China team develops efficient multifunctional catalyst for conversion of CO2 to gasoline-range hydrocarbons
A research team led by Dr. Jian Sun and Prof. Qingjie Ge at the Dalian Institute of Chemical Physics in China has developed an efficient, stable, and multifunctional Na-Fe3O4/HZSM-5 catalyst for the direct production of gasoline-range hydrocarbons from CO2 hydrogenation. This catalyst exhibited 78% selectivity to C5-C11 as well as low (4%) CH4 at a CO2 conversion of 22% under industrial relevant conditions.
The gasoline fractions are mainly isoparaffins and aromatics, thus favoring the octane number. Moreover, the multifunctional catalyst exhibited a remarkable stability for 1,000 h on stream, showing potential to be a promising industrial catalyst for CO2 conversion to liquid fuels. An open-access paper on their work is published in the journal Nature Communications.
Because CO2 is a fully oxidized, thermodynamically stable and chemically inert molecule, the activation of CO2 and its hydrogenation to hydrocarbons or other alcohols are challenging tasks. Most research to date has therefore focused on selective hydrogenation of CO2 to short-chain products, while few have tackled conversion to long-chain gasoline-range hydrocarbons. The key to such a process is a highly efficient catalyst.
The Dalian multi-functional catalyst provides three types of active sites (Fe3O4, Fe5C2 and acid sites), which cooperatively catalyze a tandem reaction. The team found that the appropriate proximity of three types of active sites plays a crucial role in the successive and synergetic catalytic conversion of CO2 to gasoline.
During CO2 hydrogenation, CO2 is initially reduced to CO by hydrogen via the reverse water-gas shift (RWGS) on Fe3O4 sites, followed by a subsequent hydrogenation of CO to α-olefins via Fischer–Tropsch synthesis (FTS) on Fe5C2 sites. The olefin intermediates generated on the iron-based catalyst then diffuse to the zeolite acid sites, on which they undergo oligomerization, isomerization and aromatization. The gasoline-range isoparaffins and aromatics are selectively formed and finally diffuse out of zeolite pores.
This work was financially supported by the National Natural Science Foundation of China, and the Hundred-Talent Program of DICP, Chinese Academy of Sciences.
Jian Wei, Qingjie Ge, Ruwei Yao, Zhiyong Wen, Chuanyan Fang, Lisheng Guo, Hengyong Xu & Jian Sun (2017) “Directly converting CO2 into a gasoline fuel” Nature Communications 8, Article number: 15174 doi: 10.1038/ncomms15174