Preparation and Hydrodesulfurization Catalytic Performance of Ni2P/SiO2/Cordierite Monolithic Catalysts

The monolithic catalysts containing nickel phosphide precursors were prepared by dipping the silica sol containing nickel nitrate and phosphoric acid into the pretreated cordierite (Cord) support. Then, a series of N12P/S10,/Cord monolithic catalysts with different Ni contents were prepared by temperature-programmed reduction method in H2 flow. The structure of the catalysts was characterized using X-ray diffraction (XRD), N, adsorption-desorption and scanning electron microscope (SEM). The catalytic performances of the hydrodeSillfurization (HDS) were evaluated in a fixed-bed micro-reactor using dibenzothiophene (DBT) as the model compound. The XRD results indicated that the nickel phosphides were well dispersed on the surface of catalysts while the Ni content was less than 3.2wt%. However, there was the NO phase in the N12P/Si02/Cord catalysts while the Ni content was more than 6.4wt%. The results of N2 ad so rpti on -desorption isotherius showed that the pore size of the catalysts was around 3.6 rim. The SEM results show that the coating thickness of the cordierite support was about 20 [Lm. The active evaluation results indicated that the Ni,)P/SiO2/Cord monolithic catalysts had very good catalytic performances for the HDS. The conversion of the DBT can reach 92.0% under the condition of the liquid hourly space velocity (LHSV) of 1.9 h-1 and reaction temperature at 360 'C in the NiY/Si02/Cord monolithic catalysts with Ni content of' 12.8wt%. Simultaneity, the selectivity of bipbenyl (13P) and cyclohexylbenzene (CHB) were 69.8% and 30.2%, respectively. It was indicated that the mechanism of the HDS was mainly the direct desulfurization (DDS) over the N12P/Si02/Cord catallyst.s.