Reverse water-gas shift reaction:steady state isotope switching study of the reverse water-gas shift reaction using in situ DRIFTS and a Pt/ceria catalyst

摘要

A previous investigation using steady state isotope switching in combination with DRIFTS demonstrated that surface formates exchange rapidly in a low temperature shift feed for the forward reaction.Transient decomposition of the pseudo-stable formate indicated that water autocatalyzes the forward shift reaction.In the present study,and including water in the RWGS feed (H_2 and CO_2),surface formates were found to exchange more rapidly during RWGS over Pt/ceria than when a dry feed was used.An earlier claim suggested that Pt-CO and carbonate were intermediates,as they exchange rapidly during RWGS.However,in the present study of ~(12)CO_2 to ~(13)CO_2 switching,Pt-CO and carbonate exchange rapidly even in the absence of reaction.Furthermore,the formate exchange rate during RWGS in the absence of added water proceeds at a much slower rate,indicating that conclusions on the mechanism of forward shift cannot be inferred on the basis of dry RWGS results.