有机胺修饰的Ru-Ir/γ-Al_2O_3催化剂上对氯硝基苯选择性加氢

Selective Hydrogenation of p-Chloronitrobenzene over Ru-Ir/γ-Al_2O_3 Catalyst Modified by Organic Amines

采用浸渍法制备了Ru-Ir/γ-Al2O3双金属催化剂,考察了添加有机胺修饰剂对该催化剂催化对氯硝基苯加氢反应性能的影响.结果表明,添加乙二胺或L-赖氨酸时,催化剂的活性和产物对氯苯胺的选择性均大幅度提高.在乙二胺的存在下,加氢反应的转化率由未添加修饰剂的37.2%提高到95.6%,对氯苯胺的选择性达到100%.同样,L-赖氨酸存在时,催化剂的活性明显增强,副反应完全被抑制.乙二胺或L-赖氨酸对Ru-Ir/γ-Al2O3催化性能的促进作用可能是由于它们与催化剂上的金属活性中心发生配位,导致Ru-Ir/γ-Al2O3上的Ru和Ir两种金属组分之间产生了强烈的协同效应的缘故.

A Ru-Ir/γ-Al2O3 bimetallic catalyst was prepared by impregnating γ-Al2O3 with a isopropylalcohol solution of RuCl3 and H2IrCl6. The effect of organic amine modifiers on the selective hydrogenation of p- chloronitrobenzene （p-CNB） over Ru-Ir/γ-Al2O3 was investigated. The addition of ethylenediamine and L-lysine remarkably improved the catalytic activity of Ru-Ir/γ-Al2O3 and the selectivity for p-chloroaniline （p- CAN） at high conversion of p-CNB. In the presence of ethylenediamine, the conversion of p-CNB increased from 37.2 % to 95.6 % and the selectivity for p-CAN was maintained at 100 %. Similarly, the addition of L-lysine greatly enhanced the catalyst activity and completely suppressed the formation of by-products. The promotion effect was attributed to the coordination of ethylenediamine or L-lysine with the metal center, with improved the cooperation between ruthenium and iridium.