JPH0815555B2 - Alkane isomerization catalyst with platinum enriched in the surface layer - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to improved catalyst particles useful in the conversion of hydrocarbons, especially for use in alkane isomerization processes. In particular, it relates to an improved catalyst particle composed of a platinum component of the surface layer and a Friedel-Crafts metal halide component supported by a porous refractory oxide.

[0002]

BACKGROUND OF THE INVENTION Copolymerization of light naphtha is a process of increasing importance due to the refinement of stored gasoline by petroleum refiners. As the removal of tetraethyl lead anti-knock agents from gasoline has become universal and the demand for high performance internal combustion engines has increased, the need for "octane" or anti-knock performance in gasoline stores has increased. In the early days of lead removal initiation, refiners relied primarily on increasing the "octane number" of the product through catalytic reforming processes and liquid catalyzed cracking processes. These relatively inexpensive high-quality methods have been selected and utilized to a great extent, but in recent years, attention has been paid to the high quality of relatively low octane and high naphtha components.

The catalyst and process technology for the isomerization of light alkanes is already well known. However, due to the growing interest in recent years, the technology has made remarkable progress. Advances in catalyst and process technology have led to lower operating temperatures, and the product octane is favorably affected by isomer equilibrium. The significant reduction in the amount of hydrogen required for stable operation resulted in a significant cost savings, primarily by eliminating the need for a hydrogen recycle system. The development of both of the above technologies has led to the predominance of liquids in the isomerization reaction feed, as opposed to the gas phase operation of the prior art.

Catalysts that exhibit the dual functions of cracking and hydrogenation-dehydrogenation are widely applied in the petroleum refining and petrochemical industries for hydrocarbon reforming and isomerization. These catalysts generally have the decomposition function imparted by inorganic oxides, zeolites or halogens, and the hydrogenation-dehydrogenation function normally imparted by platinum group components. A catalyst useful in isomerization is formulated so as to achieve a desired conversion efficiency for a long period of time and effectively utilize an expensive platinum group metal component so that both its decomposition and hydrogenation-dehydrogenation functions are appropriately balanced. It must be.
The performance of the catalyst in the isomerization process is typically determined by its activity,
Evaluated by selectivity and stability. Activity is the ability of the catalyst to isomerize the reactants to the required product isomers at the specified reaction conditions. Stability is the rate of change of activity and selectivity over the life of the catalyst. The main reason for the low stability of the catalyst is the formation of coke (a high molecular weight, hydrogen-deficient, carbon-containing material) on the surface of the catalyst. Therefore, researchers involved in isomerization technology must face the challenge of developing catalysts that have high activity and stability, while at the same time suppressing coke formation or being largely independent of the presence of coke.

Researchers in the art have recently been concerned with the development of a cost-effective catalyst that fulfills the above-mentioned objectives, accompanied by the tendency to lower the isomerization temperature and increase the ratio of liquid reactants. Face to face. Including platinum group metal components and Friedel Crafts metal halide components,
The isomerization catalyst using a refractory inorganic oxide carrier is a well-known technique. For example, US Patent 2,
900,425 (Bloch et al.) Describes an isomerization process featuring catalysts consisting of alumina, platinum group metals and Friedel-Crafts metal halides. Aluminum chloride has been sublimed onto the alumina-platinum composite. Bloch et al. Have not elucidated the platinum group metals in the surface layer, but other methods of synthesizing platinum group metals and alumina have all been performed prior to catalyst particle formation. At the same time, US Patent 2,924,629 (Don
aldson), 2,999,074 (Bloch
Et al.) And 3,031,419, which describes a method for making catalysts. None of these have clarified the platinum group metal component of the surface layer. US Patent 3,963,643 (G
ermanas et al.) synthesize platinum group metals with alumina,
It describes a method for producing a catalyst which is important in the paraffin isomerization process by reacting the compound with Friedel-Crafts halogen metal and polyhalogen compounds. Other than Germanas et al., Apart from the platinum group metal in the surface layer, it is customary to impregnate alumina with an aqueous chloroplatinic acid solution that has been acid-treated with hydrochloric acid in order to promote uniform dispersion of platinum in alumina. … ”(2nd line 49-53)
I have pointed out. Layer formation of platinum group metal components in catalyst particles has already been elucidated by prior art.
US Patent 3,259,589 (Michaiko) 3,388,077 (Hoekstra)
And 3,931,054 (Lester) describe a method for preparing a catalyst for forming an inner surface layer of a Group VIII metal or platinum within the catalyst particles. US Patent 3,367,888 (Hoekstra)
Describes a method for preparing a catalyst for depositing a Group VIII metal on the outer surface of a support, and US Pat. No. 3,651,167 (deRosset) describes a hydrogenation method featuring a catalyst comprising a Group VIII metal or alumina with an impregnated surface. Each is explained. Furthermore, US Patents 3,897,368 (Ohara) and 4,431,75
0 (McGinnis) clarified a catalyst preparation method in which a precious metal or a platinum group metal was vapor-deposited on a support surface at a high concentration, and US Patent
4,520,223 shows a method for preparing a precious metal catalyst whose surface is impregnated, which is effective in the dehydrogenation method. U.S. Patent 4,71
6,143 (Imai) and 4,786,625 (Imai et al.) Show a catalyst consisting of surface-impregnated platinum, but at the same time show that it reduces unwanted side reactions such as isomerization. There is. US Patent 4,556,646 (B
ezman) described a catalyst with a uniform radial distribution of the noble metal and found that less permeation of palladium into the catalyst base increased coke generation in the hydrocracking reaction. It should be noted that none of the above patents elucidates the basic components of the current catalyst Friedel-Crafts halogen metal.

