REACTION-MECHANISM OF OXIDATIVE CARBONYLATION OF METHANOL TO DIMETHYLCARBONATE IN CU-Y ZEOLITE

The Cu(I)Y catalyst, as prepared by solid-state ion exchange at 650 de grees C, shows higher productivity and less deactivation than the know n carbon-supported CuCl2 catalyst for gas-phase oxidative carbonylatio n of methanol to make dimethyl carbonate. The ion-exchanged Cu(II)Y sh owed very little activity for the same reaction. An in situ FTIR techn ique was applied to elucidate the reaction mechanism. The first step i s the oxidation of methanol and Cu(I) to from Cu(II)-methoxide. The in sertion of CO to Cu(II)-methoxide, forming probably a carbomethoxide, is the rate-limiting step. Finally, methanol and oxygen react with car bomethoxide to from dimethyl carbonate. (C) 1996 Academic Press, Inc.