多级孔HZSM-5分子筛的制备及其催化丙烷脱氢反应性能
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摘要
以十八水合硫酸铝、硅溶胶、四丙基氢氧化铵(TPAOH)、硝酸铵(NH_4NO_3)为原料,合成硅铝物质的量比为100的HZSM-5分子筛。采用乙酸钠溶液处理HZSM-5分子筛后加入TPAOH溶液进行二次晶化,通过对处理前、后的HZSM-5分子筛负载Pt,制得Pt/HZSM-5催化剂用于丙烷脱氢反应。利用XRD、SEM、XRF、BET、NH_3-TPD和H_2化学吸附对处理前、后的HZSM-5分子筛进行了表征,考察了不同浓度的TPAOH溶液对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,采用乙酸钠溶液处理后的HZSM-5分子筛在TPAOH溶液中发生了二次晶化,不仅形成了微孔-介孔多级孔结构,还能调变分子筛的表面酸性;当TPAOH溶液浓度为0.3 mol/L、晶化温度为170℃、晶化时间为24 h时,得到的Pt/HZSM-5催化丙烷的初始转化率和丙烯选择性均达到最高值,分别为34.2%和99.0%。
Aluminium sulphate[Al_2(SO_4)_3×18H_2O],silica sol,tetrapropylammonium hydroxide(TPAOH)and ammonium nitrate(NH_4NO_3)were used as raw materials to synthesize HZSM-5 zeolites with a SiO_2/Al_2O_3 molar ratio of 100.The HZSM-5 zeolites were treated by adding TPAOH solution for secondary crystallization after pre-treating with sodium acetate solution.Pt/HZSM-5 catalysts were prepared for propane dehydrogenation by loading Pt onto HZSM-5 zeolites before and after treatment.The samples were characterized by XRD,SEM,XRF,BET,NH_3-TPD and H_2 chemisorption.The effects of different TPAOH crystallization concentrations on the crystal structure,surface morphology,pore structure,surface acidity and propane dehydrogenation of HZSM-5 zeolites were investigated.The results showed that HZSM-5zeolite treated with CH_3COONa solution was recrystallized in TPAOH solution,which not only formed microporous-mesoporous hierarchical structure,but also modulated the surface acidity of the zeolite.When the concentration of TPAOH solution was 0.3 mol/L,the crystallization temperature was 170℃,the crystallization time was 24 h,the prepared Pt/HZSM-5 showed excellent catalytic performance for propane dehydrogenation,and the propane conversion and propylene selectivity reached 34.2%and 99.0% respectively.
Aluminium sulphate[Al_2(SO_4)_3×18H_2O],silica sol,tetrapropylammonium hydroxide(TPAOH)and ammonium nitrate(NH_4NO_3)were used as raw materials to synthesize HZSM-5 zeolites with a SiO_2/Al_2O_3 molar ratio of 100.The HZSM-5 zeolites were treated by adding TPAOH solution for secondary crystallization after pre-treating with sodium acetate solution.Pt/HZSM-5 catalysts were prepared for propane dehydrogenation by loading Pt onto HZSM-5 zeolites before and after treatment.The samples were characterized by XRD,SEM,XRF,BET,NH_3-TPD and H_2 chemisorption.The effects of different TPAOH crystallization concentrations on the crystal structure,surface morphology,pore structure,surface acidity and propane dehydrogenation of HZSM-5 zeolites were investigated.The results showed that HZSM-5zeolite treated with CH_3COONa solution was recrystallized in TPAOH solution,which not only formed microporous-mesoporous hierarchical structure,but also modulated the surface acidity of the zeolite.When the concentration of TPAOH solution was 0.3 mol/L,the crystallization temperature was 170℃,the crystallization time was 24 h,the prepared Pt/HZSM-5 showed excellent catalytic performance for propane dehydrogenation,and the propane conversion and propylene selectivity reached 34.2%and 99.0% respectively.
引文
[1]Zhao Dan(赵丹),Yuan Meihua(袁美华),Zhang Yaoyuan(张耀远),et al.Incorporation of Cr in ZSM-5 zeolite framework as bifunctional catalysts for n-butane catalytic cracking[J].CIESC Journal(化工学报),2016,67(8):3400-3407.
[2]Zhang Y,Zhou Y,Shi J,et al.Comparative study of bimetallic Pt-Sn catalysts supported on different supports for propane dehydrogenation[J].Journal of Molecular Catalysis A:Chemical,2014,381(1):138-147.
