Catalyst – solid sorbent – or support therefor: product or process – Catalyst or precursor therefor – Metal – metal oxide or metal hydroxide
Reexamination Certificate
2000-05-22
2001-09-18
Wood, Elizabeth D. (Department: 1755)
Catalyst, solid sorbent, or support therefor: product or process
Catalyst or precursor therefor
Metal, metal oxide or metal hydroxide
C502S022000, C502S027000, C502S028000, C502S029000, C502S306000, C502S313000, C502S314000, C502S315000, C502S316000, C502S319000, C502S320000, C502S321000, C502S322000, C502S323000, C502S326000, C502S332000, C502S333000, C502S334000, C502S335000, C502S337000, C502S339000, C502S208000, C502S209000, C502S210000, C502S211000, C502S213000, C502S514000
Reexamination Certificate
active
06291394
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to high activity catalysts based upon gamma alumina containing substrates impregnated with one or more catalytically active metals, processes for preparing the same and uses thereof More specifically, the present invention relates to process for improving the activity of such catalysts, the improved activity catalysts produced thereby, and various specific catalysts and uses thereof.
2. Description of Related Art
The art relating to particulate porous gamma alumina containing supports, impregnating such supports with various catalytically active metals, metal compounds and/or promoters, and various uses of such impregnated supports as catalysts, is extensive and relatively well developed. As a few of the many exemplary disclosures relating to these fields may be mentioned the following United States patents, all of which are incorporated herein by reference for all purposes as if fully set forth 2935463, 3032514, 3124418, 3152865, 3232887, 3287280, 3297588, 3493493, 3749664, 3778365, 3897365, 3909453, 3983197, 4090874, 4090982, 4154812, 4179408, 4255282, 4328130, 4357263, 4402865, 4444905, 4447556, 4460707, 4530911, 4588706, 4591429, 4595672, 4652545, 4673664, 4677085, 4732886, 4797196, 4861746, 5002919, 5186818, 5232888, 5246569 and 5248412.
While the prior art shows a continuous modification and refinement of such catalysts to improve their catalytic activity, and while in some cases highly desirable activities have actually been achieved, there is a continuing need in the industry for even higher activity catalysts, which are provided by the present invention.
As an example of this need may be mentioned the need for a higher activity first stage hydrocracking catalyst. In a typical hydrocracking process, higher molecular weight hydrocarbons are converted to lower molecular weight fractions in the presence of a hydrocracking catalyst which is normally a noble metal impregnated silica-alumina/zeolite. State-of-the-art hydrocracking catalysts possess a very high activity and are capable of cracking high volume throughputs. Such catalysts, however, are highly sensitive to contaminants such as sulfur, metals and nitrogen compounds, which consequently must be removed from the hydrocarbon stream prior to the cracking. This is accomplished in first stage hydrocracking processes such as hydrodenitrogenation, hydrodesulfurization and hydrodemetallation. Hydrotreating catalysts utilized in these processes are typically a combination Group VIB and Group VIII metal impregnated alumina substrate. State-of-the-art hydrotreating catalysts, however, are not sufficiently active to allow processing of the same high volume throughputs as can be processed by the hydrocracking catalysts. As such, the first stage hydrocracking processes form a bottleneck in the overall hydrocracking process, which must be compensated, for example, in the size of the hydrotreating unit relative to the hydrocracking unit.
SUMMARY OF THE INVENTION
In accordance with the present invention, there is provided a high activity catalyst composition comprising, in one aspect, a particulate porous support containing gamma alumina, having a surface area of at least 100 square meters (as measured by nitrogen adsorption) and a pore volume of at least 0.25 cubic centimeters per gram (as measured by mercury porosimetry), and impregnated with one or more catalytically active metals. whereby the catalyst further contains in part a nanocrystalline phase of alumina of a crystallite size at the surface of up to 25Å.
In another aspect, the present invention provides a high activity catalyst comprising a particulate porous support containing gamma alumina, having a surface area of at least 100 square meters (as measured by nitrogen adsorption) and a pore volume of at least 0.25 cubic centimeters per gram (as measured by mercury porosimetry), and impregnated with one or more catalytically active metals, and which catalyst displays a relative volume activity (RVA) of at least 115, preferably at least 120, and especially at least 125, in a first stage hydrocracking process as measured by the procedure described in the article by Carruthers and DiCamillo, “Pilot Plant Testing of Hydrotreating Catalysts,”
Applied Catalysts
, 43 (1988) 253-276, utilizing as the standard a catalyst commercially available under the trade designation HC-H (as of May 1994) from Unocal Corporation, Brea, Calif.
In addition to the above catalyst, the present invention also provides a process for improving the activity of a catalyst composition comprising a particulate porous support comprising gamma alumina and amorphous alumina, having a surface area of at least 100 square meters (as measured by nitrogen adsorption) and a pore volume of at least 0.25 cubic centimeters per gram (as measured by mercury porosimetry), and impregnated with one or more catalytically active metals, by the steps of:
(1) wetting the catalyst composition by contact with a chelating agent in a carrier liquid;
(2) aging the so-wetted substrate while wet;
(3) drying the so-aged substrate at a temperature and under conditions to substantially volatilize the carrier liquid; and
(4) calcining the so-dried substrate.
This process can readily be applied to existing catalysts comprising a particulate porous support containing gamma alumina and amorphous alumina, or can be utilized in a catalyst manufacture process prior to, concurrently with and/or subsequent to the impregnation of the support containing gamma alumina and amorphous alumina, with one or more catalytically active metals and/or compounds thereof. In addition, the process can be utilized to improve the activity of spent catalysts during regeneration, which spent catalysts comprise a particulate porous support containing gamma alumina and amorphous alumina, wherein the spent catalyst is wetted as in step (1) above subsequent to the removal of carbonaceous deposits therefrom, followed by steps (2), (3) and (4).
By performing these steps in the indicated order, it is believed (without wishing to be bound by any particular theory) that an interaction takes place between at least the amorphous gamma alumina, chelating agent and catalytically active components, resulting in the appearance of a nanocrystalline phase of alumina of a crystallite size at the surface of the catalyst of up to 25Å, and preferably between 8Å and 25Å, in combination with the gamma alumina which has a crystallite size at the surface of the catalyst of greater than 30Å, and typically in the range of 30Å to 70Å. Crystallite size at the catalyst surface can be measured via well-known techniques involving transmission electron microscopy.
Concurrent with the appearance of this nanocrystalllne phase, an increase in the surface area of the catalyst is also achieved. In addition, in preferred embodiments, an at least bimodal mesopore structure is generated with a porosity peaking in a first region of pore size 40Å or less, and more preferably in the range of 20Å to 40Å, and in a second region of pore size 50Å or greater, and more preferably in the range of 50Å to 150Å, as measured by nitrogen porosimetry using the desorption isotherm.
The resulting high activity catalysts find use in a wide variety of fields as detailed in the many previously incorporated references. A particularly preferred use is as a first stage hydrocracking catalyst in hydrodenitrogenation, hydrodesulfurization and hydrodemetallation.
These and other features and advantages of the present invention will be more readily understood by those of ordinary skill in the art from a reading of the following detailed description.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Substrates
As indicated above, substrates suitable for use preparing the catalysts of the present invention are particulate porous substrates which comprise at least in part gamma alumina and amorphous alumina, and preferably at least 5 wt% amorphous alumina based on
Carruthers James Donald
Lostaglio Vincent Joseph
Shukis Peter Joseph
Shell Oil Company
Wood Elizabeth D.
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