Pt-catalyzed oxidative carbonylation of methane to acetic acid in sulfuric acid

The oxidative carbonylation of methane to acetic acid was investigated using Pt(II) cations as the catalyst and sulfuric acid as the solvent. The reactions were carried out at 180 °C in a sealed batch reactor containing either fuming or concentrated (96 wt%) sulfuric acid (3 ml) and PtCl2 (20 mM) in the liquid-phase, and pressurized with CH4 (400 psi) and CO (400 psi). In the absence of CO, the only product is methyl bisulfate, but in the presence of CO, this product undergoes carbonylation to acetic acid. CO also serves as a reducing agent and can reduce the catalytically active Pt(II) to Pt(0), which is inactive. The catalyst activity can be increased by promoting the re-oxidation using co-catalyst, such as CuCl2 and O2. Thus, a balance must be maintained between oxidizing and reducing conditions in order to minimize or avoid the loss of Pt(II).

Graphical abstractPt(II) catalyzes the oxidative carbonylation of methane to acetic acid. Methyl bisulfate is an intermediate that CO carbonylates to produce acetic acid. CO also reduces the active catalyst from Pt(II) to Pt(0). Catalytic activity can be increased by promoting re-oxidation using a co-catalyst and O2. Figure optionsDownload full-size imageDownload as PowerPoint slide