New catalyst design raises methanol output from carbon dioxide
Researchers in China report a catalyst that separates reaction steps and produces about three times as much methanol as standard commercial catalysts.
By Priya Raghavan · Science Reporter
2 min read
Researchers at the Dalian Institute of Chemical Physics say they have designed a catalyst that improves the conversion of carbon dioxide into methanol, a fuel and chemical feedstock. The work targets a barrier that has held back CO2-to-methanol chemistry: conditions that favor methanol often slow the reaction, while faster conditions can produce more unwanted byproducts.
The study, led by Prof. Jian Sun and Prof. Jiafeng Yu of the Dalian Institute of Chemical Physics at the Chinese Academy of Sciences, was published in Chem, according to the institute. The paper reports a catalyst architecture that separates key active sites, allowing different parts of the reaction to occur in different places on the catalyst surface.
How the catalyst changes the reaction
According to the institute, CO2 conversion to methanol is more favorable at lower temperatures, but CO2 is harder to activate under those conditions. Higher temperatures can accelerate the chemistry, the researchers said, but they also promote the reverse water-gas shift reaction, which forms carbon monoxide and cuts methanol selectivity.
The team used what the institute described as a strong metal-support interaction, or SMSI, to create an overlayer structure on the catalyst. That structure spatially separates active sites, changing how reactants attach to the catalyst, split apart and proceed through the reaction pathway, according to the researchers.
In tests, the catalyst reached a space-time yield of 1.2 grams per gram of catalyst per hour at 300 degrees Celsius and 3 megapascals, the Dalian Institute of Chemical Physics reported. The institute said that output was about three times higher than conventional commercial copper-zinc-aluminum catalysts.
Steering CO2 toward methanol
The researchers found that the new catalyst pushes CO2 adsorption and activation mainly onto zirconia, or ZrO2, sites, according to the institute. That steers the reaction toward methanol through the formate pathway, rather than encouraging carbon monoxide formation.
The institute said the sequence differs from conventional copper-based catalysts. In the usual route described by the researchers, activation starts with cleavage of the carbon-oxygen double bond before hydrogenation; in the new design, hydrogenation occurs first on ZrO2 sites, followed by carbon-oxygen bond cleavage.
That change reduces carbon monoxide byproducts while keeping copper sites available to dissociate hydrogen efficiently, according to the research team. Prof. Sun said the study may offer a new route for addressing the trade-off between activity and selectivity in methanol synthesis from CO2.
The journal article is titled “Disentangling the activity-selectivity trade-off in CO2 hydrogenation to methanol,” by Habib Zada, Jiafeng Yu, Chuanyan Fang and Jian Sun. The Dalian Institute of Chemical Physics said the findings point to a catalyst-design strategy for improving CO2 recycling into methanol.
This story draws on original reporting from ScienceDaily.