Non-oxidative dehydrogenation of methanol to formaldehyde over supported GaOx-based catalysts

• Published in: Journal of catalysis 2023-11, Vol.427, p.115111, Article 115111
• Main Authors: Merko, Mariia, Delsing, Sara, Busser, G.Wilma, Muhler, Martin
• Format: Article
• Language: English
• Subjects: Gallium oxide; Methanol dehydrogenation; Non-aqueous formaldehyde; Reaction pathways; Silica; Supported catalysts
• ISSN: 0021-9517; 1090-2694
• DOI: 10.1016/j.jcat.2023.115111

[Display omitted] •Supported gallium oxide is highly active in CH3OH dehydrogenation to CH2O and H2.•A high formaldehyde production rate was observed at 550 °C using SiO2 as support.•The formed by-products and the rate of deactivation depend on the Ga loading.•Deactivated catalysts can be completely regenerated by an oxidative treatment.•A two-path mechanism of CH2O formation over GaOx-based catalysts is proposed. The non-oxidative dehydrogenation of methanol to formaldehyde is a potential alternative to the established industrial oxidative dehydrogenation. Advantages are the production of anhydrous formaldehyde and of hydrogen as a coupled valuable by-product. The catalytic performance of supported GaOx catalysts prepared by wet impregnation of SiO2 and γ-Al2O3 was compared with bulk β-Ga2O3. Fumed SiO2 was identified as the more suitable support, and already at a loading of 4 wt% Ga on SiO2, a high formaldehyde production rate was observed at 550 °C. Significant by-products were dimethyl ether over low-loaded catalysts characterized by the presence of well-dispersed GaOx species, and CH4, CO, and CO2 over the Ga2O3-like phase present at high Ga loadings. Deactivation by coke deposition was faster for increasing Ga loadings, but the catalysts were completely regenerated by an O2 treatment. A two-path mechanism for CH2O formation is proposed comprising a stepwise and a concerted pathway.