US2781324A - Method of preparing a platinum composite reforming catalyst - Google Patents

Description

cyclicized to form aromatics.

United States Patent Vladimir Haensel, Hinsdale, Ill., assignor to Universal Oil Products Company, Des Plaines, 111., a corporation of Delaware No Drawing. Application July 7, 1953,

Serial No. 366,522

14- Claims. (Cl. 252-466) This invention relates to hydrocarbon conversion processes involving the treatment and conversion of hydrovarbons and to the manufacture of catalysts for use therein. The present application is a continuation-inpart of my copending application Serial No. 318,085 (now abandoned), filed October 31, 1952, as a continuation-in-part of application Serial No. 220,740, filed April 12, 1951, now Patent No. 2,623,860.

The term reforming is well known in the petroleum industry and refers to the treatment of gasoline fractions to improve the antiknock characteristics thereof. The petroleum fraction that is up-graded in reforming may be a full boiling range straight run gasoline having an initial boiling point within the range of from about 50 F. to about 100 F. and an end boiling point within the range of from about 350 F. to about 425 F. It may also be a natural gasoline as obtained from the refining of natural gases or it may be any selected fraction of the natural gasoline. The natural gasoline or the natural gasoline fraction will have an initial boiling point and end boiling point substantially the same as that of the gasoline hereinbefore described. In the reforming process the gasoline fraction that is selected usually is the higher boiling fraction commonly referred to as naphtha and generally will have an initial boiling point of from about 150 F. to about 250 F. and an end boiling point Within the range of from about 350 F. to about 425 F. The catalyst of the present invention may also be appled to the reforming of cracked gasoline or mixtures of cracked and straight run and/or natural gasoline. Reference to gasoline in the present specification therefore means a full boiling range gasoline or any fraction thereof and also that the gasoline fraction may contain components boiling above the gasoline range.

In the reforming process there are four major reactions. The first is an aromatization reaction in which naphthene hydrocarbons are converted to aromatics. The second is a dehydrocyclization reaction in which the straight chain or slightly branched chain parafiins are Third is an isomerization reaction in which straight chain or slightly branched chain parafiins are converted to more branched chain paraffins. This reaction occurs as a result of a strain put upon a carbon to carbon bond so that there is a shift of a carbon atom in the molecule to form a more branched chain molecule. In this specific reaction there is no change of molecular Weight. The reaction may also be characterized as increasing the number of methyl groups in the hydrocarbon molecule. The fourth is a cracking reaction in which the heavier straight chain or slightly branched chain parafiins, which have low antiknock characteristics, are converted to lighter straight chain or branched chain parafiins which have higher antiknock characteristics. When this last reaction is conducted in the presence of hydrogen, the unsaturated hydrocarbon which is formed as a result of the cracking operation is saturated to the paraflin by reaction with hydrogen in the presence of. the reforming catalyst. The

2,781 ,324 Patented Feb. 12, 1957 cracking or splitting of the carbon to carbon bond is one of the more important reactions in a successful reforming process. It is necessary that the splitting of the carbon to carbon bond be controlled so that there is no unnecessary formation of normally gaseous products. For example, it would be possible to crack a C10 hydrocarbon to form ten molecules of methane, however, unless methane is the specifically desired product, it would be uneconomical in a reforming process to crack the C10 hydrocarbon to form methane. It is more desirable to crack a C10 hydrocarbon so that two molecules of pentane are formed and it would be still more desirable if during the reaction, isomerization would simultaneously take place so that the product obtained would be isopentane. It is an object of the present invention to provide a catalyst wherein the cracking activity is controlled and selective so that excessive amounts of normally gaseous products are not produced in a reforming process.

Uncontrolled or non-selective cracking results in the more rapid formation of larger quantities of coke or carbonaceous matter which deposits on the catalyst and decreases or detroys its activity to catalyze the desired reactions. This in turn results in shorter processing cycles or periods with the necessity of more frequent regeneration of the catalyst by burning the carbonaceous products therefrom, or should the catalyst activity be destroyed it will be necessary to shut down the unit to remove the old catalyst and replace it with new catalyst.

Another important feature in a successful reforming process is the matter of hydrogen production and consumption. Investigation has shown that the presence of hydrogen in the reforming zone further tends to decrease the amount of carbonaceous deposit on the catalyst. In view of the fact that the cost of hydrogen is quite high, it is essential that there be no new consumption of hydrogen or, in other Words, at least as much hydrogen must be produced in the process as is consumed therein.

