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 CO 2 conversion to liquid fuels. An open-access paper on their work is published in the journal Nature Communications .

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-Fe 3 O 4 /HZSM-5 catalyst for the direct production of gasoline-range hydrocarbons from CO 2 hydrogenation. This catalyst exhibited 78% selectivity to C 5 -C 11 as well as low (4%) CH 4 at a CO 2 conversion of 22% under industrial relevant conditions.

Because CO 2 is a fully oxidized, thermodynamically stable and chemically inert molecule, the activation of CO 2 and its hydrogenation to hydrocarbons or other alcohols are challenging tasks. Most research to date has therefore focused on selective hydrogenation of CO 2 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 CO 2 hydrogenation reaction over Na–Fe 3 O 4 /Zeolite multifunctional catalyst takes place in three steps: (1) an initially reduced to CO intermediate via RWGS; (2) a subsequent hydrogenation of CO to α-olefins intermediate via FTS; and (3) the formation of gasoline-range hydrocarbons via the acid-catalyzed oligomerization, isomerization and aromatization reactions. Wei et al.Click to enlarge.

The Dalian multi-functional catalyst provides three types of active sites (Fe 3 O 4 , Fe 5 C 2 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 CO 2 to gasoline.

During CO 2 hydrogenation, CO 2 is initially reduced to CO by hydrogen via the reverse water-gas shift (RWGS) on Fe 3 O 4 sites, followed by a subsequent hydrogenation of CO to α-olefins via Fischer–Tropsch synthesis (FTS) on Fe 5 C 2 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.

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