Mineral oils: processes and products – Refining – Sulfur removal
Reexamination Certificate
1999-09-27
2001-07-31
Griffin, Walter D. (Department: 1764)
Mineral oils: processes and products
Refining
Sulfur removal
C208S21600R, C208S2160PP, C208S25100H, C208S25400R, C208S264000, C208S111300, C208S111350, C502S313000, C502S238000, C502S254000, C502S257000, C502S258000, C502S259000, C502S260000, C502S261000, C502S262000, C502S235000, C502S263000, C502S314000
Reexamination Certificate
active
06267874
ABSTRACT:
FIELD OF INDUSTRIAL UTILIZATION
This invention relates to a hydrotreating catalyst and a method for hydrotreatment of hydrocarbon oils using the same, more particularly to the catalyst high in tolerance to inhibiting effects by hydrogen sulfide and nitrogen compounds and high in activity and activity-maintenance, and the method using the same for various hydrotreating purposes, e.g., hydro-desulfurization, hydrodenitrogenation,hydrocracking,hydrodearomatization, hydroisomerization and hydrofining.
BACKGROUND OF THE PRESENT INVENTION
Various types of catalysts have been proposed for hydrotreating hydrocarbon oils. The so-called two-element catalysts, with the Group 6 elements (e.g., molybdenum and tungsten) and Group 8 elements (e.g., cobalt and nickel) as the active metallic components carried by refractory inorganic oxides (e.g., alumina, silica and magnesia), have been already commercialized. These catalysts have been further developed to have higher desulfurization and/or denitrogenation activity, both from active metallic components and carriers. The applicant of the present invention have already studied to further improve catalyst activity by improving dispersibility of the active metallic components, to propose an extremely high-activity catalyst with high desulfurization activity, which is prepared by supporting cobalt and/or nickel as the Group 8 metals on a silica-alumina carrier in the first step, and further supporting molybdenum and/or tungsten as the Group 6 metals on the same carrier in the second step, to finely disperse molybdenum as the major component on the carrier (Japanese Laid-open Patent application No. 225645/1985).
The carriers have been also developed, by controlling pore size distributions of silica-alumina carriers, to improve desulfurization activity of the catalysts for hydrotreating by maximizing the pores having a diameter of 30 Å to 100 Å.
Recently, however, reduction of sulfur content of gas oils is strongly required for environmental reasons, especially for stocks of higher sulfur contents, e.g., light gas oil (LGO) and vacuum gas oil (VGO). In particular, sulfur content of LGO is strongly required to be reduced to 0.05 wt. % or lower for environmental reasons. Whether this is achieved or not largely depends on whether sulfur compounds difficult to remove, e.g., 4-methyl dibenzothiophene and 4,6-dimethyl dibenzothiophene, are efficiently desulfurized, in particular at a high hydrogen sulfide partial pressure.
It is however known that the two-element catalysts are rapidly deactivated, when deeply hydrotreating hydrocarbon oils of high sulfur content, as a result of increased hydrogen sulfide partial pressure in the reaction atmosphere. In particular, the Ni—Mo catalyst, although showing a high desulfurization activity at a low hydrogen sulfide partial pressure, is rapidly deactivated at a high hydrogen sulfide partial pressure, because of its insufficient tolerance to the inhibiting effects by hydrogen sulfide. On the other hand, the Co—Mo catalyst, although higher in tolerance to hydrogen sulfide to some extent, has a disadvantage of lower desulfurization activity. It is therefore necessary to develop a catalyst simultaneously showing a high desulfurization activity and tolerance to the inhibiting effects by hydrogen sulfide, in order to deeply desulfurize hydrocarbon oils.
