Ga2O3／HZSM-5催化剂上丙烷脱氢反应

Dehydrogenation of Propane to Propene over Ga_2O_3/HZSM-5 Catalysts

以直接水热合成和低硅沸石高温水蒸气脱铝两种方法制备了不同Si/Al摩尔比的HZSM-5载体,考察了Ga2O3/HZSM-5催化剂上丙烷脱氢制丙烯的反应性能.结合XRD,N2气吸附,27Al MAS NMR和NH3-TPD等表征方法,讨论了催化剂酸性质和孔性质与性能的关系.实验结果表明,减少催化剂表面的中强酸量可以显著提高反应的稳定性和丙烯的选择性;水蒸气脱铝所增加的介孔有同样的效果,这可能是由于介孔的存在有利于丙烯的脱附和扩散而抑制了寡聚、环化等副反应的发生,减少了表面积炭的可能性.

Dehydrogenation of propane to propene in the presence of CO2 was carried out over Ga2O3 catalysts supported on HZSM-5 with different Si/Al molar ratios. The structural and acidic properties were characterized by XRD, XRF, N2 adsorption, ^27Al MAS NMR, NH3-TPD and model acid-catalyzed reaction. It is found that the stability of supported Ga2O3 catalysts for the reaction improves with increasing Si/Al molar ratio of HZSM-5 support, which is thought to be caused by the decrease of the acidity of the catalysts, resulting in the suppression of the side reactions. The stability can also be enhanced by the mesopores generated by steaming, due to the promotion of the diffusion and desorption of the propene.