Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Reexamination Certificate
1999-04-16
2002-10-29
Keys, Rosalynd (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
C568S671000, C585S638000, C585S639000, C585S640000, C502S202000, C502S208000, C502S214000, C502S232000, C502S240000, C502S263000
Reexamination Certificate
active
06472569
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to catalyst systems useful in hydrocarbon upgrading processes and to methods for their production and use. In another aspect, this invention relates to processes for converting oxygenated hydrocarbons to C
2
-C
4
olefins and/or ethers, such as dimethyl ether (DME), with an increase in olefin or ether selectivity and a reduction in coke formation resulting from the conversion of such oxygenated hydrocarbons in the presence of such catalyst systems. The term “oxygenated hydrocarbons” as employed herein comprises hydrocarbons containing aliphatic moieties such as, but not limited to, alcohols, halides, mercaptans, sulfides, amines, ethers, and carbonyl compounds (aldehydes, ketones, carboxylic acids and the like) or mixtures thereof.
It is known to convert oxygenated hydrocarbons to olefins and/or ethers in the presence of catalysts which contain a silicoaluminophosphate (SAPO), as is described in U.S. Pat. Nos. 4,861,938; 5,475,182; 5,248,647 and 5,663,471, the disclosures of each are incorporated herein by reference.
One concern with the use of SAPO catalysts in the conversion of oxygenated hydrocarbons to olefins and/or ethers is the excessive production of coke during the conversion reaction. Coke formed during the SAPO catalyzed conversion of oxygenated hydrocarbons tends to cause catalyst deactivation. It is desirable to improve processes for the conversion of oxygenated hydrocarbons to olefins and/or ethers by minimizing the amount of coke formed during such processes. It is also desirable to have a SAPO catalyst that is useful in producing significant quantities of olefin and/or ether conversion products.
SUMMARY OF THE INVENTION
It is an object of this invention to provide an improved SAPO material which when used in the conversion of oxygenated hydrocarbons results in increased olefin yield and decreased coke production.
A further object of this invention is to provide a method for making an improved SAPO material having such desirable properties as providing for increased olefin yield and decreased coke production when used in the conversion of oxygenated hydrocarbons.
Another object of this invention is to provide an improved process for the conversion of oxygenated hydrocarbons in which the yield of olefins is increased and the production of coke is decreased.
Yet another object of this invention is to provide an improved SAPO material which when used in the conversion of oxygenated hydrocarbons results in increased ether yield and decreased coke production.
A yet further object of this invention is to provide a method for making an improved SAPO material having such desirable properties as providing for increased ether yield and decreased coke production when used in the conversion of oxygenated hydrocarbons.
Yet another object of this invention is to provide an improved process for the conversion of oxygenated hydrocarbons in which the yield of ether is increased and the production of coke is decreased.
The inventive catalyst system comprises a SAPO impregnated with a compound selected from the group consisting of phosphoric acid, boric acid, tributyltin acetate, and combinations of any two or more thereof. The inventive catalyst system can be prepared by impregnating the SAPO, under suitable conditions, with such compound. The inventive catalyst system can be used in the conversion of an oxygenated hydrocarbon to olefins and/or ethers by contacting, under conversion conditions, a hydrocarbon feedstock with the inventive catalyst system.
Other objects and advantages of the invention will become apparent from the detailed description and the appended claims.
DETAILED DESCRIPTION OF THE INVENTION
The SAPO material used in preparing the inventive catalyst system can be any SAPO that is effective in the conversion of oxygenated hydrocarbons to olefins and/or ethers when contacted under conversion conditions with oxygenated hydrocarbons.
SAPO catalysts exhibit properties of both aluminosilicate zeolites and aluminophosphates. The SAPO's have a three-dimensional microporous crystal framework structure of PO
2
, AlO
2
and SiO
2
tetrahedral units. The chemical composition (anhydrous) is:
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 has a value of from zero to 0.3, the maximum value in each case depending upon the molecular dimensions of the templating agent and the available void volume of the pore system of the particular SAPO species involved, and “x”, “y” and “z” represent the mole fractions of silicon, aluminum and phosphorus, respectively.
Examples of such templating agents include, but are not limited to, tetramethylammonium hydroxide, tetraethylammonium hydroxide, and tetrapropylammonium hydroxide. Further details relating to the formation of SAPO compositions, including molar amounts of each oxide source, can be found in the Lok et al. U.S. Pat. No. 4,440,871, the entire disclosure of which is expressly incorporated herein by reference.
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-34.
The SAPO can be combined or mixed with a binder material in a liquid such as water or a hydrocarbon, by any means known to one skilled in the art such as stirring, blending, kneading, or extrusion, following which the resulting mixture can be dried in air at a temperature in the range of from about 20° C. to about 125° C., for a time period in the range of from about 0.5 hour to about 4 hours under any pressures that accommodate the temperatures, preferably atmospheric pressure.
Any binders known to one skilled in the art for use with a SAPO are suitable for use herein. Examples of suitable binders include, but are not limited to, aluminas such as for example &agr;-alumina and &ggr;-alumina; silicas; alumina-silica; aluminum phosphate; aluminum chlorohydrate; clays such as kaolinite, halloysite, vermiculite, chlorite, attapulgite, smectite, montmorillonite, illite, saconite, sepiolite, palygorskite, and combinations of any two or more thereof. Because these binders are well known to one skilled in the art, descriptions of which are omitted herein. The presently preferred binder, if employed, is silica.
The SAPO, or SAPO-binder mixture, can be extruded into pellets or tablets by any method known to those skilled in the art.
The SAPO, whether bound in a SAPO-binder mixture, and whether or not extruded, can be impregnated with a compound selected from the group consisting of phosphoric acid, boric acid, tributyltin acetate, and combinations of any two or more thereof, by any suitable means or method known in the art for impregnating such compounds into a substrate material to thereby form an impregnated SAPO.
It is preferred to use any standard incipient wetness technique for impregnating the SAPO with such compound. A preferred method uses a liquid impregnation solution containing the desirable concentration of the compound. The concentration of the compound in the impregnation solution is generally in the range of from about 0.01 to about 10 mole percent, preferably from about 0.05 to about 7 mole percent, and most preferably from 0.1 to 5 mole percent, based on the total moles of the solution.
When the compound is phosphoric acid or boric acid it is particularly desirable to use an aqueous solution formed by dissolving the compound in water. When the compound is tributyltin acetate it is particularly desirable to use a solution formed by dissolving the tributyltin acetate in a hydrocarbon solvent, such as in a C
6
to C
10
cycloalkane, benzene, toluene, ethylbenzene, xylene(s), and the like. The presently preferred solvent for tributyltin acetate is cyclohexane.
The weight percent of the compound present in the impregnated SAPO is generally in the range upwardly t
Drake Charles A.
Wu An-hsiang
Yao Jianhua
Keys Rosalynd
Phillips Petroleum Company
Stewart Charles W.
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