Mineral oils: processes and products – Refining – Sulfur removal
Reexamination Certificate
2000-11-02
2002-06-04
Griffin, Walter D. (Department: 1764)
Mineral oils: processes and products
Refining
Sulfur removal
C208S209000, C208S211000, C208S213000, C208S21600R, C208S217000
Reexamination Certificate
active
06398949
ABSTRACT:
The present invention relates to a catalyst and process for hydrodesulfurizing hydrocarbon streams.
BACKGROUND OF THE INVENTION
Naphtha streams are primary products in petroleum refineries. These naphtha streams are typically blended to make up what is referred to in the industry as the “gasoline pool”. Naphtha streams contain valuable olefins and aromatics which contribute to the octane number of the gasoline pool. However, one problem associated with such naphtha streams, especially those which are products of a cracking process, such as fluidized catalytic cracking, is that they contain relatively high levels of sulfur. Although cracked naphthas typically constitute less than 40 percent of the total gasoline pool, cracked naphthas frequently contribute over 70 percent of the sulfur to the gasoline pool.
Due to ever stricter government regulations limiting the amount of sulfur in gasoline, there is a continuing need for improved processes and catalysts for hydrodesulfurizing hydrocarbon streams so that the sulfur level of the gasoline pool can be lowered. Although a variety of hydrodesulfurization processes and catalysts are in commercial use today, conventional hydrodesulfurization processes capable of removing a substantial amount of sulfur from hydrocarbon streams typically cause significant octane loss. Thus, there exists a continuing need for improved hydrodesulfurization processes and catalysts which maximize sulfur removal while minimizing octane loss.
SUMMARY OF THE INVENTION
An object of this invention is to provide a process and catalyst for hydrodesulfurizing a hydrocarbon stream, whereby the conversion of organic sulfur compounds to inorganic sulfur compounds is maximized while octane loss is minimized.
A further object of this invention is to provide a process and catalyst for hydrodesulfurizing a hydrocarbon stream, whereby the conversion of organic sulfur compounds to inorganic sulfur compounds is maximized while saturation of aromatic compounds is minimized.
A still further object of this invention is to provide a process and catalyst for hydrodesulfurizing a hydrocarbon stream, whereby the conversion of organic sulfur compounds to inorganic sulfur compounds is maximized while saturation of olefins is minimized.
Further objects and advantages of the present invention will become apparent from consideration of the detailed description of the invention and appended claims.
In accordance with another embodiment of the present invention, a hydrodesulfurization process is provided. The hydrodesulfurization process comprises contacting a hydrocarbon feed containing a concentration of organic sulfur compounds and a concentration of aromatic compounds with a catalyst composition comprising a cobalt compound, a molybdenum compound, and a SAPO molecular sieve under conditions sufficient to convert a portion of the organic sulfur compounds to inorganic sulfur compounds.
In a fourth embodiment of the present invention, a hydrodesulfurization process is provided. The process comprises separating a full range hydrocarbon feed containing organic sulfur compounds and aromatic compounds into a heavy hydrocarbon fraction and a light hydrocarbon fraction, contacting the heavy hydrocarbon fraction with a catalyst composition comprising a cobalt compound, a molybdenum compound, and a SAPO molecular sieve under conditions sufficient to convert a portion of the organic sulfur compounds to inorganic sulfur compounds, and combining the hydrodesulfurized heavy hydrocarbon product with the light hydrocarbon fraction to produce a hydrodesulfurized full range hydrocarbon product.
DETAILED DESCRIPTION OF THE INVENTION
The present invention employs a catalyst composition comprising a cobalt compound, a molybdenum compound, and a SAPO molecular sieve.
As used herein, the term “SAPO” shall mean a silicoaluminophosphate molecular sieve. Details relating to the formation of SAPO compositions can be found in Lok et al. U.S. Pat. No. 4,440,871, the entire disclosure of which is expressly incorporated herein by reference. Preferably, the SAPO molecular sieve employed in the present invention has an essentially chemical composition in the as-synthesized and anhydrous form which can be represented as follows:
mR:(Si
x
Al
y
P
z
)O
2
wherein “R” represents at least one organic templating agent present in the intracrystalline pore system; “m” represents the moles of “R” present per mole of (Si
x
Al
y
P
z
)O
2
, and “x”, “y”, and “z” represent the mole fractions of silicon, aluminum, and phosphorous, respectively.
