Preparation And Performance Of Supported Ni₂P Catalysts On B₂O₃-Modified Supports For Hydrodesulfulrazation

Transition metal phosphides Ni2P shows higher hydrodesulfurization activity than the traditional catalyst such as Co(Ni)-Mo-S.In order to avoid the formation of crystalline AIPO4 and crystalline Ni-2P5 during the synthesis the Ni2P loaded on Al2O3 by temperature-programmed reduction(TPR)method,the Al2O3 is modified by B2O3.For comparison,the SiO2 modified by B2O3 is also used as the support for Ni2P.At the same time,the effect of boron addition to Al2O3 and SiO2 support on the hydrodesulfurization properties of Ni2P catalysts is investigated.Both supports were prepared by a wetness impregnation method using boric acid to modify the support yielding a B2O3 layer on the surface of the Al2O3 and SiO2 supports.B2O3 was loaded on the supports with two solvents,water and methanol solution,by impregnation method and the Ni2P prepared by consecutive impregantion method.The precursors were converted into the Ni2P catalysts with different P/Ni ratios using TPR.These catalysts were subjected to a series of characterization techniques including X-ray diffraction(XRD),temperature-programmed desorption of ammonia(NH3-TPD),transmission electron microscopy(TEM)and Infrared pyridine spectroscopy(IR),Brunauer-Emmett-Teller(BET)to probe the effects of B2O3 on catalyst properties.The pure Ni2P can be loaded on the B2O3/Al2O3-20%with a low ration of P/Ni(1.2)and B2O3 weight loading of 20%successfully,which is identified by the XRD.After loading of B2O3,the surface area of Al2O3 increased at 10 wt.%and then decreased at 20 wt.%.For SiO2 support,the surface area is decreased with the increasing of B2O3 loading.The addition of B2O3 make these weak acidity increase in amount and intensity.Py-IR shows that much acid generated by B-OH.These catalyst with B2O3 shows higher than that catalyst without B2O3,due to the acid.The Ni2P/B2O3/Al2O3 catalysts were tested under HDS reaction conditions to determine the optimal B-loading for sulfur removal from Dibenzothiophene,as well as the role of the phosphorous source in determining catalytic properties.At 360?,the DBT conversion with value 99.2%over Ni2P/B2O3/Al2O3-20%is higher than that over Ni2P/B2O3/SiO2-20%with value of 98.0%.The difference between Ni2P/B2O3/Al2O3 and Ni2P/B2O3/SiO2 is HDS path at high temperature,in which Ni2P/B2O3/Al2O3 and Ni2P/B2O3/SiO2 favors DDS and HYD path,respectively.