Hydrogenation of CO2 to Olefins over Iron-Based Catalysts: A Review

Abstract

The widespread use of fossil fuels has caused high CO2 concentrations in the atmosphere, which have had a great impact on climate and the environment. Methods for efficiently utilizing CO2 to produce high value-added chemicals have received increasing attention. Among the products of CO2 hydrogenation, olefins, an important petrochemical feedstock, are one of the essential target products. Therefore, CO2 hydrogenation to olefins has been extensively studied, especially for the development of high-performance catalysts. Iron-based catalysts, which are widely used in Fischer–Tropsch synthesis reactions, have also been considered attractive for use in the CO2 hydrogenation to olefins due to their excellent performance in catalytic activity and reaction stability. Most studies have focused on the modulation of morphology; reduction and adsorption properties by tuning the methods of catalyst syntheses; pretreatment conditions and the composition of catalysts, in order to improve hydrogenation activity and olefin yield. In this review, we briefly discuss a thermodynamic overview of the CO2 hydrogenation to olefins reaction, the optimization of catalyst modifications, and current insights into the reaction mechanism; moreover, we summarize current challenges and future trends in the CO2 hydrogenation to olefins.

Topotactic transformation of metal–organic frameworks to iron-based catalysts for the direct hydrogenation of CO2 to olefins

“…It is generally accepted that the CO mediated mechanism of the CO 2 hydrogenation reaction occurs via a tandem of active sites, Fe 3 O 4 and Fe 5 C 2 , which first undergoes the RWGS reaction (the active site is Fe 3 O 4 ) to convert CO 2 to CO, followed by the F–T reaction of CO (the active site is χ -Fe 5 C 2 ) to produce olefins. 61–63 Therefore, we carried out a series of characterization techniques on the reacted catalysts. To investigate the evolution of the phase of the MFe/C catalysts after the CO 2 hydrogenation reaction, XRD was performed.…”

Advanced zeolite and ordered mesoporous silica-based catalysts for the conversion of CO2to chemicals and fuels

“…Iron-based catalysts have been widely studied for the catalytic conversion of CO 2 via modified FTS due to its properties to catalyze both the RWGS and FTS reactions. 739,740 Under working reaction conditions, iron based catalysts exhibit Fe 3 O 4 active sites for RWGS and Fe 5 C 2 active sites for FTS. 741 Moreover, the addition of alkali metals such as K and Na allowed improving the effectiveness of iron catalysts owing to improved surface carburization and weakened secondary hydrogenation ability of olefins.…”

Oxide Supported Cobalt Catalysts for CO2 Hydrogenation to Hydrocarbons: Recent Progress

“…Similarly, despite their higher activity for RWGS, Fe and Fe‐Co based catalysts require careful design and promoter addition to improve their activity and selectivity toward C 2+ products. [ 7–10 ] Moreover, due to their lower hydrogenation ability, such catalysts produce more olefins and oxygenates products. [ 7–10 ]…”

“…[ 7–10 ] Moreover, due to their lower hydrogenation ability, such catalysts produce more olefins and oxygenates products. [ 7–10 ]…”

“…Similarly, despite their higher activity for RWGS, Fe and Fe-Co based catalysts require careful design and promoter addition to improve their activity and selectivity toward C 2+ products. [7][8][9][10] Moreover, due to their lower hydrogenation ability, such catalysts produce more olefins and oxygenates products. [7][8][9][10] Here we present an overview of the progress achieved toward the single-step hydrogenation of CO 2 to long-chain hydrocarbons over oxide-supported Co-based catalysts.…”