Cobalt Loading-Dependent Performance of Co/SiO2 Catalysts for the Selective Dehydrogenation of 1,4-Butanediol to γ-Butyrolactone

Abstract

Cobalt-supported catalysts (Co/SiO₂) of different metal loadings (5-15 wt.%) were developed and assessed for the vapour-phase dehydrogenation of 1,4-butanediol to γ-butyrolactone and tetrahydrofuran. Catalysts were also systematically characterised by N₂ physisorption, X-ray diffraction and H₂ temperature-programmed reduction (H₂-TPR). BET studies illustrated a gradual decrease of the total specific surface area with cobalt loading due to possible clogging of the pores by cobalt oxides species. XRD confirmed the formation of crystallised Co₃O₄ phases with higher loadings leading to larger crystallite sizes. H₂-TPR profiles confirmed better reducibility and lower metal-support interaction at elevated cobalt loadings. Catalytic analysis showed an increase of 1,4-butanediol conversion and 1,4-butanediol selectivity with reaction temperature and cobalt loading, with the highest conversion (80%) obtained at 580 K using a 15Co/SiO₂ catalyst. Time-on-stream experiments demonstrated good stability of the catalyst with only negligible deactivation observed during 7 h continuous operation. High cobalt loading significantly enhanced the catalytic activity of Co/SiO₂ catalysts by increasing the number of reducible cobalt species and the availability of accessible metallic active sites. These findings demonstrate that high-loading Co/SiO₂ catalysts are highly promising for the green and atom-economical dehydrogenation of biomass-derived diols.