Deactivation of activated carbon supported nickel-palladium catalyst for vapor phase carbonylation of methanol

Vapor phase carbonylation of methanol was investigated over Ni-Pd/AC catalyst under the conditions of 260°C, 1.5 MPa, CO/CH3OH/CH3I(molar ratio)20/19/1, W/F=7.5 gcat·h·mol−1. The structure and surface property of the fresh and deactivated Ni-Pd/AC catalysts were characterized by BET specific surface area, Pyrolysis-FTIR (Py-FTIR) and XPS. It was found that the deactivation at the primary step appeared to be consistent with a strong adsorption of reaction products that plugged the catalyst pores and led to a diffusion limitation. With the proceeding of the reaction, the carbonylation active site Ni migrated gradually and enriched on the catalyst surface, resulting in easy carbon deposition, which enhanced the deactivation of the catalyst. Further investigation revealed that the carbon deposited on the catalyst surface has graphite structure or is similar to graphite structure.