Cr–Containing Magnetic Oxides in a Methanol Synthesis: Does Cr Ion Distribution Matter?

Here, we report on the development of novel Cr-containing magnetic oxide nanoparticles (NPs) as catalysts for a syngas-to-methanol reaction which constitutes a sustainable route to obtain value-added chemicals. These NPs have been synthesized in a one-pot reaction by thermal decomposition of Cr acetylacetonate and doping metal acetylacetonates (if used) in the reaction solution of preformed magnetite NPs stabilized by polyphenylquinoxaline. For all the samples, the NP surface is enriched with Cr. At the same time, the Cr species are finely dispersed in the magnetite phase. This exposes Cr catalytic species to reacting molecules and creates an intimate contact between Cr3+ and Fe3O4. As a result, the methanol productivity rate for the Cr-containing magnetic oxide prepared with 0.5 mmol of the Cr precursor is approximately three orders of magnitude higher than that for the conventional Cu/ZnO/Al2O3 catalyst. Additional doping of this Cr-containing magnetic oxide with small amounts of Ni or La leads to even higher catalytic activity (by 40–49%).