The direct production of light α‐olefins (C2=‐C4=) from CO2 is of great importance as this process can convert the greenhouse gas into the desired chemicals. In this study, the crucial roles of Na and Mn promoter in CO2 hydrogenation to produce light α‐olefins via the Fischer‐Tropsch synthesis (FTS) over Fe3O4‐based catalysts are investigated. The results indicate that both Na and Mn promoter can enhance the reducibility of Fe3O4. In situ XPS and DFT calculations show that Na facilitates the reduction by electron donation from Na to Fe as the oxygen vacancy formation energy is reduced by Na. In contrast, Mn promotes the reduction by the presence of oxygen vacancy in MnO as the oxygen in Fe oxide can spillover to the vacancy in MnO spontaneously. For un‐promoted Fe3O4 catalysts, CO2 hydrogenation dominantly produces light n‐paraffins. The addition of Na remarkably shifts the selectivity to light α‐olefins with a sharp decline in the selectivity to light n‐paraffins, which is attributed to the electron donation from Na to Fe resulting in the promoted CO dissociation and the favorable β‐H abstraction of surface short alkyl‐metal intermediates. The addition of Mn into Na‐containing Fe3O4 catalysts can obviously further enhance the selectivity to light α‐olefins as the spatial hindrance of Mn suppresses the chain growth to increase the amount of surface short alkyl‐metal intermediates.

The conversion efficiency of CO2 in CO2-FTS over Fe-based catalysts is significantly enhanced by driving the conversion of the CO intermediate via the FTS reaction over a second kind of FT component, Co or Ru, without WGS activity.

Iron-based Fischer-Tropsch (FT) synthesis in combination with hydroisomerization in the presence of zeolitesfor the synthesis of isoparaffins from CO 2 /H 2 wasc onducted in af ixed-bed reactor.R elative to supported iron catalysts,t he precipitated one efficiently converted intermediate CO into hydrocarbonsb y supplying ah igh density of FT active sites on the catalyst surface. Removing water by interstage cooling and promoting the CO conversion step in the FT synthesis were effective approaches in achieving ah igh CO 2 conversion,b ecause of an increase in the driving force to the reaction equilibrium. Particle mixing of 92.6 Fe7.4 Kw ith either 0.5 Pd/b or HZSM-5z eolite effectively hydroisomerized the resulting FT hydrocarbons into gasoline-range isoparaffins. Particularly,H ZSM-5d isplayed ah igher isoparaffin selectivity at approximately 70 %, which resulted from easier hydrocracking and hydroisomerization of the olefinic FT primary products.The high energy density and ease of transport of gasoline and other liquid hydrocarbons have made them the mainstay of the world's transportation infrastructure. Although researchers continuet op ursuet he use of low-carbon gases such as methane and hydrogen as transportation fuels ande ven though electric cars are proliferating, there is no good alternative to liquid fuels for long-distancet rucks and other heavy vehicles, as well as aviation.[1] Given the limited availability of crude oil and the conversion of coal into synthetic liquid fuelb ys yngas (a mixtureo fCOand H 2 )followed by Fischer-Tropsch synthesis (FTS), [2][3][4][5][6][7][8][9] this dependence poses major security and environmental problems.[10] Arguably, the conversion and utilization of such carbon-rich fossil fuels are the main contributors to the emission of the greenhouseg as CO 2 ,w hichl eads to climate change.[11] Reducing CO 2 emissions must indeed be an urgent and long-term task for sustainable development in the energy and environmentals ectors. [12,13] It has been confirmedf or many years that the hydrogenationr eactioni sa mongst the most important chemical conversionso fh ighly concentrated CO 2 . [11,14] However,w epoint out that, authentically, to realize the recycling of CO 2 ,h ydrogen sources cannotb eg enerated by remaining fossil fuels but from splitting water by electrolysis or othercleavage reactions. [15][16][17][18][19] The aim to reach CO 2 production of fuels has prompted some researchers to focus on FTS by using CO 2 in place of CO. [20][21][22][23][24][25][26] Iron catalysts are no doubt the bestc hoice for CO 2 -based FTS, because they also catalyze the reversew ater-gas shift (RWGS)r eactiont oc leave one of the oxygen atoms in CO 2 to make CO [Eq. (1)].T he CO thus generated can then be combined with H 2 to make acombination known as renewable syngas, whichc an be converted into hydrocarbonsb yF TS [Eq. (2)].A st he chain propagation mechanism of FTS is to synthesize aw ide distribution of normalh ydrocarbons unsuitable as gasoline fuel, it is desired that ah ighly selec...