Improved catalytic performance of Pd-Cu/NaY zeolite by tunning Al distribution for the synthesis of dimethyl carbonate

Abstract

Dimethyl carbonate (DMC) is a green chemical that is widely used in the synthesis of polycarbonate and the electrolyte of batteries. The Coal to DMC is a cost-effective pathway and the carbonylation of methyl nitrite (MN) is a critical step. The Pd-based catalysts have been extensively investigated for this reaction. However, the effect of the catalyst support (NaY zeolite) is rarely studied and unclear. Here, the mechanisms are disclosed by combining experiments and theoretical simulations. We find in experiments that the activity of the catalysts increases when the Si/Al molar ratio of NaY zeolite increases from 1.37 to 1.75, and then decrease when the Si/Al ratio reaches 2.33. Density functional theory (DFT) simulations results indicate that the CO adsorption strength on the catalysts is affected by not only the Si/Al ratio but also the distribution pattern of Al substitutions. The CO adsorption strength is moderated by the population of the Al-O-Si-O-Si-O-Al and Al-O-Si-O-Al linkages in Pd-NaY. The theoretical results provide useful information to clarify the effects of Al distribution for the catalysts with NaY zeolite as support.