Catalyst – solid sorbent – or support therefor: product or process – Zeolite or clay – including gallium analogs – And additional al or si containing component
Reexamination Certificate
2000-01-06
2003-02-04
Silverman, Stanley S. (Department: 1754)
Catalyst, solid sorbent, or support therefor: product or process
Zeolite or clay, including gallium analogs
And additional al or si containing component
C502S071000, C502S077000, C502S085000, C585S417000, C585S420000
Reexamination Certificate
active
06514896
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to an improved process for converting hydrocarbons, preferably non-aromatic hydrocarbons, in the presence of an improved zeolite material, to aromatic hydrocarbons and lower olefin hydrocarbons preferably with a low rate of coke formation during the conversion of such hydrocarbons in the presence of such improved zeolite material.
It is known to catalytically crack gasoline boiling range hydrocarbons (in particular, non-aromatic gasoline boiling range hydrocarbons, more in particular, paraffins and olefins) to lower olefins (such as ethylene and propylene) and aromatic hydrocarbons (such as benzene, toluene, and xylene, and also ethylbenzene) in the presence of catalysts which contain a zeolite (such as ZSM-5), as is described in an article by N.Y. Chen et al. in Industrial & Engineering Chemistry Process Design and Development, Volume 25, 1986, pages 151-155. The reaction product of this catalytic cracking process contains a multitude of hydrocarbons such as unconverted C
5
+ alkanes, lower alkanes (methane, ethane, propane), lower alkenes (ethylene and propylene), C
6
-C
8
aromatic hydrocarbons (e.g., benzene, toluene, xylene, and ethylbenzene), and C
9
+ aromatic hydrocarbons. Depending upon the relative market prices of the individual reaction products, it can be desirable to increase the yield of certain of the more valuable products relative to the others.
One concern with the use of zeolite catalysts in the conversion of hydrocarbons to aromatic hydrocarbons and lower olefins is the excessive production of coke during the conversion reaction. The term “coke” refers to a semi-pure carbon generally deposited on the metal surfaces of process equipment or a catalyst. Coke formed during the zeolite catalyzed aromatization of hydrocarbons tends to cause catalyst deactivation. It is desirable to improve processes for the aromatization of hydrocarbons, and the formation of lower olefins from hydrocarbons, by minimizing the amount of coke formed during such processes. It is also desirable to have a zeolite catalyst that is useful in producing significant quantities of the aromatic and olefin conversion products.
SUMMARY OF THE INVENTION
It is an object of this invention to provide a zeolite catalyst composition used to at least partially convert hydrocarbons to lower olefins (such as ethylene and propylene) and aromatic hydrocarbons (such as benzene, toluene, xylene and ethylbenzene, i.e., BTX).
A further object of this invention is to provide an improved process for the conversion of hydrocarbons in which the rate of coke formation during such conversion of hydrocarbons is minimized.
A yet further object of this invention is to provide an improved zeolite material which, when used in the conversion of hydrocarbons, results in less coke formation than alternative zeolite materials.
Another object of this invention is to provide an improved zeolite material that gives an improved yield of lower olefins when such improved zeolite material is utilized in the conversion of hydrocarbons.
Yet another object of this invention is to provide hydrocarbon conversion processes which have an acceptably low coke production rate and/or which produce a conversion product containing suitable quantities of lower olefins and BTX aromatics.
Yet another further object of this invention is to provide a method for making an improved zeolite material having such desirable properties as providing for low coke production and improved yields of lower olefins, with an especially improved ratio of lower olefins to aromatics in the product, when used in the conversion of hydrocarbons.
One embodiment of the invention is a novel process of making a zeolite catalyst composition used in the conversion of hydrocarbons, preferably non-aromatic hydrocarbons, to aromatic hydrocarbons and lower olefins. The novel process comprises ion-exchanging the original ions (specifically cations) such as, for example, alkali metal ions or alkaline earth metal ions, of a zeolite with hydrogen ions by acid-treating such zeolite. The cations, preferably hydrogen ions, of such acid-treated zeolite are then further ion-exchanged with ions of zinc and at least one other metal selected from the group of metals consisting of Group 6B of the periodic table of elements to thereby provide an acid-treated, ion-exchanged zeolite. The ion-exchange of such acid-treated zeolite occurs in the presence of an ion-exchange medium, preferably comprising an aqueous solution of an ammonium-containing compound, a zinc-containing compound, and a compound containing at least one other metal, which promotes the exchange of ions of the acid-treated zeolite with ions of zinc and at least one other metal. The acid-treated, ion-exchanged zeolite is then subjected to a steam treatment to provide the final improved zeolite catalyst composition.
Another embodiment of the invention is a process for the conversion of non-aromatic hydrocarbons to aromatic hydrocarbons and lower olefins by contacting, under conversion conditions, a hydrocarbon-containing fluid with an acid-treated, ion-exchanged, steam-treated zeolite catalyst composition.
Yet another embodiment of the invention is the novel composition of an acid-treated zeolite of which the ions of such zeolite have been ion-exchanged with ions of zinc and at least one other metal selected from the group of metals consisting of Group 6B of the periodic table of elements. The acid-treated, ion-exchanged zeolite is then subjected to a steam treatment to provide the final improved zeolite catalyst composition.
Yet another embodiment of the invention is the novel composition, i.e., product, made by the novel process of ion-exchanging the original ions (specifically cations) such as, for example, alkali metal ions or alkaline earth metal ions, of a zeolite with ions of hydrogen by acid-treating such zeolite. The cations, preferably hydrogen ions, of such acid-treated zeolite are then farther ion-exchanged with ions of zinc and at least one other metal from the group of metals consisting of Group 6B of the periodic table of elements. The ion-exchange of such acid-treated zeolite occurs in the presence of an ion-exchange medium, preferably comprising an aqueous solution of an ammonium-containing compound, a zinc-containing compound, and a compound containing at least one other metal, which promotes the exchange of ions of the acid-treated zeolite with ions of zinc and at least one other metal. The acid-treated, ion-exchanged zeolite is then subjected to a steam treatment to provide the final improved zeolite catalyst composition.
Other objects and advantages of the invention will become apparent from the detailed description and the appended claims.
DETAILED DESCRIPTION OF THE INVENTION
The inventive composition includes a zeolite starting material that has been ion-exchanged such that a predominant proportion of such zeolite's exchangeable ions (specifically cations) are hydrogen (H
+
) ions. Preferably, such zeolite starting material has been treated with an acid to thereby provide an acid-treated zeolite in which a predominant proportion of such acid-treated zeolite's exchangeable ions (specifically cations) are hydrogen (H
+
) ions. In general, it is contemplated that more than 50 percent and preferably more than 75 percent of the cationic sites of such acid-treated zeolite will be occupied by hydrogen ions. After further ion-exchange of such acid-treated zeolite, the resulting inventive composition further contains ions of zinc and at least one other metal or element selected from the group of elements consisting of Group 6B of the periodic table of elements. It is understood herein that any reference to at least one other metal in addition to zinc contained in the inventive composition will be an element from the Group 6B elements including Chromium (Cr), Molybdenum (Mo), and Tungsten (W). As the term is used within this description and in the claims, any reference to metals will include zinc and those Group 6B elements listed above.
Drake Charles A.
Wu An-hsiang
Nguyen Cam N.
Phillips Petroleum Company
Silverman Stanley S.
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