β沸石催化苯酚甲基化反应

STUDY ON THE ALKYLATION OF PHENOL WITH METHANOL OVER ZEOLITE β

研究了氢型β沸石和改性β沸石对苯酚甲醇烷基化反应的催化性能．发现β沸石作用下的反应网络与复合氧化物基本相同．沸石的酸碱性影响反应的活性和选择性；提高沸石硅铝比，反应活性降低，氧上烷基化反应的选择性提高．β沸石改性调变酸性后，可有效地抑制甲醇高温分解和生成积炭等副反应；酸碱中心的协同作用，降低了氧上烷基化反应的选择性．还考察了反应温度及反应物料配比对该反应的影响．降低酚醇比可以提高苯酚转化率，但甲醇的有效利用率降低．

The alkylation of PhOH with MeOH on Hβ and metal modified β zeolite has been studied. It has been found that the methylation of PhOH occurs at both the carbon atom of aromatic ring and the oxygen atom of hydroxy, the reaction network over zeolite β is similar to that over complex oxides, but shows no shape selectivity. The acidity and basicity of zeolite β are important to the reactivity. The higher SiO 2/Al 2O 3 molar ratio of zeolite β is, the lower conversion of PhOH and the higher selectivity for anisole. Modification of zeolite β with Mg, Mn and La leads to changes in acidity and in basicity, the synergism of acid and base sites inhibits self decomposition of MeOH, coke formation and alkylation at oxygen atom of hydroxy. The reaction temperature affects the distribution of products, and the decrease of PhOH/MeOH molar ratio can improve the conversion of PhOH but lessen the efficiency of MeOH.