KR900005092B1 - Method of dehydro cyclizing alkans - Google Patents

Abstract

Hydrocarbons are reformed by contacting with a wide-pore zeolite contg. (a) at least one VIII GP. metal, pref. Pt., and (b) Ca, Sr or Ba. The zeolite has pores of dia. 0.7-0.9nm and is zeolite X, Y or L. The selectivity index of the catalyst for the conversion of paraffins to aromatics must be at least 60%. The catalyst pref. contains 0.1-35 wt.% Ba and 0.1-5 wt.% Pt. The reaction is carried out pref. at 400-600 deg.C, 0.3-5, 1-35 atmospheres, and a ratio H2/hydrocarbon of 1:1-10:1.

Description

[Name of invention]

How to dehydrogenate alkanes

Detailed description of the invention

The present invention relates to a new process for dehydrocyclizing new catalysts and acyclic compounds, and more particularly to a process for dehydrocyclizing alkanes comprising at least six carbon atoms to form the corresponding aromatic hydrocarbons.

The reforming of catalysts is well known in the petroleum industry and involves the treatment of naphtha fractionation to improve octane number. The most important hydrocarbon reactions that occur during the reforming process include dehydrogenation of cyclohexane to an aromatic compound, dehydroisomerization of alkylcyclopentane to an aromatic compound, and aromatic compoundation by dehydrocyclization of paraffins. Hydrocracking reactions that produce light gaseous hydrocarbons, ie, methane, ethane, propane and butane in high yields, are minimized during reforming reactions, especially since this reduces the yield of gasoline boiling products.

Dehydrocyclization is one of the main reactions in the reforming process. Conventional methods of carrying out these dehydrocyclization reactions are based on the use of catalysts containing precious metals as carriers. Known catalysts of this kind are based on alumina having a platinum ratio of 0.2 to 0.8% by weight and better secondary metals.

The possibility of using a carrier other than alumina has also been studied, and it has been proposed to use any molecular sieve, such as the appropriately expressed X and Y zeolites, which is sufficient to allow molecules of reactants and products to pass through the pores of the zeolite. Suggested that it was small. However, catalysts based on these molecular sieves have not been commercially successful.

In the conventional method of carrying out the above-mentioned dehydrocyclization, the paraffin to be converted is not affected by the catalyst at a temperature of 500 ° C. and a pressure of 5 to 30 bar in the presence of hydrogen. Portions of the hydrocarbons were converted to aromatic hydrocarbons, and the reaction was carried out by isomerization and decomposition reactions, which also converted paraffins to isoparaffins and lighter hydrocarbons. The rate of conversion of hydrocarbons to aromatic hydrocarbons varies depending on the reaction conditions and the nature of the catalyst.

The catalyst used so far, but got the result quite satisfactory medium wave Lapin, C ₆ ~C ₈ paraffins, in particular C ₆ paraffins to give less satisfactory results. Catalysts based on L-type zeolites have better selectivity with respect to dehydrocyclization reactions, and typically to improve the conversion rate to aromatic hydrocarbons without requiring higher temperatures which have a significant adverse effect on the stability of the catalyst. As a result, the production of C ₆ -C ₈ paraffins was remarkable, but the process duration and reproducibility is a problem, and a satisfactory regeneration process is not known.

One method of desaturating unsaturated hydrocarbons is to contact the hydrocarbons in the presence of hydrogen with a catalyst consisting essentially of L-type zeolites with exchangeable cations in order to convert at least the feedstock portion into aromatic hydrocarbons. The exchangeable cations here consist of at least 90% of the ions of lithium, sodium, potassium, rubidium and cesium and have at least one metal selected from the group consisting of metals of Group VIII on the periodic table, tin, germanium and dehydrogenation. And an alkali metal ion selected from the group of atoms containing the metal or other metals comprising at least one metal located in the group on the periodic table. Particularly advantageous methods of this process are cesium or platinum / alkali metal / L type zeolite catalysts due to the excellent activity and selectivity of this catalyst when converting hexane and heptanes into aromatics. However, the issue of process duration remains.

