H_3PW_(12)O_(40)/Al_2O_3催化剂在甘油脱水制备丙烯醛反应中的性能评价研究

采用等体积浸渍法制备了H3PW12O40/Al2O3催化剂,在常压连续流动固定床反应器中,对催化剂的活性稳定性进行了考察,同时利用BET、SEM和XRD等对反应前后的催化剂进行了基本表征。结果显示,在反应过程中,催化剂上的积炭量呈上升趋势,尤其在催化剂活性增长期其积炭生成速率很快。较高的空速有利于减少催化剂上的积炭量。积炭可能是由丙烯醛在杂多酸催化剂上的聚合而产生的,它覆盖在催化剂表面,堵塞了孔道,从而引起了催化剂活性降低。但积炭并没有破坏催化剂的结构,催化剂仍然保持Keggin结构,仍具有催化活性。

Performance evaluation of a H3PW12O40/Al2O3 catalyst for preparation of acrolein by glycerol dehydration

The performances of a H3PW12O40/Al2O3 heteropoly acid catalyst prepared by incipient wet impregnation method were evaluated for glycerol dehydration to acrolein.The activity stability of the catalyst was investigated in a continuous flow fixed-bed reactor,and the fresh and coked catalysts were characterized by BET,SEM and XRD.The results showed that a rapid carbon deposi-tion occured in the catalytic activity growth period,following by a slowly coke deposition in subsequent reaction time.The amount of coke deposition on the catalyst decreased with increase of liquid space velocity.The probable cause resulted in the decrease of catalyst activity was acrolein polymerization.The polymer covered catalyst surface and blocked the pores.But the Keggin structure of the H3PW12O40 wasn’t changed by carbon deposition,so the carbon-deposited catalyst still exhibited catalytic activity.