Enhanced Transfer Hydrogenation Activity of Zr‐Doped Mesoporous Silica through Sol‐Gel Method for the Reduction of Biomass‐Derived Unsaturated Carbon‐Oxygen Bonds

• Published in: ChemistrySelect (Weinheim) 2018-10, Vol.3 (39), p.11071-11080
• Main Authors: Zhou, Yi‐Han, Luo, Yu‐Jia, Lin, Yu‐Ting, Huang, Yao‐Bing
• Format: Article
• Language: English
• Subjects: Levulinate; mesoporous silica; transfer hydrogenation; Zr catalyst; γ-valerolactone
• ISSN: 2365-6549; 2365-6549
• DOI: 10.1002/slct.201802176

Efficient reduction of unsaturated functionalities of biomass derived molecules enables the production of new value‐added chemical. Herein, we reported a highly efficient and robust mesoporous silica catalyst (SBA‐15) doped with Zr metal sites for the reduction of biomass derived unsaturated molecules through transfer hydrogenation reaction. Specifically, ethyl levulinate was selected as model compound to investigate the reduction activities of the as‐prepared catalysts. An almost quantitative γ‐valerolactone (GVL) yield of 99%, through the ketone reduction and intramolecular cyclisation, was obtained at 160 °C for 18 h in the presence of hydrogenation donor 2‐Butanol (2‐BuOH). Comparative experiments among different type of Zr catalysts showed that the mesoporous structure of SBA‐15 was beneficial for maximizing the activity and the stability of the Zr sites though highly metal dispersion and metal‐chelation effect, respectively. Detailed studies on the catalyst characterization and optimization revealed the ratio of Si/Zr also affected the above reactivity. Mechanistic studies revealed that the interaction between polar C=O group was key to the reaction efficiency and poisoning experiments confirmed the existence of acid‐base sites for transfer hydrogenation process. The catalyst was also successfully recycled without much loss in reactivity. Finally, the catalyst was also applied to the reduction of a variety of unsaturated molecules with high yields. Highly dispersed Zr‐doped mesoporous SBA‐15 catalysts were developed to catalyze the reduction of biomass derived unsaturated compound ethyl levulinate to offer corresponding γ‐valerolactone through the transfer hydrogenation reaction in the presence of hydrogen donor 2‐buthanol.