MXPA99010178A - Improved catalyst composition useful for conversion of non-aromatic hydrocarbons to aromatics and light olefins - Google Patents

Abstract

A novel zeolite catalyst comprising an acid treated zeolite impregnated with zinc and at least one other metal selected from the group consisting of Group 4B, Group 6B, Group 3A, Group 4A and Group 5A of the periodic table of elements, a method of making such zeolite catalyst, and the use thereof for converting paraffin hydrocarbons to olefins and aromatics with a low rate of coke formation during such conversion.

Description

COMPOSITION IMPROVED TASTING TASTING USED FOR THE CONVERSION OF NON-AROMATIC TO AROMATIC HYDROCARBONS AND LIGHTWEIGHT OLEFINS The invention relates to an improved process for converting non-aromatic hydrocarbons in the presence of an improved zeolite material to aromatic hydrocarbons and lower olefins, preferably with a low coke formation rate during the conversion of such hydrocarbons in the presence of such a zeolite material. I prayed.

It is known that to catalytically fractionate non-aromatic hydrocarbons from the boiling range of gasoline (in particular paraffins and olefins) to lower olefins (such as ethylene and propylene) and aromatic hydrocarbons (such as benzene, toluene and xylenes) in the presence of catalysts containing a zeolite (such as ZSM-5), as described in an article by NY Chen et al in Industrial & Engineering Chemistry Process Design and Development, Volume 25, 1986, pages 151-155. The reaction product of this catalytic thermofraction process contains a multitude of hydrocarbons such as non-converted C5 + alkanes, lower alkanes (methane, ethane, propane), lower alkenes R? F .: 31679 (ethylene and propylene), aromatic hydrocarbons C6- C8 (benzene, toluene, xylenes and ethylbenzene) and Cg + aromatic hydrocarbons. Depending on the relative costs in the market for individual reaction products, it may be desirable to increase the production of some of the most valuable products relative to the others.

One such 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 coke formed during the aromatization catalyzed by. Hydrocarbon zeolite tends to cause deactivation of the catalyst. It is desirable to improve processes for the aromatization of hydrocarbons and the formation of lower olefins from hydrocarbons, to minimize the amount of coke formed during such processes: It is also desirable to have a zeolite catalyst that is used in the production of significant amounts of the aromatic and olefin conversion products.

It is an object of this invention to at least partially convert hydrocarbons to aromatics of ethylene, propylene and BTX (benzene, toluene, xylene and ethylbenzene).

A further objective of this invention is to provide an improved zeolite material that when used in the conversion of hydrocarbons results in less coke formation than alternative zeolite materials.

A further objective of this invention is to provide an improved zeolite material which yields an improved production of lower and aromatic BTX olefins when used in the conversion of hydrocarbons.

Another objective of this invention is to provide the hydrocarbon conversion processes, which have an acceptably low coke production rate and / or which produce a conversion product containing the appropriate quantities of BTX olefins and aromatics.

Yet another objective of this invention is to provide a method for making an improved zeolite material having such desirable properties, as those provided for the production of lower coke and the favorable production of BTX olefins and aromatics when the conversion of hydrocarbons is used. .

One of the inventive processes provides the conversion of non-aromatic hydrocarbons to aromatic hydrocarbons and lower olefins by contacting under conversion conditions a hydrocarbon feed with a treated zeolite impregnated with acid comprising, an acid-treated zeolite having incorporated into the same zinc and at least one other metal from the group consisting of Group 4B, Group 6B, Group 3A, Group 4A and Group 5A of the periodic table of the elements.

Another embodiment of the invention is a new composition used in the conversion of hydrocarbons. The novel composition comprises a zeolite treated with acid impregnated with zinc and at least one other metal selected from the group consisting of Group 4B, Group 6B, Group 3A, Group 4A and Group 5A of the periodic table of the elements. The new composition could be made by incorporating zinc and at least one other metal from the group consisting of Group 4B, Group 6B, Group 3A, Group 4A and Group 5A of the periodic table of the elements in an acid treated zeolite to thereby provide a zeolite treated with impregnated acid.

Other objects and advantages of the invention will become apparent from the detailed description and appended claims.

