Efficient Production Of High Value-added Chemicals From Furfural Catalyzed By Metal Organic Frameworks

Biomass energy is considered as one of the important substitutes of traditional fossil energy by researchers due to its advantages of renewability,cleanliness,extensive source and huge reserves.In addition to traditional biomass pyrolysis,gasification and hydrolysis technologies,the catalytic production of high value-added chemicals from biomass has become a promising approach for biomass energy utilization.As a hydrogenation product of the important platform compound levulinic acid,γ-valerolactone can be not only directly used as fuel additive,but also can be used as a lubricant,plasticizer,etc.Moreover,it is an important precursor of liquid hydrocarbon fuels such as gasoline and diesel.Therefore,the efficient production ofγ-valerolactone has important research value and industrial value.In this paper,the series of Zr and Hf based Ui O and DUT metal organic frameworks were prepared via a hydrothermal method and used as catalyst for the hydrogenation reaction of furfural and isopropyl levulinate.The differences of catalytic activity of MOFs with different coordination numbers were investigated,and the mechanism was also studied.Then,sulfated DUT-67（Hf）,a novel bifunctional catalyst,was synthesized via a post-synthetic modification method.The heterogeneous catalysts with both Br（?）nsted and Lewis acid sites has proved to be promising and useful because they offer an efficient way to tandem cascade reactions from furfural toγ-valerolactone.Finally,the optimum reaction condition of modified metal organic framework DUT-67was investigated,and the catalytic performance of this catalystl was evaluated.The unmodified series of Ui O and DUT metal organic frameworks were characterized by XRD、FTIR、SEM、NH₃-TPD、Py-FTIR、XPS、ICP-OES and BET,which was found that series of Ui O and DUT metal organic frameworks could be used as heterogeneous catalysts for the hydrogenation reaction of furfural to furfuryl alcohol,but these catalysts without enough Br（?）nsted acid cannot catalyze the one-pot conversion from furfural toγ-valerolactone.The Br（?）nsted acidity of the sulfated DUT-67 could be adjusted by submersion in different concentrations of aqueous sulfuric acid.Sulfated DUT-67（Hf）possessed by 0.06 mol/L aqueous sulfuric acid exhibited optimal catalytic activity and were able to catalyze the one-pot conversion of furfural toγ-valerolactone.In addition,the selection of hydrogen donor was optimized according to the difference of reducing potential of hydrogen donor.In summary,the DUT-67（Hf）possessed by 0.06 mol/L aqueous sulfuric acid showed optimal catalytic activity and could obtain an 87.1%yield ofγ-valerolactone under the optimal reaction conditions（0.05 mol/L furfural in 25 m L isopropyl alcohol,catalysts 0.3 g,24 h,180°C and 0.6 MPa initial N₂ pressure）.The study on the modification of DUT-67 by post-synthetic modification method can not only efficiently catalyze the one-pot conversion of furfural toγ-valerolactone,but also provide a new way to change the density of Br（?）nsted acidity and Lewis acidity on the metal organic frameworks by adjusting the concentration of aqueous sulfuric acid.Therefore,this study has certain guiding significance for the related research.