The research team of the University of Science and Technology of China realizes the hydrogenation of carbon dioxide under normal pressure to produce long-chain olefins

Recently, the research team of Professor Zeng Jie from the Hefei National Research Center for Microscale Matter Science and the Department of Chemical Physics, University of Science and Technology of China, designed and constructed a copper-iron carbide interface catalyst to achieve high selectivity for the preparation of long-chain olefins by hydrogenation of carbon dioxide at atmospheric pressure
.

Long-chain olefins have a wide range of applications in the field of fine chemicals, such as synthetic detergents, high-octane gasoline, lubricating oils, pesticides, plasticizers,
etc.
At present, the main way to synthesize long-chain olefins is olefin polymerization which relies on the petrochemical industry
.
If using renewable energy to electrolyze water to produce hydrogen, and then react with the greenhouse gas carbon dioxide to directly produce long-chain olefins, there will be huge environmental benefits
.
Due to the small scale and scattered layout of the water electrolysis equipment, in order to directly connect the electrolyzed water for hydrogen production, the carbon dioxide hydrogenation reaction needs to be carried out under normal pressure
.
However, at present, the hydrogenation of carbon dioxide to produce long-chain olefins is mostly carried out under high pressure reaction conditions
.
Therefore, the realization of carbon dioxide atmospheric hydrogenation to produce long-chain olefins is still a huge challenge
.

The hydrogenation of carbon dioxide to produce olefins is mainly through methanol intermediate and carbon monoxide intermediate routes
.
Since low pressure is not conducive to either the methanol synthesis reaction nor the methanol-to-hydrocarbon reaction, the research team chose the carbon monoxide intermediate route
.
The challenge of this route is to design a suitable Fischer-Tropsch synthesis active site at atmospheric pressure
.
Drawing on the design idea of ​​modified Fischer-Tropsch catalysts for alcohol synthesis, the researchers introduced copper sites with non-dissociative adsorption capacity for carbon monoxide on the basis of iron-based catalysts, and prepared a copper-iron carbide interface working under normal pressure.
The copper-iron catalyst contains various phases such as metallic copper, iron tetroxide and iron carbide
.

The research results show that the catalyst has a high selectivity to long-chain olefins of 66.
9%, while the conversion of carbon dioxide is 27.
3% and the selectivity of carbon monoxide is 43.
7%
.
Compared with traditional iron-based catalysts, the catalyst has lower selectivity to carbon monoxide and methane, and higher selectivity to long-chain olefins
.
The researchers found that the long-chain olefin selectivity of the catalyst decreased after a prolonged reaction, but could be recovered after a simple regeneration treatment
.

The results of this study reveal the coupling mechanism of carbon-carbon bonds during the hydrogenation of carbon dioxide, and also provide ideas for the design of catalysts for the hydrogenation of carbon dioxide to long-chain olefins
.