TPAOH处理HZSM-5分子筛及其催化丙烷脱氢反应性能研究
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摘要
用不同浓度的四丙基氢氧化铵(TPAOH)溶液对HZSM-5分子筛进行处理,对碱处理前后的HZSM-5分子筛负载Pt,制备Pt/HZSM-5催化剂并将其用于丙烷脱氢反应。利用XRD、SEM、N_2吸附-脱附、NH_3-TPD、H_2化学吸附、FT-IR和TG等手段对处理前后的HZSM-5分子筛进行表征,考察了不同浓度的TPAOH溶液处理对HZSM-5分子筛的晶体结构、表面形貌、孔结构、表面酸性及丙烷脱氢性能的影响。结果表明:采用TPAOH溶液处理HZSM-5分子筛,能够在对分子筛的晶体结构和表面形貌影响较小的基础上有效地引入介孔结构,具有高度的可调控性,且能够调变HZSM-5分子筛的酸性;随TPAOH溶液浓度的增加,丙烷脱氢反应活性先升高后降低,当TPAOH溶液浓度为0.2mol/L时,丙烷初始转化率和丙烯选择性均达到最高值,分别为32.7%和98.6%。
HZSM-5 zeolites were treated with different concentrations of TPAOH solutions.Pt/HZSM-5 catalysts were prepared for propane dehydrogenation by loading Pt on HZSM-5 zeolites before and after alkali treatment.The HZSM-5 samples before and after alkali treatment were characterized by XRD,SEM,BET,NH_3-TPD,H_2 chemisorption,FT-IR and TG techniques to investigate the effects of different concentrations of TPAOH solutions on the crystal structure,surface morphology,pore structure,surface acidity.The propane dehydrogenation on Pt/HZSM-5 catalysts was tested.The results showed that the treatment of HZSM-5 by TPAOH solution could effectively introduce mesoporous structure with less influence on the crystal structure and surface morphology of the zeolite,the formation of mesoporous structure is highly adjustable and could modulate the acidity of HZSM-5 zeolites.With the increase of TPAOH concentration,the activity of propane dehydrogenation increases first and then decreases.When the concentration of TPAOH solution is 0.2 mol/L,the initial propane conversion and propene selectivity are 32.7%and 98.6%,respectively.
HZSM-5 zeolites were treated with different concentrations of TPAOH solutions.Pt/HZSM-5 catalysts were prepared for propane dehydrogenation by loading Pt on HZSM-5 zeolites before and after alkali treatment.The HZSM-5 samples before and after alkali treatment were characterized by XRD,SEM,BET,NH_3-TPD,H_2 chemisorption,FT-IR and TG techniques to investigate the effects of different concentrations of TPAOH solutions on the crystal structure,surface morphology,pore structure,surface acidity.The propane dehydrogenation on Pt/HZSM-5 catalysts was tested.The results showed that the treatment of HZSM-5 by TPAOH solution could effectively introduce mesoporous structure with less influence on the crystal structure and surface morphology of the zeolite,the formation of mesoporous structure is highly adjustable and could modulate the acidity of HZSM-5 zeolites.With the increase of TPAOH concentration,the activity of propane dehydrogenation increases first and then decreases.When the concentration of TPAOH solution is 0.2 mol/L,the initial propane conversion and propene selectivity are 32.7%and 98.6%,respectively.