The present invention eliminates the drawbacks of the prior art using catalysts comprising large pore zeolites, alkaline earth metals and Group VIII metals to convert hydrocarbons at extreme high selectivity to convert alkanes into aromatics.

The hydrocarbon is contacted with a catalyst comprising an alkaline earth metal selected from a large pore zeolite of at least one Group VIII metal (preferably platinum) and an atomic group consisting of barium, strontium and calcium (preferably barium).

In one form of the present invention, the process conditions are adjusted such that the selectivity for η-hexane dehydrocyclization is at least 60%. In another form, the selectivity index of the catalyst is greater than 60% and the catalyst gives a satisfactory process duration.

Even better, the large pore zeolite is an L-type zeolite containing 0.1 to 5 wt% platinum and 0.1 to 40 wt% barium. Hydrocarbons at a temperature of 400 ° C. to 600 ° C. (better 430 ° C. to 550 ° C.), LHSV of 0.3 to 5, 1 atm to 500 psing (better to 50 to 300 psig) and 1: 1 to 10: 1 (preferably) Preferably in contact with a barium-exchanged zeolite at a H ₂ / Hc ratio of 2: 1 to 6: 1).

In view of the broad aspects of the present invention, the present invention relates to the use of catalysts comprising large pore zeolites, alkaline earth metals and Group VIII metals in the reforming of hydrocarbons, in particular to alkane with extreme high selectivity which converts hexane into aromatics. The use of this catalyst for dehydrocyclization.

As used herein, "selectivity" is defined as the percentage of the number of moles of paraffin converted to an aromatic compound relative to the number of moles converted to aromatic compounds and degradation products.

In other words,

Isomerization and the formation of alkylcyclopentane were not considered in determining the selectivity.

As used herein, "selectivity to η-hexane" is defined as the percentage of the number of moles of η-hexane converted to the compound proportional to the number of moles converted to the aromatic compound and the degraded product.

The selectivity for converting paraffins to aromatics is a measure of the efficiency of the process in the conversion of paraffins to the necessary and valuable products, ie aromatics and hydrogen, as opposed to the undesirable hydrolysis products.

One unique characteristic of some dehydrocyclic and catalysts is their selectivity index. The selectivity index is defined as "Selectivity for η-hexane" operating at 490 ° C, 100 psig, 3LHSV and 3H ₂ / Hc 20 hours after using η-hexane as feedstock.

Catalysts with higher selectivity produce more hydrogen than catalysts with less selectivity because hydrogen is produced when the paraffins are converted to aromatics and consumed when the paraffins are converted to degraded products. Increasing the selectivity of the process increases the amount of hydrogen produced (more aromatization) and reduces the amount of hydrogen consumed (less decomposition).

Another advantage of using a catalyst with high selectivity is that the hydrogen produced by the catalyst with high selectivity is much purer than that produced by a catalyst with lower selectivity. This high purity is the result of more hydrogen being produced when fewer, lower boiling hydrocarbons (decomposition products) are produced.

The purity of the hydrogen produced in the reforming process is at a critical point if the hydrogen produced is used in a consistent process such as hydrotreating and hydrocracking, as in the case of a consistent purifier, at least a constant minimum partial pressure of hydrogen is required. Done. If the purity is too low, the hydrogen cannot already be used for this purpose and should be used for less valuable applications such as fuel gas.

The feed hydrocarbons in the process according to the invention preferably comprise non-aromatic hydrocarbons comprising at least six carbon atoms.

Preferred feedstocks are substantially known sulfur inhibitors, nitrogen, metals and other known catalyst inhibitors for improving the catalyst.

Dehydrocyclization is carried out in the presence of hydrogen at a pressure adjusted to thermodynamically make the reaction favorable and to limit unnecessary hydrocracking reactions by physical methods. The pressure used is preferably modified from 1 atm to 500 psig, better from 50 to 300 psig, with a preferred molar ratio of hydrocarbon to hydrogen from 1 to 1 to 10: 1, better from 2: 1 to 6: 1. Good to do.

