Methane generates more warming than other greenhouse gases, and is the subject of newly announced emissions restrictions in the United States, which is difficult to decompose and stay away from the atmosphere.

This is not to say that the main components of natural gas are chemically complex. A methane molecule has only one carbon atom and four hydrogens.

But these carbon-hydrogen bonds are difficult to break.

Generally, this involves high temperatures and mixing combustible gas with oxygen to produce syngas to produce methanol and hydrogen to produce ammonia. That is expensive and potentially explosive.

Other conversion reactions are not efficient and will produce the most abundant greenhouse gas carbon dioxide.

So, is there another way to use methane and exclude it from the atmosphere? Which is safe and efficient? A return value? Is one that helps combat climate change?

For many years, Yue Wu and his research team at Iowa State University have been looking for ways to complete all these experiments. These failures and discoveries were all failed experiments. Now they and a group of authors have discovered and tested a catalyst technology, which seems to be an answer.

"This result provides a potential solution to this long-term challenge and represents the best stability, conversion rate and selectivity for the conversion of methane to ethane or ethylene, the two main precursors of the modern petrochemical industry. "Said Wu, a professor of chemical engineering. In Iowa.

A recent research paper published in the journal Nature Catalysis reports this discovery. Wu and Yang Xiao, a senior research engineer at Purdue University in Indiana, are the corresponding authors. The first author is Li Zhe. He received his Ph.D. from Iowa State University in 2019 and is currently a postdoctoral researcher at Johns Hopkins University in Maryland. The Office of Innovation and Commercialization at Iowa State University is applying for a patent for this technology.

The catalyst consists of one or two layers of platinum, each layer only one atom thick, deposited on a two-dimensional metal carbide structure called "MXenes". In this case, the structure is made of carbon, molybdenum and titanium.

Wu said his research team found that the thin layer essentially allows every platinum atom to be used as a catalyst and prevents the formation of residues that cover and deactivate platinum. This means that less platinum is needed to make the catalyst.

Wu said that his team started researching carbides, a combination of carbon and metals, with the support of the Office of Naval Research about five years ago. The initial work was to determine the electrical and thermal properties of various carbides. But this work did not go as expected-the thermal conductivity of the material was much lower than expected.

"You can think of this as a failure," Wu said.

However, the researchers found that the surface of MXene is very active and can absorb many molecules. Therefore, with the support of Wu's Stiles professorship and Iowa State College of Engineering, Wu's research team began to study these MXenes as potential catalysts.

"We have never seen such an active carbide," Wu said. "It is usually very inert. For example, it is used for high-speed drills-the surface is hard and inert."

They began to use this technology to remove hydrogen from shale gas, which is natural gas found in shale formations. This work evolved to study other reactions involving natural gas.

"No one has tried to use these carbides for these high-volume reactions before," Wu said.

Wu said that the key to the conversion of methane to ethane/ethylene is to make the carbides pure enough and the surface clean enough to support the reaction. All goes well. In a continuously operating fixed-bed reactor, the methane conversion rate of these reactions is about 7%, and the selectivity to ethane/ethylene is about 95%. Products can be made into plastics and resins, such as the common and ubiquitous polyethylene plastics.

"It is worth noting that these new catalysts have been running continuously for 72 hours without any signs of deactivation, which indicates that the technology suitable for industrial-scale development is off to a good start," Wu wrote.

He said that this is all very good news.

After all, methane emissions are an important factor in climate change, so much so that world leaders took measures to limit them during COP26, the recent United Nations Climate Change Summit in Glasgow, Scotland. President Joe Biden announced that the United States will take measures to limit methane emissions from existing oil and gas businesses. More than 100 countries have also signed a global methane pledge to reduce methane emissions by 30% in the next nine years.

The researchers’ new catalyst technology can advance efforts to keep methane out of the atmosphere. Wu called the technology "revolutionary" and said it "opened the door for the future to reduce the emission of methane and its combustion product carbon dioxide."

Republished by Iowa State University. Photo: Iowa State University Chemical and Biological Engineer Professor Yue Wu (right), PhD student Xiaopeng Liu (left), and postdoctoral researcher Fan Yang (middle) are team members developing catalysts that convert greenhouse gases into chemicals to make plastics and others Material. Image credit: Christopher Gannon/Iowa State University

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