The Preparation And Characterization Of Pr-Ni-P Catalyst For Hydrogenation Transformation Of Biomass-derived Platform Molecules

Due to its abundant reserves,low cost,and renewable advantages,biomass has become the main source of replacing fossil fuels to produce high-value-added fuels and chemicals,and has always received extensive attention from academia and industry.At present,most of the molecular conversion processes of biomass platforms rely on metal catalysts,but metal catalysts have high cost（noble metals）,low selectivity,and easy to lose in the reaction environment,causing environmental pollution and performance degradation.Thus,looking for economical,efficient,and easy-to-obtain non-metal catalysts has received much attention.In view of the inherent limitations of the metal catalytic system and combined with our previous work,the following studies were carried out in this paper:（1）Using Ni（NO₃）₂·6H₂O,Pr（NO₃）₃·6H₂O,（NH₄）₂HPO₄ as raw materials,a series of Pr-Ni-P catalyst with different Pr:Ni molar ratios were prepared through a simple and easy-to-operate hydrothermal synthesis method.XRD,SEM,TEM,HAADF-TEM,XPS characterizations show that the catalyst is a composite material composed of Pr PO₄ and Ni₂P tightly combined,which can be labeled as（Pr PO₄）_m/Ni₂P.The m is measured in the range of 0.24-11.0 by ICP-OES characterization.（2）Three typical biomass platform molecules levulinic acid,furfural and maleic anhydride were selected to characterize the catalytic performance of the catalyst.The results show that 91-98%yield can be achieved for different target productsγ-valerolactone,furfuryl alcohol and diethyl succinate by controlling the m in the（Pr PO₄）_m/Ni₂P catalyst under the reaction conditions of 100℃and 4 MPa for 2 h-4 h.And the reaction conversion frequency TOF can reach 0.10-0.45 s^-1,indicating that the catalytic activity of the catalyst is comparable to some precious metal catalysts.In addition,the cycle stability experiment and the filtration comparative experiment show that the catalyst can maintain good structural stability and superior reusability in a liquid phase environment.（3）Since the hydrogenation reaction of levulinic acid includes hydrogenation,dehydration,isomerization and other processes,further chemical adsorption,kinetic analysis and investigation of the reaction mechanism have been carried out for the hydrogenation reaction of levulinic acid.Pyridine adsorption infrared spectroscopy（Py-FTIR）and NH₃-TPD characterization showed that the catalyst has abundant acidic sites to promote the dehydration and isomerization process during the reaction.The study of surface chemistry and kinetic mechanism further revealed the synergistic catalytic effect of the above two components especially the unique hydrogen activation ability of Pr PO₄ which can promote the reaction to complete the hydrogenation conversion process through the Langmuir-Hinshelwood mechanism.These findings imply that the easily-prepared,cost-affordable and robust RE-M-P nanocomposites like present Pr-Ni-P could act as efficient and general catalyst for chemical transformation of biomass derivatives,which could be of interest not only for exploiting novel non-metallic catalysts to propel heterogeneous catalysis application conventionally trapped by the defects of metallic catalyst,but also for applying mimic composites to expand the material base for other green mass-transformation techniques involving hydrogen and organic substrate such as corresponding optical and electrical transformations.