负载Mo、W氧化物对Y型分子筛结构及酸性的影响

Effects of Molybdenum/Tungsten Oxides Loading on the Structure and Acidity of Y Zeolites

采用等体积浸渍法将Mo、W氧化物负载在USY分子筛上,并通过固体核磁共振、X射线衍射、N2吸附-脱附、NH3程序升温脱附和吡啶红外吸附等分析手段,研究了Mo、W氧化物的负载对USY分子筛结构及酸性的影响。结果表明,当Mo、W氧化物负载质量分数不大于8%时,USY分子筛骨架结构依然存在,但结晶度下降。Mo、W氧化物的负载造成了分子筛骨架脱铝;且随负载量的增加,分子筛脱铝的程度加深。负载Mo氧化物之后,USY分子筛的总酸量和L酸量增加;但随负载量的提高,总酸量和中强酸降低,B酸减少。负载量相同时,Mo氧化物对分子筛的作用大于W氧化物。

Mo or W oxide were supported on a series of USY zeolite by means of incipient-wetness impregnation method.The structures of Mo（W）/USY samples were characterized by XRD and N2 adsorption-desorption,and the influences of Mo and W oxides on the chemical states of Al,Si and acidities in USY were investigated by MAS NMR,NH3-TPD and Pyridine-IR.Compared with parent USY zeolite,the faujasite framework of Mo（W）/USY samples were retained,but the crystallinity reduced.The phenomenon of zeolite dealumination was found after Mo or W oxide loaded.Simultaneously,the total acid amount,Brnsted and Lewis acid sites in the samples were increased,which,however,were decreased with the increase of Mo oxide amount.Moreover,the influence of Mo oxide was more obvious than that of W oxide with the same amount.