Optimization of Ru/ZSM-5 catalyst for selective d-glucose hydrogenation to sorbitol: A box-behnken design approach

• The catalyst is highly selective to sorbitol under optimization by BBD • The 0.5 %Ru/ZSM-5 gave 99.6 % conversion and 99.4 % sorbitol yield. • 0.5 % Ru/ZSM-5 showed high stability over 7 cycles with <0.001 ppm Ru leaching • Scale-up testing confirmed validity of prediction model The hydrogenation of D-glucose to sorbitol holds significant importance in biomass biorefineries. With a focus on enhancing the efficiency and selectivity of this reaction, this research investigated various optimization parameters (catalyst dosage, reaction time, and temperature) over 0.5 %Ru/ZSM-5 prepared via impregnation method. The optimization process was carried out using Box-Behnken design (BBD). The results showed accurate predictive equations for all reaction responses, with R 2 values exceeding 97 % and no significant errors observed. Additionally, the 2D contour plot revealed the relationship between time and temperature, highlighting that a long reaction time and high temperature could lead to reduced sorbitol yield due to the formation of by-products. Under the optimal catalyst dosage of 0.6 g, reaction time of 100 min, and temperature of 120°C, the D-glucose conversion and sorbitol yield were 99.6 ± 0.35 % and 99.43 ± 0.45 %, respectively. NMR results confirmed the exclusive production of sorbitol under these optimal conditions. Furthermore, the study demonstrated that the catalyst could be reused at least seven times without a significant decrease in D-glucose conversion or sorbitol yield, while ICP-OES analysis confirmed no Ru leaching during the reaction. Therefore, this research provides a biomass valorization strategy by optimizing the production process of sorbitol via D-glucose hydrogenation.