Dehydrocyclization reactions in the temperature range of 400 ° to 600 ° C. occur at acceptable rates and selectivity.

If the process temperature is 400 ° C. or less, the reaction rate is insufficient, and thus the yield is too low for industrial purposes. Dehydrocyclization equilibrium is also disadvantageous at low temperatures. When the process temperature is above 600 ° C., disturbed secondary reactions such as hydrogenation and coke occur, which substantially reduces the yield and increases the catalyst and deactivation rate. Therefore, it is not fair to exceed 600 ℃ or more.

The preferred temperature range for dehydrocyclization (430 ° C. to 550 ° C.) is at optimum conditions depending on the activity, selectivity and stability of the catalyst of the process.

The liquid hourly space viscosity of the hydrocarbon is preferably between 0.3 and 10.

The catalyst according to the invention is a large pore zeolite fused to one or more dehydrogenation components. The definition of “large porosity zeolite” is defined as a zeolite having an effective pore diameter of 6 to 15 mm 3.

Among the large pore crystalline zeolites known to be useful in the examples of the present invention, L-type zeolite and synthetic zeolite having a faujasite structure such as zeolite X and zeolite Y are the most important and the pore sizes in the order of 7 to 9 mm3. Indicates. The composition of L-type zeolite shown as molar ratio of oxide is typical as follows.

(0.9-1.3) H ₂ / _n O: Al ₂ O (5.2-6.9) SiO ₂ : yH ₂ O where M represents a cation, n represents the valence of M, and y represents any value from 0 to about 9 Value. Zeolite L, its X-ray diffraction model, its properties and methods of making it are described in detail in US Pat. No. 3,216,789. US Patent No. 3, 216, 789 is hereby incorporated by reference to indicate a preferred monument of the present invention. The actual formula can be modified without changing the crystal structure, for example, the molar ratio (Si / Al) of aluminum to silicon can be varied from 1.0 to 3.5.

The chemical general formula expressed as the molar ratio of oxide can be expressed as follows.

(0.7-1.1) Na ₂ O: Al ₂ O ₃ : XSiO ₂ : YH ₂ O where X is greater than 3 to about 6 and Y is up to about 9. Zeolite Y has a characteristic X-ray powder diffraction model which can be used in the same general formula as above. Zeolite Y is described in more detail in US Pat. No. 3, 130, 007. US Patent No. 3, 130, 007 is hereby incorporated by reference to indicate the zeolite useful in the present invention.

Zeolite X is a molecular sieve of synthesized crystalline zeolite represented by the following general formula.

(0.7-1.1) M ₂ / _n O: Al ₂ O ₃ : (2.0-3.0) SiO ₂ : yH ₂ O where M represents a metal, in particular alkali and alkaline earth metals, n is the valence of M, y Are several values up to about 8 due to the identity of M and the degree of hydration of the crystalline zeolite. Zeolite X, its X-ray diffraction pattern, its properties, and its preparation are described in detail in US Pat. No. 2, 882, 244. US Patent No. 2, 882, 244 shows utility in the present invention and is incorporated herein by reference.

Preferred catalysts according to the invention are L-type zeolites filled with one or more dehydrogenated components.

An essential element in the present invention is the presence of alkaline earth metal in the large porosity zeolite. The alkali metal should be barium, strontium, or calcium for barium.

Alkaline metals can be combined with zeolites by synthesis, implantation or ion exchange. Barium is preferred as another alkaline earth metal because it remains as some form of weakly acidic catalyst. Strong acidity is unnecessary as a catalyst because it results in lower selectivity while promoting decomposition.

One point is that at least the alkaline moieties are exchanged to barium using known techniques for ion exchange of zeolites. This involves contacting the zeolite with a solution containing excess Ba ⁺⁺ ions. Barium should be composed of 0.1 to 35% by weight of the zeolite.

