摘要
疏水性固体酸具有在含水体系中活性组分不易流失、催化剂活性高和催化剂重复使用性好等优点,是环境友好型催化剂,具有广泛的应用前景。通过浸渍法将硫酸负载到活性炭(AC)上,然后用三甲基氯硅烷(Cn)改性制备得到疏水性固体酸催化剂AC-H2SO4-Cn,通过XRD、IR及TG对其进行表征,并将其用于乙酸与乙醇的酯化反应,考察了催化剂制备条件对催化剂活性的影响。结果表明,经硅烷化处理后,三甲基氯硅烷在催化剂表面形成疏水基团,提高了催化剂的重复使用性能。制备方法对催化剂疏水性能影响明显,先负载硫酸后硅烷化改性制备的催化剂的重复使用性能优于未改性及先硅烷化改性后负载硫酸的催化剂。在硅烷浸渍液浓度为15%(v/v),处理温度为60℃,处理时间为2 h条件下,乙酸最高转化率为90.3%,其重复使用过程中的催化性能均优于其它经不同浓度和温度处理得到的催化剂。
The hydrophobic solid acid catalysts possess the advantages of having the stable active sites, high catalytic activity and better reusability, which are considered to be the environmentally friendly catalysts and have promising application prospect. The catalyst of hydrophobic solid acid AC-H2SO4-Cn was prepared through two steps as follows： activated carbon （AC） was firstly impregnated in sulfuric acid to form the sulfuric acid loaded catalyst, and then modified it with trimethylchlorosilane （Cn）. The prepared AC-H2SO4-C, was characterized by XRD, IR and TG. It was found that the trimethylchlorosilane forms hydrophobic groups on the surface of the catalyst after the process of silicane-modification, which enhance the reusability of the catalyst. The effect of the sequence of the preparation process on the catalytic activity and hydrophobicity was investigated via the esterification reaction of the acetic acid with ethanol. The results show that the catalyst loaded firstly with sulfuric acid and then modified by silicane exhibits a better reusability than that of the catalyst prepared by the method with reversed process sequence. When the catalyst used was prepared under the conditions as follows： the trimethylchlorosilane concentration of the impregnating solution is 15%（V/V）, the impregnation temperature is 60℃ and the impregnation time is 2 h, the maximum conversation ratio of acetic acid can reach 90.3%. Besides, the reused catalyst activity of the catalyst prepared under above mentioned conditions is better than that of the catalysts prepared under conditions different from those mentioned above.
出处
《高校化学工程学报》
EI
CAS
CSCD
北大核心
2012年第4期612-617,共6页
Journal of Chemical Engineering of Chinese Universities
基金
山东省优秀中青年科学家科研奖励基金(BS2009CL004)
关键词
活性炭
硅烷
疏水
固体酸
酯化
activated carbon
silicane
hydrophobicity
solid acid
esterification
