Mineral oils: processes and products – Refining – Sulfur removal
Reexamination Certificate
1999-06-17
2001-01-16
Yildirim, Bekir L. (Department: 1764)
Mineral oils: processes and products
Refining
Sulfur removal
C208S108000, C208S143000, C502S204000
Reexamination Certificate
active
06174432
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a hydrotreating catalyst for heavy hydrocarbon oil; it's preparation process; and a hydrotreating method using the catalyst. More particularly, the present invention relates to a hydrotreating catalyst for heavy hydrocarbon oil comprising sulfur, asphaltene and a heavy metal, such as nickel, vanadium, and the like; a process for producing the catalyst; and a hydrotreating method using the catalyst.
BACKGROUND ART
In recent years, the need for low-sulfur fuel oil has ever been increasing for prevention of environmental pollution. On the other hand, as crude oil has become heavy globally, there is a tendency that crude oil having a high content of sulfur, asphaltene, metal and the like should be treated, and the conditions of hydrotreating atmospheric residual oil or vacuum residual oil to obtain low-sulfur fuel oil have been getting stricter. The prolonged demand structure involving a shortage of middle cuts is also a background of this tendency. As a result, improvements in activity and deactivation of a hydrotreating catalyst have been studied intensively, aiming at increase of production of low-sulfur fuel oil by hydrotreating heavy hydrocarbon oil.
Heavy hydrocarbon oil often contains metal compounds, mainly nickel, vanadium, and the like. If such heavy hydrocarbon oil is used as a raw material in a catalytic treatment step, these metal compounds deposit on the catalyst to diminish the catalyst activity and to shorten the catalyst life. Therefore, the metal content should be removed from the heavy hydrocarbon oil before catalytical treatments.
DISCLOSURE OF THE INVENTION
It is necessary for a catalyst having a high demetallization function to have a large pore size so as to treat metal-containing macromolecular components contained in heavy hydrocarbon oil and also to have a large pore volume so as to prohibit poisoning by the metal deposition.
However, there is a problem that an increased pore size or an increased pore volume of a catalyst results in weakness of catalyst strength.
Herein, SCS (side crushing strength) is expressed as an index of catalyst strength. It is generally accepted that a catalyst having SCS of 2 lb/mm or less is broken when used in an industrial reactor to cause the plugging of the catalyst bed.
An object of the present invention is to provide a hydrotreating catalyst which has improved strength and an extended life while having a great pore size and a great pore volume, and a hydrotreating process using the catalyst.
In order to accomplish the above object, the inventors of the present invention have conducted extensive investigation and found, as a result, that a catalyst having an average pore size of 19 nm or more and a pore volume of 0.65 g/ml or more and yet having a strength (SCS) of 3 lb/mm or more can be produced using an alumina carrier containing a specific amount of boron, and have also found that heavy hydrocarbon oil is demetallized with relative ease by hydrotreating in the presence of this catalyst and that the catalyst has an extended catalyst life. The present invention has been completed based on these findings.
That is, the above and other objects of the present invention have been accomplished by a hydrotreating catalyst composition for heavy hydrocarbon oil, which comprises a boron-containing alumina carrier containing 1 to 12 wt %, in terms of an oxide, of boron based on the catalyst, having supported thereon a metal in the Group VI, wherein the catalyst has an average pore size of 19 to 25 nm, a pore volume of 0.65 to 0.8 ml/g, a catalyst strength of 3 lb/mm or more, and a specific surface area of 70 to 130 m
2
/g.
Furthermore, the above and other objects of the present invention have been accomplished by a method for preparing the above-described catalyst composition, which comprises gelatinizing an aqueous solution containing a raw material for alumina, mixing the resulting gel with boron to prepare a boron-containing alumina carrier, and supporting a metal in the Group VI on the boron-containing alumina carrier thus prepared.
Moreover, the above and other objects of the present invention have been accomplished by a method for hydrotreating heavy hydrocarbon oil, which comprises conducting a catalytic reaction of heavy hydrocarbon oil in the presence of the above-described catalyst composition at a temperature of 300 to 500° C., a pressure of 3 to 20 MPa, a hydrogen/oil ratio of 400 to 3000 Nl/l, and LHSV of 0.1 to 1.5 hr
−1
.
The present invention will hereinafter be described in detail.
The hydrotreating catalyst composition for heavy hydrocarbon oil according to the present invention (hereinafter simply referred to as a hydrotreating catalyst of the invention) comprises, as a carrier, a boron-containing alumina carrier containing 1 to 12 wt %, in terms of an oxide, of boron based on the catalyst. Boron can exist either in the form of a simple substance or in the form of a compound. It is preferred that boron is well-dispersed in alumina.
The boron content is from 1 to 12 wt %, preferably from 2 to 10 wt %, in terms of an oxide based on the catalyst. If the boron content is less than 1 wt %, the catalyst strength cannot be increased. On the other hand, if the boron content is more than 12 wt %, the pore volume or surface area cannot be increased sufficiently.
The hydrotreating catalyst of the invention has a metal in the Group VI supported on the boron-containing alumina carrier. Examples of the Group VI metal includes Mo and W. Particularly, Mo is preferred. The Group VI metal may be present either in the form of a simple substance or in the form of a compound, such as a sulfide and the like. The Group VI metals can be used either alone or as a combination of two or more thereof.
The hydrotreating catalyst of the invention can have supported thereon other hydrogenation active metals in combination with the Group VI metal. Preferred examples of the hydrogenation active metals which can be supported in combination include the Group VIII metals, such as Ni, Co, Fe, and the like. These hydrogenation active metals to be supported in combination may be used either alone or as a combination of two or more thereof. Examples of the combination include molybdenum-nickel, molybdenum-cobalt, and tungsten-nickel. The molybdenum-nickel combination is preferably used.
While not particularly limited, the amount of the Group VI metal to be supported is preferably from 2 to 15 wt %, particularly 4 to 12 wt %, in terms of an oxide based on the catalyst. The amount of the hydrogenation active metals to be supported in combination is selected appropriately, and is usually from 0.001 to 4 wt %, preferably from 1 to 3 wt %, in terms of an oxide based on the catalyst. An increase of the hydrogenation active metal brings about an increase in hydrotreating activity, especially hydrodemetallizing activity, but tends to decrease the pore volume. On the other hand, a decrease of the active metal tends to result in a failure to obtain sufficient hydrotreating activity, especially hydrodemetallizing activity.
The average pore size of the hydrotreating catalyst of the invention is from 19 to 25 nm, preferably from 20 to 24 nm. If the average pore size is less than 19 nm, demetallizing activity cannot be obtained sufficiently. On the other hand, if the average pore size is more than 25 nm, the hydrotreating activity cannot be obtained sufficiently.
The pore volume of the hydrotreating catalyst of the invention is from 0.65 to 0.8 ml/g, preferably from 0.67 to 0.78 ml/g. If the pore volume is less than 0.65 ml/g, hydrotreating activity and a life cannot be obtained sufficiently. If the pore volume is more than 0.8 ml/g, the catalyst cannot be obtained sufficiently.
The catalyst strength of the hydrotreating catalyst of the invention is 3 lb/mm or more, preferably from 3 to 4.5 lb/mm, in terms of SCS. SCS, an index of the catalyst strength, is a crushing strength per unit length of a catalyst, which is obtained by applying a load on a horizontally placed catalyst, measuring the load at which the
Mizutani Yoshihiro
Nagata Keizou
Shibata Yukio
Yamamoto Yasuo
Petroeum Energy Center
Sughrue Mion Zinn Macpeak & Seas, PLLC
Yildirim Bekir L.
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