Aqueous-Phase Hydrogenative Rearrangement Of Furfural To Cyclopentanone Over Supported Ni₃P Catalysts

Furfural,an important biomass-based platform compound,could be utilized to synthesize a variety of important fine chemicals.Among the various products,cyclopentanone can be used to synthesize pharmaceutical intermediates,spices,pesticides.Traditionally,cyclopentanone was produced by high-temperature pyrolysis of adipic acid（and its derivatives）and oxidation of cyclopentene.The raw materials in these processes were originated from the fossil resources.Due to the shortage of raw materials,high cost and more side reactions,these production processes are limited.In the aqueous-phase hydrogenative rearrangement of furfural to form cyclopentanone,the raw material derived from the biomass platform compound,solving the problem of fossil energy consumption,meeting the market demand of cyclopentanone,and improving the utilization rate of biomass energy.In this paper,Ni₃P/γ-Al₂O₃ and Ni₃P/CePO₄ catalysts were prepared,and characterized by XRD,N₂-physical adsorption,ICP,TEM,NH₃-TPD and Py-IR to study the crystal phase composition and properties.The hydrogenative rearrangement performance and kinetics of the catalysts were investigated using furfural in water as the feed.Ni₃P/γ-Al₂O₃ was prepared by the method of deposition-precipitation followed by electroless plating.The effects of preparation conditions,reaction temperature,pressure,time,solvent and furfural concentration on the catalytic performance of hydrogenative rearrangement of furfural were investigated.The results of XRD and TEM showed that the main active phase was Ni₃ P,with mean particle size of 4.3nm.The active Ni₃ P particles were uniformly dispersed on the catalyst.Ni₃P/γ-Al₂O₃ exhibited excellent performance in aqueous-phase hydrogenative rearrangement of furfural.The conversion of furfural and selectivity of cyclopentanone were 95% and 91%,respectively,at 1 MPa H₂,160 ?C for 5 h.Water played a crucial role in the hydrogenative rearrangement of furfural to cyclopentanone.Under the investigated experimental conditions,the hydrogenative rearrangement reaction of furfural over Ni₃P/γ-Al₂O₃ catalyst could be treated as pseudo-first-order and the calculated activation energy was about 79.2 k J·mol-1.The active phase of the Ni₃P/γ-Al₂O₃ catalyst did not change after the reaction.After 3 cycles,the selectivity of cyclopentanone stayed the same but the conversion of furfural decreased.The CePO₄ supports were prepared by co-precipitation,sol-gel and hydrothermal methods.The Ni₃P/CePO₄ catalysts were prepared by H₂-TPR followed by co-impregnation method.The effects of the preparation methods,Ni₃ P loading and reaction conditions on the catalytic performance in hydrogenative rearrangement of furfural were investigated.During the preparation of CePO₄ by co-precipitation,as the calcination temperature increased,the specific surface area of the supports decreased,due to the agglomeration of CePO₄ at high temperature.Over the catalyst with low Ni₃ P loading,the hydrogenation activity was too poor to transform the furfural effectively.However,the high loading of Ni₃ P would lead to overhydrogenation of cyclopentanone to cyclopentanol.The conversion of furfural and the selectivity of cyclopentanone were 94% and 90%,respectively,at 0.5 MPa H2,160 ?C for 2 h.The hydrogenative rearrangement of furfural over Ni₃P/CePO₄ catalyst could be treated as a pseudo-first-order reaction and the calculated activation energy was about 60.2 k J·mol-1.The stability investigation showed that the Ni₃P/CePO₄ catalyst performed excellent recyclability during the reaction.After 4 cycles,the conversion of furfural decreased slightly,while the selectivity of cyclopentanone was almost unchanged.