Novel Ni/Zn MOFs for Sorbitol Production via Catalytic Transfer Hydrogenation

Researchers continue to explore alternative catalysts that are more abundant and effective for hydrogenation reactions to produce sorbitol, such as those using nickel, ruthenium, or zirconium metal centers. This study examined the catalytic transfer hydrogenation of glucose to sorbitol using different alcohol hydrogen donors, specifically ethanol, isopropanol, 1,4-butanediol, and 1,4-cyclohexanediol, with the prepared Ni/Zn MOF catalysts. It also assessed how sacrificial alcohols affected the transformation and selectivity toward sorbitol. The results confirmed the successful catalytic activity and feasibility of this process using MOFs, especially the Ni-based one, which produced up to 51.8% sorbitol, while the Zn-based catalyst yielded 42.3% sorbitol in 1,4-cyclohexanediol. Sacrificial diols exhibited enhanced efficacy as hydrogen donors relative to short-chain alcohols, specifically terminal diols such as 1,4-butanediol and 1,4-cyclohexanediol, which provided substantial hydrogen donation potential and improved selectivity in the conversion of glucose to sorbitol, achieving maximum yields of 45.12% with 1,4-butanediol and 51.8% with 1,4-cyclohexanediol. Regarding the catalysts, both Ni and Zn MOFs improved the transfer hydrogenation process in sugar alcohol mixtures compared to aqueous solutions, and particularly the Ni MOF, with its high surface area and multiple active sites, enhanced the catalytic transformation process. The results clearly indicate that the structural and chemical properties of these alcohols affect the quantity of hydrogen generated and transferred, which is crucial for the efficient overall yield of sorbitol. This insight enhances the understanding of this engineered system and its potential future applications in sustainable biomass utilization.