The dehydrocyclization catalyst according to the invention is charged with one or more Group VIII metals, for example nickel, rudenium, rhodium, palladium, iridium or platinum.

Better Group 8 metals are platinum, which has better selectivity with respect to iridium and in particular with respect to dehydrocyclization, and is also more stable under dehydrocyclization than other Group 8 metals. Preferred% of platinum as catalyst is between 0.1% and 5%.

Group 8 metals are charged into large pore zeolites by synthesis, injection or exchange in an aqueous solution of a suitable salt. Even when two Group 8 metals are needed in the monument, the process can proceed simultaneously or in sequence.

By the method of the embodiment, platinum can be introduced by injecting zeolite with an aqueous solution of tetraminplatinum (II) nitrate, tetraminplatinum (II) hydroxide, dinitro diamino-platinum or tetraminplatinum (II) chloride. have. In the ion exchange process, platinum may be introduced using cationic platinum complexes such as tetraminplatinum (II) nitrate.

Inorganic oxides may be used as carriers to bind large pore zeolites containing Group 8 metals and alkaline earth metals. The carrier may produce an inorganic oxide or a mixture of inorganic oxides, either naturally or synthetically. Typical inorganic oxide auxiliary materials may include clay, alumina and silica, with the acidic part being exchanged by cations that do not carry strong acidity (sodium, potassium, rubidium, cesium, calcium, strontium or barium).

The catalyst may be used in some conventionally known apparatus. It may be used in various models arranged in the form of pills, pellets, granules, broken fragments or in the form of fixed needles in the reaction zone, and the filling reservoir may be liquid, medium or mixed, It can also be passed to flow downward.

Alternatively, it may be manufactured in a suitable form for use in a moving needle bed or for a fluid bed-solid process, in which the incoming feedstock passes upwards through the rough needle bed of the finely divided catalyst.

After the required metals or other metals have been introduced, the catalyst is treated with air at about 260 ° C. and reduced to hydrogen at temperatures from 200 ° C. to 700 ° C., more preferably from 400 ° C. to 620 ° C.

At this stage, it is easy to use in the dehydrocyclization process. However, in some cases, for example, when a necessary metal or other metals are introduced by an ion exchange process, an aqueous solution of any salt or an appropriate alkali or alkaline earth element is used to neutralize some hydrogen ions formed during the reduction of metal ions by hydrogen. The catalyst may be treated with a hydroxide of to remove some of the remaining acidity of the zeolite.

In order to obtain the optimum selectivity, the temperature must be controlled so that the reaction rate can be discerned, but the conversion is within 98% since the excess temperature or overreaction may adversely affect the selectivity. The pressure must also be adjusted within the appropriate range. Too high a pressure will put the thermodynamic (equilibrium) limit in the required reaction, especially for the aromatization of hexane, and too low a pressure may result in the formation and deactivation of coke.

Although the inherent benefit of the present invention is in improving the selectivity for converting paraffins (especially C ₆ -C ₈ paraffins) into aromatics, it has also been surprisingly found to have excellent selectivity for converting methylcyclopentane to benzene. It was.

This reaction, which includes an acid that promotes the isomerization process in conventional catalyst reforming based on chlorinated alumina, also occurs as the catalyst of the invention with the same or better selectivity as in chlorinated alumina based on prior art catalysts.

Thus, the present invention can also be used to highly promote the conversion of raw materials in 5-membered-ring-alkyl naphthenes to aromatic materials.

Another benefit of this invention is that the catalyst of the present invention is more stable than the catalyst of conventional zeolite. The stability or resistance of the deactivation of the catalyst determines its useful process duration. Longer process times result in much less time and cost to regenerate or replace the charge catalyst.

In one embodiment of the present invention, a hydrocarbon feed is contacted with a first catalyst which is a conventional reforming catalyst and a second catalyst which is a dehydrocyclization catalyst comprising large pore zeolites, alkaline metals and Group 8 metals.

