V_2O_5催化烷基化合成2,3,5-三甲基苯酚的研究

制备并考察了甲醇烷基化法合成2,3,5-三甲基苯酚系列固体酸催化剂,筛选出烷基化反应适宜的催化剂,对催化剂载体进行了扩孔实验,并进行了烷基化反应工艺条件的优化研究。筛选出的催化剂以V2O5为主催化剂,Cr2O3为助催化荆,γ-Al2O3为载体。实验结果表明,载体的孔结构对产物的选择性有明显的影响;最优工艺条件:反应温度350℃、液态空速0.29 h-1、n(3,5-二甲基苯酚)/n(甲醇)/n(水)=1/2/1;原料3,5-二甲基苯酚的转化率达95.89％,目的产物2,3,5-三甲基苯酚的收率为70.92％。

Vapor Phase Synthesis of 2,3,5-Trimethyl Phenol on Vanadium Catalyst

Vapor phase synthesis of 2,3,5- trimethyl phenol from methanol and 3,5-dimethyl phenol on solid acid catalyst was studied in a fixed bed reactor. A series of solid acid catalysts were prepared by different methods:impregnation, precipitation, and mechanical mixing. The catalyst with addition of Cr2O3 on V2O5-based catalyst was the best. Effects of temperature, ratio of feed materials, space velocity, especially pore expansion of support on performance of catalysts were investigated. The optimum process conditions were: temperature,350 ℃ ;space velocity,0.29 h-1; and n (3,5- dimethly phenol)/n (methanol)/n (water), 1/2/1. Yield of product under optimum conditions was above 70 % .