In the above formula, nonlimiting examples of a suitable organic templating agent, “R”, include tetramethylammonium hydroxide, tetraethylammonium hydroxide, and tetrapropyammonium hydroxide. In the above formula, “m” is preferably from about zero to about 0.3, more preferably from zero to 0.06; “x” is preferably from about 0.02 to about 0.98, more peferably from 0.10 to 0.30; “y” is preferably from about 0.02 to about 0.60, more preferably from 0.30 to 0.50; and “z” is preferably from about 0.02 to about 0.60, more preferably from 0.30 to 0.50.
SAPO compositions useful in the present invention include, but are not limited to, SAPO-4, SAPO-5, SAPO-11, SAPO-16, SAPO-17, SAPO-20, SAPO-31, SAPO-34, SAPO-35, SAPO-37, SAPO-40, SAPO-41, SAPO-42, and SAPO-44. The presently more preferred SAPO is SAPO-5.
The catalyst composition preferably contains from about 10 weight percent to about 95 weight percent of the SAPO molecular sieve, more preferably from 25 weight percent to 75 weight percent of the SAPO molecular sieve.
The cobalt compound and molybdenum compound of the catalyst composition may be present either in elemental form or any other suitable form. The amount of cobalt compound present in the catalyst composition is preferably such that the weight of the cobalt component of the cobalt compound as a percentage of the total weight of the catalyst composition is from about 0.1 percent to about 10 percent, more preferably from about 0.5 percent to about 5 percent, and most preferably from 1 percent to 3 percent. The amount of molybdenum compound present in the catalyst composition is preferably such that the weight of the molybdenum component of the molybdenum compound as a percentage of the total weight of the catalyst composition is from about 1 percent to about 50 percent, more preferably from about 2 percent to about 25 percent, and most preferably from 3 percent to 10 percent. The atomic ratio of cobalt to molybdenum in the catalyst composition is preferably from about 0.1:1 to about 10:1, more preferably from 0.2:1 to 2:1.
The catalyst composition can further comprise an inorganic oxide. The inorganic oxide is preferably silica or alumina, with silica being especially preferred. The catalyst composition preferably contains from about 10 weight percent to about 90 weight percent inorganic oxide, more preferably from 25 weight percent to 75 weight percent inorganic oxide.
The catalyst composition is preferably pre-sulfided in a manner such that it contains from about 0.1 weight percent to about 10 weight percent sulfur, more preferably from 1 weight percent to 5 weight percent sulfur.
The catalyst composition can be made by incorporating a cobalt compound and a molybdenum compound into a SAPO molecular sieve, and sulfiding the cobalt/molybdenum-modified catalyst composition.
Either before or after, preferably before, incorporating the cobalt and molybdenum compounds into the SAPO molecular sieve, the SAPO molecular sieve can be mixed with a carrier to bind the SAPO molecular sieve and give the catalyst additional strength. The carrier can be a natural or synthetically produced inorganic oxide or a combination of inorganic oxides. The amount of carrier mixed with the SAPO molecular sieve is preferably an amount such that the weight ratio of the SAPO molecular sieve to the carrier is from about 0.2:1 to about 5:1, more preferably from 0.5:1 to 2:1. After mixing the SAPO molecular sieve and the carrier, the resulting mixture can be formed into individual catalyst pieces by any method known in th
Bares Joseph E.
Drake Charles A.
Wu An-hsiang
Griffin Walter D.
Nguyen Tam M.
Phillips Petroleum Company
Richmond, Hitchcock, Fish & Dollar
LandOfFree
Sapo-supported hydrodesulfurization catalyst and processes... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Sapo-supported hydrodesulfurization catalyst and processes..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Sapo-supported hydrodesulfurization catalyst and processes... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2941990