钯系催化剂的氨中毒研究

Study on Ammonia Poisoning of Pd System Catalyst for CO Coupling Reaction to Diethyl Oxalate

考察了CO常压气相偶联合成草酸酯反应体系中在不同氨含量下Pd系催化剂活性随反应时间的变化 .结果表明 ,随着氨含量的增加 ,催化剂活性降低的速率加快 ,氨含量不超过 0 5 4%时 ,仅引起催化剂活性下降 ,但不会造成催化剂完全失活 ;当氨含量达 1 16 %时 ,催化剂活性随反应时间迅速下降 ,直至完全失活 .同时 ,观测了催化剂氨中毒的不可逆性 .利用XPS和TEM表征手段探讨了Pd系催化剂氨中毒机理 。

The effect of ammonia of different contents on the activity of Pd system catalyst for CO coupling reaction to diethyl oxalate was experimentally investigated. The experimental results showed that the deactivation rate of the catalyst is getting faster and faster with increasing ammonia contents. Ammonia, not more than 0.54%, only causes the catalyst activity to decrease. But the catalyst is rapidly poisoned until full loss of the catalytic activity when ammonia content is up to 1.16%. After removing ammonia from the reaction system, the activity of the poisoned catalyst can not be fully recovered. The mechanism of ammonia poisoning for Pd system catalyst and the reasons for irreversibility of ammonia poisoning under reaction conditions were discussed on the basis of XPS and TEM measurement results of the catalyst.