纳米ZSM-5分子筛的液相沉积改性及其催化己烯-1芳构化反应性能

Liquid deposition modification of nano-ZSM-5 zeolite and catalytic performance in aromatization of Hexene-1

烯烃芳构化是催化裂化(FCC)汽油改质、高辛烷值燃料油的重要手段。采用预制晶种法合成了纳米ZSM-5分子筛,并采用液相沉积法制备了Ga沉积量不同的系列改性纳米ZSM-5分子筛,分别采用XRD、N2物理吸附、SEM、TEM、XPS、H2-TPR和Py-IR等表征手段对改性前后的纳米ZSM-5分子筛的形貌、织构特性和酸性等进行了表征,并采用固定床微型反应器对其催化己烯-1芳构化反应性能进行了评价,研究了Ga改性对纳米ZSM-5分子筛的物理化学性质及催化性能的影响规律。Ga液相沉积改性的ZSM-5分子筛中Ga物种主要以Ga_(2)O_(3)和提供强Lewis酸性位的GaO^(+)形式存在,由于Ga改性提高了分子筛的脱氢反应活性,己烯-1芳构化反应的芳烃选择性显著提高,以Ga沉积量适宜的Ga4.2/NZ5为催化剂时,芳烃选择性高达55.4%。

The Olefin aromatization is an important method for the upgrade of catalytic cracking(FCC)gasoline and production of fuel oil with high octane number.The nano-ZSM-5 zeolite were synthesized via a seed-induced method,a series of modified nano-ZSM-5 zeolite samples with different Ga deposition amount were prepared by Ga liquid deposition method.The XRD,N2 physical adsorption,SEM,TEM,XPS,H2-TPR and Py-IR measurements were used to characterize the morphology,textural properties and acidity of the modified ZSM-5 zeolites.The catalytic performance of the Hexene-1 aromatization was evaluated on a fixed-bed microreactor.The effects of Ga modification on the physicochemical and catalytic performance of nano-ZSM-5 zeolites were investigated.The Ga species in the modified nano-ZSM-5 zeolites mainly exist as the form of Ga_(2)O_(3) and GaO^(+),which provide strong Lewis acid sites.The aromatics selectivity over Ga modified nano-ZSM-5 zeolite in the Hexene-1 aromatization was significantly increased,which could be attributed to the improvement of the dehydrogenation activity.The selectivity for aromatics over the Ga4.2/NZ5 catalyst with suitable Ga deposition amount reached 55.4%.