A paper by a joint research team from CAS Key Laboratory of Low-Carbon Conversion Science and Engineering of Shanghai Advanced Research Institute (SARI) and SARI-ShanghaiTech University Joint Lab was published in the leading scientific journal Nature Chemistry on June 12, 2017.  

The research team has found a new approach to convert carbon dioxide directly into gasoline by using a bifunctional catalyst contained a reducible oxide (In₂O₃) and a zeolite (HZSM-5), which will not only help to alleviate the global warming caused by increasing atmospheric CO₂ concentration, but also offer a solution to replace dwindling fossil fuels. 

“Because carbon dioxide is extremely inert, previous recycling was mainly on converting it to chemicals like methanol. But our findings are able to convert the greenhouse gas into value-added chemicals with two or more carbons like gasoline directly. And the conversion is of very high efficiency due to the newly developed catalyst.” said ZHONG Liangshu, one of the project researchers. 

Currently, CO₂-based Fischer–Tropsch synthesis (FTS) route over modified Fe-based catalysts can be used for the production of hydrocarbons. According to Anderson–Schulz–Flory distribution, however, the chain growth probability of FTS limits the proportion of desired C₅–C₁₁ hydrocarbons only with 48% at maximum of C₅–C₁₁ selectivity. In addition, the degree of hydrogenation of surface-adsorbed intermediates in CO₂-based FTS is higher due to the slower adsorption rate of CO₂ when compared to CO hydrogenation, leading to more readily formation of methane with a decrease in chain growth. In the present work, the bifunctional catalyst exhibits excellent performance for the direct production of long-chain hydrocarbons from CO₂ hydrogenation with high selectivity. The C₅₊ selectivity in hydrocarbons distribution (carbon atom-based) reached up to 78.6% with only 1% CH₄ at a CO₂ conversion of 13.1% (Figure). There was no obvious catalyst deactivation over 150 h, and much better performance was observed with internal gas recycling. Such results suggest a promising potential for its industrial application.

Figure: Direct conversion of CO₂ into liquid fuels with high selectivity over a bifunctional catalyst （Image by GAO Peng）

China is the world's biggest carbon emitter and much attention has been paid to cut emissions. Chinese President Xi Jinping made the pledge that China would peak CO₂ emissions by around 2030 in his speech at the United Nations Conference on Climate Change in Paris. If CO₂ can be directly and efficiently converted into liquid fuels, the dream toward cycling carbon by mimicking nature will come true.