US3827972A - Method of producing aromatic hydrocarbons - Google Patents

Abstract

METHOD OF PRODUCING AROMATIC HYDROCARBONS WHICH COMPRISES HYDROFORMING A HYDROCARON AT A TEMPERATURE FROM 300*C. TO 650*C. OVER A CATALYST COMPRISING PLATINUM AND LEAD PREPARED BY AN IMPREGNATION PROCEDURE.

Description

Ag- 5, 1974 NAoYA KoMlNAMl Erm. 3,827,972

METHOD 0F PRODUCING ROMATIC HYDROCRBONS Filed Nov. 18, 1971 m t E Tl. P B b A P B P o/h A 6 W u 5 A 5 O. m y mn 4 /x -3 X l 2 .H v LE Pm 5m ,l O( llulcqul." l u l u 1 v n u .A O O O O O 5 4 3 2 l Olm; mgomq United States Patent O Mice U.S. Cl. 208-139 8 Claims ABSTRACT OF THE DISCLOSURE Method of producing aromatic hydrocarbons which comprises hydroforming a hydrocarbon at a temperature from 300 C. to 650 C. over a catalyst comprising platinum and lead prepared by an impregnation procedure.

RELATED APPLICATIONS This application is a continuation-in-part of our application Ser. No. 6,948, iiled Ian. 29, 1970. It is related to applications: Ser. No. 200,065, which is directed to the catalysts described in this application; Ser. No. 200,023 which describes hydroforming of a hydrocarbon charge with a Pt-Pb catalyst prepared by a sequential impregnation method wherein Pt is first supported on a carrier prior to supporting Pb on the carrier; and Ser. No. 200,- 071 which describes hydroforming of a hydrocarbon charge with a Pt-Pb catalyst prepared by coprecipitation; all tiled concurrently herewith.

BACKGROUND OF THE INVENTION Field of the Invention This invention relates to a method of producing aromatic hydrocarbons from petroleum sources at high yields. More particularly, it is concerned with a method of producing a distillate of high aromatic concentration in high yield by highly selectively subjecting naphthenic hydrocarbons to dehydrogenation and paraftinic hydrocarbons to dehydrocyclization.

Description of the Prior Art A number of investigations have been made heretofore on methods for producing aromatic hydrocarbons from petroleum sources to establish several industrial processes employing catalysts comprising platinum, chromina, molybdena and the like. In these processes, naphtha is used as the starting material, which is subjected to catalytic reaction in gas phase at a high temperature. The liquid product thus produced contains isomers of parainic hydrocarbons at a high concentration and is often used as gasoline for motor cars, etc. because of its high octane number. However, its content of aromatic hydrocarbons is so low that an additional extraction or dealkylation step is needed in order to obtain benzene, toluene, xylene and the like. In addition, the yield of aromatic hydrocarbons based on the starting material employed is so low that the operation of these steps is costly.

On the other hand, demand for aromatic hydrocarbons is being increased rapidly due to rapid growth of industries related to aromatics such as plastic and synthetic ber industries. In this respect, it has become necessary to develop a process for producing aromatics in a higher yield. Moreover, the gasoline industry needs higher and higher octane numbers.

3,827,972 Patented Aug. 6, 1974 of production because it depends upon the production of ethylene.

SUMMARY OF THE INVENTION As a result of extensive investigations on the process commercially advantageous in consideration of the source and demand of aromatics as well as the process economy as mentioned above, we have discovered a process with many advantages including the improved yield of aromatics. The present invention, derived from the discovery, is concerned with a method of producing aromatic hydrocarbons which comprises treating a hydrocarbon or a hydrocarbon mixture at a temperature from 300 C. to 650 C. over a catalyst comprising platinum and lead or a catalyst comprising platinum, lead and at least a member selected from lithium, sodium, potassium, rubidium, cesium, beryllium, magnesium, calcium, strontium, barium, zinc, cadmium, mercury, germanium, bismuth, chromium, molybdenum, tungsten, uranium, rhenium, ruthenium, rhodium, palladium, osmium and iridium. The catalyst is prepared by an impregnation procedure.