While the catalyst of the present invention is particularly suitable for the reforming of gasoline, it is understood that this novel catalyst may be utilized for the conversion of other hydrocarbon fractions. Thus the catalyst may be used for the dehydrogenation of selected hydrocarbon fractions such as 'naphthenes to produce aromatics including specifically the dehydrogenation of cyclohexane to benzene, methylcyclohexane to toluene, ethylcyclohexane to ethylbenzene, etc., the dehydrogenation of paraffins to produce the corresponding olefins, including specifically dehydrogenation of butane to butene, pentane to pentene, hexane to hexene, etc., the dehydrogenation of mono-olefins to produce the corresponding diolefins including specifically dehydrogenation of butene to butadiene, pentene to pentadiene, etc. The catalyst may also be utilized to effect dehydrocyclization reactions including specifically the conversion of normal hexane to benzene, normal heptane to toluene, etc. The catalyst may also be used for effecting isomerization reactions including the isomerization of normal or mildly branched chain parafl'ins, the isomerization of alkyl cyclic compounds to isomers thereof, including the isomerization of methylcyclopentane to cyclohexane, ethylcyclopentane to methylcyclohexane, etc., the isomerization of alkyl benzenes, etc. Furthermore, the catalyst may be used for effecting hydrogenation reactions including non-destructive hydrogenation, as for example, the hydrogenation of butene to butane, pentene to pentane, aromatics to cycloparaifins, etc., and destructive hydrogenation of heavier oil to gases and/or gasoline fractions. In still another embodiment the catalyst of the present invention may be used for effecting oxidation of hydrocarbons to form the corresponding oxides,

such as the oxidation of normal butene to normal butyl alcohol. The catalysts are also very effective for desulfurizing sulfur-containing fractions. The desulfurization maybe effected in the presence .or absence of hydrogen. .In the de'sulfurization reaction the organic sulfurcompounds such as mercaptans or thiophencs are converted to hydrogen sulfide which may be stripped out in subsequent operations.

In one embodiment the present invention relates to a conversion process which comprises subjecting a hydrocarbon to contact at conversion conditions witha catalyst prepared by commingling alumina with a platinum compound, ammonium hydroxidesolution and anoxidizinglagent, in an amount to form a final catalyst containing from about 0.01% to about 1% by weight of platinum.

, .Inia'nother embodiment the'pres'ent invention relates to aprocess for reforming a gasoline fraction which comprises subjecting said fraction to contact at reforming conditions with a catalyst prepared by combining a halogen with alumina'in an amount of from about 0.1% to about 8% by weight of said alumina, commingling there- .with -.a platinum fcompound, ammonium. hydroxide solution and an oxidizing agent, in an amount to form a final catalyst containing from about 0.01% to about 1% by weight of platinum.

In still another embodiment the present invention relates to a method of manufacturing a catalyst which comprises commingling alumina with a platinum compound, ammonium hydroxide solution and an oxidizing agent, in an amount to forma final catalyst containing from about 0.01% to about 1% by weight of platinum.

In a specific embodiment the present invention relates to a method of manufacturing a catalyst which comprises combining a halogen with alumina in an amount of from about 0.1% to about 8% by weight of said alumina on a dry basis, forming the alumina into par ticles of substantially uniform size and shape, calcining said particles at a temperature 'of from aboutlOOO. F. to about 1400 F., commingling .with .the calcined particles a platinum compound, ammonium hydroxide, ammonium nitrate solution in anamountto form afinal catalyst containing fromabout'0.0l% .to about 1% by weight of platinum, .and heating the composite at a temperature of from about 500 F. to abouti1100'F.

The use of platinumas acatalyst for conversion processes has been iofj limited'commercial acceptance because of the high cost of 'the catalyst. 'Ihe presehtinvention is based on the discovery that exceplionallygood catalysts maybe preparedtocontain very'low concentrationsof platinum. While 'ftliese catalysts mayfcontain larger quantities of platinum, which may range up to about 10% by weight or more of the alumina, it has been found that exceptionally good catalysts may be prepared ,to

contain aslow'as from'about 0.01% to about 1% by weightfof platinum. Catalysts of these low platinum concentrations are particularly. preferred "in the present invention becauseof the, considerably lower cost of the catalyst. .It is well known that platinum is very expensive and any satisfactorymethod of reducing the amount of platinum considerably reduces the cost of the catalyst andthus enhances the attractiveness of the catalyst for use in commercial processes.

