Iron oxide-supported InNiC intermetallic catalyst for the CO hydrogenation to methanol: Effect of pyrolyzed FeO support precursors.

Interest in renewable methanol produced from green hydrogen and CO has given particular momentum to the exploration of efficient catalysts. Although the newly developed InNiC/FeO catalyst, derived from the InO-NiO/α-FeO system, shows significant potential as a catalyst for the CO hydrogenation to methanol reaction, a comprehensive understanding of the chemical and structural origins that are inherently linked to catalyst synthesis is still insufficient. Herein, the study is focused on the effect of α-FeO precursors on catalyst performance of as-obtained InNiC/FeO. A series of α-FeO oxides obtained by directly pyrolyzing 6 routine ferric/ferrous organic acid salts, were used as support precursors for InNiC/FeO catalyst preparation by the impregnation/carburation method. With no exception, the InNiC/FeO could be well formed in all cases while showing strong dependence of catalytic performance on their support source. The catalyst obtained by using the α-FeO pyrolyzed from (NH)Fe(CO)·3HO came out on top, achieving 12.6% CO conversion and 90.5% methanol selectivity for a feed gas of H/CO = 5/1, at 260 °C, 4.0 MPa and 12,000 mL g h. The others showed either low activity or poor selectivity (especially with CH formation). Additional research reveals that the oxygen deficiency in the catalysts prepared through direct pyrolysis of organic acid salts exhibits variations. Concurrently, experimental data indicates a positive correlation between the oxygen deficiency and the strength of the electronic metal-support interaction (EMSI) in these catalysts. Moreover, this approach would be a cleaner way to obtain a qualified InNiC/FeO catalyst, compared to the precipitation method previously used for α-FeO preparation from iron nitrates with discharge of a large amount of high concentration nitrogen-containing wastewater.