引文
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[24]Zhao Liang,Xu Chunming,Gao Shan,et al.Effects of concentration on the alkali-treatment of ZSM-5zeolite:A study on dividing points[J].Journal of Material Science,2010,45(19):5406-5441
[2]刘昌呈,王春明,马爱增.工艺条件对Pt-Sn-K/Al2O3催化剂丙烷脱氢性能的影响[J].石油炼制与化工,2013,44(4):34-38
[3]刘淑鹤,方向晨,张喜文,等.丙烷脱氢催化反应机理及动力学研究进展[J].化工进展,2009,28(2):259-266
[4]Kumar S M,Chen D,Holmen A,et al.Dehydrogenation of propane over Pt-SBA-15and Pt-Sn-SBA-15:Effect of Sn on the dispersion of Pt and catalytic behavior[J].Catalysis Today,2009,142(1/2):17-23
[5]Zhang Yiwei,ZhouYuming,Shi Junjun,et al.Comparative study of bimetallic Pt-Sn catalysts supported on different supports for propane dehydrogenation[J].J Mol Catal A:Chem,2014,381(1):138-147
[6]谢在库.新结构高性能多孔材料[M].北京:中国石化出版社,2009:5-6
[7]邱安定,李恩霞,范以宁.载体组成对负载型PtSn/ZSM-5催化剂上丙烷脱氢反应性能的影响[J].催化学报,2007,28(11):970-974
[8]王秀玲.分子筛载体对Pt-Sn-Na三组分丙烷脱氢催化剂性能的影响[J].石油化工,2012,41(12):1346-1350
[9]黄镜怡,周钰明,唐梦涵,等.氟对PtSnNaLa/ZSM-5催化剂丙烷脱氢反应性能的影响[J].应用化学,2015,32(2):207-213
[10]邱安定,李恩霞,范以宁.载体组成对负载型PtSn/ZSM-5催化剂上丙烷脱氢反应性能的影响[J].催化学报,2007,28(11):970-974
[11]邱安定,范以宁.添加锡组分对Pt/ZSM-5催化剂丙烷脱氢反应性能的影响[J].燃料化学学报,2008,36(5):637-640
[12]Suzuki T,Okuhara T.Change in pore structure of MFI zeolite by treatment with NaOH aqueous solution[J].Microporous and Mesoporous Mater,2001,43(1):83-89
[13]Ogura M,Shinomiya S.Alkali-treatment technique-New method for modification of structural and acid-catalytic properties of ZSM-5zeolites[J].Appl Catal A:Gen,2001,219(3):33-43
[14]Fathi S,Sohrabi M,Falamaki C.Improvement of HZSM-5performance by alkaline treatments:Comparative catalytic study in the MTG reactions[J].Fuel,2014,116(12):529-537
[15]于素霞.多级孔道结构ZSM-5沸石分子筛的合成及其催化应用[D].大连:大连理工大学,2009
[16]赵岑,刘冬梅,魏民,等.多级孔ZSM-5分子筛的制备及催化噻吩烷基化性能研究[J].燃料化学学报,2013,40(10):1256-1260
[17]黄力,王向华,孙勇,等.以碱液处理ZSM-5分子筛为载体的Pt-Sn-Na丙烷脱氢制丙烯催化剂[J].石化技术与应用,2015,33(3):216-220
[18]Groen J,Moulijn J A.Decoupling mesoporosity formation and acidity modification in ZSM-5zeolites by sequential desilication-dealumination[J].Microporous and Mesoporous Mater,2005,87(2):153-161
[19]Groen J,Peffer L A A,Moulijn J A,et al.Mechanism of hierarchical porosity development in MFI zeolites by desilication:The role of aluminium as a pore-directing agent[J].Chem Eur J,2005,11(17):4983-4994
[20]张一卫,周钰明,范以宁,等.Na对PtSn/ZSM-5催化丙烷脱氢反应性能的影响[J].物理化学学报,2006,22(6):672-678
[21]Viswanadham N,Saxena S K,Kumar J,et al.Catalytic performance of nano crystalline HZSM-5in ethanol to gasoline(ETG)reaction[J].Fuel,2012,95(1):298-304
[22]颜贻春,谢常实,秦关林.氨在HZSM-5沸石上的吸附与程序升温脱附[J].催化学报,1984,5(1):87-90
[23]Song Yueqin,Feng Yanlong,Liu Feng,et al.Effect of variations in pore structure and acidity of alkali treated ZSM-5on the isomerization performance[J].J Mol Catal A:Chem,2009,310(1/2):130-137
[24]Zhao Liang,Xu Chunming,Gao Shan,et al.Effects of concentration on the alkali-treatment of ZSM-5zeolite:A study on dividing points[J].Journal of Material Science,2010,45(19):5406-5441