Effect of boron promoter on the structure and hydrodesulfurization activity of Ni2P/SBA-15 catalysts

Abstract

The catalyst precursors of B-Ni2P/SBA-15 were synthesized by co-impregnation using (NH4)2HPO4 as the source of phosphorus, Ni(NO)3 as the source of nickel and H3BO3 as the source of boron. The B-Ni2P/SBA-15 catalysts with an initial P/Ni molar ratio of 0.8 and a boron content from 0.35% to 2.10%(w) were prepared by temperature-programmed reduction in a H2 flow. The structure of the catalysts was characterized by X-ray diffraction (XRD), N2 adsorption-desorption, transmission electron microscopy (TEM) and NH3 temperature-programmed desorption (NH3-TPD). The catalytic performances of hydrodesulfurization (HDS) were evaluated in a fixed-bed microreactor using dibenzothiophene (DBT) as a model compound. The results showed that the B-Ni2P/SBA-15 catalysts still retained mesoporous structure. The Ni2P phase was mainly active phases in all the catalysts. The proper addition of boron reduced the Ni2P active phases but increased the specific surface area of the catalysts. The amount of acid in B-Ni2P/SBA-15 also increased with addition of boron. When the reaction temperature was increased from 300 to 360 °C, the HDS conversion of DBT over the catalyst clearly improved with an increase in the content of boron. The B-Ni2P/SBA-15 catalyst with a boron content of 1.40%(w) had the best catalytic activity. The mechanism of the HDS of DBT consisted of main direct desulfurization (DDS) over the B-Ni2P/ SBA-15 catalysts. © Editorial office of Acta Physico-Chimica Sinica.