However, in order to obtain improved resultswith these low platinum concentrations, it is necessary that aparticular type of supporting component be composited .with

the platinum. It has been'foun'd that 'al'umina shows unexpected advantages for use as a supporting component for the low platinum concentrations. apparently due to some peculiar association of the alumina with the platinum, either as a' chemical combination or asa physical association. It has been found that the specific combination of alumina and low platinum concentration not only is a very active [catalyst but'also .has .a. long catalyst life; that is, the catalyst retains its high activity for long periods of service. After these long periods of service, the catalyst may show a drop in activity and it has further been found that the particular combination of alumina and platinum renders the catalyst susceptible to ready regeneration. Platinum on other supports such as alumina-silica, alumina-titania, and alumina-boron oxide also shows catalytic activity and the method of our invention for compositing platinum wtih alumina may also be used for compositing platinum with these other alumina-containing components but not necessarily with equivalent results.

As another essential feature of the present invention, impregnation of the alumina is effected in the presence of ammonium hydroxide and an oxidizing agent. A particularly suitable method of impregnation is by means of a solution of a suitable platinum compound. It has been found that, when the impregnation is eliected in the presence of ammonium hydroxide veven distribution of the platinum in or on the alumina particles is obtained, however, even though the distribution is uniform the ammonium hydroxide will tend to reduce the platinum to metallic platinum and thereby take the platinum out of its intimate association with the alumina. This is clearly illustrated inrthe examples. When the impregnation is effected in the absence of ammonium hydroxide, uneven distribution of the platinum in or on the alumina particles is obtained. Usually this uneven distribution comprises surface coating, that is the platinum compound is distributed only on the surface of the particles and not evenly throughout the mass. By effecting the impregnation in the presence of ammonium hydroxide solution, even distribution of the platinum throughout the alumina particles is obtained, however, an oxidizing agent is added to the alumina-platinum composite before final calcination in order that ammonium hydroxide will not take the platinum out of its association with the alumna.

A particularly satisfactory method of impregnating the alumina comprises the use of an aqueous solution of chloroplatinic acid. In a preferred embodiment the aqueous solution of chloroplatininc acid is commingled with an ammonium hydroxide solution containng an oxdizing agent and the mixture is added to alumina particles. In another embodiment, the ammonium hydroxide-oxidizing agent solution may be added to the alumina particles and the chloroplatinic acid solution is thereafter added to the mixture. In still another embodiment, the chloroplatinic acid solutionmay be added to the alumina particles and the ammonium hydroxide-oxidizing agent solution is thereafter added. In a further embodiment the ammonium hydroxide-chloroplatinic acid solution may be added to the alumina particles and an oxidizing agent is thereafter added. Ina still further embodiment the oxidizing agent, either directly or as a solution, may be mixed with the aluminaand then the alumina-oxidizng agent mixture may be commingled with the platinum compound and ammonium hydroxide. In any event, the mixture is allowedto stand, preferably with or after suitable agitation, so that thorough mixing is obtained and even distribution of the platinum throughout the alumina particles is effected.

The oxidizing agent that is chosen is selected so that an insoluble compound of platinum is not formed by its use at the conditions under which it is used. Any suitable oxidizing agent may be used with the nitrates and peroxides being preferred and with the particularjcompound, ammonium nitrate being specifically preferred.

The addition .of ammonium nitrate may form a precipitate which dissolves when the solution is heated. When ammonium nitrate is added to a heated solution of chloroplatinic acid and ammonium hydroxide a precipitate does not form.

With proper selection of the chloroplatinic acid solution, ammonium hydroxide solution and of the oxidizing agent, commin'gling of these will not form a precipitate or the precipitate will dissolve upon heating and, there fore, will not forfri ammonium chloroplatinate. Applicant is not certain as to the exact chemical formula of the compound formed but, in any event, it is apparent that the clear solution formed upon the mixing of ammonium hydroxide with chloroplatinic acid solution is different from the ammonium chloroplatinate precipitate formed upon the addition of ammonium chloride to chloroplatinic acid solution. If ammonium chloroplatinate solution is formed, either with or without the oxidizing agent as hereinbefore set forth, or due to the use of a too highly concentrated solution of chloroplatinic acid, the ammonium chloroplatinate solution may be redissolved to form the clear solution which is no longer ammonium chloroplatinate and apparently is the compound hereinbefore set forth. The difference between the two compounds is further evidenced by the fact that the addition of the carbonate ions, as by the addition of sodium carbonate, will not form a precipitate in the case of the mixture of ammonium chloride with chloroplatinic acid upon heating, but will form a precipitate in the case of the solution of ammonium hydroxide with chloroplatinic acid upon heating.