A variety of techniques have been proposed to solve these problems, viewed from carrier types, carrier structures, active metal components and method for supporting active metals on the carriers. For example, Japanese Laid-open Patent application No. 164334/1997 discloses the hydrotreating catalyst to desulfurize the difficult-to remove sulfur compounds present in gas oil, where an inorganic oxide carrier supports 5 mass % to 20 mass % (as oxide, percentage being based on the catalyst) of molybdenum in the first stage, which is dried and calcined, and then with 5 mass % to 15 mass % (as oxide) of molybdenum and 1 mass % to 10 mass % (as oxide) of nickel in the second stage, which is dried and calcined at 150° C. to 350° C. This catalyst, however, is an insufficient one for the catalyst for deep desulfurization of hydrocarbon oils, because of its low tolerance to the inhibiting effects by hydrogen sulfide.
DISCLOSURE OF THE PRESENT INVENTION
It is an object of the present invention to provide a hydrotreating catalyst, developed to solve the above problems involved in the conventional catalysts, which shows high tolerance to the inhibiting effects by hydrogen sulfide formed massively in the reaction atmosphere during the hydrotreatment process of hydrocarbon oils of high sulfur content, high activity for hydrotreatment of the compounds containing difficult-to-remove sulfur compounds, and can be used also for, e.g., hydrodenitrogenation, hydrocracking, hydrodearomatization and hydrofining.
It is another object of the present invention to provide an alumina-based hydrotreating catalyst of high silica content, in which silica is finely dispersed.
It is still another object of the present invention to provide a hydrotreating catalyst in which the active metals are finely dispersed by virtue of high dispersibility of silica.
It is still another object of the present invention to provide a method of hydrodesulfurization capable of deeply desulfurizing hydrocarbon oils containing difficult-to-remove sulfur compounds. The inventors of the present invention have studied extensively to solve the problems involved in the conventional catalysts, to find that the Brønsted acid sites on the hydrotreating catalyst carrier interacts with the catalyst active metals to greatly improve the catalyst tolerance to the inhibiting effects by hydrogen sulfide, with the result that the difficult-to-remove sulfur compounds can be efficiently removed, reaching the present invention.
The present invention relates firstly to the hydrotreating catalyst comprising the carrier having a Br&phgr;nsted acid content of 50 &mgr;mol/g or more, which supports at least one active component (A) selected from the elements of Group 8 of the Periodic Table, and at least one active component (B) selected from the elements of Group 6 of the Periodic Table.
The present invention relates secondly to the hydrotreating catalyst, comprising the carrier of silica-alumina or the carrier of silica-alumina a third component, which supports at least one active component (A) selected from the elements of Group 8 of the Periodic Table, and at least one active component (B) selected from the elements of Group 6 of Periodic Table, wherein,
(i) silica content is 30 wt. % or more, based on the total weight of the carrier, and
(ii) the spectral patterns of the carrier observed by the nuclear magnetic resonance analysis [
29
Si-NMR (79.5 MHz)] are characterized by:
{circle around (1)} the combined area of peaks at −80 ppm, −86 ppm and −92 ppm being at least 15% of the total area of all peaks, and
{circle around (2)} the combined area of peaks at −80 ppm, −86 ppm, −92 ppm and −98 ppm being at least 50% of the total area of all peaks.
The present invention relates thirdly to the method for hydrotreating hydrocarbon oils with hydrogen under the hydrotreatment conditions in the presence of the first or second catalyst of the present invention.
REFERENCES:
patent: 4837193 (1989-06-01), Akizuki et al.
patent: 5944983 (1999-08-01), Hayashi et al.
patent: 0 160 475 B1 (1985-11-01), None
patent: 0 875 287 A2 (1998-11-01), None
patent: 60-225645 (1985-11-01), None
patent: 5-192587 (1993-08-01), None
patent: 6-296879 (1994-10-01), None
patent: 7-196308 (1995-08-01), None
patent: 9-164334 (1997-06-01), None
patent: 7-196308 (1998-11-01), None
patent: 10-296091 (1998-11-01), None
patent: 0 875 287 A2 (1998-04-01), None
Iijima Masahiko
Okayasu Yoshinobu
Griffin Walter D.
Haddaway Keith G.
Schneller Marina V.
TonenGeneral Sekiyu K.K.
Venable
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