CeO₂ Frustrated\nLewis Pairs Improving CO₂ and CH₃OH Conversion\nto Monomethylcarbonate

Abstract

Frustrated Lewis pairs (FLPs), discovered in the last\nfew decades\nfor homogeneous catalysts and in the last few years also for heterogeneous\ncatalysts, are stimulating the scientific community’s interest\nfor their potential in small-molecule activation. Nevertheless, how\nan FLP activates stable molecules such as CO₂ is still\nundefined. Through a careful spectroscopic study, we here report the\nformation of FLPs over a highly defective CeO₂ sample prepared\nby microwave-assisted synthesis. Carbon dioxide activation over FLP\nis shown to occur through a bidentate carbonate bridging the FLP and\nimplying a Ce³⁺-to-CO₂ charge transfer, thus\nenhancing its activation. Carbon dioxide reaction with methanol to\nform monomethylcarbonate is here employed to demonstrate active roles\nof FLP and, eventually, to propose a reaction mechanism clarifying\nthe role of Ce³⁺ and oxygen vacancies.