Modification And Hydrodeoxygenation Performance Of Supported Ni₂P/SiO₂

Biomass is widely available,low-cost and clean,which is regarded as a new sustainable renewable energy with great economic potential.Crude bio-oil can be obtained by rapid pyrolysis of biomass,but its high oxygen content and low calorific value seriously limit its practical application.Therefore,crude bio-oil needs to be upgraded.Hydrodeoxygenation（HDO）are effective ways to upgrade bio-oil,the key of the research lies in the development and utilization of the catalysts with high activity,selectivity.Ni₂P has become an important research object of HDO catalyst due to its unique electron transfer and geometric configuration.In this paper,a series of catalysts based on nickel phosphide were prepared,with lignin-derived phenolic compounds m-cresol as the substrate,and the properties of catalyst HDO were investigated.Combined with XRD,BET,TEM,XPS and NH₃-TPD,the structure,physicochemical properties and catalytic performance of the catalyst were systematically investigated,and the reaction path of m-cresol HDO on the prepared catalyst was analyzed.The main research contents and conclusions are as follows:Ni-P/Si O₂-x catalysts with different initial P/Ni molar ratios were prepared using nickel chloride as Ni source and ammonium hypophosphate as P source.The effect of initial P/Ni molar ratio on the structure,acidity,HDO activity and product distribution of Ni-P/Si O₂-x catalyst was studied.The results show that P can increase the active site of the acid center of the catalyst,showing good hydrogen hydrolysis ability of C-OH bond,and the selectivity of the ideal target product MCH.Compared with Ni/Si O₂（18%）,the selectivity of Ni-P/Si O₂-1.0to anaerobic products was significantly improved（99.4%）.When reaction condition is at250°C,3 MPa,1h,the m-cresol（g）/catalyst（g）was 3,the m-cresol conversion rate was about 100%,the selectivity of the main product MCH reached 99.4%,and the HDO reaction path was mainly HYD path.Using Ni citrate,Ni chloride and Ni acetate as Ni source,ammonium hypophosphate as P source and urea as nitrogen source,three kinds of Ni source N-doped catalysts were studied.and Ni acetate shows the best performance.Then Ni₂P（Ac）-N_y/Si O₂ catalysts were prepared by changing the N doping amount,and the effect of N doping amount on the HDO energy of m-cresol was studied.Appropriate N-Doping amount can promote the formation of active phase,modify the electronic structure of Ni and P,thus improving the activity of catalyst.Ni₂P（Ac）-N_1.0/Si O₂ shows the best HDO performance,and the conversion rate is 93.2%and the selectivity of the ideal product MCH is 94%at 250°C,3 MPa,1 h and m-cresol（g）/catalyst（g）was 7.5.HYD was also the main path for HDO reaction over Ni₂P（Ac）-N_1.0/Si O₂.Preparation of Cox P-Ni2P/Si O2-y catalyst doped with metal Co.Cox P-Ni2P/Si O2-y catalysts with different P/M were prepared using nickel acetate as Ni source,cobalt acetate as Co source,ammonium hypophosphate as P source.The effects of metal Co doping and the molar ratio of P/M on the formation of active phase and the performance of HDO were investigated.The hydrogenation activity of Cox P-Ni2P/Si O2-y catalyst increased.However,the selectivity of the target product MCH decreased slightly due to the decrease of Bronsted acid.HDO of m-cresol was catalyzed by Cox P-Ni2P/Si O2-y at the condition of 250°C,2MPa,1h,m-cresol（g）/catalyst（g）was 7.5.Cox P-Ni2P/Si O2-0.5 shows the best catalytic activity,and the conversion rate is 39%higher than that of Ni₂P/Si O₂-1.0,reaching 94%.HYD is also the main catalytic path for m-cresol HDO.