核壳型多级孔道ZSM-5/MCM-41分子筛的制备及其在汽油改质中的应用

Synthesis of Hierarchical ZSM-5/MCM-41 Core-Shell Zeolite and Its Application as Catalyst in Gasoline Hydro-Upgrading

在碱处理ZSM-5的浆液中外加模板剂和新的硅铝源,采用水热合成法合成了具有微孔和介孔孔道的多级孔道H-ZSM-5/MCM-41分子筛,采用XRD、BET和HRTEM等方法对其表征。在2.0 MPa、350℃、体积空速2h-1、氢/油体积比300的条件下,采用固定床反应器,考察了合成分子筛经等体积浸渍法负载不同n(Ni)/n(Mo)双金属活性组分所得催化剂对加氢脱硫后的FCC汽油重组分的加氢改质催化性能。结果表明,合成的H-ZSM-5/MCM-41分子筛中外加硅铝源的Si/Al摩尔比为50时,可以得到孔道结构较好的多级孔道分子筛,该分子筛具有以ZSM-5分子筛相作为核、介孔MCM-41相作为壳的核壳结构。多级孔道分子筛负载NiMo双金属活性组分的催化剂催化汽油加氢异构化和芳构化性能与其酸性和孔结构密切相关,当催化剂中n(Ni)/n(Mo)=1/2,w(Ni)=3.0%时,其汽油加氢异构化和芳构化催化性能较好。

Hierarchical ZSM-5/MCM-41 zeolites were synthesized by the introduction of template and new silica-alumina species in the alkali-treated ZSM-5 serif lux, and characterized by XRD, N 2 adsorption and HRTEM. The NiMo hydro-upgrading catalysts of different Ni/Mo molar ratios and with as-synthesized zeolites as support were prepared by impregnation. Under such operating conditions as 〉 = 2. 0 MPa , 350℃,LHSV = 2. 0h^-1 and V（H2）/V（Oil） = 3 0 0,the effects of Ni/Mo molar ratios on hydroisomerization and aromatization performances of the catalysts for the heavy FCC gasoline fraction after desulfurization FCC gasoline hydro-upgrading were investigated in a fixed bed microreactor. The results showed that the ZSM-5/MCM-41 sample with nSi/nAi = 50 of the new silica-alumina sources possessed better micro-mesoporous structure, with clear core-shell structure, in which the morphologies of ZSM-5 was as the core and the morphologies of MCM-41 as the shell. The hydroisomerization and aromatization activities of the hydro-upgrading catalyst were closely related to is textural properties and the acid type. When then（Ni）/n（Mo） = 1/2, w（Ni）= 3.0%, the prepared hydro-upgrading catalyst exhibited high hydroisomerization and aromatization abilities.