Highly Selective Oxidation of Methane into Methanol over Cu-Promoted Monomeric Fe/ZSM-5

The selective oxidation of methane into methanol is of paramount importance but poses significant challenges in achieving high methanol productivity and selectivity, especially under mild reaction conditions. We show that a Cu-modified monomeric Fe/ZSM-5 catalyst is a highly efficient material for the direct conversion of methane into methanol in the liquid phase using H2O2 as an oxidant at low temperatures, which exhibits an excellent methanol productivity of 431 mol(MeOH).mol(Fe)(-1).h(-1) (with a methanol selectivity of similar to 80% over the Cu-Fe(2/0.1)/ZSM-5 catalyst). Combining the control experiments and comprehensive characterization results by among others, Mossbauer spectroscopy, and electron paramagnetic resonance as well as density functional theory calculations, we found that Cu species in the Cu-Fe(2/0.1)/ZSM-5 catalyst play a pivotal role in facilitating the formation of .OH radicals, which quickly react with .CH3 radicals to form CH3OH. These findings provide valuable insights into the rational design of metal-zeolite combinations for the selective oxidation of methane into methanol.

Automated summary

The study demonstrates that the Cu-modified Fe/ZSM-5 catalyst is highly efficient for the direct conversion of methane into methanol in the liquid phase using H2O2 as an oxidant. Cu species in the catalyst play a crucial role in facilitating the formation of .OH radicals, which react quickly with .CH3 radicals to form methanol. This provides valuable insights into the rational design of metal-zeolite combinations for the selective oxidation of methane into methanol.