The use of reforming catalysts comprising aluminum supports, platinum and rhenium has been fully introduced in US Pat. No. 3,415,737, which is incorporated herein by reference to indicate the use of beneficial conventional reforming catalysts. Other advantageous bimetallic catalysts include platinum-tin, platinum-germanium, platinum-lead and platinum-iridium.

The hydrocarbon can be contacted with a series of two catalysts, first of which is contacted with a first (normal) reforming catalyst and then with a second (dehydrocyclization) catalyst or with a second catalyst first. Contact with the first catalyst. It is also possible to contact one fraction of the hydrocarbon in which the hydrocarbon is contacted with the first catalyst and the other fraction of the hydrocarbon in contact with the second catalyst in parallel. The hydrocarbon can also be contacted with both catalysts in the same reactor.

[Examples]

The invention has been described in more detail in the following examples which describe particularly advantageous methods and the subject matter thereof.

The examples are presented to illustrate the invention but are not intended to limit it.

Example 1

Hydrogen-purified Arabian lightweight direct discharge naphtha was modified at 100 psig, 2LHSV and 6H ₂ / Hc with three different catalysts to remove sulfur, oxygen and nitrogen. The feedstock contained 80.2 vol% paraffin, 16.7 vol% naphthene and 3.1 vol% aromatics and it contained 21.8 vol% C ₅ , 52.9 vol% C ₆ , 21.3 vol% C ₇ and 3.2 vol% C ₆ . Arabian Lightweight Direct Process Napata in the first process was modified at 499 ° C. using commercial sulfide, platinum-renium-alumina, prepared as introduced in US Pat. No. 3,415,737. In the second process, the Arabian lightweight direct discharge naphtha was modified at 493 ° C. using a platinum-potassium-L-type zeolite catalyst formed by:

(1) Injecting platinum-L type zeolite containing 0.8% platinum using tetramine platinum (II) nitrate.

(2) Drying the catalyst.

(3) calcining the catalyst at 260 캜;

(4) reducing the catalyst with hydrogen at 480 ° -500 ° C. for one hour.

In the third process, the method of the present invention, the Arabian lightweight direct discharge naphtha was modified at 493 ° C using a platinum-barium-L type zeolite catalyst formed by the following process.

(1) Ion exchange potassium-L-type zeolite with a volume of 0.17 mol of barium nitrate solution sufficient to contain excess barium as compared to the ion exchange performance of the zeolite.

(2) drying the resulting barium exchanged L-type zeolite catalyst.

(3) Calcining the catalyst at 590 ° C.

(4) Inject the catalyst with 0.8% platinum using tetraminplatinum (II) nitrate.

(5) Drying the catalyst.

(6) calcining the catalyst at 260 캜;

(7) reducing the catalyst with hydrogen at 480 ° C. to 500 ° C. for one hour.

The results of these three processes are shown in Table 1.

TABLE 1

This series process shows that the use of platinum-barium-L type zeolite catalysts in reforming provides a selectivity for converting hexanes to benzene significantly better than in the prior art. This good selectivity bond indicates the heavy acid of hydrogen gas that can be used in another process. It also shows that the purity of hydrogen is much higher for the platinum / barium / L process because more hydrogen is produced and less C ₁ + C ₂ is produced.

Example 2

The second series of processes was designed to show that in addition to the L-type zeolite, the process can also be carried out with another large pore zeolite. The index of selectivity was measured for four catalysts.

This second series process was performed using η-hexane as a raw material. All processes in this series were conducted at 490 ° C, 100 psig 3LHSV and 3H ₂ / Hc.

In the first step, platinum-potassium-L-type zeolite prepared by the method shown in the second step of Example 1 was used.

Also in the second step, the platinum-barium-L zeolite prepared by the method shown in the third step of Example 1 was used except that the barium nitrate solution was 0.3 mole instead of 0.17 mole.

In the third step, sodium-zeolite Y is injected together with P + (NH ₃ ) ₄ (NO ₃ ) ₂ , which is 0.8% platinum, followed by drying, followed by calcining the catalyst at 260 ° C. to hydrogen reduction at 480 to 500 ° C. Platinum-sodium-zeolite Y prepared was used.

