Promotional effect of Ga for Ni2P catalyst on hydrodesulfurization of 4,6-DMDBT

Ni2P catalysts supported on SiO2 and Ga-SiO2 were prepared by incipient wetness impregnation technique, and the effect of the electronic properties of Ni2P on hydrodesulfurization (HDS) performance was studied. X-ray diffraction (XRD), X-ray absorption near edge structure (XANES), and in situ FT-IR with CO adsorption studies were used to examine structural and electronic properties of the supported Ni2P catalysts. The catalytic activity in hydrodesulfurization (HDS) was measured at 3.0 MPa and at three different temperatures of 613, 628, and 643 K in a three-phase fixed bed reactor using a model feed containing 500 ppm S as 4,6-DMDBT, 6000 ppm S as DMDS, 100 ppm N as quinoline, 1 wt% tetralin, and 0.5 wt% n-nonane in n-tridecane balance. In both cases, the HDS conversion was very high over 90%. For the product distributions, the Ni2P/SiO2 maintained a low direct desulfurization (DDS) selectivity at 26.5%, while the Ni2P/Ga-SiO2 exhibited higher DDS selectivity of 32.1% at 643 K. The Ni K-edge XANES and CO-adsorbed FT-IR analysis confirmed the electron enriched property of Ni2P on SiO2, but with the electron deficiency of Ni2P phase supported on Ga-SiO2 support. These results thus suggest that the electron deficient Ni2P favors σ-bonding with S compounds to promote direct desulfurization of 4.6-DMDBT.