The inventive composition includes a zeolite initiator material that has been treated with an acid to thereby provide an acid-treated zeolite. The inventive composition further contains zinc and at least one other metal or element selected from the group consisting of Group 4B, Group 6B. , Group 3A, Group 4A and Group 5A of the periodic table of the elements. It is understood herein that, any reference to another metal in addition to the zinc contained in the inventive composition, will be an element of the Group 4B elements that include Titanium (Ti), Zirconium (Zr) and Hafnium (Hf); Group 6B elements including Chromium (Cr), Molybdenum (Mo), Tugstene (W); Group 3A elements that include Boron (B), Aluminum (Al), Gallium (Ga), Indian (In), Thallium (TI); Group 4A elements that include Silicon (Si), Germanium (Ge), Tin (Sn) and Lead (Pb); Group 5A elements that include Phosphorus (P), Arsenic (As), Antimony (Sb), and Bismuth (Bi). Some of the elements listed above could not be considered by those skilled in the art, which are a metal by the conventional meaning of such term, but, as the term is used within this description and in the claims, any reference to metals will include zinc and the elements listed above.

An important aspect of the invention, if not critical, is the requirement that the composition be promoted by two metals, with zinc as the first or primary metal and at least one other metal as the second or secondary metal. A further important aspect of the inventive composition is the initiator zeolite material, which is modified to provide the inventive composition having the desirable properties as previously described herein, to be treated with an acid to give an acid-treated zeolite. The acid-treated zeolite is further modified by the incorporation of the two zinc metal promoters and at least one other metal.

Any suitable means or method can be used to treat the zeolite initiating material with acid. It is preferred that the zeolite be rinsed with an acid solution by any suitable means known in the art to contact the zeolite with such an acid solution. The acid solution used to treat the zeolite can be a solution of any acid that appropriately provides leaching of the aluminum atoms of the zeolite particles. Preferably, the concentration of the acid in this solution is about 1-10 equivalents per liter. Examples of such suitable acids include sulfuric, phosphoric, nitric and hydrochloric acids. The preferred acid solution is aqueous hydrochloric acid. The zeolite is rinsed in the acid solution (preferably at a temperature of about 50-100 ° C) for a period in excess of about 15 hours, but preferably from 0.1 hour to 12 hours. After rinsing, the resulting zeolite treated with acid is washed free of acid and then can be dried or calcined, or both.

The zeolite starter material used in the composition of the invention may be a zeolite which is effective in the conversion of non-aromatics to aromatics when brought into contact under the appropriate reaction conditions with non-aromatic hydrocarbons. Preferably, the zeolite has a coercion index (as defined in U.S. Patent 4,097,367, which is incorporated herein by reference) in the range of about 0.4 to about 12, preferably about 2-9. In general, the molar ratio of Si02 to A1203 in the crystal structure of the zeolite is at least about 5: 1 and can be in the range of up to infinity. Preferably, the molar ratio of SiO2 to A1203 in the structure of the zeolite is from about 8: 1 to about 200: 1, more preferably from about 12: 1 to about 100: 1. Preferred zeolites include ZSM-5, ZSM-8, ZSM-11, ZSM-12, ZSM-35, ZSM-38, and mixtures thereof. Some of these zeolites are also known as "MFI" or "Pentasil" zeolites.The currently most preferred zeolite is ZSM-5.

The inventive composition further includes, in addition, the zeolite leached with the acid, zinc and at least one other metal. These metals could be incorporated into the zeolite leached with the acid by any means or appropriate method known in the art to incorporate the metal elements into a substrate material. A preferred method is the use of any standard incipient drying technique to impregnate the acid leached zeolite substrate with the metal promoters. The preferred method uses a liquid impregnation solution containing the desired concentrations of zinc and other metals to finally provide the final effective composition having the required metal concentration.

It is particularly desirable to use the impregnation of the aqueous solutions of the acid-treated zeolite of one or more of the metal promoters that are incorporated in the acid-treated zeolite. The acid treated zeolite could be impregnated with the metal promoters described herein simultaneously or sequentially, or both, finally providing the treated zeolite with acid containing zinc and at least one other metal. The preferred impregnation solution is an aqueous solution formed by dissolving a salt of the metal in question in water. However, it is acceptable to use enough acid solution to aid in the dissolution of the metal salt. It is most preferred for the acid treated zeolite to be co-impregnated with zinc and at least one other metal promoter, by using a solution containing a first zinc salt and a second salt of at least one other metal promoter as described. here .

