合成方法对MCM-22分子筛的结构、性质及催化性能的影响

在水热条件下分别以动态法和静态法合成了高纯度和高结晶度的MCM-22分子筛.采用N2吸附、XRD、TEM和FTIR等方法研究了制备方法对分子筛的结构及性质的影响.结果表明,动态法合成的MCM-22比静态法合成的分子筛的晶粒小,酸量低.在丙酮一步法合成甲基异丁基酮反应中,静态条件下合成的MCM-22为载体的催化剂的丙酮转化率较高,这是由于该分子筛的酸量较高所致.而MIBK的选择性则呈相反趋势,这可能与动态条件下合成的分子筛粒径小、孔道短有关.

Influence of Synthesis Method on Structure and Catalytic Performance of MCM-22 Zeolites

Pure MCM-22 with a high crystalline was hydrothermally synthesized by dynamic and static(methods,) respectively.The influence of the synthesis conditions on the structure and properties of MCM-22 was studied by means of N_(2) adsorption,XRD,TEM and FTIR. MCM-22 synthesized by dynamic method shows much smaller crystal and lower concentration of acid sites than those of synthesized by static method.The Pd-supported catalyst on MCM-22 synthesized by static method shows a higher acetone conversion than that prepared by dynamic method in one-step synthesis of methyl isobutyl ketone(MIBK) from acetone.We attributed this to the higher concentration of acid sites of MCM-22 synthesized by static method.While the selectivity to MIBK exhibited an adverse trend,this might be due to shorter distance of the channel,which decreased the contact time of the reactants in the channels.As a result,the selectivities of the further condensation and hydrogenation products decreased.