[3]Kumar S M,Chen D,Holmen A,et al.Dehydrogenation of propane over Pt-SBA-15 and Pt-Sn-SBA-15:effect of Sn on the dispersion of Pt and catalytic behavior[J].Catalysis Today,2009,142(1/2):17-23.
[4]Cai Jinpeng(蔡金鹏),Wang Fei(王非),Hu Jianheng(胡建恒),et al.Preparation and hydrodesulfurization performance of ZSM-5-MCM-41supported Ni Mo bimetallic sulfide catalysts[J].Fine Chemicals(精细化工),2017,34(8):887-892.
[5]Wang Xiuling(王秀玲).Effect of zeolite support on catalytic performance of Pt-Sn-Na catalyst for propane dehydrogenation[J].Petrochemical Technology(石油化工),2012,12(41):1346-1350.
[6]Qiu Anding(邱安定),Fan Yining(范以宁).Effect of addition of tin on the catalytic properties of Pt/ZSM-5 catalyst in propane dehydrogenation[J].Journal of Fuel Chemistry and Technology(燃料化学学报),2008,36(5):637-640.
[7]Si Zhenliang(司振良),Zhang Ruizhen(张瑞珍),Song Lanlan(宋兰兰).Alkylation of toluene with methanol over modified HZSM-5catalysts[J].Fine Chemicals(精细化工),2011,28(5):461-466.
[8]Suzuki T,Okuhara T.Change in pore structure of MFI zeolite by treatment with NaOH aqueous solution[J].Microporous Mesoporous Materials,2001,43(1):83-89.
[9]Wang Yaquan(王亚权),Lin Yongjie(林永杰),Liu Wei(刘伟),et al.Effect of TS-1 treatment by tetrapropyl ammonium hydroxide on1-hexene epoxidation[J].Journal of Tianjin University(天津大学学报),2017,50(1):65-70.
[10]He Yingping(何英萍),Liu Min(刘民),Dai Chengyi(代成义),et al.Modification of nanocrystalline HZSM-5 zeolite with tetrapropylammonium hydroxide and its catalytic performance in methanol to gasoline reaction[J].Chinese Journal of Catalysis(催化学报),2013,34(6):1158-1158.
[11]Liu Dongmei(刘冬梅),Tie Daxing(铁大兴),Gao Chenyi(高晨义),et al.Preparation of micro-mesoporous ZSM-5 zeolite through mixed alkali treatment and its catalytic performance in the alkylation of thiophene[J].Journal of Fuel Chemistry and Technology(燃料化学学报),2017,45(2):200-212.
[12]Liu Dongmei(刘冬梅),Zhai Yuchun(翟玉春),Ma Jian(马健),et al.Study on the ophene alkylation performance of hierarchical ZSM-5zeolites modified by different alikali[J].Journal of Fuel Chemistry and Technology(燃料化学学报),2015,43(4):462-469.
[13]Perez-Ramirez J,Verboekend D,Bonilla A,et al.Zeolite catalysts with tunable hierarchy factor by pore-growth moderators[J].Advance Functional Materials,2009,19(24):3972-3979.
[14]Zhao L,Xu C M,Gao S,et al.Effects of concentration on the alkali-treatment of ZSM-5 zeolite:A study on dividing points[J].Journal of Material Science,2010,45(19):5406-5441.
[15]Nagabhatla V,Sandeep K S,Jitendra K,et al.Catalytic performance of nano crystalline HZSM-5 in ethanol to gasoline(ETG)reaction[J].Fuel,2012,95(1):298-304.
[16]Yan Yichun(颜贻春),Xie Changshi(谢常实),Qin guanlin(秦关林).Adsorption and temperature programmed desorption of ammonia on zeolite HZSM-5[J].Chinese Journal of Catalysis(催化学报),1984,5(1):87-90.
[17]Song Y Q,Feng Y L,Liu F,et al.Effect of variations in pore structure and acidity of alkali treated ZSM-5 on the isomerization performance[J].Journal of Molecular Catalysis A:Chemical,2009,310(1/2):130-137.
[18]Zhang Yiwei(张一卫),Zhou Yuming(周钰明),Fan Yining(范以宁),et al.Effect of Na addition on catalytic performance of PtSn/ZSM-5catalyst for propane dehydrogenation[J].Acta Physico-Chimica Sinica(物理化学学报),2006,22(6):672-678.
[2]Zhang Y,Zhou Y,Shi J,et al.Comparative study of bimetallic Pt-Sn catalysts supported on different supports for propane dehydrogenation[J].Journal of Molecular Catalysis A:Chemical,2014,381(1):138-147.