The other metallic promoter, or secondary metal, as previously noted, includes the metals or elements selected from the group consisting of the elements of Group 4B, the elements of Group 6B, the elements of Group 3A, the elements of Group 4A, and the elements of Group 5A. Among these, the preferred metals include Ti, Zr, Cr, Mo,, B, Al, Si, Ge, Sn, Pb, P As and Sb. The most preferred secondary metals include Ti, Cr, Mo, B, Si and P .

The amounts of the zinc primary metal promoter and the secondary metal promoter incorporated or impregnated in the zinc treated zeolite should be such as to give effective concentrations to provide the desired properties of the favorable aromatics and the yields of the conversion of olefins with low Coke production, when the inventive composition is used in the conversion of a hydrocarbon feed. In general, the atomic ratio of the secondary metal to zinc in the treated zeolite impregnated with acid is in the range of about 0.1: 1 to about 10: 1. A preferred atomic ratio of secondary metal to zinc in the impregnated acid-treated zeolite is in the range of about 0.2: 1 to about 5: 1 and, more preferably, the atomic ratio is in the range of about 0.5: 1 to 3: 1.

The weight percent of zinc present in the impregnated acid treated zeolite is generally in the range greater than about 10 weight percent of the zeolite treated with the impregnated acid. The preferred concentration of zinc in the impregnated acid-treated zeolite is in the range of about 0.05 to about 8 weight percent and, more preferably, 0.1 to 6. weight percent. The secondary metal in general should be present in the treated zeolite with impregnated acid in the range greater than about 15 weight percent. Preferably, the concentration of the secondary metal is in the range of about 0.1 to about 12 weight percent and, more preferably, 0.2 to 10 weight percent.

It is theorized that the unique properties of the inventive composition described herein result from the zinc component of the acid-treated zeolite being promoted by two metals which provides increased activity with respect to the production of aromatics and olefins in the conversion of a feed of hydrocarbons. Nevertheless, this increased activity with respect to the production of aromatics and the products of the conversion of olefins also results in an undesirable increase in the production of coke. To compensate for this trend of increased coke production caused by the presence of zinc, secondary metal is added as a coke suppressant. The secondary metal, however, does not have a significant negative impact on the production of the conversion products and could still promote the production of such conversion products. In this way, the zeolite treated with acid promoted by two metals provides an improved olefin and the production of the product of the aromatic conversion with a low rate of coke production.

The inventive compositions described herein may also contain an inorganic binder (also called matrix material) preferably selected from the group consisting of alumina, silica, alumina-silica, aluminum phosphate, clays (such as bentonite), and mixtures thereof. The content of the component of the acid-treated zeolite impregnated with the mixture of the treated zeolite with the impregnated acid and the inorganic binder is about 1-99 (preferably about 5-80)% by weight, and the content of the listed inorganic binders previously in the mixture of the treated zeolite with impregnated acid and the inorganic binder is about 1-50% by weight. In general, the components of the zeolite treated with impregnated acid and the inorganic binder are composed and sequentially formed (such as by pelletizing, extrusion or tabletting). In general, the surface area of the composite composition is about 50-700 m2 / g, and its particle size is about 1-10 mm.

The zeolite treated with impregnated acid can be subjected to a first heat treatment step, whereby it is exposed by any suitable method known in the art to an atmosphere of a first gas under conditions of temperature and pressure and for a period of time that provides appropriately a first heat-treated material. The first gas used in the first heat treatment consists of inert gases (for example, nitrogen, helium and argon gases), reducing gases (for example, carbon monoxide and hydrogen gases), air, oxygen and steam the first preferred gas it is selected from the group consisting of air, oxygen, nitrogen, vapor and mixtures thereof. More preferably, the first gas is selected from the group consisting of air, oxygen, nitrogen and mixtures of one or two of the my sites.

The first heat treatment could be carried out at any pressure and temperature condition that appropriately provides the first heat-treated material. In general, the first heat treatment could be carried out at a pressure of below atmospheric to above about 1000 pounds per absolute square inch (psia). The most typical pressures, however, are in the range of about atmospheric to about 100 psia.

