多级结构SAPO-34分子筛的制备及其催化反应性能
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摘要
以干凝胶法为基础,通过改变凝胶脱水方式制备了纳米颗粒堆积的多级结构SAPO-34分子筛,采用XRD、SEM、物理吸附仪、O_2-DTA以及激光粒度仪等对其进行表征,并开展MTO催化反应性能研究。结果表明,多级结构的SAPO-34分子筛颗粒尺寸较大,由片状结构堆叠而成,片状结构则由80～150nm之间小颗粒聚集而组成,总比表面积和介孔孔容分别为702m~2/g和0.44mL/g,介孔平均孔径达到19.5nm;与水热合成法以及常规干凝胶法制备的SAPO-34分子筛相比,含多级结构的SAPO-34分子筛具有更好的扩散性能,在其催化MTO反应进行至200min后,甲醇转化率仍可达到96.8%,双烯烃(乙烯+丙烯)选择性达到83.48%,表现出较好的抗积炭能力和反应性能。
Based on the dry gel conversion method, the hierarchical SAPO-34 molecular sieve of nanopartical aggregates was successfully synthesized by changing the way of gel dehydration. The molecular sieve samples were characterized by XRD, SEM, N_2 adsorption-desorption, O_2-DTA and laser particle size analyzer, and their catalytic performances inmethanol-to-olefins(MTO) reaction were investigated. The results showed that the hierarchical SAPO-34 molecular sieve had a larger particle size and was stacked from flaky structures which composed of small particles between 80-150 nm. The total surface area, mesopore volume and average pore size reached to 702 m~2/g, 0.44 mL/g and 19.5 nm, respectively. Compared with the samples synthesized by the hydrothermal method and conventional dry gel method, the hierarchical SAPO-34 molecular sieve had better diffusion properties, and exhibited better carbon resistance and catalytic performance. When the MTO reaction was carried out to 200 minutes, the conversion of methanol and the total selectivity of ethylene and propylene still reached 96.8% and 83.48%, respectively.
Based on the dry gel conversion method, the hierarchical SAPO-34 molecular sieve of nanopartical aggregates was successfully synthesized by changing the way of gel dehydration. The molecular sieve samples were characterized by XRD, SEM, N_2 adsorption-desorption, O_2-DTA and laser particle size analyzer, and their catalytic performances inmethanol-to-olefins(MTO) reaction were investigated. The results showed that the hierarchical SAPO-34 molecular sieve had a larger particle size and was stacked from flaky structures which composed of small particles between 80-150 nm. The total surface area, mesopore volume and average pore size reached to 702 m~2/g, 0.44 mL/g and 19.5 nm, respectively. Compared with the samples synthesized by the hydrothermal method and conventional dry gel method, the hierarchical SAPO-34 molecular sieve had better diffusion properties, and exhibited better carbon resistance and catalytic performance. When the MTO reaction was carried out to 200 minutes, the conversion of methanol and the total selectivity of ethylene and propylene still reached 96.8% and 83.48%, respectively.
引文
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[18]Zhao H R,Shi S M,Wu J X,et al.Charge compensation dominates the distribution of silica in SAPO-34[J].Chin J Catal,2016,37(2):227-233.
[2]崔宇,王垚,魏飞.SAPO-34分子筛硅铝比对甲醇制烯烃反应性能及积炭组成的影响[J].化工学报,2015,66(8):2982-2989.
[3]Qian Q Y,Javier R M,Mohamed M,et al.Single-catalyst particle spectroscopy of alcohol-to-olefins conversions:Comparison between SAPO-34 and SSZ-13[J].Catal Today,2014,226(1):14-24.
[4]Li Z B,Joaquin M T,YuJ H,et al. Conversion of methanol to olefins:Stabilization of nanosized SAPO-34 by hydrothermal treatment J].J Catal,2015,329:379-388.
[5]Nishiyama N,Kawaguchi M,Hirota Y,et al.Size control of SAPO-34 crystals and their catalyst lifetime in the methanol-to-olefin reaction[J].Appl Catal A,2009,362(1-2):193-199.
[6]Chen D,Moljord K,Fuglerud T,et al.The effect of crystal size of SAPO-34 on the selectivity and deactivation of the MTO reaction[J].Microporous Mesoporous Mater,1999,29(1):191-203.
[7]Yuichiro H,Kenji M,Shunsuke T,et al.Dry gel conversionsynthesis of SAPO-34 nanocrystals[J].Mater Chem Phys,2010,123:507-509.
[8]Ren S,Liu G J,Wu X,et al.Enhanced MTO performance over acid treated hierarchical SAPO-34[J].Chin J Catal,2017,38(1):123-130.
[9]白亚东,郑家军,范彬彬.“一步法”合成多级孔SAPO-34分子筛[J].无机化学学报,2015,31(8):1505-1510.
[10]崔杏雨,王晶晶,潘梦,等.多级SAPO-34的合成及其在甲醇制烯烃反应中的催化性能[J].无机化学学报,2018,34(3):300-308.
[11]梁光华,狄春雨,王龙,等.不同铝源合成SAPO-34分子筛及其MTO催化性能[J].石油学报(石油加工),2014,30(5):885-890.
[12]Li J Q,Li Z,Han D Z,et al.Facile synthesis of SAPO-34with small crystal size for conversion of methanol to olefins[J].Powder Technol,2014,262:177-182.
[13]李志宏,李晓峰,狄春雨,等.蒸汽相体系下合成SAPO-34分子筛及其MTO催化性能.石油学报(石油加工),2017,33(6):1192-1200.
[14]刘中民,黄兴云,何长青,等.SAPO-34分子筛的热稳定性及水热稳定性[J].催化学报,1996,17(6):540-543.
[15]韩磊,崔晓,刘欣梅.SAPO-11分子筛的粒度调控[J].无机化学学报,2013,29(3):565-570.
[16]Li J Q,Li Z,Han D Z.Facile synthesis of SAPO-34 with small crystal size for conversion of methanol to olefins[J].Powder Technol,2014,262:177-182.
[17]Hassan S,Majid T.Optimization of nano-sized SAPO-34synthesis in methanol-to-olefin reaction by response surface methodology[J].J Ind Eng Chem,2015,24:59-70.
[18]Zhao H R,Shi S M,Wu J X,et al.Charge compensation dominates the distribution of silica in SAPO-34[J].Chin J Catal,2016,37(2):227-233.