New catalyst turns methane into valuable chemicals at lower temperatures and lasts 240 hours
Researchers at Institute of Science Tokyo made a five-element oxide catalyst that starts converting methane into ethane and ethylene at 525°C and kept its performance for 240 hours.
Chemists at Institute of Science Tokyo have developed a catalyst that converts methane into more valuable hydrocarbons at lower temperatures than earlier catalysts and keeps working for at least 240 hours, the institute said. The study, led by Professor Keigo Kamata, was published on 8 October in the Journal of the American Chemical Society.
Turning natural gas into building blocks for plastics is hard
Methane is the main component of natural gas. A reaction called oxidative coupling of methane can turn it directly into ethane and ethylene, raw materials for plastics and other chemicals. But methane's bonds are very stable, and the products react more easily than methane itself, so they tend to burn on to carbon oxides.
Conventional catalysts for the reaction need temperatures near 800°C and lose activity over long runs, which has held back industrial use.
Five rare-earth elements in one crystal
The team screened 55 "high-entropy" oxides, materials that mix five or more metals in one crystal structure. The best candidate combines lanthanum, samarium, europium, gadolinium and dysprosium. It started producing ethane and ethylene at 525°C and reached a 12.3% yield at 600°C.
At 600°C, its yield was essentially unchanged after 240 hours, and it lost activity more than 25 times more slowly than the single oxides it is made from. The researchers trace the performance to moderately basic sites on the catalyst's surface, which they could tune through the average size of the metal ions.
“By establishing the average ionic radius as a descriptor for surface basicity, our study provides a rational framework for designing selective oxidation catalysts that convert methane at lower temperatures with sustained activity.” — Professor Keigo Kamata, Institute of Science Tokyo
The work is a laboratory result, and a 12.3% yield is still far from an industrial process. The team, which included the University of Tokyo, sees the design principle as the main contribution. Other labs are also chasing cleaner chemistry, such as Oregon State's light-driven hydrogen production without a metal catalyst.
Like what you're reading?
Related stories
Japanese Scientists Make DNA Strands Grow, Move and Link Into Networks Like Living Cells
Researchers at Institute of Science Tokyo and Kyoto University grew long DNA strands on protein tubes and used motor proteins to move them, forming networks within minutes, a step toward materials that can build and reshape themselves.
Researchers Used Quantum Vacuum Fluctuations to Raise a Superconductor's Critical Temperature by Up to 5.4%
Placing a thin superconductor inside a specially built terahertz cavity strengthened the quantum fluctuations of empty space around it and raised its critical temperature by up to 5.4%, a team at the University of Science and Technology of China reports.
Bristol Spinout Turns Moth-Wing Science Into Soundproofing Up to 10 Times Thinner
Attacus Acoustics, a new University of Bristol spinout, is commercializing a sound-absorbing material inspired by moth wings that it says can be up to ten times thinner than conventional soundproofing.
