Direct conversion from methane to methanol using gold-palladium nano particles
Converting methane - the primary component of abundant natural gas into methanol is currently achieved by an indirect process which requires high heat and pressure. Now researchers have discovered a new approach that allows the direct conversion of methane to methanol utilizing molecular oxygen under much milder reaction conditions.
For the study published in the journal, Science, a team led by Graham J. Hutchings at the Cardiff Catalysis Institute, and Christopher J. Kiely at Lehigh, used colloidal gold-palladium (Au-Pd) nanoparticles to directly oxidize methane to methanol with high selectivity in aqueous solution at low temperatures. “Our work has shown that if a stable supply of methyl radicals can be established—for example, by incorporating a very small amount of hydro- gen peroxide into the reaction mixture—then the selective oxidation of methane to methanol using molecular oxygen is entirely feasible,” said Kiely, the Harold B. Chambers Senior Professor of Materials Science and Chemical Engineering. According to Kiely, the researchers were surprised to find that for this particular reaction to proceed they needed the Au-Pd nanoparticles to exist as free-floating colloids in a very weak hydrogen peroxide solution into which they injected pressurized methane and oxygen gas.
“Usually when we use Au-Pd nanoparticles as catalysts they are nearly always dispersed on high surface area oxide supports such as titania,” said Kiely. “In this case however, the presence of the ceramic support turned out to be highly detrimental.In the chemical industry methane is currently converted indirectly to methanol via the production of synthesis gas (carbon monoxide and hydrogen) at high temperatures and pressures, which is an expensive and energy intensive process. The new simplified approach we have demonstrated brings us a step closer to making the direct conversion of methane to methanol- a practically viable proposition,” said Kiely.