Catalyst – solid sorbent – or support therefor: product or process – Catalyst or precursor therefor – Boron or compound containing same
Reexamination Certificate
2000-08-31
2003-06-10
Nguyen, Ngoc-Yen (Department: 1754)
Catalyst, solid sorbent, or support therefor: product or process
Catalyst or precursor therefor
Boron or compound containing same
C502S208000, C502S232000, C502S254000, C502S257000, C502S259000, C502S260000, C502S305000, C502S314000, C502S315000, C502S325000, C502S332000, C502S337000
Reexamination Certificate
active
06576584
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims priority to Japanese Patent Application No. 287425/1999, filed Oct. 7, 1999, which is incorporated herein by reference.
FIELD OF THE INVENTION
This invention relates to a method for producing a hydrotreating catalyst for a hydrocarbon oil, more particularly to a method for producing a multi-component solid hydrotreating catalyst containing a uniform, crystalline, composite metal compound, prepared by simultaneous precipitation and accompanying coprecipitation of the catalyst components from the mixture containing at least one hydrogenation-active component.
BACKGROUND OF THE INVENTION
Solid catalysts for chemical reactions normally comprise a carrier on which one or more active components are deposited by impregnation, vapor deposition or the like. In oil refining, various types of catalysts have been proposed for hydrotreating hydrocarbon oils, e.g., those with one or more hydrogenation-active components deposited in two stages on a refractory inorganic oxide. The refractory inorganic oxides useful as the carrier include alumina, silica-alumina, magnesia and zirconia, and useful hydrogenation-active metal components include at least one of the group 6A and group 8 metals, such as molybdenum, tungsten, cobalt and nickel, in particular a combination of the group 6A and group 8 metals, such as molybdenum-cobalt, molybdenum-nickel and molybdenum-cobalt-nickel.
The basic characteristics a solid hydrotreating catalyst is required to exhibit include high reactivity and activity maintenance, for which the active sites of the active metal component must be dispersed uniformly and extensively. Therefore, the essential properties of the catalyst are large specific surface area and pore volume. For such a catalyst to be realized, it is necessary to provide a carrier of large specific surface area and pore volume, and to keep these essential properties while it is deposited with an active metal component. One of the disadvantages involved in the two-stage process, which has been developed so far to produce solid catalysts, is weak bond between the active metal component and carrier, because the carrier is impregnated with a solution of the active component, with the result that it is merely adsorbed or precipitated on the carrier. As a result, the active metal component is highly mobile during the catalyst production process from adsorption or precipitation to completion of drying, making it difficult to disperse the active metal component uniformly and extensively. Another disadvantage is limited content of the active component and hence limited catalyst activity, because the active component is immobilized on the carrier already prepared, by which is meant that content of the active component is limited by total pore volume of the carrier.
In an attempt to solve the above problems, Japanese Laid-open Patent Application No. 83603/1986 discloses a method for producing the solid catalyst involving no independent carrier production step, in which an oxygenated organometallic compound dissolved in a polar compound as the solvent is hydrolyzed, and the resultant sol is gelled. However, this method involves several problems; (1) the uniform sol (colloidal solution) prepared by the hydrolysis must be totally gelled, which limits ratio of the oxygenated compound to the polar compound, (2) it is difficult to produce a high-density or high-strength compound metal oxide, when the whole sol is to be gelled, which makes this method unsuitable for production of practical hydrotreating catalysts required to be serviceable for extended periods, and (3) the active metal component is substantially limited to an easily reducible metallic compound which forms a precipitate by hydrolysis with water, and another compound is difficult to use, even though it is soluble in the hydrolysis effluent solution, and (4) the gel formed by the gelation process is agar-like, difficult to be uniform by agitation, causing insufficient or incomplete hydrolysis. On the other hand, when the mixing ratio is high enough to allow sufficient agitation, the agar-like gel cannot be continuously discharged from the vessel to totally gel the sol. This method, therefore, has not been used for production of high-activity hydrotreating catalysts, because of the above difficulties which make it unsuitable for commercial production of the catalyst.
Recently, reduction of sulfur content of gas oil is strongly required for environmental reasons, especially by deep desulfurization of stocks of high sulfur contents, e.g., light gas oil (LGO), vacuum gas oil (VGO) and cracked gas oil. In particular, sulfur content of diesel fuel is required to be reduced to 0.05 wt. % or lower. It is now considered that 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 by development of high-activity catalysts.
It would be desirable to provide a method for producing a solid catalyst, in particular hydrotreating catalyst which exhibits high activity in desulfurization, denitrogenation, dearomatization and the like for hydrotreating hydrocarbon oils, which exhibits high activity maintenance for the above reactions, and that has an increased content of hydrogenation-active component dispersed uniformly and extensively, and large specific surface area and pore volume.
SUMMARY OF THE INVENTION
Knowing that the conventional two-stage process used for producing the solid catalysts has a limitation of further increasing catalyst activity, the inventors of the present invention have extensively pursued methods which give a catalyst with an active component high in homogeneity and dispersibility without separating the carrier production and active component deposition steps from each other, to find that all of the catalyst components (a), (b
1
) and (b
2
) of different precipitation characteristics can be simultaneously precipitated by dissolving these catalyst components uniformly in a non-aqueous solvent and adding a precipitant solution to the above solution for simultaneous precipitation and accompanying coprecipitation.
The present invention relates to a method for producing a hydrotreating catalyst, which comprises (1) dissolving catalyst components (a), (b
1
) and (b
2
), wherein said catalyst components are defined as:
(a) (i) an aluminum compound soluble in a non-aqueous solvent, or
(ii) a mixture of the above aluminum compound and at least one of the compounds selected from silicon, phosphorus and boron, soluble in the above solvent,
(b
1
) at least one of the compounds selected from group 6A metals, and
(b
2
) at least one of the compounds selected from group 8 metals in a non-aqueous solvent to form a homogeneous solution, (2) preparing a gel slurry from the homogeneous solution by adding a precipitant solution to the homogeneous solution, and (3) drying and calcining the gel slurry to form a homogeneous, crystalline composite metal compound.
Another embodiment relates to a method for producing a hydrotreating catalyst, which comprises (1) dissolving at least one of catalyst components (a), (b
1
) and (b
2
), wherein said catalyst components are defined as:
(a) (i) an aluminum compound soluble in a non-aqueous solvent, or
(ii) a mixture of the above aluminum compound and at least one of the compounds selected from silicon, phosphorus and boron, soluble in the above solvent,
(b
1
) at least one of the compounds selected from group 6A metals, and
(b
2
) at least one of the compounds selected from group 8 metals in a non-aqueous solvent to form a homogeneous solution, (2) preparing a gel slurry from the homogeneous solution by adding a precipitant solution further containing any remaining catalyst components not added to the non-aqueous solvent in step (1) to the homogeneous solution, and (3) drying and calcining the gel slurry to form a homogeneous, crystalline composite metal compound.
The present invention for producing a multi-component, simultaneously
Hashimoto Takao
Iijima Masahiko
Isoda Takeshi
Okayasu Yoshinobu
Nguyen Ngoc-Yen
Takemoto James H.
Tonen Corporation
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