Hydrotreating of coker light gas oil on Ti-HMS supported heteropolytungstic acid catalysts
Ti-HMS substrates were synthesized by using dodecylamine as structure-directing agents. A series of HPW/Ti-HMS catalysts with different Si/Ti ratios, promoted by Ni was prepared using Keggin-type heteropolyacids (H3PW12O40) as active phase precursors. These catalysts were compared with corresponding NiW/HMS catalysts prepared from the traditional precursors (ammonium metatungstate). Prepared supports and catalysts were characterized by small- and wide-angle XRD, N2 physisorption, FT-IR, Raman, DRIFT, TEM, and SEM. Catalytic activity was assessed for hydrodesulfurization (HDS) and hydrodenitrogenation (HDN) of coker light gas oil (CLGO) derived from Athabasca bitumen, in a trickle bed reactor at a temperature, pressure, and LHSV of 370 °C, 8.8 MPa, and 2.0 h−1, respectively. The W catalysts prepared from heteropolyacids showed better performance for hydrotreating than their counterparts prepared from traditionally used W ammonium salts. The incorporation of Ti into HMS afforded catalysts that were more active than the Ti-free counterpart, due to the larger number of coordinately unsaturated sites (CUS) of the metal sulfide on Ti-loaded catalysts. Under steady-state conditions, the NiPW/Ti-HMS (20) catalyst with a Si/Ti ratio of 20 was the most active among the catalysts studied due to more uniform distribution of active species.
Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (199 K)Download as PowerPoint slideHighlights► Keggin-type HPAs as starting materials for catalysts preparation has beneficial effect on hydrotreating activity. ► Keggin structure was preserved during impregnation of Ti-HMS and calcination steps. ► NiPW/Ti-HMS catalysts showed better performance in deep HDS and HDN of CLGO.
Journal: Applied Catalysis A: General - Volume 398, Issues 1–2, 15 May 2011, Pages 27–36