Enhancement of Carbon Oxides Hydrogenation on Iron‐Based Nanoparticles by In‐Situ Water Removal

• Published in: ChemCatChem Vol. 10; no. 18; pp. 4047 - 4051
• Main Authors: Bordet, Alexis, Asensio, Juan Manuel, Soulantica, Katerina, Chaudret, Bruno
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 20.09.2018; Wiley
• Subjects: Carbon dioxide; Carbon oxides; Chemical Sciences; CO2 Hydrogenation; Hydrogenation; Hyperthermia; Iron Carbide; Iron carbides; Magnetic Hyperthermia; Molecular sieves; Nanoparticles; Physics; Synthesis gas; Water Removal; Nanoparticles; Magnetic Hyperthermia; Iron Carbide; Water Removal; CO2 Hydrogenation
• ISSN: 1867-3880; 1867-3899; 1867-3899
• DOI: 10.1002/cctc.201800821

The carbidization of Fe(0) nanoparticles (NPs) under syngas (CO/H2) produces crystalline Fe2.2C iron carbide NPs (ICNPs) displaying excellent hyperthermia properties, however, this transformation is significantly delayed by the concomitant water formation. Consequently, very long carbidization times (∼140 h) are needed to obtain ICNPs with high specific absorption rate. In this paper, we show that the rate of the carbidization process can be greatly enhanced by the in‐situ removal of water using activated molecular sieves. As a result, ICNPs displaying very high heating power were obtained after only 40 h. Using this strategy, CO was successfully replaced by CO2 as a carbon source in the carbidization process, resulting in the efficient conversion of Fe(0) NPs to ICNPs at relatively low temperature (230 °C). Without water removal, carbidization did not occur under these conditions, and the Fe(0) NPs were clearly oxidized. In addition, this approach was successfully applied to displace the equilibrium of CO2 hydrogenation and accelerate the rate of the magnetically induced hydrogenation of CO2 on ICNPs. Interestingly, the in‐situ water removal had also a strong influence on the product distribution and especially the chain growth process, leading to a higher selectivity towards the formation of C3H8 (∼11 %). Enchanting water: The synthesis of Fe2.2C iron carbide NPs was improved by removing the water produced during the reaction. This strategy dramatically reduces the time needed to produce NPs with exceptional hyperthermia properties and prevent their oxidation. Iron carbide NPs were used for the magnetically induced hydrogenation of CO2, during which the removal of water lead to an enhancement of the CO2 hydrogenation and to an increase in the yield of C3H8.