Enhancing the synergism of Fe3O4 and Fe5C2 to improve the process of CO2 hydrogenation to olefines

CO2 hydrogenation to olefines is a feasible carbon capture and utilization (CCU) route. The process includes sequential reactions of reverse water gas shift (RWGS) reaction and Fischer-Tropsch synthesis (FTS) reaction. The acceleration of FTS is crucial to improve the olefines yield. A microemulsion anti-solvent extraction (MAE) method was proposed to prepare Fe-based catalyst on the support of Al2O3. Ethanol solution of Fe(NO3)3 was encapsulated in microdroplets, and then loaded on Al2O3 by the extraction of ethanol from the microdroplets to isooctane phase. The average size of micro droplets was 7.5 nm. After calcination, the particle size of Fe2O3 was 6 nm. After carburization with CO, the interface formed between Fe3O4 and Fe5C2 was restricted in a narrow space with a mean size of 12 nm. Through TEM-Mapping, XRD, XPS and TPC characterization, the distribution uniformity of Fe and the neighboring degree of Fe3O4 and Fe5C2 on the as-prepared catalyst MAE-Fe1K1 was improved effectively. An enhanced synergistic effect between Fe3O4 and Fe5C2 was obtained. The catalytic performance evaluation results showed that yield of C2-C4 olefins reached 0.063 mmol·gFe−1·s−1 after 12 h of reaction. It exhibited better catalytic performance than most catalysts reported in the literatures. The results showed that the proposed microemulsion anti-solvent extraction strategy is an effective method to prepare Fe-based catalyst for CO2-FTO reaction with an excellent catalytic performance.