To further improve these catalysts, it is a preferred feature of the present invention that the final catalyst contains halogen ions in a specific concentration. It has been found that the presence of halogen ions within a specific range effects a considerable improvement in the catalyst. It is believed that the halogen enters into some chemical combination or loose complex with the alumina and/or platinum thereby seems to improve the final catalyst.

While any of the halogen ions will serve to effect improved results, fluoride ions are particularly preferred. Next in order are the chloride ions, while the bromide and iodide ions are generally not preferred. Mixtures of the halogens may also be used and their concentrations will lie within the ranges hereinafter specified. It is understood that, while any of the halogens will serve to elfect an improvement, they are not necessarily equivalent.

In still another preferred feature of the present invention the final composite of alumina-platinum compound and combined halogen is calcined in the presence of an oxygen-containing gas, particularly air, at a temperature of from about 500 F. to about ll F. for a period of two to twelve hours or more. Calcination in the presence of air results in a final gasoline product 1 of higher octane number than is obtained when the catalyst only is calcined in the presence of a reducing atmosphere. In still another embodiment of the invention the final composite may be reduced in the presence of hydrogen and then calcined in the presence of air. Both the reduction and calcination being effected at a temperature within the range of from about 500 F. to about 1100 F.

In a preferred embodiment of the invention the alumina is formed into particles of uniform size and shape prior to the impregnation with the platinum compound. As another particular feature of this embodiment the alumina particles of uniform size and shape are subjected to calcination at a temperature above 1000 F. and preferably within the range of from about 1000 F. to about 1400 F.'for a period of one to eight hours or more. The temperature and time of heating are correlated; that is, shorter times are employed with higher temperatures and longer times are employed with lower temperatures. On the other hand, the final composite containing platinum compound must not be heated at a temperature above 1100 F. and preferably is calcined in air at a temperature of from about 500 F. to about 1100 F. for a period of two to twelve hours or more as hereinbefore set forth.

It is an essential feature of the present invention that an oxidizing agent be added to the composite before the calcination step. The oxidizing agent may be added to the alumina and may be added thereto directly or as a solution. The oxidizing agent may be added to the solution of chloroplatinic acid, the oxidizing agent may be added to the ammonium hydroxide solution or it may be added to the solution of chloroplatinic acid and ammonium hydroxide. In still another embodiment the oxidizing agent may be added to the alumina after it has been composited with the chloroplatinic acid solution and/or the ammonium hydroxide solution.

The catalyst of the present invention may be prepared in any suitable manner. A particularly preferred method is to prepare alumina by adding a suitable reagent, such as ammonium hydroxide, ammonium carbonate, etc. to a salt of aluminum such as aluminum chloride, aluminum nitrate, aluminum acetate, etc. in an amount to form aluminum hydroxide which, upon drying is converted to alumina and in the interest of simplicity, the aluminum hydroxide is referred to as alumina in the present specification and claims in order that the percentages are based on the alumina free of combined water. Aluminum chloride is generally preferred as the aluminum salt, not only for convenience in subsequent washing and filtering procedures, but also because it appears to give best results.

After the alumina has been formed it is generally washed to remove soluble impurities. Usual washing procedures comprise washing with water, either in combination with filtration or as separate steps. It has been found that filtration of the alumina is improved when the wash-water includes a small amount of ammonium hydroxide. The severity of washing will depend upon the particular method employed in preparing the catalyst. In one embodiment of the invention, the alumina is thoroughly washed with a suitable amount of Water and preferably water containing ammonium hydroxide to reduce the chlorine content of the alumina to below about 0.1%. In another embodiment of the invention this washing may be selective to retain chloride ions in an amount of from about 0.2% to about 8% by weight of the alumina on a dry basis. In general, it is preferred to wash the alumina thoroughly, and if it is desired to add chlorine it is added as a separate step because better control of the amount of chlorine is obtained in this manner.

In some cases it is desirable to prepare the catalyst in the form of pills of uniform size and shape and this may readily be accomplished by grinding the partially dried alumina cake with a suitable lubricant such as stearic acid, rosin, graphite, etc. and then forming the pills in any suitable pelleting or extrusion apparatus. The halogen may be added before or after forming the alumina into particles of uniform size and shape. In still another embodiment the halogen and platinum addition may be effected prior to forming the composite into particles of uniform size and shape.

