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

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.