According to this invention, a variety of advantages may be enjoyed as compared with prior methods as set forth below.

First, benzene, toluene, Xylenes and polymethylbenzenes are produced by quite simple procedures at low cost because of high concentration and yield of aromatics in the reformate produced according to this invention. vFor example, a distillate of higher boiling point than toluene or xylene in the reaction product contains neither paraffin nor naphthene and then separation can be effected by distillation only, without application of solvent extraction. Such a distinction from the prior processes is ascribed to high activity and selectivity of the catalyst of this invention in terms of aromatic formation, namely dehydrogenation or dehydrocyclization reactions.

In other words, in the conventional reforming processes known heretofore, since hydrocracking, isomerization, dehydrogenation or dehydrocyclization are the main reactions involved, an attempt to obtain a liquid fraction having a high aromatic concentration leads to an increase in hydrocracking with attendant results in low liquid yield and degraded economy. If on the other hand, the liquid yield is made higher, then the paraffin concentration in the resulting liquid becomes higher.

However, when the catalyst of the present invention is employed, quite unexpectedly, hydrocracking and isomerization are suppressed remarkably while dehydrogenation of naphthene or dehydrocyclization of paratiin occurs preferentially, and, in addition, the catalyst activity is quite high.

While lead has been shown to be a poison for a platinum catalyst in hydroforming catalyst (U.S. Pat. No. 3,001,811 of Murray et al.), it has been found that particular Pt-Pb combinations containing specified Pb contents in specied P'b/ Pt ratios are excellent hydroforming catalysts. If the amount of Pb supported on a carrier with Pt is excessive, Pb exhibits a poisoning effect. Also, if the ratio of Pb to Pt on a carrier exceeds a specified value, then the Pb catalyst is poisoned. Influencing the effectiveness of the catalysts also is the method by which they are prepared. Surprisingly, then, when the amount o of Pb is controlled Within prescribed limits, the Pb/Pt ratio is also so controlled, and a particular method of aszrpra preparation is selected, hydroforming catalysts of high activity and high selectivity can be obtained.

Thus, utilization of features of the present invention as described above serves to produce aromatics having high carbon numbers from high boiling fractions having high carbon numbers such as, for example, kerosene and gas oil, in high yields. The same thing applies to naphtha and the process of the present invention affords far higher yields in the production of trimethylbenzene, durene and the like than known processes.

Secondly, purity and yield of the hydrogen are so high that hydrogen can be supplied at a low cost.

Thirdly, life of the catalyst of this invention is so long that frequency in regeneration of the catalyst is reduced under normal reaction conditions in industrial operation.

Fourthly, the catalyst of this invention is operative at lower pressures than in prior processes. As the rate of degradation in activity in the prior catalysts is much more drastic and they become inoperative during long operation, and, therefore, the process on an industrial scale d has to be carried out under high pressures. On the contrary, the catalyst of this invention is stable in the course of a long operation to give a high yield of aromaties.

As the platinum component of the catalyst, there may be used, for example, the hydroxide, platinum halides, chloroplatinic acid or hydrate or ammonium salt thereof. Especially preferred are substances containing a halogen. This is due to the fact that in a compound containing platinum and halogen, the halogen and especially chlorine present in the compound advantageously contribute to the catalytic activity li-ke in other platinum reforming catalysts. The preferable amount of chlorine contained in the catalyst of the present invention is in the range of l 0.1-2.0% by Weight and particularly in the range of 0.5-

1.5% by weight based on the total weight of catalyst components. As the lead component, there may be employed halogenides, inorganic and organic salts, hydroxide, oxide and the like. The element used as the third component may be in the form of its oxide, hydroxide, halide or other inorganic and organic salt or complex. The platinum, lead and the third components may be in the form of a salt containing each of them.

Contents of the platinum, lead and the third components are 0.\l5% by weight, Q01-5% by weight and 0-3% by weight, respectively, and preferably 0.05-l% by weight, Q01-3% by weight and 0-1% by weight, respectively based on the total weight of catalyst components, with the ratio of lead to platinum ranging from 0.1 to 3.

