Chinese researchers figure out new near zero-carbon olefin production route

BEIJING, Oct. 31 (Xinhua) -- A group of Chinese researchers has developed a simple yet highly effective catalytic tuning strategy that almost completely eliminates carbon dioxide by-products during Fischer-Tropsch synthesis (FTS), offering a new route to green syngas conversion and low-carbon chemical manufacturing.

This achievement was published on Thursday in the journal Science.

FTS converts the syngas of carbon dioxide and hydrogen into liquid fuels or high-value chemicals such as olefins. It serves as the pivotal bridge for turning coal, natural gas, biomass and other carbon resources into fuels and value-added chemicals.

Thanks to their low cost and high yield to fuels, iron-based catalysts now account for more than two-thirds of global FTS capacity.

However, a water-gas shift reaction proceeds almost unavoidably during the iron-catalyzed FTS process -- generating large amounts of carbon dioxide and squandering valuable carbon.

By integrating the syngas with just a bit of methyl bromide at a concentration of five ppm -- the researchers gained surgical control over the reaction pathways on the iron surface.

Experimental data show that such ppm-level methyl bromide switches off the carbon dioxide-forming route, cutting its selectivity from around 30 percent to below 1 percent -- and achieving virtually zero emissions.

FTS has long been a cornerstone of China's coal-to-liquid and syngas chemical industries, yet the seemingly unavoidable formation of carbon dioxide by-products remained one of the biggest roadblocks to its green upgrade, said Ma Ding, a professor of Peking University.

"Our study delivers a simple yet effective technical fix that enables green and low-carbon production of olefins or liquid fuels," Ma added.

Paired with renewable hydrogen and low-carbon dioxide coal-gasification, the study is expected to open a fresh pathway in decarbonizing coal-to-liquid or coal-to-chemicals processes.