A catalyst and process for the manufacture of ultra-low sulfur distillate product (Shell)

PATENT
A catalyst and process for the manufacture of ultra-low sulfur distillate product (Shell)
Publication number US20130296163 A1
Publication type Application
Application number US 13/932,471
Publication date Nov 7, 2013
Also published as CA2659797A1, 9 More »
Inventors
Opinder Kishan Bhan
Original Assignee
Shell Oil Company
Abstract
Described is a catalyst and process useful in the hydrodesulfurization of a distillate feedstock to manufacture a low-sulfur distillate product. The catalyst comprises a calcined mixture of inorganic oxide material, a high concentration of a molybdenum component, and a high concentration of a Group VIII metal component. The mixture that is calcined to form the calcined mixture comprises molybdenum trioxide in the form of finely divided particles, a Group VIII metal compound, and an inorganic oxide material. The catalyst is made by mixing the aforementioned starting materials and forming therefrom an agglomerate that is calcined to yield the calcined mixture that may be used as the catalyst or catalyst precursor.
This invention relates to a catalyst and process for the manufacture of a hydrocarbon product having a low sulfur concentration. The invention further relates to a process for the manufacture of an ultra-low sulfur distillate product and a distillate hydrodesulfurization catalyst for use in such process.
U.S. governmental regulations are imposing more severe limits on the maximum sulfur concentration permitted for on-road diesel with the maximum sulfur concentration limit currently being set at 15 parts per million (ppm). The European Union has set a sulfur concentration limit for diesel fuel of less than 50 ppm. Other organizations are supporting even stricter requirements of as low as 5 to 10 ppm sulfur in diesel. Due to these low sulfur concentration limits, there are ongoing efforts by industry to develop improved distillate hydrodesulfurization catalysts that may suitably be used in the hydrodesulfurization of distillate feedstocks that contain sulfur high concentrations to produce low sulfur distillate products.
A typical prior art hydroprocessing catalyst is disclosed in U.S. Pat. No. 5,223,472 (Simpson et al.), which teaches that its hydroprocessing catalyst is an alumina support impregnated with a Group VIII metal and a Group VIB metal. The catalyst is said to be characterized by a relatively narrow pore size distribution and containing from 0.1 to 5.0 weight percent of a Group VIII metal and from 2.0 to 10.0 weight percent of a Group VIB metal. The preferred catalyst is made by impregnating formed support particles by using an impregnation solution containing dissolved metal hydrogenation components. If a Group VIB metal component is desired in the final catalyst, the Group VIB metal compounds that may be used in the impregnation solution are chosen from those that are soluble in aqueous media, including salt compounds that contain the Group VIB metal. There is no mention in the patent of the incorporation of a molybdenum hydrogenation component into a hydroprocessing catalyst by the comulling of molybdenum trioxide with the inorganic support material.
U.S. Pat. No. 5,686,375 (Iyer et al.) mentions hydroprocessing catalysts that contain underbedded Group VIII metal components with the preferred catalyst comprising underbedded nickel and an overlayer of molybdenum. The patent states that many nickel and molybdenum compounds are useful for impregnation or comulling including precursors of molybdenum trioxide, but it does not specifically mention the comulling of molybdenum trioxide with the porous refractory support material in the preparation of its catalyst support that has an underbedded molybdenum component. The patent does, however, mention the incorporation of molybdenum onto the support that contains underbedded nickel by comulling instead of by impregnation. But, there is no teaching in the '375 patent of the preparation of a hydrotreating catalyst for making ultra-low sulfur distillate by the comulling of an inorganic support material with both a molybdenum trioxide and a Group VIII metal compound followed by the resulting mixture being calcined to thereby form the catalyst.
Disclosed in U.S. Pat. No. 4,888,316 (Gardner et al.) is a hydrotreating catalyst made from spent hydrotreating catalyst that comprises molybdenum and/or tungsten and/or nickel and/or cobalt. The spent catalyst is subjected to a grinding step whereby it is ground to a suitable particle size. The ground spent hydrotreating catalyst is mixed with alumina material and formed into shaped particles that are calcined to give the hydrotreating catalyst. There is no mention in the patent of the incorporation of a molybdenum hydrogenation component into a hydroprocessing catalyst by the comulling of molybdenum trioxide with the inorganic support material.
Intl. Pub. No. WO 02/32570 (Bhan) discloses a hydroprocessing catalyst made by mixing alumina with fines produced by crushing a commercial hydroprocessing catalyst that contains a Group VIB metal and, optionally, a Group VIII metal, and forming the resulting mixture into particles, preferably by extrusion, followed by calcination of the formed particles. A suitable amount of Group VIB metal in the finished catalyst is from 0.5 wt. % to 10 wt. % of the catalyst, with in the case of molybdenum, between 2 wt. % and 6 wt. % being preferred. There is no mention in the patent of the incorporation of a molybdenum hydrogenation component into a hydroprocessing catalyst by the comulling of molybdenum trioxide with the inorganic support material or that it is undesirable to comull a molybdenum salt with the inorganic support material.
U.S. Pat. No. 6,030,915 (de Boer) discloses a hydroprocessing catalyst that uses regenerated spent hydroprocessing catalyst fines in the manufacture of a hydroprocessing catalyst. The patent further indicates that additional hydrogenation metals may be added to the catalyst composition by impregnation using an impregnation solution comprising water soluble salts of the hydrogenation metals to be incorporated into the catalyst composition. Also, an alternative method of incorporating the extra metal into the catalyst composition is indicated as including the mixing of either solid state or dissolved metal components with the mixture of regenerated spent hydroprocessing catalyst fines, binder, and, optionally, additive. The solid state metal may include solid molybdenum oxide. The '915 patent requires the regenerated spend hydroprocessing catalyst fines to be mixed with at least one additive, which may include a binder, in the preparation of its catalyst.
It is desirable to have a catalyst that has a low production cost and which is useful in the hydrodesulfurization of a sulfur-containing distillate feedstock to yield an ultra-low sulfur distillate product. It is further desirable for the hydroprocessing catalyst to have good sulfur removal activity and to be highly stable by exhibiting a low rate of decline in its sulfur removal activity.
Thus, accordingly, provided is a composition for use as a distillate hydrodesulfurization catalyst in the manufacture of an ultra-low sulfur distillate product, wherein said composition comprises: a calcined mixture made by calcining a mixture comprising an inorganic oxide material, molybdenum trioxide, and a Group VIII metal compound selected from the group consisting of a nickel compound and a cobalt compound, wherein said calcined mixture has a molybdenum content in the range of from 7 weight percent to 22 weight percent with the weight percent being based upon the molybdenum as metal and the total weight of the calcined mixture, and a Group VIII metal content in the range of from 3 weight percent to 12 weight percent with the weight percent being based upon the Group VIII metal in its elemental form and the total weight of the calcined mixture.
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