The temperature of the first heat treatment is, in general, in the range of about 30 ° C to about 400 ° C. Preferably, this temperature range is from about 40 ° C to about 300 ° C and, more preferably, the temperature of the first heat treatment is in the range of 50 ° C to 200 ° C.

The period of time to carry out the first heat treatment step should be sufficient to provide a substantially dry material, ie, free of water. In general, the period for exposing the impregnated acid-treated zeolite to the atmosphere of the first gas at the appropriate temperature conditions can be in the range of about 0.1 hours to about 30 hours. Preferably, the step of the first heat treatment is carried out for a period of about 0.25 hours to about 25 hours and, more preferably, 0.5 hours to 20 hours.

The first heat treated material may be subjected to a second heat treatment step in which it is exposed by any suitable method known in the art, to an atmosphere of a second gas under the conditions of temperature and pressure and for such a period of time that a second heat treated material having the desired properties is obtained as will be referred to herein.

The second gas used in the second heat treatment of the first heat-treated material can be selected from the group consisting of inert gases (for example, the gases' nitrogen, helium and argon), reducing gases (for example, carbon monoxide gases). and hydrogen), air, oxygen and steam. The second preferred gas is selected from the group consisting of air, oxygen, nitrogen, vapor and mixtures thereof. More preferably, the second gas is vapor.

The second heat treatment could be carried out at any pressure and temperature condition that appropriately provides the second heat-treated material. In general, the second heat treatment could be carried out at a pressure of below atmospheric to above about 3000 psia. The most typical pressures, however, are in the range of about atmospheric to about 2500 psia. The temperature of the second heat treatment is generally in the range of about 100 ° C to about 1500 ° C. Preferably, this temperature range is from about 200 ° C to about 1300 ° C and, more preferably, the temperature of the second heat treatment is in the range of about 400 ° C to 1200 ° C. When steam is used in the second stage of heat treatment, it is preferred that it be overheated and not saturated.

The period of time to carry out the stage of the second heat treatment should be sufficient to provide a second heat-treated material having the desired properties of good activity and catalytic resistance for the formation of coke. In general, the period for exposing the first heat treated material to the atmosphere of the second gas at the appropriate temperature and pressure conditions may be in the range of about 0.1 hours to about 20 hours. Preferably, the second heat treatment step is carried out for a period of from about 0.25 hours to about 18 hours and, more preferably, from 0.5 hours to 15 hours.

Any suitable hydrocarbon feed comprising paraffins (alkanes) and / or olefins (alkenes) and / or naphthenes (cycloalkanes), wherein each of these hydrocarbons contains 2-16 carbon atoms per molecule, can be used as the feed to be in contact with the inventive compositions under appropriate process conditions, to obtain a reaction product comprising lower alkenes containing 2-5 carbon atoms per molecule and aromatic hydrocarbons. Frequently, these feeds also contain aromatic hydrocarbons. Non-limiting examples of the appropriate, available feeds include gasolines from petroleum catalytic heat-fractionation processes (eg, FCC and hydrotherm fractionation), gasoline pyrolysis from thermo-fractionation processes of thermal hydrocarbons (eg, ethane, propane) and naphtha), naphthas, petroleum gases, reformates, linear chain petrol and the like. The preferred feed is a hydrocarbon feed of the boiling range of gasoline suitable for use as at least one gasoline mixture, which generally has a boiling range of about 30-210 ° C. In general, the paraffin content exceeds the combined content of olefins, nephthenes and aromatics (if present).

The hydrocarbon feed stream can be contacted by any suitable means with the inventive compositions described herein contained within a reaction zone. The contact stage can be operated as an intermittent or process step. Preferably, as a continuous process step. In the latter operation, a solid catalyst bed or a moving catalyst bed or a fluidized catalyst bed can be employed. Any of these operational forms has advantages and disadvantages, and for those skilled in the art, they can select the most appropriate one for a particular food and catalyst.

The contacting step is preferably carried out, within a reaction zone, where the inventive composition is placed, and under the reaction conditions that appropriately promote the formation of olefins, preferably light and aromatic olefins, preferably BTX, from at least a portion of the hydrocarbons in the hydrocarbon feed. The reaction temperature of the contact stage is more particularly, in the range from about 400 ° C to about 800 ° C, preferably, from about 450 ° C to about 750 ° C and, more preferably, from 500 ° C to 700 ° C. The contact pressure may be in the range of atmospheric pressure to above about 500 psia, preferably from about atmospheric to about 450 psia, and more preferably from 20 psia to 400 psia.

