Researchers from the Tokyo Institute of Technology have developed a novel multifunctional catalyst to convert methane, a greenhouse gas, into valuable hydrocarbons and nitrogen gas. The method presents an alternative energy-efficient and sustainable alternative to common sequential conversion techniques.
In typical methane reformation techniques, methane is first converted into methanol before subsequent reactions convert it into hydrocarbons. Due to the stability of methane, this sequential conversion requires tremendous amounts of energy and complex industrial setups. To overcome these challenges, the team of researchers developed and analyzed a novel bifunctional zeolite catalyst containing varying concentrations of copper.
In the study, published in Nature Communications, the team investigated the effects that copper concentration and copper proton proximity have on the reaction. During analysis, the researchers discovered that when copper sites were closer together, the methane had a higher probability of over-oxidizing and turning into carbon dioxide. In contrast, when copper and acid sites were closer together, the methanol reacted with nearby nitrous oxide to produce hydrocarbons and nitrogen gas.
"We concluded that for stable and efficient production of methanol and ultimately useful hydrocarbons from methane, it is necessary to uniformly distribute Cu sites and acid sites and have them be at an appropriate distance from each other," said Associate Professor Toshiyuki Yokoi. "We also found that the distribution of products obtained is also influenced by the acid properties and pore structure of the zeolite catalyst."
One of the key advantages of the catalyst developed is its ability to sustain tandem reactions. This ability will be critical in making the method attractive to industrial applications.
"Our work will hopefully guide future efforts to achieve methane oxidation to methanol and open avenues for promoting hydrocarbon synthesis using methanol as an intermediate," added Yokoi.