In the fourth step, platinum-sodium-zeolite Y prepared by injecting sodium-zeolite Y with 0.3 mol of barium nitrate at 80 ° C. and then drying, calcining the catalyst at 260 ° C. and reducing it with hydrogen at 480-500 ° C. Was used.

In the fourth process, sodium-zeolite Y is ion-exchanged with 0.3 mol of barium nitrate at 80 ° C., dried, calcined at 590 ° C. and then P + (NH ₃ ) ₄ (NO ₃ ) ₂ , which becomes 0.8% platinum. The zeolite was injected and then dried to use the platinum-barium-zeolite Y prepared by calcining the catalyst at 260 ° C. and hydrogen reduction at 480 to 500 ° C.

The results of this process are given in Table 2 below.

TABLE 2

Thus, in the process, the binding of barium to large pore zeolites, such as Y-type zeolites, is a dramatic improvement in the selectivity of η-hexanes. It shows that the platinum-barium-L type zeolite has excellent stability. After 20 hours, there was no defect following conversion when the platinum-barium-L type zeolite catalyst was used.

Example 3

The third series process was performed to show the effect of adding added ash to the catalyst. This third process is carried out using hydrogen purified raw materials to remove sulfur, oxygen and nitrogen while containing 80.9 vol% paraffin, 16.8 vol% naphthene and 1.7 vol% aromatics. The feedstock also contained 2.6 volume% C ₅ , 47.6 volume%, 43.4 volume% and 6.3 volume% C ₆ . All processes in this series consisted of 100 psig, 2.0 LHSV and 6.0 H ₂ / Hc at 490 ° C.

In the first step, platinum-sodium-zeolite Y was produced by the method shown in the third step of Example 2.

In the second step, platinum-barium-zeolite Y was produced by the method shown in the fourth step of Example 2.

In the third process, platinum-rare-stone-stone Y was prepared by injecting commercial earth-stone zeolite Y from Strem Chemical Company and obtained 0.8% platinum using P + (NH ₃ ) ₄ (NO ₃ ) ₂ and then Was dried, calcined at 260 ° C. and reduced at 480-500 ° C.

In the fourth process, platinum-rare earth-barium-zeolite Y was prepared by ion exchange of rare earth zeolite Y of a commercial strem chemical company with 0.3 mol of Ba (NO ₃ ) ₂ solution at 80 ° C., and dried to 590 ° C. The zeolite was calcined at, and the zeolite was injected with P + (NH ₃ ) ₄ (NO ₃ ), which became 0.8% platinum, and then dried, and the zeolite was calcined at 260 ° C. and reduced at 480 to 500 ° C. The results of these processes are given in Table 3.

TABLE 3

This series shows that the addition of rare earth to the catalyst has an adverse effect on selectivity.

Example 4

Key to remove sulfur, oxygen and nitrogen by reforming the naphtha Arabian purified hydrogen from 100psig to 3LHSV and 3H ₂ / Hc, were produced two C ₅ ⁺ product made by different processes including the aromatic component of 82% by weight. The raw material was hydrogen purified Arabian naphtha containing 67.9% paraffin, 23.7% naphthene and 8.4% aromatics. The distillation results obtained by the D ₈₆ method are: starting point-230 ° F, 5% -219, 10% -224, 30% -248, 50% -265, 70% -291, 90% -321, 95% -337, end point -307 ° F.

In the first process, Arabian naphtha was reformed to 516 ° C. in a reactor using a conventional reforming catalyst comprising 0.3% platinum, 0.6% rhenium, 1.0% chlorine with alumina. It was separately sulfurized.

In the second process, Arabian naphtha was reformed at 493 ° C. in the same reactor. Here, the upper half of the reactor contained a catalyst of the same type as the catalyst of the first process, and the lower half of the reactor contained a platinum-barium-L type zeolite catalyst formed by the process shown in Example 1.