The catalyst is prepared by simultaneously supporting platinum and lead on a carrier by conventional impregnation methods; or by supporting lead on a carrier and thereafter supporting platinum on the carrier, again using conventional impregnation methods. Preferred Pb/Pt ratios, lead and platinum contents, and third component content with the two impregnation methods are as follows:

Simultaneous Pb, th en Pt impregnation impregnation Pb, percent wt; 0. l.2 0. 1-2. 5 0. 1- l 0. 1-1 0. 8-2 0. 3-2. 5 3rd component, percent Wt- 0-1 0-1 4 calcined at a temperature from 400 C. to 700 C., preferably 450 C. to 600 C.

In the sequential impregnation method, the catalyst is prepared by immersing a carrier in an aqueous solution containing a lead compound such as, eg., lead nitrate and lead chloride, to support the lead component on the carrier, drying the resulting material and then calcining the dried product at a temperature ranging from 300 C. to 800 C. The calcined product is then immersed in an aqueous solution containing a platinum compound such as, eg., chloroplatinic acid, to support the platinum component thereon, drying the resulting assembly and then calcining the dried product at a temperature ranging from 400 C. to 700 C., preferably from 450 C. to 600 C.

In the simultaneous impregnation method and in the sequential impregnation method mentioned above, amounts of platinum, lead and a third component contained in the solution of platinum compound, lead compound and third component are, in general, 0.01-5 wt. percent platinum; 0.01-5 wt. percent lead and 0-3 wt. percent third component. However, in the simultaneous impregnation method, the ranges preferably are 0.1-l wt. percent platinum; 0.1-2 wt. percent lead and 0-1 wt. percent third component. On the other hand, in the sequential impregnation method, the ranges preferably are 0.1-1 Wt. percent platinum; 0.1-2.5 wt. percent lead and 0-1 Wt. percent third component.

Lead to platinum weight ratio in the solution generally ranges from 0.1 to 3.0, and preferably, in the simultaneous impregnation method, it ranges from 0.3 to 2.0, and in the sequential impregnation method, it ranges from 0.3 to 2.5.

The effective Pb/Pt ratio varies depending upon the process for the preparation of catalyst and upon the reaction pressure. In case of using the catalyst prepared by the process of the present invention under atmospheric pressure and reaction pressures of 5 kg./cm.2, 10 kg./cm.2 and not less than 20 kg./cm.2, the maximum effective Pb/ Pt ratios are 3.8, 3.5, 3.2 and 3.0, respectively. This will be illustrated by the examples as set forth hereinafter.

As with the conventional catalysts, the proportion of contents of the components depends, for example, upon the type of carrier, surface area, order of the addition, method of the calcination and the like.

In order to increase the activity of the catalyst, the use of a carrier such as silica alumina, alumina, alumina hydrate, silica, zeolite, kaolin, acid clay or bentonite is effective and preferable carriers are alumina, silica alumina, zeolite and the like.

The hydrocarbons which may be used in the present invention as the starting material include those mainly comprising paraffins, olelins and naphthenes having a boiling point Within the range of from 40 to 350 C., which may be used alone or in admixture of two or more kinds. Preferable hydrocarbons are those having from 6 to l2 carbon atoms.

Most advantageous materials from the industrial standpoint are naphthas having a boiling range of 40-190" C., kerosene having a boiling range of -260 C., and gas oil having a boiling range of 220-350 C.

Feeding ratio of hydrogen to hydrocarbon in gas volume is from 0.5 to l5 and preferably from 2 to l0. Prior to the reaction, the catalyst may be pretreated with hydrogen at or near the reaction temperature to activate it.

Feeding rate of the hydrocarbon in terms of LHSV, which stands for liquid hourly space velocity (the feeding amount of hydrocarbon per unit time, per unit volume of catalyst, in ml.) is from 0.2 to l0 hr.1 and preferably from 0.5 to 5 hrl.

