_α)和晶格氧(O_β)的比例O_α/O_β为72%,掺杂Ce后O_α/O_β升高至85%,Ce掺杂还能促进相邻V~(5+)和V~(4+)的形成,提高催化剂的氧化还原性能.Ce掺杂对催化剂的表面酸性影响较大,当Ce/V为1/4时催化剂表面Br?nsted酸最强,这与活性测试相吻合.控制烟气中SO_2和水蒸气的体积浓度分别为200×10~(-6)和4vol.%,催化剂的脱硝活性在150～300℃温度范围内最高下降约15.8%,当温度高于300℃时催化剂的脱硝活性几乎不下降,且反应后的催化剂表面无硫酸根生成,催化剂呈现出较强的抗SO_2和水蒸汽的性能.
In this paper, the surface acidity and the closely related microstructure of supported vanadium phosphate(VPO/TiO_2) were adjusted by Ce. The denitration performance of VPO-Ce/TiO_2 was also investigated. The results showed that when the P/V was 1/3, the Ce/V 1/4, the loading of active component 10% and the calcination temperature 400℃, the activity of denitrifying catalyst functioned the best with a de-NOx rate above 96% at temperature range of 250～350℃. The BET results showed that the specific surface area of 0.1VP(0.33)O-Ce(0.25)/TiO_2 is 10.74m~2/g and it was 58.6% higher than that of 0.1VP(0.33)O/TiO_2. The mole ratio of chemisorbed oxygen(Oα) and lattice oxygen(Oβ) Oα/Oβ of 0.1VP(0.33)O/TiO_2 was 72% and the Oα/Oβ increased to 85% after Ce doping. Moreover, Ce doping could promote the formation of adjacent V5+ and V4+ and improve the redox performance of catalysts. Ce doping had a great effect on the surface acidity of catalyst and the intensity of Br?nsted acidity of catalyst was highest when Ce/V is 1/4, which was consistent with the activity test. With 200×10-6 SO_2 and 4vol.% water vapor in the feed gas, the denitration activity of 0.1VP(0.33)O-Ce(0.25)/TiO_2 dropped by 20% at most at temperature of 150～300 and it hardly decreased when the temperature ℃was above 300℃. There was no sulfate generated on the 0.1VP(0.33)O-Ce(0.25)/TiO_2 after the activity test and the catalyst showed excellent resistance ability to SO_2 and water vapor.
In this paper, the surface acidity and the closely related microstructure of supported vanadium phosphate(VPO/TiO_2) were adjusted by Ce. The denitration performance of VPO-Ce/TiO_2 was also investigated. The results showed that when the P/V was 1/3, the Ce/V 1/4, the loading of active component 10% and the calcination temperature 400℃, the activity of denitrifying catalyst functioned the best with a de-NOx rate above 96% at temperature range of 250～350℃. The BET results showed that the specific surface area of 0.1VP(0.33)O-Ce(0.25)/TiO_2 is 10.74m~2/g and it was 58.6% higher than that of 0.1VP(0.33)O/TiO_2. The mole ratio of chemisorbed oxygen(Oα) and lattice oxygen(Oβ) Oα/Oβ of 0.1VP(0.33)O/TiO_2 was 72% and the Oα/Oβ increased to 85% after Ce doping. Moreover, Ce doping could promote the formation of adjacent V5+ and V4+ and improve the redox performance of catalysts. Ce doping had a great effect on the surface acidity of catalyst and the intensity of Br?nsted acidity of catalyst was highest when Ce/V is 1/4, which was consistent with the activity test. With 200×10-6 SO_2 and 4vol.% water vapor in the feed gas, the denitration activity of 0.1VP(0.33)O-Ce(0.25)/TiO_2 dropped by 20% at most at temperature of 150～300 and it hardly decreased when the temperature ℃was above 300℃. There was no sulfate generated on the 0.1VP(0.33)O-Ce(0.25)/TiO_2 after the activity test and the catalyst showed excellent resistance ability to SO_2 and water vapor.
引文
[1]胡强,熊志波,白鹏,等.铈钛掺杂促进铁氧化物低温SCR脱硝性能的机理[J].中国环境科学,2016,36(8):2304-2310.Hu Q,Xiong Z B,Bai P,et al.Mechanism of niobium titanium doping promoting low temperature SCR denitrification performance of iron oxide[J].China Environmental Science,2016,36(8):2304-2310.
