In a method known as photo-oxidation, a team of researchers successfully turned methane into methanol by using light and dispersed transition metals such as copper. According to a study published in the journal Chemical Communications, the reaction was the best achieved to date for turning methane gas into liquid fuel at ambient temperature and pressure (25 °C and 1 bar, respectively). The term bar as a pressure unit is derived from the Greek word for weight (baros). One bar equals 100,000 Pascals (100 kPa), which is about equivalent to the ordinary atmospheric pressure at sea level (101,325 Pa). The findings of the study are an important step toward making natural gas available as an energy source for the development of alternative fuels to gasoline and diesel. Despite being a fossil fuel, natural gas conversion into methanol produces less carbon dioxide (CO2) than other liquid fuels in the same category.
Methanol is essential in the biodiesel and chemical industries in Brazil, where it is used to synthesis a wide range of goods. Furthermore, methane removal from the atmosphere is crucial for minimizing the harmful effects of climate change because the gas has 25 times the capacity to contribute to global warming as CO2. “The scientific community is divided on the amount of the planet’s methane reserves. They may have twice the energy potential of all other fossil fuels combined, according to some estimations. “We’ll have to tap into all this methane at some time in the transition to renewables,” Marcos da Silva, the article’s initial author, told Agência FAPESP. Silva is a doctoral student in the Physics Department at the Federal University of Socorro (UFSCar). FAPESP, the Higher Research Council (CAPES, an institution of the Ministry of Education), and the National Council for Scientific and Technological Development all provided funding for the study (CNPq, an arm of the Ministry of Science, Technology, and Innovation).
The photocatalyst utilized in the study was a crucial invention, according to Ivo Freitas Teixeira, a professor at UFSCar, Silva’s thesis advisor, and the article’s final author. “Our group greatly innovated by oxidizing methane in a single stage,” he stated. “In the chemical industry, this conversion occurs in at least two phases and under extremely high temperature and pressure conditions.” Our achievement in producing methanol under moderate temperatures while using less energy is a significant step forward.”
The findings, according to Teixeira, pave the path for further research into the utilization of solar energy in this conversion process, perhaps lowering its environmental impact even more. The researchers created active visible-light photocatalysts in the laboratory by synthesizing crystalline carbon nitride in the form of polyheptazine imide (PHI) with non-noble or earth-abundant transition metals, particularly copper.
The photocatalysts were then employed in methane oxidation processes with hydrogen peroxide as an initiator. The copper-PHI catalyst produced a significant amount of oxygenated liquid products, particularly methanol (2,900 micromoles per gram of material, or mol.g-1 in four hours).
“We determined the optimal catalyst as well as other conditions critical to the chemical reaction, such as employing a significant amount of water and only a tiny amount of hydrogen peroxide, which is an oxidizing agent,” Teixeira explained. “The next step is to learn more about the material’s active copper sites and their role in the reaction.” We also intend to use oxygen directly in the reaction to make hydrogen peroxide. If successful, the procedure should become even safer and more economically viable.”
Another topic that the panel will continue to look into is copper. “We use diffused copper.” We didn’t know whether we were dealing with single atoms or clusters when we authored the essay. “We now know they’re clusters,” he says.
The scientists utilized pure methane in the study, but in the future, they will extract the gas from renewables such as biomass. According to the United Nations, methane has been responsible for around 30% of global warming since the pre-industrial era. Human-caused methane emissions might be decreased by up to 45% in the coming decade, preventing a 0.3°C rise by 2045.
The approach of turning methane into liquid fuel using a photocatalyst is novel and not commercially available, but it has tremendous potential in the near term. “We started our research four years ago. “We now have far better results than 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 from universities in the United States and the United Kingdom, led by Graham Hutchings, a professor at Cardiff University in Wales.