Surface properties NiMo catalysts

The appropriate selection of hydroprocessing catalysts depends on a careful inspection of the chemical properties of the feedstock and the expected products. For conventional distillate HDT (naphtha, kerosene, and gas oil), the specific surface area and the composition of the active phase are the most relevant features. CoMo-based catalysts are the traditional HDS catalysts used in the industry. NiMo catalysts are better for saturation reactions and HDN due to their higher hydrogenation power. Therefore, Ni-promoted catalysts are preferred over CoMo catalysts when the chemistry of the process proceeds through the hydrogenation route (i.e., gas oil feeds containing aromatic S- and N-compounds). NiW catalysts exhibit remarkable hydrogenation properties, but they are rarely used in... 

Layered crystalline titanates (CT) [Anthony and Dosch, U.S. Patent 5 177 045 (1993)] are pillared with tetraethyl orthosilicate, 3-aminopropyltrimethoxysilane, and aluminum(III) acetylacetonate to prepare porous and high surface area supports for sulfided NiMo catalyst. Tetraethyl orthosilicate or aluminum(III) acetylacetonate intercalated CT are prepared by stepwise intercalation. First, the basal distance is increased by n-alkylammonium ions prior to intercalation with inorganic compounds. However, an aqueous solution of 3-aminopropyltrimethoxysilane can directly pillar CT without first swelling the titanate with n-alkylamine. The catalytic activities for hydrogenation of pyrene of sulfided NiMo supported silica or alumina pillared CT are higher than those of commercial catalysts (Shell324 and AmocatlC). The silicon and aluminum contents of the pillared CT, used as supports, have considerable effects on the catalytic activities and physical properties of the supports. 

Results from textural characterization of the supports and catalysts (Table 1) indicate that the incorporation of Ni and Mo (W) species on the supports surface produced a decrease in the textural properties, which was stronger for the samples supported on Zr-SBA-15. This decrease points out the possibility of some obstruction of the Zr-SBA-15 pores by deposited metal oxide species. Nevertheless, both NiMo and NiW catalysts supported on Zr02-containing SBA-15 had surface areas twice larger than those of y-Al203-supported samples. 

For all experiments, a commercial NiMo-supported y-alumina catalyst was used. Its properties are specific surface area of 175 m /g, mean average pore volume of 0.56 cmVg, mean average pore diameter of 127 A, molybdenum content of 10.66 wt%, and nickel content of 2.88 wt%. The tetralobular commercial catalyst had a diameter of 2.54 mm. 

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