Nickel phosphide catalysts supported on SBA-15 for hydrodesulfurization of 4,6-dimethyldibenzothiophene

Abstract

Ni2P catalysts supported on SiO2 and SBA-15 were successfully prepared by temperature-programmed reduction (TPR), and the effect of Ni2P dispersion on the 4,6-dimethyldibenzothiophene hydrodesulfurization (HDS) activity was studied. The surface areas of the samples varied from low (Ni2P/SiO2, 127 m 2·g-1) to high (Ni2P/SBA-15, 283 m 2·g-1), with corresponding Ni2P average crystallite sizes decreasing from 20 to 5 nm. Extended X-ray absorption fine structure (EXAFS) studies were used to confirm the formation of Ni2P phase. Transmission electron microscopy (TEM) analysis showed that the SBA-15-supported Ni2P sample consisted of nanoparticles, which were probably located in the mesoporous channels or the external surfaces. The catalytic activity for HDS was measured at 613 K and 3.1 MPa in a three-phase fixed bed reactor using a model liquid feed containing 500 ppm S as 4,6-dimethyldibenzothiophene, 1000 ppm S as dibenzothiophene, 200 ppm N as quinoline, and 1% aromatics as tetralin in tridecane solvent. The Ni 2P/SBA-15 catalyst had a steady-state HDS conversion of 99% at 613 K, much higher compared to the Ni2P/SiO2 catalyst with a HDS conversion of 54%. These results are probably due to the enhanced dispersion of the Ni2P particles on the high surface area SBA-15 support, as confirmed by CO chemisorptions, TEM and EXAFS analysis.