Researchers from the University of Tokyo in Japan and the University of Sydney in Australia have made an interesting discovery while evaluating the potential of a special type of zeolite to catalyze the conversion of methane into energy sources.
Methane is a highly potent greenhouse gas, about 30 times more effective at trapping heat from the sun in our atmosphere than carbon dioxide. Unfortunately, methane concentrations in the atmosphere are on the rise. This is largely attributed to human activities, such as fossil fuel burning and livestock farming. Current records indicate that methane accounts for 16% of total global greenhouse gas emissions, making it the second most prevalent greenhouse gas in the atmosphere after carbon dioxide. If nothing is done to reduce these emissions, global warming and climate change will further intensify.
One approach that researchers believe could help solve the methane problem is capturing methane and converting it into an energy source. Through a series of chemical reactions, this greenhouse gas can be transformed into methanol and further processed into hydrocarbons, which can be used for energy generation. However, methane is a very stable molecule. Hence, a substantial amount of energy is needed for these processes to occur.
With this in mind, researchers from the University of Tokyo in Japan and the University of Sydney in Australia have investigated the potential of a special type of zeolite to facilitate the conversion of methane into methanol and then into hydrocarbons. Zeolites are porous minerals composed of silicon, oxygen, and aluminum that can be used as catalysts.
During the study, the researchers synthesised aluminosilicate AEI-type zeolites with varying distributions of copper and acid sites. The copper sites were locations within the zeolites where copper ions were incorporated, whereas the acid sites were those that exhibited acidic properties. Then, the researchers evaluated the ability of the different versions of aluminosilicate AEI-type zeolites to catalyze the conversion of methane in a fixed-bed flow reactor.
Based on the results, they found that the aluminosilicate AEI-type zeolites effectively catalysed methane’s conversion. However, the resulting products varied depending on the spatial arrangement of the copper and acid sites within the zeolites. The zeolites with closely packed copper sites favored the formation of carbon dioxide, while those with closely positioned copper and acid sites promoted the production of hydrocarbons. “These findings will guide [the] design of efficient catalysts to control side reactions and increase methanol yield in [the] direct oxidation of methane to methanol reaction, as well as open up an avenue for direct oxidation of methane to hydrocarbons at low temperatures,” said the researchers in their paper, which was published in the peer-reviewed journal Nature Communications.