摘要
以石棉为硅源,四丁基溴化铵为模板剂以及铝酸钠、氢氧化钠和水,用水热法合成了一种ZSM-5沸石嵌入石棉的复合HZSM-5沸石/石棉催化剂。在287℃下,该复合催化剂上的甲醇转化反应仍有着较高的低碳烯烃（C<sub>2</sub><sup>=</sup>—C<sub>4</sub><sup>=</sup>）选择性,是与它的表面上有酸中心（沸石的外表面上）和碱中心（石棉上的MgO）共同存在有关。甲醇分子价键在这种沸石和石棉交界处的酸、碱中心协同作用下易于断裂,以α-消去反应的机理生成烯烃。
A composile HZSM-5 zeolite/asbestos catalyst, tiny HZSM-5 zeolite particles embedded in the asbestos fiber remnants, was Synthesized by hydrothermal method with asbestos as silicon resource, tetrabulylammonium bromide as a template, sodium aluminatc, sodium hydroxide and water. Their crystalline phase, morphology, composition, acid and base properties and so on were characterized by XRD, SEM, IR, TPD, BET gravimetric adsorption and activity evaluation. The results showed that the high selectivity of the composite catalyst for low er olefins in methanol conversion was due to the synergistic effect of acid sites on the external surface of zeolite and the basic sites of MgO on asbestos remnants. Olefin formation was explained by an α-elimination mechanism, the scission of the methanol bond was facilitated by the cooperation action of acidic and basic sites on the boundary between zeolite and asbestos.
基金
国家自然科学基金
