Synthesis gas conversion to liquid fuels using promoted fused-iron catalysts

This study was carried out with the objective of preparing more active and stable nitrided iron catalysts for the conversion of synthesis gas to a product with a high alcohol content that could be used directly as an automotive fuel or converted to a gasoline-like product over a shape selective zeolite in a dual reactor unit. The rationale is given for the preparation of a molybdenum-promoted nitrided fused iron catalyst. Catalyst characterization yielded equivocal results as to whether a mixed Fe-Mo nitride was formed. Regardless of the nature of the Mo-containing species, these catalysts were significantly more active than unpromoted nitrided fused iron catalyst. Characterization of fused iron catalysts using thermogravimetric analysis indicated the rates of reduction, carburization, and nitriding were strongly dependent on reaction temperature and particle size as well as the nature of the promoter. X-ray diffraction measurements indicated the metal crystallite size of the reduced catalysts was strongly dependent on reduction temperature. A microreactor unit capable of on-line gas chromatographic analysis was constructed for the screening of a variety of carbided iron catalysts. The carbon number distribution obtained using a carbided fused iron catalyst was found to correlate with the Anderson-Schluz-Flory equation.