Temperatures from 300 C. to 650 C., preferably from 430 C. to 580 C., are employed for the reaction.

The reaction pressure is dependent upon the desired quality of product and economy and may be optionally chosen within the range of from 1 to 50 kg./cm.2 and preferably from 5 to 20 kg./cm.2. In order to. improve the space time yield in the commercial productlon, the reaction is preferably carried out under an elevated pressure.

DESCRl'PTION OF PREFERRED EMBODIMENTS In order to illustrate the invention examples are given below.

Example 1 In an aqueous solution of a mixture of chloroplatinic acid and lead chloride was immersed fy-alumina. After being dried, the resulting mass was calcined at 550 C. for 2 hours to prepare a catalyst with a composition: 0.5% Pt-0.25% Pb-Al2O3. Percent is by weight herein unless otherwise noted.

Through a catalyst layer containing 20 ml. of the catalyst, which was heated in advance in the presence of hydrogen at 500 C. for 2 hours, was passed a gaseous mixture of hydrogen and n-heptane at a molar ratio of 3 :1 at an LHSV of 0.5 hr.-1 under atmospheric pressure, while maintaining the layer at a temperature of 490 C. The average molar yields of the products in hours were: Benzene 2.2% toluene 63.5% and xylenes including ethylbenzene 2.1% and the total aromatics 67.8%.

Example 2 A hundred milliliters of a catalyst prepared by the same method as in Example 1, the composition being 0.5% Pt-0.5% Pb-A12O3, was heated under hydrogen at 500 C. for 2 hours. Through the catalyst layer -was passed a gaseous mixture of hydrogen and naphtha with the composition given below at a feeding ratio of 3:1 (by gas volume) at an LHSV of 2.0 hr.1 under a total reaction pressure of 10 kg./cm.2 (gauge) continuously for 48' hours, 'while maintaining the layer at a temperature of 500 C. Yields by weight of the products were: Hydrogen 4.5%, benzene 5.4%, toluene 15.3%, xylenes 30.6% and the total aromatics 76.7%.

Component of the naphtha source (percent by volume) Parains 65.7 Olens 0 Naphthenes 22.8 Aromatics 11.5

Example 3 Composition of the starting material (percent by volume):

Parains 65.5 Olens 0.2 Naphthenes 23.7 Aromatics 10.6

Example 4 With 100 cc. of a catalyst composition comprising 0.5% platinum, 0.5% lead and 'y-alumina was supported 0.3% potassium carbonate by impregnation and after the catalyst was reduced by hydrogen for an hour at 530 C., a gaseous mixture of hydrogen and naphtha having a composition shown below in a volume ratio of 10:1 was passed therethrough at an LHSV of 1.0 hr.-1 at a reaction temperature of 480 C. under a reaction pressure of 4 kg./ cm.2 (gauge).

Composition of the starting naphtha:

Ingredient: Vol. percent Paratins 65.5 Oleins 0.2 Naphthenes 23.7 Aromatics 10.6

As a result, the yields of the reaction products based on the starting naphtha were as follows:

Catalyst composition: Pt-Pb-KzCOs Example 5 'y-Alumina granulated in a ball of a diameter of 2 mm. was immersed in an aqueous solution of rubidium hydroxide, followed by drying and calcination at 570 C. to give a carrier of the composition 0.21% rubidium- 99.79% A1203. The carrier was then immersed in an aqueous solution of a mixture of chloroplatinic acid and lead chloride. After being dried in 2 hours and calcined at 550 C. for 2 hours, there was prepared a catalyst of the composition: 0.5%Pt0.5%Pb-0.2%Rb-Al203. A reactor 1.25 inches in diameter was filled with the catalyst and treated under hydrogen for 45 minutes during which period the temperature was raised from 410 C. to 530 C. A gaseous mixture of hydrogen and naphtha with the composition given below in a ratio of 7.5 :1 was passed through the reaction tube at an LHSV of 2.0 hr.-1 and a temperature of 510 C. under a pressure of 10 kg./ cm?. Yields by weight on average of the products after 25 hrs., on the naphtha basis, were: Benzene 4.4%, toluene 14.9%, xylenes 33.6% and the total aromatics 77.9%.

