Ca[sub.2]Fe[sub.2]O[sub.5]-Based WGS Catalysts to Enhance the H[sub.2] Yield of Producer Gases

• Published in: Catalysts 2023-12, Vol.14 (1)
• Main Authors: Antunes, Isabel, Ruivo, Luís C. M, Tarelho, Luís A. C, Frade, Jorge R
• Format: Article
• Language: English
• Subjects: Biomass energy; Catalysts
• ISSN: 2073-4344; 2073-4344
• DOI: 10.3390/catal14010012

Ca[sub.2]Fe[sub.2]O[sub.5]-based catalysts were synthesized from siderite and calcite precursors, which were processed in the form of pelletized samples and tested as water gas shift catalysts. Catalytic tests were performed in a tubular reactor, at temperatures in the range 400–500 °C and with different H[sub.2]O:CO ratios, diluted with N[sub.2]; this demonstrates the positive impact of Ca[sub.2]Fe[sub.2]O[sub.5] on conversion of CO and H[sub.2] yield, relative to corresponding tests without catalyst. The catalytic performance was also remarkably boosted in a microwave-heated reactor, relative to conventional electric heating. Post-mortem analysis of spent catalysts showed significant XRD reflections of spinel phases (Fe[sub.3]O[sub.4] and CaFe[sub.2]O[sub.4]), and SiO[sub.2] from the siderite precursor. Traces of calcium carbonate were also identified, and FTIR analysis revealed relevant bands ascribed to calcium carbonate and adsorbed CO[sub.2]. Thermodynamic modelling was performed to assess the redox tolerance of Ca[sub.2]Fe[sub.2]O[sub.5]-based catalysts in conditions expected for gasification of biomass and thermochemical conditions at somewhat lower temperatures (≤500 °C), as a guideline for suitable conditions for water gas shift. This modelling, combined with the results of catalytic tests and post-mortem analysis of spent catalysts, indicated that the O[sub.2] and CO[sub.2] storage ability of Ca[sub.2]Fe[sub.2]O[sub.5] contributes to its catalytic activity, suggesting prospects to enhance the H[sub.2] content of producer gases by water gas shift.