[3]Kumar S M,Chen D,Holmen A,et al.Dehydrogenation of propane over Pt-SBA-15 and Pt-Sn-SBA-15:effect of Sn on the dispersion of Pt and catalytic behavior[J].Catalysis Today,2009,142(1/2):17-23.
[4]Cai Jinpeng(蔡金鹏),Wang Fei(王非),Hu Jianheng(胡建恒),et al.Preparation and hydrodesulfurization performance of ZSM-5-MCM-41supported Ni Mo bimetallic sulfide catalysts[J].Fine Chemicals(精细化工),2017,34(8):887-892.
[5]Wang Xiuling(王秀玲).Effect of zeolite support on catalytic performance of Pt-Sn-Na catalyst for propane dehydrogenation[J].Petrochemical Technology(石油化工),2012,12(41):1346-1350.
[6]Qiu Anding(邱安定),Fan Yining(范以宁).Effect of addition of tin on the catalytic properties of Pt/ZSM-5 catalyst in propane dehydrogenation[J].Journal of Fuel Chemistry and Technology(燃料化学学报),2008,36(5):637-640.
[7]Si Zhenliang(司振良),Zhang Ruizhen(张瑞珍),Song Lanlan(宋兰兰).Alkylation of toluene with methanol over modified HZSM-5catalysts[J].Fine Chemicals(精细化工),2011,28(5):461-466.
[8]Suzuki T,Okuhara T.Change in pore structure of MFI zeolite by treatment with NaOH aqueous solution[J].Microporous Mesoporous Materials,2001,43(1):83-89.
[9]Wang Yaquan(王亚权),Lin Yongjie(林永杰),Liu Wei(刘伟),et al.Effect of TS-1 treatment by tetrapropyl ammonium hydroxide on1-hexene epoxidation[J].Journal of Tianjin University(天津大学学报),2017,50(1):65-70.
[10]He Yingping(何英萍),Liu Min(刘民),Dai Chengyi(代成义),et al.Modification of nanocrystalline HZSM-5 zeolite with tetrapropylammonium hydroxide and its catalytic performance in methanol to gasoline reaction[J].Chinese Journal of Catalysis(催化学报),2013,34(6):1158-1158.
[11]Liu Dongmei(刘冬梅),Tie Daxing(铁大兴),Gao Chenyi(高晨义),et al.Preparation of micro-mesoporous ZSM-5 zeolite through mixed alkali treatment and its catalytic performance in the alkylation of thiophene[J].Journal of Fuel Chemistry and Technology(燃料化学学报),2017,45(2):200-212.
[12]Liu Dongmei(刘冬梅),Zhai Yuchun(翟玉春),Ma Jian(马健),et al.Study on the ophene alkylation performance of hierarchical ZSM-5zeolites modified by different alikali[J].Journal of Fuel Chemistry and Technology(燃料化学学报),2015,43(4):462-469.
[13]Perez-Ramirez J,Verboekend D,Bonilla A,et al.Zeolite catalysts with tunable hierarchy factor by pore-growth moderators[J].Advance Functional Materials,2009,19(24):3972-3979.
[14]Zhao L,Xu C M,Gao S,et al.Effects of concentration on the alkali-treatment of ZSM-5 zeolite:A study on dividing points[J].Journal of Material Science,2010,45(19):5406-5441.
[15]Nagabhatla V,Sandeep K S,Jitendra K,et al.Catalytic performance of nano crystalline HZSM-5 in ethanol to gasoline(ETG)reaction[J].Fuel,2012,95(1):298-304.
[16]Yan Yichun(颜贻春),Xie Changshi(谢常实),Qin guanlin(秦关林).Adsorption and temperature programmed desorption of ammonia on zeolite HZSM-5[J].Chinese Journal of Catalysis(催化学报),1984,5(1):87-90.
[17]Song Y Q,Feng Y L,Liu F,et al.Effect of variations in pore structure and acidity of alkali treated ZSM-5 on the isomerization performance[J].Journal of Molecular Catalysis A:Chemical,2009,310(1/2):130-137.
[18]Zhang Yiwei(张一卫),Zhou Yuming(周钰明),Fan Yining(范以宁),et al.Effect of Na addition on catalytic performance of PtSn/ZSM-5catalyst for propane dehydrogenation[J].Acta Physico-Chimica Sinica(物理化学学报),2006,22(6):672-678.