负载贵金属的HMCM-56催化剂上C_9~+重芳烃加氢脱烷基反应

采用等体积浸渍法制备了负载不同贵金属的M/HMCM-56催化剂(M=Pt,Re,Pd)用于工业C9+重芳烃加氢脱烷基制苯、甲苯和二甲苯(BTX),研究了贵金属负载量(质量分数)对催化剂性能的影响;选取活性组分Re进一步制备了二元复合活性组分催化剂Re-NiO/HMCM-56,用XRD、H2-TPR、氮吸附和吡啶吸附红外光谱等技术研究了活性组分复合及浸渍顺序对催化剂物性结构及性能的影响。实验结果表明,随贵金属负载量的提高,C9+重芳烃转化率增加,BTX选择性和收率降低;Re/HMCM-56催化剂的性能较为优异,Re负载量为0.3%时,BTX收率高达52.68%。Re负载量为0.3%、NiO负载量为6.0%的Re-NiO/HMCM-56催化剂中Re与NiO未产生协同催化作用形成更有利于反应进行的新活性中心;引入Re减弱了NiO与HMCM-56分子筛的相互作用,使更多的NiO以颗粒状态存在,同时也抑制了催化剂的B酸和L酸中心;加入NiO抑制了B酸中心,促进了L酸中心的形成;Re和NiO的浸渍顺序对催化剂物性结构和性能的影响较小。

Hydrodealkylation of C +9 Heavy Aromatics over Noble Metal Supported HMCM 56 Molecular Sieve Catalyst

HMCM-56 catalysts with different supported noble metals were prepared through incipient wetness impregnation and used in hydrodealkylation of commercial C9+ heavy aromatics.Effect of noble metal loading on catalyst performance was studied.Then Re was selected as one of active components to prepare binary composite catalyst Re-NiO/HMCM-56.Effects of active component recombination and impregnation sequence on structure and catalytic performance of the catalysts was investigated by means of XRD,H2-TPR,N2 adsorption-desorption and Py-FTIR.With increase of noble metal loading,conversion of C9+ aromatics increased but selectivity to BTX(benzene,toluene and xylene) dropped significantly so yield of BTX decreased.For 0.3%(w)Re/HMCM-56,yield of BTX could reach 52.68%.For 0.3%(w)Re-6.0%(w)NiO/HMCM-56 catalyst,synergetic catalysis caused by recombination of Re and NiO and corresponding new active sites which were more beneficial to the hydrodealkylation could not form.Incorporation of Re weakened the interaction between NiO and HMCM-56 so that more NiO species existed as particles,and both Brnsted and Lewis acid sites were restrained.The addition of NiO restrained Brnsted acid sites,but increased Lewis acid sites.Impregnation sequence of Re and NiO had little effect on the structure and catalytic performance of Re-NiO/HMCM-56.