金属氧化物催化剂表面性质对苯酚/甲醇气相烷基化反应的影响

苯酚／甲醇在固定床连续式等温反应器上，以TiO2、MgO、V2O5、V2O5／TiO2、MgO／TiO2和不同V／Mg原子比的V2O5／MgO二元复合氧化物为催化剂进行烷基化，选择性合成邻甲酚，2，6-二甲酚及甲氧基苯。考察了各种氧化物的表面性质，研究了不同氧化物的表面酸碱性对苯酚转化率、目的产物选择性的影响。实验结果表明，固体表面具有酸性的氧化物，苯酚转化率及2，6－二甲酚、甲氧基苯选择性高；具有碱性表面的氧化物，对邻甲酚有高的选择性。在纯MgO中加入V2O5组成不同V／Mg原子比的V2O5／MgO二元复合氧化物，使固体表面酸基浓度增加，苯酚转化率及2，6－二甲酚、甲氧基苯选择性提高，邻甲酚选择性则相应降低。

EFFECTS OF SURFACE PROPERTIES ON VAPOUR-PHASE ALKYLATION REACTION OF PHENOL/METHANOL OVER METALLIC OXIDES

Vapour phase methylation of phenol with methanol was carried out over TiO2,, MgO, V2O5,V2O5/TiO2, MgO/TiO2 and a series of binary mixtures of V2O5 and MgO of different atomic ratios in a fixed - bed continous flow reactor, to selectively synthesise o - cresol, 2, 6 - xylenol, and anisole.The acid - base property of the various oxides were investigated and compared with their catalytic activity and selectivity in the alkylation of phenol with methanol. The testing results indicated that an increase in acidity increase the total phenol conversion and the selectivity for 2, 6 - xylenol and anisole,while an increase in basicity increases the selectivity for o - cressol over TiO2, MgO, V2O5, V2O5/TiO2, MgO/TiO2. Addition of a certain amount of V2O5 to MgO improves the acidity and also the catalytic activity and selectivity for 2, 6 - xylenol and anisole.