Composition of the naphtha source (percent by volume):

Parains 55.2

lOlefins 0.1

Naphthenes 31.3

Aromatics 13.4

Example 6 Benzene 2.9%, toluene 13.3%, xylenes 29.3% and the total aromatics 71.5%.

Examples 7-27 Twenty milliliters of a catalyst comprising 0.5% platinum, 0.2% lead and a third component were heated at 500 C. for 2 hours in the presence of hydrogen. Through the catalyst layer was passed a gaseous mixture of hydrogen and n-heptane in a molar ratio of 5:1 at an LHSV of 0.5 hr.-1 under atmospheric pressure, while maintain- I ing the layer at 510 C. Molar yields of aromatcs were as follows:

8 a carrier, then, after vaporized to dryness, calcined at 550 C. for 3 hours, and, subsequently, immersed in 200 cc. of an aqueous solution containing 00077-2026 mol/ Third Added Y. 1d f liter of chloroplatinic acid, followed by vaporizing to iltriionent (irgi amatigs 5 dryness and calcining at 550 for 3 hours. Example catalyst h y Stam t 1 (molar As shown in Table 1I, following, the resulting catalyst (e ement) weg t) g ma em percent) had a composition of 0.3-1.0 Wt. percent Pt; 0.3-5.0 Wt. 0.5 LiCl 69.1 percent Pb and A1203, while Pb/Pt ratio was within the 0.5 NMCOi 68.0 f 5 5 O 1.3 (1350150055100 55.1 fange 0 3(1) gaggai-mm ggg 10 After 10 cc. of the resulting catalyst were heated at 012 Zmoigo 5510 530 C. under a hydrogen stream for 2 hours, a mixed g@ ggg): ggg gas consisting of hydrogen and naphtha having a com- OI 52,012.23@ 751 position shown below in a molar ratio of 7:1 was passed 5-3 CTO: 6&1 through the catalyst layer maintained at 500 C. under 1.5 HQMOAAHQO 67.5 2 1 5 WC13 6,5 9 15 a total reaction pressure of 5 lig/cm. at a liquid hourly 0.3 Rech 6v- 2 space velocity of 1.5 hrrl. Reaction results after 20 hours 0.05 Buon 53.9

0 1 RhC134H20 55 7 0f Operation are tabulated 111 Table II. 0.3 Paoli-21320 08.0 U H014 54-0 Composition of naphtha (vol. percent):

;1}Rbiso1+ZnCh 09.2 Param 655 Sn g2g Geol., suoli-2R10 75.4 20 Oln 02 26 Rigi-211+ o.i+o.(i)4 nusoiznoiioscii 70.0 Naphthen 237 S 27 None 63* Aromatics 10.6

*Dissolved in HC1. BP (o C), 88189 TABLE II Concentration of- Weight percent Lead nitrate Chloro- Weight percent Pb/Pt Overall Solution (moll platinic acid (wt Liquid aromatic Run number liter) (mol/liter) Pt Pb ratio) yield yield 1 0.0072 0.0077 0.3 0.3 1.0 86.2 77.4 2. 0. 0145 0.0077 0. 3 0. e 2. o 87. 9 71. 7 3- 0. 0217 0. 0077 o. 3 0. 9 3. 0 s?. 0 52. 2 4. 0.0072 0. 015 o. e 0. a 0. 5 85. 0 75. 3 5- 0. 0145 o. 015 0. e 0. 5 i. 0 85. 1 77. o e. 0. 029 0. 015 o. o i. 2 2. 0 S7. 5 72. 0 7 0.043 0.015 0.5 1.8 3.0 57.1 63.5 s (eomparanve).- 0. 05s 0.015 o. e 2. 4 4.0 87. 0 47. 2 9 0. 024 0. 020 i. o 1.0 1. 0 83. 0 76. 0 1o..-. 0. 049 0. 025 1. 0 2. 0 2. 0 85. 3 75. 5 11 0. 073 0. 02s 1.0 3. 0 e. o se. 7 se. 1 i2 (comparativ 0.122 0.020 1.o 5 0 5 0 87.4 41.5 13 (comparative). 0. 0077 0. 3 84. 1 47. 3 14 (comparative). 0.015 0.5 70.0 51. 2 15 (comparative) 0.026 1.0 77.9 62. 6

