The development of non-noble metal catalysts provides a cost-effective and sustainable route for glucose oxidation to gluconic acid. In this study, a series of catalysts based on inexpensive transition metals (Cr, Cu, Ni, Fe) and/or Au were synthesized using siliceous supports (SiO2 and MCM-41) and systematically evaluated. The aim was to partially or fully replace noble metals with lower-cost alternatives, while maintaining high catalytic performance. Comprehensive characterization—including ICP-AES for composition, N2 adsorption–desorption for porosity, XRD for structure, H2-TPR for reducibility, and NH3-TPD for acidity—was conducted to establish structure–property relationships. Among the tested catalysts, Ni- and Fe-based systems exhibited superior stability, with NiO/SiO2 achieving gluconic acid yields comparable to Au. The bimetallic Au–Ni/SiO2 catalyst displayed enhanced metal–support interactions and minimal leaching (<2%), while Au–Fe/SiO2 improved selectivity, yielding up to 23% gluconic acid, surpassing 5Fe/SiO2 (18%) and 0.3Au/SiO2 (15%), albeit with lower stability. These results highlight the potential of low-cost transition-metal and bimetallic catalysts as efficient and economically viable systems for selective glucose oxidation, providing insights for rational catalyst design in sustainable carbohydrate valorization.
Karakoulia et al. (Sun,) studied this question.