Alumina spheres may be continuously prepared by passing droplets of an alumina sol into an oil bath maintained at an elevated temperature and retaining the droplets in said oil bath until the droplets set to gel spheres. The spheres are continuously withdrawn from the oil bath and immediately thereafter aged prior to being contacted with water or aqueous solutions and subsequently dried and calcined at a temperature of from about 500 F. to 1400 F. or more.

Regardless of the stage of catalyst preparation at which the halogen is added, the halogen may be incorporated therein in any suitable manner. However, the halogen must be added in a form which will readily react with the alumina in order to obtain the desired results and also must not leave undesired deposits in the catalyst. A preferred method of adding the halogen is in the form of an acid such as hydrogen fluoride, hydrogen chloride, hydrogen bromide and/or hydrogen iodide. Hydrogen fluoride is preferably added as an aqueous solution for ease in handling and for control of the specific amount to be added. Another satisfactory source to be used for adding the halogenis the volatilesalts, suchas ammonium fiuoride,-amm'onium chloride, etc. The ammoniumions will beremoved during the subsequent heating of the catalyst and, therefore, will not leave undesirable deposits in the catalyst. In still another method, the halogen may be added as fluorine, chlorine, bromine or iodine, but in view of the fact that the-halogens are normallymore difficult to handle it isgenerally preferred to utilize'them in the form of a solution for ease in handling. In some cases, the inclusion of certain components will not be harmful but may be beneficial and in these cases the halogen may be added in the form of suitable salts.

The concentration of halogen ion in the finished catalyst will'be within the range of'from about 0.l% to about 8% by weight of the alumina on a dry basis. The iiuoride ion appears to'be more active and therefore will be user within the range of from about 0.1% to about 3% by weight of the alumina on a dry basis. It has been found that halogen concentrations below these lower limits do not'givet'he'desired improvement and, on the other hand, concentrations of halogen above the upper limits adversely eifect the selectivity of the catalyst thus catalyzing side reactions to an extent greater than desired.

As hereinbefore set forth, it is essential that the platinum compound be incorporated in the alumina or alumina-halogen composite in the presence of ammonium hydroxide to obtain uniform distribution of the platinum throughoutthe catalyst mass, and it is also essential that an oxidizing agent be present to obtain a catalyst in which the platinum is closely associated with the alumina. In accordance with the invention, the alumina or aluminahalogen particles are impregnated with a platinum compound, ammonium hydroxide solution containing an oxidizing agent in order to obtain even distribution of the platinum compound'throughout the alumina and close association of the platinum with the alumina. This uniform distribution has not been obtained in the absence of the ammonium hydroxide solution as may be clearly demonstrated by impregnating alumina pills in the presence and absence of ammonium hydroxide solution. Pills prepared in both of these methods may be treated with hydrogen-sulfide to fix the platinum compound as the sulfide which is a dark color. UpOn splitting open, it will be observed that the pills impregnated in the presence of ammonium hydroxide solution are of the same color throughout, Whereas the pills impregnated in the absence of am monium hydroxide are of a dark color on the outside and of a light color on the inside. Further, when an oxidizing agent is added to the composite before calcination, after calcination upon a splitting open and inspection of the pills impregnated in the presence of ammonium hydroxide,'which pills were composited with an oxidizing agent prior to calcination, it may be observed that the platinum is homogeneously distributed and further no dark color is in evidence, which dark color usually indicates the presence of metallic platinum and, therefore, the presence of the oxidizing agent keeps the platinum in close association with the alumina. The closer association of the platinum and the alumina while evidenced by the notable color differences is further evidenced by the superior activity and stability of the catalyst when used in a reforming operation.

A possible explanation of the benefits obtained with the evenly distributed catalyst pills is that the platinum molecules are spread through the pills and, therefore, are spaced further apart and will not result in the formation of large crystals of platinum. On the other hand, in the surface coated pills the platinum molecules are spaced closer together and therefore may form large crystals. Another advantage to the even distribution of the platinum throughout the catalyst is that the platinum in associationwith hydrogen tends to reduce carbonforrrration and thus, when the platinum is distributed evenly throughout the catalyst, this etfect is enhanced. On the other hand, when the platinum comprises only surface'coating, the center of; the pill may catalyze carbon formation because'of not being able' to benefit from 'thetendency of the platinum and hydrogen to reduce carbon formation.