The results of these two processes are shown in Table 4.

Although the present invention has been described in connection with the detailed description, it is intended that the present application cover these various changes and permutations as may be made by well-known techniques without departing from the spirit and scope of the appended claims.

Claims (23)

A catalyst comprising (a) at least one Group 8 metal and (b) an alkaline earth metal selected from atomic groups consisting of barium, strontium and calcium, wherein the catalyst has a large pore zeolite containing at least 60% of a selectivity index of the catalyst. Reforming the hydrocarbon by contacting the hydrocarbon. A method according to claim 1, wherein said alkaline earth metal is barium and said Group 8 metal is platinum. A process according to claim 2, wherein said catalyst is from 0.1% to 35% barium and from 0.1% to 5% platinum. A method according to claim 1 wherein said large pore zeolite has a discernable size of 7 to 9 ms. A process according to claim 4 wherein said large pore zeolite is selected from atomic groups consisting of zeolite X, zeolite Y and L-type zeolite. A method according to claim 5, wherein said large pore zeolite is zeolite Y. A method according to claim 6 wherein said large pore zeolite is an L-type zeolite. The hydrocarbon reaction according to claim 7 takes place at a temperature of 400 ° C. to 600 ° C., at an LHSV of 0.3 to 5.0, a pressure of 1 atmosphere to 500 psig and a H ₂ / Hc ratio of 1: 1 to 10: 1. How to. Wherein said catalytic reaction occurs at a temperature of 430 ° -550 ° C. at a pressure of 50-300 psig and a H ₂ / Hc ratio of ₂ : 1-6: 1. (A) Alkaline earth metals selected from atomic groups consisting of at least Group 8 metals and (B) barium, strontium and calcium, and the co-conditioning is controlled such that the selectivity for dehydrogenation of η-hexane is at least 60%. A method for reforming a hydrocarbon comprising contacting the hydrocarbon with a catalyst consisting of a large pore zeolite comprising the same. A process according to claim 10, wherein said alkaline earth metal is barium and said Group 8 metal is platinum. A process according to claim 11, wherein said catalyst has from 0.1% to 35% barium and from 0.1% to 5% platinum. A method according to claim 10 wherein said large pore zeolite is selected from atomic groups consisting of zeolite X, zeolite Y and L-type zeolite. A method according to claim 14, wherein said large pore zeolite is a doll zeolite. A method according to claim 14, wherein said large pore zeolite is a doll zeolite. A process according to claim 15 wherein said contacting reaction takes place at a temperature between 430 ° C. and 550 ° C., at a pressure of 50 to 300 psig and a H ₂ / Hc ratio of 2: 1 to 6: 1. (A) contacting said hydrocarbons in the presence of hydrogen with reforming conditions and in the presence of hydrogen, the first catalyst comprising a metal oxide base disposed in a dense mixture of platinum and rhenium; and (b) at least one Group 8 metal, barium, strontium. And contacting said hydrocarbon as a second catalyst comprising a large pore zeolite containing an alkaline earth metal selected from an atomic group consisting of calcium. The hydrocarbon conversion method according to claim 17, wherein the alkaline earth metal is barium and the Group 8 metal is platinum. A hydrocarbon conversion process according to claim 18, wherein the dehydrocyclization catalyst has 0.1% to 35% barium and 0.1% to 5% platinum. The hydrocarbon conversion method according to claim 17, wherein the large pore zeolite is selected from atomic groups consisting of zeolite X, zeolite Y and L-type zeolite. The hydrocarbon conversion method according to claim 20, wherein the large pore zeolite is zeolite Y. The hydrocarbon conversion method according to claim 21, wherein the large pore zeolite is an L-type zeolite. The hydrocarbon conversion method according to claim 17, wherein the contact reaction in step (B) takes place at a temperature of 430 ° C. to 550 ° C., at a pressure of 50 to 300 psig and a H ₂ / Hc ratio of 2: 1 to 6: 1. .