Effect of fluorine and boron modification on the HDS, HDN and HDA activity of hydrotreating catalysts

A series of fluorine- and/or boron-modified catalysts were studied, among which the catalysts simultaneously modified with fluorine and boron were prepared and studied for the first time. The hydrodesulfurization (HDS), hydrodenitrogenation (HDN) and hydrodearomatics (HDA) activities of all the catalysts were evaluated with model compounds, 4,6-DMDBT, pyridine and 1-methylnathphlene. The catalysts were also characterized by FT-IR, BET, X-ray photoelectron spectroscopy (XPS), and thermogravity/differential thermal analysis (TG/DTA) for acid type and acidity, pore structure, metal distribution on the surface of catalysts, existing state of hydrogenation metals, and decomposition of fluorine, boric and hydrogenation metal compounds. The experimental results showed that the catalyst simultaneously modified with borane isoproxyl and ammonium fluoride had the best HDN and HDA activities and good HDS activity, though the lowest acidity among the catalysts. The excellent hydrogenation activity of this catalyst may attribute to its highest dispersed active nickel and its large pore volume and surface area. The catalyst modified with NH4F and H3BO3 showed a similar performance to the catalyst modified with H3BO3 only. The incorporation of boron led to a greater increase in hydrogenation activity than the addition of fluorine which presents a detrimental effect on the HDN reaction.