Cu-Fe Catalyst Facilitates Ambient-pressure Conversion of CO2 Into Long-chain Olefins

Chinese Academy of Sciences

A research team led by Prof. ZENG Jie from the University of Science and Technology of China (USTC) developed a novel Cu-Fe catalyst that can realize the production of long-chain olefins by CO2 hydrogenation under low pressure.

The study was published in Nature Communications on May 3.
Long-chain olefins play an essential role in the production of common chemicals such as synthetic lubricants, high-octane gasoline, and corrosion inhibitors.
However, they are generally synthesized from petroleum resources, which is not environmentally friendly. Moreover, extant methods of CO2 hydrogenation for long-chain olefins production are mostly operated under high pressure.

In this study, the research team chose the CO-intermediate pathway, induced Cu sites with the capability of non-disassociation adsorption of CO, and synthesized the Cu-Fe catalyst with copper-iron carbide interfaces working under ambient pressure. The Cu-Fe catalyst, composed of Cu, iron oxides, and iron carbides, is termed activated CuFeO2.

They found that the activated CuFeO2 achieved long-chain olefins selectivity of 66.9% under 1 bar, which surpassed the current highest selectivity of 66.8% under 35 bar.

Compared to the traditional iron-based catalyst, the Cu-Fe catalyst showed lower selectivity for CO and methane and higher selectivity for long-chain olefins.

To evaluate the applicability of the activated CuFeO2, they changed the space velocity and the ratio of H2 to CO2. The results showed that the prepared catalysts could achieve good long-chain olefins selectivity under various space velocities and the ratio of H2 to CO2, indicating the applicability of activated CuFeO2 in a wide range of conditions.

“Although the activity of the catalyst decreased after a long reaction, it can be refreshed by a regeneration process that increased the pressure,” said Prof. ZENG.

Moreover, the researchers revealed that except for the C-C coupling through the carbide process on iron carbide, CO insertion also occurred on copper-iron carbide interfaces to cause carbon chain growth.

As a result, a large amount of undissociated CO on the surface of the catalyst can be utilized efficiently. The cooperation of the carbide process and the CO insertion process led to the good selectivity of long-chain olefins.

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