Enhanced Catalytic Activity of (DMSO)2PtCl2 for the Methane Oxidation in the SO3–H2SO4 System

Abstract

Among the various methane activation reactions, oleum-mediated (SO3–H2SO4) methane oxidation to methyl bisulfate (MBS), a methanol precursor, is one of the best methods in terms of methane conversion and product selectivity. In this report, we investigated the effect of the catalyst concentration on the MBS yield using the catalyst systems (bpym)PtCl2, K2PtCl4, and (DMSO)2PtCl2 at 180 °C for 3 h. (bpym)PtCl2 showed a very high stability as well as a high MBS yield of over 84%, but its catalytic activity expressed in terms of turnovers for 3 h was in the range 50–500. K2PtCl4 showed very high catalyst turnovers of over 17 000 at a low catalyst concentration; however, it deactivated rapidly to PtCl2 which prevents achieving a high MBS yield that was achieved by (bpym)PtCl2. However, (DMSO)2PtCl2 showed an enhanced catalytic performance for both the MBS yield and the turnovers. An MBS yield of over 84% with a selectivity of 94% was obtained at a catalyst concentration of 3.0 mM, and its turnovers reached ove...