HZSM-5分子筛负载磷钼酸在苯酚-异丙醇烷基化中的应用

Application of HZSM-5 molecular sieve supported phosphomolybdic acid in alkylation of phenol-isopropanol

采用浸渍法将磷钼酸(H3PMo12O40)杂多酸负载于HZSM-5分子筛上,利用X射线衍射、NH3化学吸附对分子筛进行表征,并将其应用于苯酚-异丙醇烷基化反应中考察其催化活性。结果表明低负载量时磷钼酸较好地分散在HZSM-5分子筛表面,强酸中心酸性及数量增强,总酸量略有增加负载量过高破坏晶体结构,总体酸量降低。负载量为4%的HMoP/ZSM-5分子筛是较适宜的催化剂在温度为280℃、异丙醇与苯酚进料摩尔比为0.8、空速为3.0 h^-1的条件下苯酚转化率最高对、邻异丙基苯酚总选择性接近92%。

By means of the impregnation method,phosphomolybdic acid is loaded on HZSM-5 molecular sieve to prepare a catalyst.The structure of the catalyst is characterized by X-ray diffraction(XRD)and NH3 chemical adsorption.The catalytic activity of the catalyst is evaluated through catalyzing the alkylation between phenol and isopropanol.The results show that as the loading amount is low,phosphomolybdic acid disperses well on the surface of HZSM-5 molecular sieve,the acidity and quantity of strong acid center are enhanced,and the total acid amount increases slightly.The crystal structure is destroyed when the load amount is too high,while the total acid amount goes down.On the whole,HMoP/ZSM-5 molecular sieve with a loading amount of 4%is verified to be a suitable catalyst,over which,the conversion of phenol can reach the highest,and the total selectivity of o-isopropyl phenol and isopropyl phenol can approach 92%under optimal reaction conditions such as temperature at 280℃,WHSV at 3 h^-1,and a feed molar ratio of0.8 between isopropanol and phenol.