Example 28 .In 200 cc. of an aqueous solution containing 0.0128 mol/liter of chloroplatinic acid and 00036-00605 mol/ liter of lead nitrate were immersed 140 cc. of ry-alumina having a particle size of 2-3 mm. diameter as a carrier. The resulting product was evaporated to dryness, and then calcined at 550 C. for 3 hours. As shown in Table I, following, compositions of the resulting catalysts are 0.5 wt. percent Pt; 0.l5-2.50 wt. percent Pb and A1203, while Pb/Pt ratio is from 0.3 to 5.0. After cc. of the resulting catalyst were heated at 500 C. in the presence of hydrogen for 2 hours, a mixed gas consisting of hydrogen and n-heptane in a molar ratio of 3:1 was passed through the catalyst layer maintained at 490 C. under atmospheric pressure at liquid hourly space velocity of 0.5 hr.1. As a result, molar yields of various reaction products were as shown below.

Example 30 In 200 cc. of an aqueous solution containing 0.0121 mol/liter of lead chloride were immersed cc. of 'yalumina as a carrier. They resulting product was vaporized to dryness, calcined at 550 C. for 3 hours, and, subsequently, immersed in 200 cc. of an aqueous solution containing 0.0128 mol/liter of chloroplatinic acid, followed by vaporizing to dryness and calcining at 550 C. for 3 hours.

The resulting catalyst had a composition of 0.5 wt. percent Pt; 0.5 wt. percent Pb and A1203, while Pb/Pt ratio is 1.0.

After 20 cc. of the resulting catalyst were heated at 500 C. in the presence of hydrogen for an hour, a mixed gas consisting of hydrogen and n-heptane in a molar ratio of 5:1 was passed through the catalyst layer maintained TABLE I Concentrations in aqueous i solution Amount Overall yield of Pb Pb/Pt of benzene,

Chloro- Lead added ratio toluene xyleno platinc acid nitrate wt. (by produced (mol Run number (mol/liter) (mol/liter) percent) wt.) percent) 6 (comparative) 0. 0128 0. 0505 2. 50 5. 0 23. 1

7 (comparative) 0. 0128 0 0 25. 3

Example 29 at 500 C. under atmospheric pressure at a liquid hourly In 200 cc. of an aqueous solution containing 0.0072- 0.122 mol/liter of lead nitrate were immersed 140 cc. of

space Velocity of 0.5 hr.1.

As a result, the molar yield of total aromatic hydrofy-alumina having a particle size of 2-3 mm. diameter as 75 carbons produced based ori heptane was 78.3%.

Data shown in Tables I and II are also shown graphically in the accompanying figure.

COMPARATIVE EXAMPLE 1 20 cc. of a known catalyst comprising 0.5% Pt and 99.5 'y-alumina were heated at 500 C. under a hydrogen stream for an hour. Then, there was passed a mixed gas consisting of hydrogen and n-heptane in a molar ratio of 3:1 through the catalyst layer maintained at 500 C. under atmospheric pressure at a liquid hourly space velocity of 0.5 hr.-1. As a result, molar yields of the resulting products were as follows:

Reaction products (percent):

Aromatics:

Benzene 4.5

Toluene 17.6 Xylene 3.1 C9+ aromatics Trace Total aromatics 25.3 C-C7 parafns 40.8

Gaseous component:

Methane 8.5 Ethane 6.7

Propane 6.6 Propylene 0.8 Butane 10.0

Total C1-C4 32.6

Due to a drastic decrease in catalyst activity experienced in the instant reaction, the results shown above were values obtained after operation of an hour.