The exact manner in which the oxidizing agent aids in keeping the platinumassociated with the alumina is'not known. The following theory, while substantiated by experimental data, is not conclusive and, therefore, the invention should not be limited to this explanation. It has been noted that platinum containing catalysts, as herein set forth, showed greater activity and stability when the final catalyst is calcined in'air as compared to when the final catalyst is calcined in a reducing atmosphere such as hydrogen. An explanation of this effect maybe that the reducing atmosphere converts the platinum compound into metallic platinum or a lower platinum 'oxide before the platinum compound has a chance of becoming intimately associated with the alumina either as a physical association or a chemical combination. Upon heating alumina, that is compo'sited with the chloroplatinic acidammonium hydroxide solution, the ammonium compound that is present in the composite decomposes and the ammonia which is liberated from the catalyst during the calcination appears to have a detrimental effect upon the catalyst in that it acts as a reducing agent on the platinum thereby rendering the platinum less able to associate itself with the alumina. it is probable that when an oxidizing agent is present in the catalyst prior to the calcination step, the effect of the reducing action of the ammonia is nullified.

As hereinbefore set forth, impregnation of the alumina particles with the platinum compound is effected in the presence of an ammonium hydroxide solution and in a preferred embodiment an aqueous solution of chloroplatinic acid is commingled with ammonium hydroxide in proportions to form a mixture having a pH within the range of from about 5 to about '10 and preferably within the range of from about 8 to about 10. The mixture is then heated and ammonium nitrate added thereto. This mixture is then commingled with the calcined aluminahalogen pills in the preferred embodiment of the invention, as hereinbefore set forth.

In another embodiment of the invention, the ammonium hydroxide solution or the chloroplatinic acid solution may be added to the alumina and the other solution subsequently added thereto.

It is an essential feature of the present invention that an oxidizing agent be present in the catalyst before the final calcination step. One possible explanation of the beneficial effects of the oxidizing agent are hereinbefore mentioned. Suitable but not necessarily equivalent oxidizing agents are'the nitrates, chlorates and peroxides. Ammonium nitrate is a specifically effective oxidizing agent. The concentration of the oxidizing agent to be used depends upon the particular oxidizing capacity of the compound. Suitable concentrations will usually lie within the range of from about 011% to about 5% by weight of the final catalyst. Specifically the concentration of ammonium nitrate will lie within the range of from about 0.1% to about 1.5% by weight of the final catalyst.

Regardless of the order of adding the ammonium hydroxide, the chloroplatinic acid solution, and the oxidizing agent, a particularly advantageous method of cornmingling the solutions with alumina is to soak the alumina-halogen pills in an aqueous solution of chloroplatinic acid, ammonium hydroxide and ammonium nitrate and then heat the mixture. In another embodiment of the invention the alumina pills are soaked in an aqueous solution of chloroplatinic acid and ammonium hydroxide and the oxidizing agent and the water and residual ammonium hydroxide and oxidizing agent are removed by'decanta-tion, filtering or the like. Inlthis embodiment of the invention the solution is preferably utilized as a hot solution.

The oxidizing agent may be added after the chloro platinic acid solution has been incorporated in the alumina pills and the water and residual ammonium hy-.

droxide removed therefrom. The composite is dried at a temperature of from about 200 F. to about 500 F. for a period of about two to twenty-four hours or more and the composite is then calcined in air at a temperature of from about 500 F. to 1100 F. but as hereinbefore set forth, shall not exceed 1100" F.

In the embodiment of the invention wherein pilling of the catalyst is not efiected until after the platinum compound has been added thereto the mass is dried at a temperature of about 200 F. to about 500 F. for two to twenty-four hours or more and then calcined at a temperature not to exceed 1 100 F. As hereinbefore set forth, after the platinum compound has been incorporated into the catalyst, the composite should not be heated to a temperature in excess of 1'100 Although the catalyst of the present invention will have a long life, it may be necessary to regenerate the catalyst after long periods of service. The regeneration may be effected by treatment with air or other oxygen-containing gas to burn the carbonaceous matter therefrom. In general, it is preferred to control the regeneration temperature not to exceed about 1100" F.

As hereinbefore set forth, these catalysts are particularly suitable for use in the reforming of gasoline or fractions thereof. The exact operating conditions depend upon the character of the charging stock as well as the activity of the catalyst being used, however, the conditions usually will he in the following ranges: Temperatures from about 500 F. to about 1000 F., a pressure from about "50 to about 1000 p. s. i. or more, weight hourly space velocity (defined as the weight of oil per hour per weight of catalyst in the reaction zone) of from about 0.5 to about 20 or more. The reforming is preferably effected in the presence of hydrogen which may be introduced from an extraneous source or recycled from within the process. In one embodiment of the process sufficient hydrogen will be produced in the reforming reaction to furnish the hydrogen required in the process and, therefore, it may be unnecessary to either introduce hydrogen from an extraneous source or to recycle hydrogen within the process. However, it usually will be preferred to introduce hydrogen from an extraneous source generally at the beginning of the operation and to recycle hydrogen within the process in order to be assured of a sufiicient hydrogen atmosphere in the reaction zone. The hydrogen present in the reaction zone will be within the range of from about 0.5 to about 20 mols of hydrogen per mol of hydrocarbon. In some cases the gas to be recycled will contain hydrogen sulfide introduced with the charge or liberated by the catalyst and it iswithin the scope of the present invention to treat the hydrogen containing gas to remove hydrogen sulfide or other impurities before recycling the hydrogen within the process.

