超临界甲醇处理对Ru/C催化剂结构及性能的影响

Effect of Supercritical Methanol Treatment on the Properties and Structures of Ru/AC Catalysts

采用超临界甲醇处理活性炭,传统水浸渍制备负载钌炭催化剂,用N2物理吸附、Boehm滴定、X光电子能谱仪(XPS)、程序升温还原(TPR)、扫描电镜(SEM)、透射电镜(TEM)等表征手段,研究了超临界甲醇处理活性炭对活性炭表面结构、表面基团含量,及Ru/C催化剂的还原性能、钌的分布的影响.并以葡萄糖加氢生产山梨醇为模型反应对负载钌基催化剂的性能进行了评价.研究结果表明,超临界甲醇处理活性炭,活性碳的孔结构性能变化不大,但可有效降低活性炭表面含氧酸性基团的含量,有效提高钌的分散度,使催化剂的还原温度升高,增强了载体和活性组分钌间的相互作用,提高了钌的电子结合能,从而有效的提高所负载催化剂的催化活性.在实验范围内,当超临界甲醇的温度为300℃,处理时间为12 h以上时,在4.0 MPa,120℃,葡萄糖浓度为50%(w/w)反应条件下,催化剂的反应速率达到了118.65 mmol.min-1g-1Ru,是未处理活性碳的1.96倍.

Activated carbon was modified by supercritical fluidic methanol in order to obtain materials with different surface properties.Several techniques were used to characterize the activated carbon and Ru/ AC catalysts including N2 physisorption,Boehm titration,XPS,SEM,TEM and TPR.The results showed that supercritical fluid treatment did not remarkably change the surface structure of the activated carbon,but resulted in considerable decrease of the surface acidic groups,which led to higher dispersion of Ru,enhanced interaction force between activated carbon and Ru,increase of the reduced temperature and the binding energy of Ru,and enhanced activity of the catalysts prepared by impregnation of AC supported with RuCl3 solution.The activities of Ru/ AC catalysts for hydrogenation of glucose were tested under 4.0 MPa at the temperature of 120 ℃.The results showed that activities of Ru/ AC catalysts prepared by supercritical fluid treatment were greatly increased.The optimal condition for the supercritical fluidic methanol was temperature 300 ℃ for over 12 h;the highest reaction rate for hydrogenation of glucose reached 118.65 mmol·min-1g-1Ru,which exhibited 1.96 times higher than without treatment.