Catalytic Hydrogenation Of Furfural Over MOFs-based Pd-based Catalysts

As a biomass platform compound,furfural can be converted into high value-added chemicals such as furfuryl alcohol and 2-methylfuran through selective hydrogenation.In this paper,Pd@ZIF-67,Pd-Co_xO_y@C and Fe_xO_y/Pd@UiO-66 series catalysts were prepared based on ZIF-67 and UiO-66 to study the direct hydrogenation and transfer hydrogenation of furfural.The results are as follows:（1）Pd@ZIF-67 with encapsulated structure was synthesized by one-pot method,and Pd-Co@C catalyst was prepared by pyrolytic carbonization and carbothermal reduction of MOFs.The results show that the Pd-Co@C catalyst prepared by calcination at 773 K under N₂atmosphere has the highest activity for furfural hydrogenation,the conversion rate of furfural hydrogenation under H₂reaction conditions is 94.3%,and the selectivities of furfuryl alcohol and 2-methylfuran are 57.2%and 41.3%,the hydrogenation reactions include direct hydrogenation based on metal active site（Pd,Co and Pd-Co）using H₂as hydrogen source and transfer hydrogenation based on Lewis acid site using alcohol as hydrogen donor.Direct hydrogenation is more active than transfer hydrogenation.（2）Pd@ZIF-67 was calcined in different atmospheres to prepare Pd-Co_xO_y@C catalysts by pyrolysis-oxidation method.The results show that the Pd-Co-Co O@C catalyst prepared by first calcining Pd@ZIF-67 in H₂at 573 K and then oxidizing at 473 K in air has the highest furfural hydrogenation activity.The conversion of furfural hydrogenation under H₂reaction conditions was 100%,and the selectivities of furfuryl alcohol and 2-methylfuran were 16.8%and 81.9%,the hydrogenation reaction includes direct hydrogenation and transfer hydrogenation.In the reaction,furfural first generates furfuryl alcohol,and then further hydrogenation/hydrogenolysis generates 2-methylfuran;transfer hydrogenation occurs under N₂reaction conditions,the conversion of furfural is 25.7%,and the selectivity of furfuryl alcohol reaches 93.7%.（3）FeOOH/Pd@UiO-66 was obtained by modifying Pd@UiO-66 with iron component,which was further calcined to prepare Fe_xO_y/Pd@UiO-66 catalyst.The results showed that the magnetic Fe-Fe₃O₄/Pd@UiO-66 catalyst prepared by calcination in H₂at 623 K had the highest furfural hydrogenation activity,the conversion rate of furfural hydrogenation under H₂reaction conditions was 76.9%,and the selectivity of furfural alcohol was 97.9%,the catalyst has better magnetic recovery and catalytic stability.