The role of H2 on the stability of the single-metal-site Ir1/AC catalyst for heterogeneous methanol carbonylation

•Single-site Ir1/AC catalyst is prepared for heterogeneous methanol carbonylation.•Metal leaching and carbon deposition deactivated Ir1/AC catalyst.•Volatile [Ir(CO)3I] species is supposed the form of metal leaching.•Stay species of rate-determining step is the root of carbon deposition.•H2 is essential to maintain the Ir1/AC catalyst activity.