Illuminating The Conversion Of Methane To Synthesis Gas

Researchers in Japan are one step closer to an eco-friendly catalyst for converting methane into useful gases.

AsianScientist (Feb. 17, 2020) – In a study published in Nature Catalysis, a research group in Japan has developed nanoparticles that convert greenhouse gases into ‘synthesis gases’ which can be used to produce ammonia or methanol.

By reacting methane with carbon dioxide—a process referred to as dry reforming of methane (DRM)—the chemicals sector can produce ‘synthesis gases’ which serve as building blocks for generating other useful compounds.

However, the DRM reaction is termed ‘uphill’ because it requires the consumption of external energy; the temperature in thermal reactors have to exceed 800 °C for efficient conversion. Reaching such high temperatures requires burning other fuels, resulting in massive greenhouse gas emissions, which are the leading cause of climate change. In addition, the use of high temperatures also causes the deactivation of commonly used catalysts due to aggregation and carbon precipitation (so-called coking).

In the present study, researchers led by Professor Mashiro Miyauchi have developed a catalyst that can drive the DRM reaction at dramatically lower temperatures using light. Miyauchi’s team combined strontium titanate with rhodium nanoparticles and found that, under light irradiation, the catalyst efficiently converted methane and carbon dioxide into synthesis gas without heat supply.

The researchers also determined that the photocatalyst was much more stable than previously tested catalysts and did not clump or suffer from coking.

“The proposed photocatalyst allowed us to vastly surpass the limitations of thermal catalysts, yielding high performance for synthetic gas production,” said Miyauchi.

The researchers also detailed the physical mechanisms by which the proposed photocatalyst leads to enhanced conversion of methane. In essence, under ultraviolet light, photoexcited holes and electrons drive methane oxidation over the catalytic nanoparticles, and carbon dioxide reduction occurs in tandem.

“The present study provides a strategic way to perform uphill reactions using methane and creates a connection between the fossil fuel industry and renewable energy applications. Now we are developing the visible-light-sensitive system,” said Miyauchi.

His team envisions that their findings will lead to more eco-friendly methods for synthesis gas generation in the future.

The article can be found at: Shoji et al. (2020) Photocatalytic Uphill Conversion of Natural Gas Beyond the Limitation of Thermal Reaction Systems.


Source: Tokyo Institute of Technology; Photo: Pexels.
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