对苯二甲酸催化加氢反应研究

Research on catalytic hydrogenation of p-phthalic acid

以活性炭为载体,采用浸渍法制备了Ru/C催化剂,采用XRD、H2-TPR、XPS、SEM和N2吸附-脱附等方法对催化剂进行了表征,并将其用于对苯二甲酸(PTA)催化加氢制备对苯二甲醇(BDM),考察了Ru含量、浸渍液pH和还原温度对催化剂性能的影响。实验结果表明,Ru含量为3.0%(w)、还原温度为350℃、浸渍液pH为2时,催化剂的性能较好,PTA转化率达99.8%、BDM选择性为94.86%。Ru纳米粒子粒径较小时,PTA分子以平面形式接触催化剂活性中心,反应物中的羧基和苯环均可加氢,BDM选择性低;Ru纳米粒子粒径达到一定值时,催化剂仍具有较高的活性,且由于PTA中羧基的空间位阻效应,羧基优先于苯环加氢,BDM选择性增加。

Ru/C catalyst was prepared by impregnation method with activated carbon as support and characterized by XRD,H2-TPR,XPS,SEM and N2 adsorption-desorption methods.The catalyst was used for hydrogenation of p-phthalic acid(PTA)to terephthalyl alcohol(BDM)and the effects of Ru content,pH of the impregnation solution and reduction temperature on the performance of the catalyst were investigated.The results show that the catalyst has a good performance and PTA conversion and BDM selectivity are 99.8%and 94.86%respectively when the Ru content is 3.0%(w),the reduction temperature is 350℃,and the impregnating solution pH is 2.When Ru nanoparticles are small,PTA molecules contact the active center of the catalyst in a planar form,the carboxyl and benzene rings in the reactants can be hydrogenated,and the selectivity to BDM is reduced.When the Ru nanoparticle size reaches a certain value,the catalyst still has high activity,and due to the steric hindrance effect of the PTA carboxyl group,the carboxyl group is hydrogenated in preference to the benzene ring,and the selectivity to BDM increases.