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[8]王明洪,王亮亮,刘俊,等.过渡金属对选择性催化还原脱硝CeO_2@TiO_2催化剂低温活性的促进作用[J].燃料化学学报,2017,45(4):497-504.Wang M H,Wang L L,Liu J,et al.Promotion of low temperature activity of transition metals on selective catalytic reduction and denitration CeO_2@TiO_2 catalysts[J].Journal of Fuel Chemistry,2017,45(4):497-504.
[9]解智博,宋艳军,梁金生,等.锰基催化剂低温选择催化还原处理NO_x的研究现状与展望[J].材料导报,2017,31(11):38-43.Xie Z B,Song Y J,Liang J S H,et al.Research status and prospect of low-temperature selective catalytic reduction of NOx by manganesebased catalysts[J].Materials Review,2017,31(11):38-43.
[10]马惠言,周丹,刘聚明,等.SO42-/CeO_2-TiO_2光催化材料的制备与光谱表征[J].光谱学与光谱分析,2017,37(10):3315-3320.Ma H Y,Zhou D,Liu J M,et al.Preparation and spectral characterization of SO42-/CeO_2-TiO_2 photocatalytic materials[J].Spectroscopy and Spectral Analysis,2017,37(10):3315-3320.
[11]姜烨,高翔,吴卫红.H2O和SO_2对V2O5/Ti O_2催化剂选择性催化还原烟气脱硝性能的影响[J].中国电机工程学报,2013,33(20):28-33.Jiang W,Gao X,Wu W H.Effect of H2O and SO_2 on selective catalytic reduction of flue gas denitration performance of V2O5/Ti O_2 Catalysts[J].Proceedings of the CSEE,2013,33(20):28-33.
[12]Bond G C,Tahir S F.Vanadium oxide monolayer catalysts preparation,characterization and catalytic activity[J].Applied Catalysis,1991,71(1):1-31.
[13]MelánováK,Bene?L,Vl?ek M,et al.Preparation and characterization of vanadyl phosphates modified with two trivalent metal cations[J].Materials Research bulletin,1999,34(6):895-903
[14]杨瀚.铁铈复合催化剂低温SCR脱硝性能、碱金属中毒机理及成型制备研究[D].南京:东南大学,2016.Yang H.Study on low-temperature SCR denitrification performance,alkali metal poisoning mechanism and molding preparation of ironruthenium composite catalyst[D].Nanjing:Southeast University,2016.
[15]Bagnasco G,Bene?L,Galli P,Massucci MA,atrono P,Turco M,et al.Tg/dta,Xrd and NH3-TPD characterization of layered VOPO4·2H2Oand its Fe3+-substituted compound[J].Journal of Thermal Analysis and Calorimetry 1998,52:615-630.
[16]Yang R,Huang H F,Chen Y J,et al.Performance of Cr-doped vanadia/titania catalysts for low-temperature selective catalytic reduction of NOx with NH3[J].Chinese Journal of Catalysis,2015,36(8):1256-1262.
[17]Ma Z R,Wu X D,Ya F,et al.Low-temperature SCR activity and SO_2deactivation mechanism of Ce-modified V2O5-WO3/Ti O_2 catalyst[J].Progress in Natural Science:Materials International,2015,25(4):342-352.
[18]肖峰,顾韵婕,陈智栋,等.低温SCR脱硝催化剂的制备及其催化性能[J].合成化学,2015,23(6):485-489.Xiao F,Gu Y J,Chen Z D,et al.Preparation and catalytic performance of low temperature SCR denitration catalysts[J].Chinese Journal of Synthetic Chemistry,2015,23(6):485-489.
[19]Yang R,Huang H F,Chen Y J,et al.Performance of Cr-doped vanadia/titania catalysts for low-temperature selective catalytic reduction of NOx with NH3[J].Chinese Journal of Catalysis,2015,36(8):1256-1262.
[20]Gao Y,Thevuthasan S,McCready D E,et al.MOCVD growth and structure of Nb-and V-doped TiO_2films on sapphire[J].Journal of Crystal Growth,2000,212(1/2):178-190.
[21]Liu Z M,Zhang S X,Li J H,et al.Novel V2O5-CeO_2/TiO_2 catalyst with low vanadium loading for the selective catalytic reduction of NOx by NH3[J].Applied Catalysis B:Environmental,2014,158-159:11-19.
