Polymer-supported palladium-manganese bimetallic catalyst for the oxidative carbonylation of amines to carbamate esters

The polymer-supported bimetallic catalyst PVP-PdCl2-MnCl2 (PVP=poly(N-vinyl-2-pyrrolidone)) exhibits high activity and selectivity for the oxidative carbonylation of amines with carbon monoxide and oxygen to carbamate esters under atmospheric pressure in the presence of a base (NaOAc). This catalyst is prepared by the addition of MnCl2 to the alcoholic solution of PVP-PdCl2 in situ. A remarkable bimetallic synergic effect and the role of PVP in PVP-PdCl2-MXn (MXn=the second transition metal component such as NiCl2, CoCl2, MnCl2 and FeCl3) gives rise to an obvious increase in the conversion and selectivity for the reaction. Among the second metal components tested, Mn-Pd exerts the strongest synergic effect. (C) 1999 Elsevier Science B.V. All rights reserved.

Mechanistic studies of methane partial oxidation to syngas over LiNiLaOx/Al2O3 catalyst

Temperature-programmed reduction (TPR) characterization of the LiNiLaOx/Al2O3 catalyst before or after partial oxidation of methane (POM) reaction and a series of O-2, CH4 and CH4/O-2 pulse reaction experiments over the catalyst under different pretreatments were performed. It was found that CH4 dissociatively adsorbs on active center nickel producing H-2 and surface carbon, C(a). The surface carbon reacts with surface lattice oxygen or surface adsorbed oxygen to produce CO. Because the activation barrier for the reaction C(a)+ O(a) =CO(a) is the highest among all the elementary reactions, the rate-determining step of the POM may be the reaction C(a) + O(a) =CO(a).