The flow rate at which the hydrocarbon feed is charged to the conversion reaction zone is such as to provide a space velocity per hour by weight ("WHSV") in the range exceeding 0 hours "1 up to over approximately 1000 hours "1. The term "space velocity per hour by weight", as used herein, shall refer to the numerical ratio of the rate at which a hydrocarbon feed is charged to the conversion reaction zone, in pounds per hour divided by the pounds of catalyst contained in the conversion reaction zone to which the hydrocarbon is charged. The preferred WHSV of the feed to the conversion reaction zone or contact zone may be in the range of about 0.25 hour "1 to about 250 hour" 1 and, more preferably, 0.5 hour "1 to 100 hour" The following examples are presented to further illustrate this invention and are not elaborated as to inappropriately limit its scope.

EXAMPLE I This example illustrates the preparation of various catalysts that were subsequently tested as catalysts in the conversion of a gasoline sample, which had been produced in a commercial fluidized catalytic thermal-fusing (FCC) unit, to aromatics.

LIXED ZEOLITE WITH ACID A commercially available ZSM-5 catalyst (provided by United Catalysts Inc., Louisville, KY, under the product designation "T-4480") was treated by acid leaching. To acid leach the catalyst, it was rinsed in a solution of aqueous HCl, which had a HCl concentration of 38 weight percent (about 6N) for two hours at a constant temperature of about 90 ° C. After rinsing in the catalyst it was separated from the acid solution and washed thoroughly with water and dried. The acid rinsed, washed and dried catalyst was calcined at a temperature of about 525 ° C for four hours.

CATALYST A An amount of 10.83 grams of the acid-leach catalyst ZSM-5 described above was impregnated by an incipient dryness technique with an amount of 8.3 grams of a solution containing 2 parts by weight of zinc chloride (ZnCl2), 18 parts by weight. weight of ethanol and 20 parts by weight of t et raetoxisilane (TEOS). The impregnation solution had an atomic ratio of silicon to zinc of 6.6. This acid leached zeolite, then impregnated, was dried with air at a temperature of 125 ° C for 16 hours followed by treatment in a vapor atmosphere for 6 hours at 650 ° C. The steam-treated material was then exposed to a helium gas atmosphere at a temperature of 525 ° C for 2 hours. The final product contained 1653 weight percent zinc and 4.72 weight percent silicon.

CATALYST B An amount of 10.00 grams of the acid leached zeolite material described above was impregnated with an amount of 12.50 grams of a solution containing 1.50 parts by weight of zinc nitrate hydrate (Zn (03) 2-6H20), 4.10 parts by weight. weight of chromium nitrate hydrate (Cr (N03) 3.9H20), and 6.90 parts by weight of water. The impregnation solution had an atomic ratio of chromium to zinc of 2. This acid-leached zeolite, then impregnated, was dried with air at a temperature of 125 ° C for 16 hours followed by treatment in a steam atmosphere for 6 hours at 650 ° C. The steam-treated material was then exposed to an atmosphere of helium gas at a temperature of 538 ° C for 2 hours. The final product contained 3.0 weight percent zinc and 4.8 weight percent chromium.

CATALYST C An amount of 10.00 grams of the acid leached zeolite material described above was impregnated with an amount of 8.43 grams of a solution that contained parts by weight of hydrated zinc nitrate (Zn (N03) 2.6H20) ", 6. parts by weight of hydrated ammonium molybdate ((NH4) 6Mo7024.6H20), and 84 parts by weight of water The impregnation solution had an atomic ratio of molybdenum to zinc. 1011. The acid-leached zeolite, then impregnated, was dried with air at a temperature of 125 ° C for 16 hours followed by treatment in a vapor atmosphere for 6 hours at 650 ° C. The final product contained 1822 weight percent of zinc and 2,703 weight percent molybdenum.

