Selective oxidation of methane makes formaldehyde, without generating CO2

Researchers from South Korea have discovered a high-performance catalyst for the selective oxidation of methane to formaldehyde. The study was conducted by staff from Ulsan National Institute of Science and Technology (Ulsan; www.unist.ac.kr), Ajou University (Suwon; www.ajou.ac.kr) and Hanyang University (Seoul; www.hanyang.ac.kr), and led by Ulsan’s professor Kwang-jin Ahn.

Methane is very stable and does not react easily with other substances. Temperatures above 600°C are required for a reaction that changes the chemical structure of methane. Vanadium oxide (V₂O₂) and molybdenum oxide (MoO₃) were known to be the best catalysts, but the conversion of methane to formaldehyde is low (less than 10%).

The catalyst developed by the Korean team has a core-shell structure consisting of vanadium oxide nanoparticles surrounded by a thin aluminum film. The shell protects the grain and keeps the catalyst stable and maintains stability and reactivity even at high temperatures. The team utilized hydrothermal synthesis followed by atomic layer deposition to prepare the catalyst based on the novel SiO₂@V₂O₅@Al₂O₃ core@shell nanostructures. The thickness of Al₂O₃ shells over SiO₂@V₂O₅ cores can be tuned by controlling the number of atomic layer deposition cycles.

With this catalyst the efficiency of conversion of methane to formaldehyde increased by more than 22%. Ahn says the team plans to further develop the catalyst manufacturing technology and the catalytic action in order to move to industrial application.