Non-noble supported catalyst for oxidation of glucose under mild reaction conditions
Authors
Abstract
Catalytic oxidation of D-glucose to D-gluconic acid derivative with H2O2 has been studied using non-noble Cobalt supported catalyst. The catalysts were synthesized using the scalable incipient wetness impregnation method of Co/Al2O3 and Co/TS1. The catalysts have been characterized by TGA, XRD, FESEM-EDX, BET, FTIR, and Hammett test. The oxidation of the D-glucose into D-gluconic acid with yield of 82% (as sodium gluconate) and selectivity is about 100 % have been achieved in the presence of 5 wt.% Co/Al2O3 as a catalyst under mild reaction conditions (60 oC, pH 9, 1atm, 3h). Reusability study of Co/Al2O3 was proven to be stable for subsequent cycles of reaction with no notable changes in selectivity. Besides, the physic-chemical properties of spent catalyst were similarly characterized through FTIR and Hammett test analysis. The presence of gluconic acid was confirmed by HPLC. The apparent activation energy of reaction is 15 kJ mol-1 which is lower than the value reported by prior-art using gold catalysts suggesting different mechanism with dissimilar rate-determining step. The activation of H2O2 is mediated by Co crystallites on the catalyst surfaces, forming active oxygen species via hydroxyl and peroxyl radical intermediates and/or oxometal species. The basic sites on catalyst facilitate the activation of glucose. The findings could help to make a cost-effective catalyst for D-glucose conversion into valuable organic acid chemical.