[22]Xing M Y,Zhang J L,Chen F.New approaches to prepare nitrogen-doped Ti O_2 photocatalysts and study on their photocatalytic activities in visible light[J].Applied Catalysis B:Environmental,2009,89(3/4):563-569.
[23]Eom Y,Jeon S H,Ngo T A,et al.Heterogeneous mercury reaction on a selective catalytic reduction(SCR)catalyst[J].Catalysis Letters,2008,121:219-225.
[24]Zhang Q M,Chong L S,Feng B,et al.Effect of metal oxide partial substitution of V2O5 in V2O5-WO3/TiO_2 on selective catalytic reduction of NO by NH3[J].Journal of Industrial and Engineering Chemistry,2015,24:79-86.
[25]Jiang Y,Xing Z M,Wang X C,et al.MoO3 modified CeO_2/TiO_2catalyst prepared by a simple step sol-gel method for selective catalytic reduction of NO with NH3[J].Journal of Industrial and Engineering Chemistry,2015,29:43-47.
[26]Cheng K,Liu J,Zhang T,et al.Effect of Ce doping of TiO_2 support on NH3-SCR activity over V2O5-WO3/CeO_2-TiO_2 catalyst[J].Journal of Environmental Sciences,2014,26(10):2106-2113.
[27]Benziger J B,Guliants V,Sundaresan S.New precursor to vanadium phosphorus oxide catalysts[J].Catalysis Today,1997,33(1-3):49-56.
[28]周军,贾勇,李睦,等.乙二酸再生钾中毒催化剂V2O5-WO3/TiO_2的实验研究[J].中国电机工程学报,2016,36(4):1009-1015.Zhou J,Jia Y,Li W,et al.Experimental study on V2O5-WO3/TiO_2catalyst for oxygenate regeneration potassium poisoning[J].Proceedings of the CSEE,2016,36(4):1009-1015.
[29]Shinji I,Satit P,Tadashi H,et al.Involvement of active sites of promoted vanadyl pyrophosphate in selective oxidation of propane[J].Journal of Catalysis,2005,236(2):304-312.
[30]He Y Y,Michael E F,Zhu M H,et al.Influence of catalyst synthesis method on selective catalytic reduction(SCR)of NO by NH3with V2O5-WO3/TiO_2 catalysts[J].Applied Catalysis B:Environmental,2016,193:141-150.
[31]S?ren B R,Ewelina M,Marco D,et al.Structural characteristics of an amophous VPO monolayer on alumina for propane ammoxidation[J].Catalysis Today,2012,192:96-103.
[32]Chiranjit S,Sneha S,Aniruddha M,et al.Synthesis,characterization of VPO catalyst dispersed on mesoporous silica surface and catalytic activity for cyclohexane oxidation reaction[J].Microporous and Mesoporous Materials,2016,223:121-128.
[33]Zang S M,Zhang G Z,Qiu W G,et al.Resistance to SO_2 poisoning of V_2O_5/TiO_2-PILC catalyst for the selective catalytic reduction of NOby NH3[J].Chinese Journal of catalysis,2016,37(6):888-897.
[34]Li Y X,Ma G F,Peng S Q,et al.Boron and nitrogen co-doped titania with enhanced visible-light photocatalytic activity for hydrogen evolution[J].Applied Surface Science,2008,254(21):6831-6836.
[35]Peng F,Cai L,Yu H,et al.Synthesis and characterization of substitutional and interstitial nitrogen-doped titanium dioxides with visible light photocatalytic activity[J].Journal of Solid State Chemistry,2008,181(1):130-136.
[2]刘晶,熊志波,周飞,等.新型铈钨钛复合氧化物催化剂还原脱硝机理[J].中国环境科学,2018,38(5):1670-1676.Liu J,Xiong Z B,Zhou F,et al.Mechanism of reduction and denitrification of a novel cerium-tungsten-titanium composite oxide catalyst[J].China Environmental Science,2018,38(5):1670-1676.
[3]姚小江,马凯莉,邹伟欣,等.制备方法对Mn O_x-CeO_2催化剂理化性质及低温NH3-SCR脱硝性能的影响(英文)[J].催化学报,2017,38(1):146-159.Yao X J,Ma K L,Zou W X,et al.Effect of preparation methods on physicochemical properties of MnOx-CeO_2 catalyst and denitrification performance of NH3-SCR at low temperature(In English)[J].Chinese Journal of Catalysis,2017,38(1):146-159.
