MnO_x／Al_2O_3催化苯甲酸气相加氢制备无氯苯甲醛

DIRECT HYDROGENATION OF BENZOIC ACID TO BENZALDEHYDE OVER MnO_x/Al_2O_3

采用共沉淀法制备了MnO_x/Al_2O_3催化剂,并在固定床连续反应器上考察了苯甲酸气相加氢生成苯甲醛的催化反应过程的条件。结果表明,在常压、380℃、氢气空速为760h^(-1)、氢气／酸摩尔比为68的反应条件下,苯甲酸的转化率为95．5%以上,苯甲醛的选择性可达89．5%以上。通过XRD,SEM等技术初步表明,催化剂活性降低(苯甲酸转化率下降至70%以下)可能是由催化剂表面积碳引起的。

MnOx/Al2O3 catalysts were prepared by a co-precipitation method and studied in the vapourphase hydrogenation of benzoic acid to benzaldehyde in a continuous flow and fixed-bed reactor. The experiment results showed that the catalyst had a good activity for the reaction and the conversion of the benzoic acid and the selectivity of benzaldehyde reached 95.5% and 89.5%, respectively, under the conditions of 380 ℃ and GHSV=760 h^-1. The catalysts deactivated due to coke formation on the surface as revealed by XRD and SEM.