CO₂ hydrogenation to C₅₊ hydrocarbons over K‐promoted Fe/CNT catalyst: Effect of potassium on structure–activity relationship

Abstract

Developing efficient catalysts for direct CO2 hydrogenation to fuel hydrocarbons is of great significance for the effective utilization of CO2, and C5+ selectivity is one critical indicator for the process economics. In this work, a series of K‐promoted Fe/CNT catalysts were prepared by the co‐impregnation method, and their catalytic performance for CO2 hydrogenation was studied in a slurry‐bed reactor. As a result, CO2 conversion and C5+ selectivity showed positive correlation with the increase of K/Fe ratio from 0 to 0.3, but further increase of K/Fe ratio above 0.3 slightly affected its. The catalyst with a K/Fe molar ratio of 0.3 achieved the best performance with CO2 conversion of 23.7% and C5+ selectivity of 56%. In addition, the structure–activity relationship of the catalyst was discussed based on various characterization results. K‐modified catalysts presented a higher specific surface area and stronger CO2 chemisorption, which helped to improve CO2 conversion and C5+ selectivity. However, excessive potassium loading caused a loss of specific surface area, reduction degree, and graphitization degree of the catalyst, which inhibited the CO2 chemisorption and the formation of C5+ hydrocarbons.

Light‐Enhanced Conversion of CO2 to Light Olefins: Basis in Thermal Catalysis, Current Progress, and Future Prospects

“…As such, a compromise between chemisorption, reduction, and carburization may need to be considered upon K decoration to modify the surface C:H in favor of carburization and C-C coupling. [110] Recent work by Yang et al suggested that the Fe binding energy in Fe 5 C 2 can be influenced by the alkaline species added (Li, Na, K, Rb, or Cs) and the loading, the extent of which could be correlated to the Allen electronegativity scale. A more electronegative species with lower-energy valence electrons could better enhance CO 2 adsorption and dissociation, while decreasing the adsorption strength of olefins.…”

“…As such, a compromise between chemisorption, reduction, and carburization may need to be considered upon K decoration to modify the surface C:H in favor of carburization and C–C coupling. [ 110 ]…”

Tailoring MIL-100(Fe)-derived catalyst for controlled carbon dioxide conversion and product selectivity

“…31 Specically, magnetite and iron carbide serve as the active phases for these reactions, respectively. [32][33][34][35] In our previous research work, we optimized the catalytic system composition through utilization of metalorganic framework (MOF) as a sacricial template to form a carbon-supported iron nanoparticles for converting carbon dioxide into valuable hydrocarbons. 36 This approach deviated from the conventional usage of inorganic supports like Al 2 O 3 , SiO 2 , and TiO 2 .…”

A Hybrid Plasma‐Catalysis System for CO2Hydrogenation over Perovskite‐Type Catalysts: Promoting Effect of A‐Site Substitution

“…Many efforts have been devoted on the carbon capture, utilization, and storage (CCUS). Catalytic transformation of CO 2 into high-value chemicals, [2] methane, [3,4] methanol, [5,6] olefins, [7][8][9] and C 5þ hydrocarbons [10,11] is an ideal method to reduce CO 2 emissions. Among these routes, CO 2 hydrogenation to light hydrocarbons including alkanes and olefins is one of the most promising routes.Most of the CO 2 hydrogenation reactions were conducted by the electrocatalysis, photocatalysis, or thermal-catalysis processes.…”