CrOx/ZSM-5-Al2O3复合载体催化剂对丙烷脱氢性能的影响

Effect of CrO/ZSM-5-AlO composite support catalyst on performance of propane dehydrogenation

将不同质量分数的钠型ZSM-5引入氧化铝溶胶制备复合载体,负载活性组分铬并用于丙烷脱氢催化实验。利用XRD、XRF、BET、NH3-TPD、UV-Vis等对添加不同ZSM-5质量分数的复合载体、催化剂样品进行表征,考察了不同质量分数ZSM-5对催化剂的孔分布、晶体结构、表面酸性、金属存在形式、积碳行为及丙烷脱氢性能的影响。结果表明,5%ZSM-5与氧化铝复合,增加了催化剂表面有利于脱氢反应的弱酸位点比例,增加了可被还原的Cr^6+及脱氢活性中心不饱和Cr^3+的数量,有效抑制积碳生成,提高催化剂的平均反应活性;当反应温度为600℃、C3H8与N2体积流量比为1∶15时,催化剂的丙烷转化率与丙烯选择性可达52.0%和90.0%。

A composite support is prepared by adding different mass fractions of sodium-type ZSM-5 into alumina sol.Active component chromium is loaded by the composite support and used as catalyst for propane dehydrogenation catalytic experiment.Both the composite support samples with different mass fractions of ZSM-5 and the catalyst samples are characterized by XRD,XRF,BET,NH3-TPD,and UV-Vis.The influences of the mass fractions of ZSM-5 on the catalysts’pore distribution,crystal structure,surface acidity,metal existence form,carbon deposition behavior and catalytic performance in propane dehydrogenation are investigated.The results show that the composition between 5%ZSM-5 and alumina increases the proportion of weak acid sites on the surface of catalyst,which is beneficial to the dehydrogenation reaction,increasing the amount of reducible Cr6+and the amount of unsaturated Cr3+in the dehydrogenation active center,effectively inhibiting the formation of carbon deposit and improving the average reactivity of catalyst.The propane conversion and propylene selectivity over the catalyst reach 52.0%and 90.0%,respectively when the reaction temperature is at 600℃and the ratio of propane to nitrogen is 1∶15.