Synthesis and Characterization of Iron-Based Catalysts for Carbon Dioxide Valorization

Abstract

The extensive release of carbon dioxide (CO2) into the atmosphere is associated with the detrimental impacts of the global environmental crisis. Consequently, the valorization of CO2 from industrial processes holds great significance. Transforming CO2 into high added-value products (e.g., CH4, C1-C3 deoxygenated products) has attracted considerable attention. This is feasible through the reverse water–gas shift (RWGS) and Fischer–Tropsch synthesis (FTS) reactions; CO is initially formed and then hydrogenated, resulting in the production of hydrocarbons. Iron-based materials have a remarkable ability to catalyze both RWGS and FTS reactions, enhancing the olefinic nature of the resulting products. Within this context, iron-based nanoparticles, unsupported and supported on zeolite, were synthesized and physico-chemically evaluated, applying multiple techniques (e.g., BET, XRD, FT-IR, Raman, SEM/TEM, DLS, NH3-TPD, CO2-TPD). Preliminary experiments show the potential for the production of C2+ deoxygenated products. Among the tested samples, supported Fe3O4 and Na-Fe3O4 (A) nanoparticles on HZSM-5 are the most promising for promoting CO2 valorization into products with more than two carbon atoms. Results demonstrate that product distribution is highly affected by the presence of acid sites, as low-medium acid sites and medium acidity values enable the formation of C2+ hydrocarbons.

Keywords

• iron-based materials
• nanoparticles
• heterogeneous catalysis
• zeolites
• carbon dioxide valorization