CATALYST D An amount of 10.00 grams of the acid leached zeolite material described above was impregnated with an amount of 8.0 grams of a solution containing 5.4 parts by weight of zinc nitrate hydrate (Zn (N03) 2.H20), 2.25 parts by weight. weight of hydrogen borate (H3BO3), and 42.35 parts by weight of water. The impregnation solution had an atomic ratio of boron to zinc of 2005. The acid-leached, impregnated zeolite was then dried with air at 125 ° C for 16 hours followed by treatment in a vapor atmosphere for 2 hours at 650 ° C. The final product contained 1851 weight percent zinc and 0.614 weight percent molybdenum.

CATALYST E An amount of 10.00 grams of the acid leached zeolite material described above was impregnated with an amount of 9.24 grams of a solution containing 4 parts by weight of titanium tetrachloride (TiCl4), 2.8 parts by weight of zinc chloride (ZnCl2). ), and 93.2 parts by weight of an aqueous HCl solution containing 7.40 weight percent HCl. The impregnation solution had an atomic ratio of titanium to zinc of 1.026. The acid-leached, impregnated zeolite was then dried with air at a temperature of 125 ° C for 16 hours followed by treatment in a vapor atmosphere for 6 hours at 650 ° C. The steam-treated material was then exposed to an atmosphere of helium gas at a temperature of 538 ° C for 2 hours. The final product contained 1,224 weight percent zinc and 0.920 weight percent titanium.

CATALYST F An amount of 10.00 grams of the zeolite material leached with acid described above was impregnated with an amount of 8.98 grams of a solution containing 6.00 parts by weight of zinc nitrate hydrate (Zn (N03) 2.6H20), 2.00 parts. by weight of a 85 weight percent aqueous phosphoric acid solution (H3P04), and 32.00 parts by weight of water. The impregnation solution had an atomic ratio of phosphorus to zinc of 0.86. The acid-leached, impregnated zeolite was then dried followed by the steam treatment for 6 hours at 650 ° C and then with helium for 2 hours at 525 ° C. The final product contained 2.8.23 weight percent zinc and 1151 weight percent phosphorus.

CATALYST G An amount of 16.27 grams of the acid leached zeolite material described above was impregnated with an amount of 13.86 grams of a 15 weight percent aqueous solution of hydrated zinc nitrate (n (N03) 2.6H20). The impregnated, acid-leached zeolite was dried with air at 125 ° C for 16 hours followed by steam treatment for 6 hours at 625 ° C. The steam treated material was then exposed to a helium gas atmosphere at a temperature in the range of 625 ° C to 538 ° C for a period of 6 hours. The final product contained 2,700 weight percent zinc.

CATALYST H A calcined sample of 20.00 grams of the ZSM-5 catalyst described above (not leached with acid) was impregnated with an amount of 11.83 grams of a 15 weight percent aqueous solution of zinc nitrate hydrate. This calcined, impregnated zeolite was then dried with air followed by steam treatment for 6 hours at 625 ° C. The steam treated material was then exposed to a helium gas atmosphere at a temperature of 538 ° C for 6 hours. The final product contained 1899 weight percent zinc.

EXAMPLE II This example illustrates the use of the zeolite materials described in Example I as the catalysts in the conversion of a gasoline feed to benzene, toluene and xylenes (BTX) and lower olefins (ethylene, propylene).

For each of the test runs, a 5.0 g sample of the catalyst materials described in Example I was placed in a stainless steel tube reactor (length: about 18 inches, internal diameter: about 0.5 inches). The feed in the boiling range of gasoline from a catalytic thermofraction unit of a refinery was passed through the reactor at a flow rate of approximately 14 ml / hour, at a temperature of approximately 600 ° C. and at an atmospheric pressure (approximately 0 psig). The reaction product formed excited the reactor tube and passed through several ice-cooled traps. The liquid portion remained in these traps and was weighed, while the volume of the gaseous portion that excited the traps was measured in a "moisture test meter". Samples of the liquid and gaseous product (collected at one hour intervals) were analyzed by means of a gas chromatograph. The results of eight test runs for Catalysts A through H are summarized in Table I. All test results were obtained after 8 hours in the stream. t-O 00 ? or? + propylene The results of the test presented in Table I, show that the catalyzed inventors exhibit considerably less coking (resulting in excessive deactivation of the catalyst) than the H Control Catalyst and produced more BTX and olefins and a higher olefin ratio to BTX than the Control Catalyst G. The improvement in catalyst performance is believed to be due to the acid leached zeolite promoted by two metals. The double metal promoter is zinc in combination with another metal.