[4]An W,Zhang Q,And K T C,et al.A hydrophobic Pt/fluorinated carbon catalyst for reaction of NO with NH3[J].Industrial&Engineering Chemistry Research,2002,41(1):27-31.
[5]唐晓龙,郝吉明,易红宏,等.活性炭改性整体催化剂上低温选择性还原NO_x[J].中国环境科学,2007,27(6):845-850.Tang X L,Hao J M,Yi H H,et al.Low-temperature selective reduction of NOx on activated carbon modified monolith catalyst[J].China Environmental Science,2007,27(6):845-850.
[6]Kim Y J,Kwon H J,Heo I,et al.Mn-Fe/ZSM-5 as a low-temperature SCR catalyst to move NOx from diesel engine exhaust[J].Applied catalysis B:Environmental,2012,126:9-21.
[7]Yang R,Huang H F,Chen Y J,et al.Performance of Cr-doped vanadia/titania catalysts for low-temperature selective catalytic reduction of NOx with NH3[J].Chinese Journal Catalysis,2015,36:1256-1262.
[8]王明洪,王亮亮,刘俊,等.过渡金属对选择性催化还原脱硝CeO_2@TiO_2催化剂低温活性的促进作用[J].燃料化学学报,2017,45(4):497-504.Wang M H,Wang L L,Liu J,et al.Promotion of low temperature activity of transition metals on selective catalytic reduction and denitration CeO_2@TiO_2 catalysts[J].Journal of Fuel Chemistry,2017,45(4):497-504.
[9]解智博,宋艳军,梁金生,等.锰基催化剂低温选择催化还原处理NO_x的研究现状与展望[J].材料导报,2017,31(11):38-43.Xie Z B,Song Y J,Liang J S H,et al.Research status and prospect of low-temperature selective catalytic reduction of NOx by manganesebased catalysts[J].Materials Review,2017,31(11):38-43.
[10]马惠言,周丹,刘聚明,等.SO42-/CeO_2-TiO_2光催化材料的制备与光谱表征[J].光谱学与光谱分析,2017,37(10):3315-3320.Ma H Y,Zhou D,Liu J M,et al.Preparation and spectral characterization of SO42-/CeO_2-TiO_2 photocatalytic materials[J].Spectroscopy and Spectral Analysis,2017,37(10):3315-3320.
[11]姜烨,高翔,吴卫红.H2O和SO_2对V2O5/Ti O_2催化剂选择性催化还原烟气脱硝性能的影响[J].中国电机工程学报,2013,33(20):28-33.Jiang W,Gao X,Wu W H.Effect of H2O and SO_2 on selective catalytic reduction of flue gas denitration performance of V2O5/Ti O_2 Catalysts[J].Proceedings of the CSEE,2013,33(20):28-33.
[12]Bond G C,Tahir S F.Vanadium oxide monolayer catalysts preparation,characterization and catalytic activity[J].Applied Catalysis,1991,71(1):1-31.
[13]MelánováK,Bene?L,Vl?ek M,et al.Preparation and characterization of vanadyl phosphates modified with two trivalent metal cations[J].Materials Research bulletin,1999,34(6):895-903
[14]杨瀚.铁铈复合催化剂低温SCR脱硝性能、碱金属中毒机理及成型制备研究[D].南京:东南大学,2016.Yang H.Study on low-temperature SCR denitrification performance,alkali metal poisoning mechanism and molding preparation of ironruthenium composite catalyst[D].Nanjing:Southeast University,2016.
[15]Bagnasco G,Bene?L,Galli P,Massucci MA,atrono P,Turco M,et al.Tg/dta,Xrd and NH3-TPD characterization of layered VOPO4·2H2Oand its Fe3+-substituted compound[J].Journal of Thermal Analysis and Calorimetry 1998,52:615-630.
[16]Yang R,Huang H F,Chen Y J,et al.Performance of Cr-doped vanadia/titania catalysts for low-temperature selective catalytic reduction of NOx with NH3[J].Chinese Journal of Catalysis,2015,36(8):1256-1262.
[17]Ma Z R,Wu X D,Ya F,et al.Low-temperature SCR activity and SO_2deactivation mechanism of Ce-modified V2O5-WO3/Ti O_2 catalyst[J].Progress in Natural Science:Materials International,2015,25(4):342-352.
[18]肖峰,顾韵婕,陈智栋,等.低温SCR脱硝催化剂的制备及其催化性能[J].合成化学,2015,23(6):485-489.Xiao F,Gu Y J,Chen Z D,et al.Preparation and catalytic performance of low temperature SCR denitration catalysts[J].Chinese Journal of Synthetic Chemistry,2015,23(6):485-489.
