Washington [US]Aug 3 (ANI): Following new research, scientists have discovered a new technique for converting methane gas into methanol using light and dispersed transition metals such as copper.
According to a study published in Chemical Communications, the response was the best yet achieved for the conversion of methane gas into liquid fuel under ambient conditions of temperature and pressure (25°C and 1 bar, respectively).
The term bar as a unit of pressure is derived from the Greek word for weight (baros). One bar is equal to 100,000 pascals (100 kPa), which is very close to normal atmospheric pressure at sea level (101,325 Pa).
The results of the study are an important step towards making natural gas available as an energy source for the production of alternative fuels to petrol and diesel. Although natural gas is considered a fossil fuel, its conversion into methanol emits less carbon dioxide (CO2) than other liquid fuels of the same category.
In Brazil, methanol plays a key role in biodiesel production and in the chemical industry, which synthesizes many products from it.
In addition, capturing methane from the atmosphere is crucial to mitigating the negative effects of climate change, as the gas has 25 times the potential to contribute to global warming, for example.
“There is a great deal of debate in the scientific community about the size of the planet’s methane reserves. According to some estimates, they may have twice the energy potential of all other fossil fuels combined. In the transition to renewable energy, we’re going to have to resort to all this methane at some point,” Marcos da Silva, first author of the article, told Agencia FAPESP. Silva is a PhD student in the Department of Physics at the Federal University of Sao Carlos (UFSCar).
The study was supported by FAPESP through two projects (20/14741-6 and 21/11162-8), the Higher Research Council (CAPES, an agency of the Department of Education) and the National Council for Scientific and Technological Development (CNPq, a branch of the Ministry of Science, Technology and Innovation).
According to Ivo Freitas Teixeira, Professor at UFSCar, Silva’s supervisor and last author of the article, the photocatalyst used in the study was a key innovation. ‘Our group has made a significant innovation by oxidizing methane in a single step,’ he said. “In the chemical industry, this conversion takes place via the production of hydrogen and CO2 in at least two stages and under very high temperature and pressure conditions. Our success in obtaining methanol under mild conditions while using less energy is a big step forward.”
According to Teixeira, the results pave the way for future research into harnessing solar energy for this conversion process, potentially reducing the environmental impact even further.
photocatalysts
In the laboratory, scientists synthesized crystalline carbon nitride in the form of polyheptazinimide (PHI) using base or earth-abundant transition metals, particularly copper, to produce active visible-light photocatalysts.
They then used the photocatalysts in methane oxidation reactions with hydrogen peroxide as the initiator. The copper-PHI catalyst produced a large volume of oxygenated liquid products, particularly methanol (2,900 micromoles per gram of material, or umol.g-1 in four hours).
“We discovered the best catalyst and other conditions essential to the chemical reaction, such as using a large amount of water and only a small amount of hydrogen peroxide, which is an oxidizing agent,” Teixeira said. “The next steps involve a better understanding of the active copper sites in the material and their role in the reaction. We also plan to use oxygen directly to produce hydrogen peroxide in the reaction itself. If successful, this should make the process even safer and more viable.”
Another issue that the group will explore further is copper. “We work with dispersed copper. When we wrote the article, we didn’t know whether we were dealing with isolated atoms or clusters. We now know they are clusters,” he explained.
In the study, the scientists used pure methane, but in future they will produce the gas from renewable raw materials such as biomass.
According to the United Nations, methane has caused about 30% of global warming since the pre-industrial era. Methane emissions from human activities could be reduced by up to 45% over the next decade, avoiding an increase of almost 0.3°C by 2045.
The strategy of converting methane into liquid fuel using a photocatalyst is new and not commercially available, but its near-term potential is significant. “We started our research more than four years ago. We now have far better results than those of Professor Hutchings and his group in 2017, which motivated our own research,” Teixeira said, referring to a study published in the journal Science by researchers associated with universities in the United States and United Kingdom led by Graham Hutchings, Professor at Cardiff University in Wales.
(ANI)