Processes using the catalyst of the present invention may be effected in any suitable equipment. The finished catalyst may be deposited as a fixed bed in a reactor and the hydrocarbons to be treated are passed therethrough in either upward or downward flow. The catalyst may be used in a fluidized type of operation in which the catalyst and hydrocarbons are maintained in a state of turbulence under hindered settling conditions, or a fluidized fixed bed type of operation may be used in which zone, and the catalyst may also be used in the suspensoid type of operation in which the catalyst and hydrocarbons are passed as a slurry through the reaction zone. The reactants from any of the hereinbefore mentioned reaction zones are normally subjected to a further treat ment, such as the stabilization of the product to separate normally gaseous paraflins therefrom to obtain a final reformed product of the desired volatility and vapor pressure.

The following example is given to further illustrate the novelty and utility of the present invention, but is not given for the purpose of unduly limiting the generally broad scope of the present invention.

EXAMPLE A catalyst was prepared in accordance with the present invention by adding ammonium hydroxide to aluminum chloride hexahydrate to form aluminum hydroxide. The resultant aluminum hydroxide was washed very thoroughly in order to reduce the chloride content to below 0.1% by weight on a dry basis. This Washing entailed six separate Washes with large amounts of Water containing a small amount of "ammonium hydroxide and a final wash with water, with intervening filtering between the washes. The alumina was dried at a temperature of about 340 F. for eight to ten 'hours in order to reduce the moisture content to about 30%. The partially dried alumina was ground, Sterotex added as a lubricant, and then pilled in a Stokes pelleting machine to form cylindrical pills of Ms" K Ma" in size. The pills were then calcined in air at a temperature of about 932 F. for six hours to remove the lubricant and then further calcined at a temperature of about 1200 F. for three hours. Concentrated ammonium hydroxide solution (30%) was added to a dilute solution of chloroplatinic acid (0.1 gram of chloropzlatinic acid in 10 cc. of Water) to bring the pH of the solution up to 9. The solution was heated to boiling and ammonium nitrate was added in an amount calculated as 0.38 weight percent of the final catalyst. The alumina pills were then soaked in this solution, the quantities being controlled to form a final catalyst containing 0.9% by weight of platinum. The mixture was then heated on a steam bath, after which the catalyst was dried at 230 F. for three hours. The pills were then extracted with hot 5% ammonium nitrate solution. About eight washes were necessary to substantially remove the chloride brought in with the chloroplatinic acid. The pills were then calcined in air at 932 F. for three hours. This catalyst is referred to in this specification as catalyst B.

Another catalyst was prepared in substantially the same manner except that ammonium nitrate was not used in the impregnating solution. This catalyst is referred toas catalyst A.

Several other catalysts were prepared in the same manner as catalyst B except that varying amounts of ammonium nitrate were used in the impregnating solution. The various catalyst preparations are tabulated below in Table I.

Table I Catalyst A study of the above catalysts showed that when using an oxidizing agent in the impregnation step the platinum associated itself with the alumina more completely. This was indicated by the fact that the pills impregnated in the 11 presence of ammonium .nitrate were lighter in color than those prepared without the oxidizing agent.

.Catalysts A and C each were separately used in the reforming of a Mid-Continent naphtha having a boiling range of from 230 F. to 413 F. and an F-l clear octane number of 34.0, at an average catalyst temperature of about 860 F., a pressure of 500 pounds per square inch, a liquid hourly space velocity of 1.99, and a hydrogen to hydrocarbon mol ratio of 2.98. The analysis of the charge stock and reformed product are shown in Table II below.

Table II Charge Catalyst A CatalystG Percent at 212 F.+1oss in Engler. 9. F-l clear octane numbcr 7.

It will be noted from the above data that catalyst C had more hydrocracking activity as shown by the higher percent at 212 F. in the Engler distillation and also that the catalyst produced a product of higher octane numher.

