Prepareation Of Supported Nickel Phosphide Catalysts For Hydrodeoxygenation By Electroless Plating

With the rapid development of the world economy and the continuous improvement of the level of industrialization,the demand for energy is increasing sharply.However,the petroleum reserves are decreasing,and a series of environmental pollution problems arise with the burning of fossil fuels.Therefore,it is urgent to develop renewable energy to replace traditional fossil energy.Compared with other renewable energy sources,biomass energy can be directly converted into liquid fuels,so it can be used as an alternative to fossil fuels.However,there is a large amount of oxygen in biomass oil,which lead to undesirable properties.Hydrodeoxygenation is an effective method of removing oxygen and upgrading biomass oil.In this paper,bifunctional Ni₃P/?-Al₂O₃ HDO catalyst was synthesized by electroless plating method.The nickel precursor of the catalyst was prepared by two methods,namely,the incipient impregnation method and the deposition-precipitation method.The prepared catalysts were characterized by means of XRD,N₂ adsorption-desorption,TEM,ICP,and NH₃-TPD.The effects of different preparation conditions on the crystal phase composition and properties of the catalyst was studied,and the hydrodeoxygenation?HDO?performance of the catalysts were investigated using phenol and its derivatives as the feed.The EP-Ni₃P/?-Al₂O₃ catalyst was prepared by impregnation and electroless plating method.The effects of preparation conditions,including molar ratios of P/Ni,types of complexing agent,and molar ratio of sodium citrate/nickel?TSC/Ni?on the crystal phase of the catalyst were investigated.It is shown that the optimal preparation conditions were as follows:P/Ni molar ratio of 6,sodium citrate as the complexing agent,TSC/Ni molar ratio of 1.The main crystal phases of the catalyst were a mixture of Ni₃P and Ni.Three kinds of acid etching agents,including hydrochloric acid,formic acid,and phosphoric acid,were used to remove Ni phase.The hydrodeoxygenation?HDO?performance of the catalysts before and after phosphoric acid etching were investigated using phenol in decalin?1 wt.%?as the feed.The results showed that the Ni could be effectively dissolved by phosphoric acid etching for 12 h,and the pure phase Ni₃P/?-Al₂O₃ catalyst was obtained.Compared with the catalyst before phosphoric acid etching,the catalyst after etching was more acidic,and showed higher HDO activity at low temperatures.At 150?,the conversion of phenol increased from 65.5%to99.0%,and the selectivity to cyclohexane doubled.The phenol conversion increased from 93.6%to 100%at 250?,and the selectivity to cyclohexane increased from 88.7%to 98.7%.The DP-EP-Ni₃P/?-Al₂O₃ catalyst was prepared by deposition-precipitation followed by electroless plating.The XRD,ICP,and TEM characterization results confirmed that the main active phase of the catalyst was Ni₃P,and the catalyst particles were as low as 4 nm with high dispersion.Compared with EP-Ni₃P/?-Al₂O₃ catalyst,DP-EP-Ni₃P/?-Al₂O₃ catalyst showed excellent HDO activity in phenol HDO reaction.At 200?,phenol was almost completely transformed,and the selectivity to cyclohexane was as high as 91.0%.The stability of the catalyst was investigated at 250?,and the results showed that the DP-EP-Ni₃P/?-Al₂O₃catalyst had good stability in phenol HDO reaction.Before and after the reaction,the active phase hardly changed and the particle size of the catalyst after the reaction became 4 nm,indicating a high dispersion.The kinetic results showed that the dehydration reaction of cyclohexanol was the rate-determining step.The HDOs of m-cresol,anisole and diphenyl ether catalyzed by DP-EP-Ni₃P/?-Al₂O₃ were investigated.The results showed that the conversion of each model compound was catalyzed by DP-EP-Ni₃P/?-Al₂O₃ via HYD pathway.The conversion order at 250?decreased in the order:m-cresol?92.2%?,>diphenyl ether?84.6%?,>anisole?76.5%?,and the selectivity to cycloalkanes decreased in the order successively:diphenyl ether?72.3%?,>m-cresol?56.1%?,>anisole?33.4%?.