It is also observed that the non-acid leached zeolite, which only contains zinc, produces a significant amount of coke with a fairly reasonable yield of BTX and Olefin. Zeolite leached with acid containing only zinc decreases the rate of coke production, but also undesirably reduces the olefin to BTX ratio and the yield of BTX and olefin. The use of secondary metals, in combination with zinc, suppresses the formation of coke while also improving the production of BTX and olefins and in most cases improves the olefin to BTX ratio in the product.

Reasonable variations, modifications and adaptations can be made within the scope of the description and appended claims, without departing from the scope of this invention.

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Having described the invention as above, the content of the following is claimed as property.

Claims (19)

RE VINDICAC ONES

1. A catalyst composition, characterized in that it comprises an acid treated zeolite and further comprises zinc and at least one other element of Group 4B, Group 6"B, Group 3A, Group 4A, or Group 5A of the elements of the periodic table.

2. A composition according to claim 1, characterized in that zinc is present in the range greater than about 10 weight percent and at least the other element is present in the range greater than about 15 weight percent.

3. A composition according to any preceding claim, characterized in that the atomic ratio of at least one other element to zinc is in the range of about 0.1: 1 to about 10: 1.

4. A composition according to any A preceding claim, characterized in that the zinc is present in the range of about 0.05 to about 8 weight percent and at least one other element is present in the range of about 0. 1 to about 12 weight percent.

5. A composition according to any preceding claim, characterized in that the atomic ratio of at least one other zinc element is in the range of about 0.2: 1 to about 5: 1 weight percent.

6. A composition according to any preceding claim, characterized in that zinc is present in the range of about 0.1 to 6 weight percent and at least one other element is present in the range of 0.2 to 10 weight percent.

7. A composition according to any preceding claim, characterized in that the atomic ratio of at least one other element to zinc is in the range of 0.5: 1 to 3: 1.

8. A composition according to any preceding indication, characterized in that it has undergone a first thermal treatment, whereby the composition is brought into contact with a first gas under high temperature conditions, thereby providing a first heat-treated material .

9. A composition according to claim 8, characterized in that the first heat treated material has been subjected to a second heat treatment, whereby the first heat treated material is contacted with a second gas under high temperature conditions, providing in this way a second material treated with heat.

10. A composition according to claim 9, characterized in that the first gas and the second gas are individually an inert gas, a reducing gas, air, oxygen, vapor or a mixture of any two or more of these gases.

11. A composition according to any of the preceding claims 8-10, characterized in that the first heat treatment is carried out at a temperature in the range of about 30 ° C, to about 400 ° C and for a period of time of about 0.1 hour to approximately 30 hours.

12. A composition according to any of the preceding claims 8-10, characterized in that the second heat treatment is carried out at a temperature in the range of about 400 ° C, to about 1200 ° C and for a period of time of about 0.1. hour to approximately 12 hours.

13. A composition according to any preceding claim, characterized in that the zeolite treated with acid has been impregnated with zinc and at least one other element.

14. A composition according to claim 13, characterized in that the impregnation of the acid-treated zeolite includes contacting the acid-treated zeolite with a solution containing a first zinc salt and a second salt of at least one other metal.

15. A composition according to any preceding claim, characterized in that at least one other metal is titanium, chromium, molybdenum, boron, silicon or phosphorus.

16. A process for the conversion of hydrocarbons, which comprises contacting under the conditions of conversion of a hydrocarbon feed with a composition according to any of the preceding claims, characterized in that a conversion product includes aromatics and olefins.

17. A process according to the rei indication 16, characterized in that the hydrocarbon feed comprises hydrocarbons containing 2-16 carbon atoms per olecule.

18. A process according to any of the preceding claims 16-17, characterized in that the conversion conditions include a reaction temperature in the range of about 400 ° C, to about 800 ° C and a contact pressure in the range above of the pressure subatmos ferica up to approximately 500 psia.

19. A process according to claim 18, characterized in that the conversion conditions further include a charge rate of the hydrocarbon feed, such that the space velocity at each hour by weight is in the range from more than 0 hour "1 up to over approximately 1000 hours "1.