1 claim as my invention:

1. A method of manufacturing a catalyst which comprises commingling alumina with a platinum compoundammonium hydroxide solution and an oxidizing agent in an amount to form a final catalyst containing from about 0.01% to about 1% by weight of platinum.

2. A method of manufacturing a catalyst which comprise-s com-mingling alumina with a platinum compoundammonium hydroxide solution and a nitrate in an amount to form a final catalyst containing from about 0.01% to about 1% by weight of platinum.

3. Method of claim 2 further characterized in that said nitrate is ammonium nitrate.

4. A method of manufacturing a catalyst which com prises combining a halogen with alumina in an amount of from about 0.1% to about 8% by weight of said alumina on a dry basis and commingling therewith a platinum compound-ammonium hydroxide solution containing an oxidizing agent in an amount to form a final catalyst containing from about 0.01% to about 1% by weight of platinum.

5. The method of claim 4 further characterized in that said oxidizing agent is ammonium nitrate.

6. A method of manufacturing a catalyst which comprises combining a halogen with alumina in an amount of from about 0.1% to about 8% by weight of said alumina on a dry basis, forming the alumina into particles of substantially uniform size and shape, calcining said particles at a temperature of from about 1000 F. to about 1400 F., commingling with the calcined particles a platinum compound-ammonium hydroxide-ammonium nitrate solution in an amount to form a final catalyst containing from about 0.01% to about 1% by weight of platinum, and heating the composite at a temperature of from about 500 F. to about 1100 F.

7. The method of claim 6 further characterized in that said halogen comprises fluorine in an amount of from about 0.1% to about 3% by weight of alumina on a dry basis.

8. The method of claim 6 further characterized in that 112 said halogen comprises chlorine in an amount of from about 0.2% to about 8% by weight of the alumina on a drybasis.

9. The method of claim .6 further characterized in that said ammonium nitrate is present in an amount of from about 0.05% to about 1.5% by weight of the final catalyst on a ,dry basis.

10. A method of manufacturing a catalyst which comprises precipitating alumina from aluminum chloride, washing to remove chloride ions to below about 0.1% by weight of said alumina, adding a dilute aqueous solution of hydrogen fluoride to said alumina in an amount to form a final catalyst containing from about 0.1% to about 3% by weight of fluorine based on said alumina, calcining the composite at a temperature of from about 1000 F. to about 1400 F. and commingling with said composite a platinum compound-ammonium hydroxideammonium nitrate solution having a pH of from about 5 to about 10, in an amount to form a final catalyst containing from about 0.01% to about 1% by weight of platinum.

11. A method of preparing a catalyst which comprises precipitating alumina from aluminum chloride, washing with water containing ammonium hydroxide to remove chloride ions to below about 0.1% by weight of said alumina, adding a dilute aqueous solution of hydrogen fluoride to said alumina in an amount to form a final catalyst containing from about 0.1% to about 3% by weight of fluorine based on said alumina, drying the composite to a moisture content of about 30%, grinding the mass and adding a lubricant, pelleting to form cylindrical pills, calcining at a temperature of from about 1000 F. to about 1400 F., commingling with the calcined pills a platinum compound-ammonium hydroxideammonium nitrate solution having a pH of from about 5 to about 10 and containing the ammonium nitrate in an amount of from about 0.05% to about 1.5% by weight of the final catalyst on a dry basis, the last-named solution being in an amount to form a final catalyst containing from about 0.1% to about 1% by weight of platinum, thereafter heating the pills to evaporate Water and resid ual ammonium hydroxide, and calcining the final composite at a temperature of from about 500 F. to about 1100 F.

12. A method of catalyst manufacture which comprises commingling with alumina a platinum compound, ammonium hydroxide and an oxidizing agent and calcining the resultant mixture.

13. The method of claim 12 further characterized in that said oxidizing agent is a nitrate.

14. A method of catalyst manufacture which comprises impregnating alumina with a mixed solution of a platinum compound, ammonium hydroxide and ammonium nitrate and calcining the thus impregnated alumina.

References Cited in theme of this patent UNITED STATES PATENTS

Claims (1)

1. A METHOD OF MANUFACTURING A CATALYST WHICH COMPRISES COMMINGLING ALUMINA WITH A PLATINUM COMPOUNDAMMONIUM HYDROXIDE SOLUTION AND AN OXIDIZING AGENT IN AN AMOUNT TO FORM A FINAL CATALYST CONTAINING FROM ABOUT 0.01% TO ABOUT 1% BY WEIGHT OF PLATINUM.