COMPARATIVE EXAMPLE 2 Twenty milliliters of a known catalyst consisting of 0.5% platinum and 99.5% y-alumina were heated under hydrogen at 500 C. for 1 hour. Through the catalyst layer was passed a gaseous mixture of hydrogen and n-heptane at an LHSV of 0.5 hr.-1 under atmospheric pressure, while maintaining the layer at 510 C. Molar yields of the products were: Benzene 8.7%, toluene 36.7%, xylenes 3.8% and the total aromatics 49.2% after a reaction time of 1 hour.

COMPARATIVE EXAMPLE 3 Composition of the naphtha source (percent by volume):

Paraiiins 48.3 Olens 0.4 Naphthenes 38.6 Aromatics 12.7

What is claimed is:

1. Method of producing aromatic hydrocarbons which comprises hydroforming a mixture of hydrogen and a hydrocarbon over a catalyst at a temperature of from 300 C. to 650 C. under a pressure of from 5 to 20 kg./cm.2, said catalyst consisting essentially of from about 0.01 to about 5 wt. percent platinum and from about 0.01 to about 5 wt. percent lead, up to about 1% by weight of a component selected from the group consisting of lithium, sodium, potassium, rubidium, cesium, beryllium, magnesium, calcium, strontium, barium, zinc, cadmium, mercury, germanium, bismuth, chromium, molybdenum, tungsten, uranium, rhenium, ruthenium, rhodium, palladium, osmium and iridium, up to 2.0% by weight of a halogen and a carrier, wherein the ratio of lead to platinum is within the range of from 0.1 to 3.0, and being prepared by simultaneously supporting said platinum and lead components on a carrier by impregnation, or first supporting said lead component on a carrier by impregnation and thereafter supporting said platinum component on said carrier by impregnation.

2. Method according to Claim 1 wherein said hydrocarbon is a member selected from the group consisting of naphtha, kerosene and light oil.

3. Method according to Claim 1 wherein said hydroforming is carried out under reaction conditions including a temperature ranging from 430 C. to 550 C., and an LHSV ranging from 0.2 to l0 hrl.

4. Method according to Claim 1 wherein said platinum component is a compound of platinum and halogen.

5. Method according to Claim 1, wherein the halogen is chlorine and the amount of chlorine contained in the catalyst is in the range of 0.1-2.0% by weight based on the total Weight of catalyst components.

6. Method according to Claim 1 wherein said carrier is a member selected from the group consisting of alumina, alumina hydrate, alumina gel, silica-alumina and a zeolite.

7. Method according to Claim l4 wherein said catalyst is treated with hydrogen-containing gas in the Vicinity of the reaction temperature prior to hydroforming.

8. Method of producing aromatic hydrocarbons which comprises hydroforming a mixture of hydrogen and a hydrocarbon ofver a catalyst at a temperature of from 300 C. to 650 C. under a pressure of from 5 to 20 kg./cm.2, said catalyst consisting essentially of from about 0.01 to about 5 wt. percent platinum and from about 0.01 to about 5 wt. percent lead and a carrier, wherein the ratio of lead to platinum is within the range of from 0.1 to 3.0, and being prepared by simultaneously supporting said platinum and lead components on a carrier by impregnation, or rst supporting said lead component on a carrier by impregnation and thereafter supporting said platinum component on said carrier by impregnation.

References Cited UNITED STATES PATENTS 2,378,209 6/ 1945 Fuller et al 260-6735 2,441,297 5/ 1948 Stirton 260-668 2,500,146 5/1950 Fleck et al 260-668 3,000,811 9/ 1961 Murray et al 208-90 3,607,728 9/ 1971 Wilhelm 208-111 3,425,792 2/ 1969 Stephens 23-2 3,649,565 3/ 1972 Wilhelm 252-466 PT 3,686,340 8/1972 Patrick et al 260-672 R 3,670,044 6/1972 Drehman et al 260-683.3

DELBERT E. GANT Z, Primary Examiner S. L. BERGER, Assistant Examiner U.S. Cl. X.R.

208-138; 252-441, 455 R, 455 Z, 466 PT

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