[19]Yang R,Huang H F,Chen Y J,et al.Performance of Cr-doped vanadia/titania catalysts for low-temperature selective catalytic reduction of NOx with NH3[J].Chinese Journal of Catalysis,2015,36(8):1256-1262.
[20]Gao Y,Thevuthasan S,McCready D E,et al.MOCVD growth and structure of Nb-and V-doped TiO_2films on sapphire[J].Journal of Crystal Growth,2000,212(1/2):178-190.
[21]Liu Z M,Zhang S X,Li J H,et al.Novel V2O5-CeO_2/TiO_2 catalyst with low vanadium loading for the selective catalytic reduction of NOx by NH3[J].Applied Catalysis B:Environmental,2014,158-159:11-19.
[22]Xing M Y,Zhang J L,Chen F.New approaches to prepare nitrogen-doped Ti O_2 photocatalysts and study on their photocatalytic activities in visible light[J].Applied Catalysis B:Environmental,2009,89(3/4):563-569.
[23]Eom Y,Jeon S H,Ngo T A,et al.Heterogeneous mercury reaction on a selective catalytic reduction(SCR)catalyst[J].Catalysis Letters,2008,121:219-225.
[24]Zhang Q M,Chong L S,Feng B,et al.Effect of metal oxide partial substitution of V2O5 in V2O5-WO3/TiO_2 on selective catalytic reduction of NO by NH3[J].Journal of Industrial and Engineering Chemistry,2015,24:79-86.
[25]Jiang Y,Xing Z M,Wang X C,et al.MoO3 modified CeO_2/TiO_2catalyst prepared by a simple step sol-gel method for selective catalytic reduction of NO with NH3[J].Journal of Industrial and Engineering Chemistry,2015,29:43-47.
[26]Cheng K,Liu J,Zhang T,et al.Effect of Ce doping of TiO_2 support on NH3-SCR activity over V2O5-WO3/CeO_2-TiO_2 catalyst[J].Journal of Environmental Sciences,2014,26(10):2106-2113.
[27]Benziger J B,Guliants V,Sundaresan S.New precursor to vanadium phosphorus oxide catalysts[J].Catalysis Today,1997,33(1-3):49-56.
[28]周军,贾勇,李睦,等.乙二酸再生钾中毒催化剂V2O5-WO3/TiO_2的实验研究[J].中国电机工程学报,2016,36(4):1009-1015.Zhou J,Jia Y,Li W,et al.Experimental study on V2O5-WO3/TiO_2catalyst for oxygenate regeneration potassium poisoning[J].Proceedings of the CSEE,2016,36(4):1009-1015.
[29]Shinji I,Satit P,Tadashi H,et al.Involvement of active sites of promoted vanadyl pyrophosphate in selective oxidation of propane[J].Journal of Catalysis,2005,236(2):304-312.
[30]He Y Y,Michael E F,Zhu M H,et al.Influence of catalyst synthesis method on selective catalytic reduction(SCR)of NO by NH3with V2O5-WO3/TiO_2 catalysts[J].Applied Catalysis B:Environmental,2016,193:141-150.
[31]S?ren B R,Ewelina M,Marco D,et al.Structural characteristics of an amophous VPO monolayer on alumina for propane ammoxidation[J].Catalysis Today,2012,192:96-103.
[32]Chiranjit S,Sneha S,Aniruddha M,et al.Synthesis,characterization of VPO catalyst dispersed on mesoporous silica surface and catalytic activity for cyclohexane oxidation reaction[J].Microporous and Mesoporous Materials,2016,223:121-128.
[33]Zang S M,Zhang G Z,Qiu W G,et al.Resistance to SO_2 poisoning of V_2O_5/TiO_2-PILC catalyst for the selective catalytic reduction of NOby NH3[J].Chinese Journal of catalysis,2016,37(6):888-897.
[34]Li Y X,Ma G F,Peng S Q,et al.Boron and nitrogen co-doped titania with enhanced visible-light photocatalytic activity for hydrogen evolution[J].Applied Surface Science,2008,254(21):6831-6836.
[35]Peng F,Cai L,Yu H,et al.Synthesis and characterization of substitutional and interstitial nitrogen-doped titanium dioxides with visible light photocatalytic activity[J].Journal of Solid State Chemistry,2008,181(1):130-136.