Therefore, in the history of the prior art for more than 20 years, the current aim is to combine the halogen metal of Friedel-Crafts and the platinum group metal component of the surface layer in a carrier of a heat-resistant inorganic oxide. No reduction is made with respect to the individual components of the catalyst particles. Consistent with the fact that the catalytic effect is unpredictable, the surprising advantages of this catalyst particle have been clearly observed in the field of modern, especially liquid phase isomerization processes.

[0007]

The object of the present invention is to make new catalyst particles which are particularly useful for the isomerization of isomerisable hydrocarbons. Thus, the object is to provide a process for isomerizing isomerisable hydrocarbons, especially alkanes having 4 to 7 carbon atoms per molecule.

[0008]

According to the present invention, catalyst particles having a Friedel-Crafts halogen metal and a platinum group metal in the surface layer on an inorganic oxide carrier enhance the octane number of a C ₅ / C ₆ naphtha stream. Therefore, it is based on the finding that it exhibits a surprising effect, and the main purpose is therefore to provide a catalyst system and its treatment which maximizes this finding.

A general embodiment of the present invention is a catalyst particle comprising a composite of a Friedel-Crafts halogen metal and a platinum group metal component of the surface layer on a heat-resistant inorganic oxide support, At this time, the concentration of the platinum group metal in each particle is 1.5 times or more the concentration of the surface core layer.
Alumina is recommended as the carrier for the heat-resistant inorganic oxide, alumina chloride is recommended as the Friedel-Crafts halogen metal, and platinum is recommended as the platinum group component of the surface layer. In the preferred embodiment, an organic polyhalogen component is added to the catalyst particles. The use of carbon tetrachloride is especially recommended. Viewed from another perspective, the present invention is recommended as a method of preparing current catalysts by surface impregnation of platinum group metal components, vapor deposition and sublimation of Friedel-Crafts metal components to an inorganic oxide support.

In a preferred process embodiment, isomerizable hydrocarbons are isomerized using the catalyst particles. Suitable materials are composed of alkanes C ₄ -C _7. In addition to the above, other objects and embodiments will be made clear in the details of the invention described later.

First, regarding the heat-resistant inorganic oxide carrier used in the present invention, the substance is preferably a carrier having a large surface area of 25 to 500 m ² / g which is porous and adsorbate. The porous carrier is also required to have compositional homogeneity and relative heat resistance to the conditions used in the process of hydrocarbon conversion. The term "composition homogeneity" as used herein means that the carrier does not form a layer, has no concentration gradient of elements due to the composition, and has a completely homogeneous composition. Thus, if the carrier is a mixture of two or more refractory substances, the substantial amount of these substances will be constant and uniform throughout the carrier. Within the scope of the present invention, the following (1), which has been commonly used as a bifunctional catalyst for hydrocarbon conversion,
It is intended to include a carrier material as described in (7). (1) Alumina, titanium dioxide, zirconium dioxide, chromium dioxide, zinc oxide, magnesia, thorium oxide, boron oxide, silica-alumina, silica-
Refractory (heat) inorganic oxides such as magnesium, chromium oxide-alumina, alumina-boron oxide, silica-zirconium oxide and the like. (2) Ceramics, porcelain, bauxite. (3) Synthetic products and silica including natural products, silica gel, silicon carbide, clays and silicates, among which acid treatment such as attaparcus clay, diatomaceous earth, fuller's earth, kaolin, etc. Some are possible and some are not. (4) Crystalline zeolite-based aluminum silicates such as hydrogen-type or non-acid-type X zeolite, Y zeolite, mordenite, and L zeolite having one or more alkali metals occupying cation-exchangeable positions. (5) Non-zeolitic molecular sieves such as aluminum phosphate, silico-aluminum phosphate, etc. (6) MgAl ₂ O ₄ , FeAl ₂ O ₄ , ZnAl ₂ O ₄ , CaAl ₂ O ₄
And other similar compounds having a molecular formula of MO—Al ₂ O ₃ (where M is a metal with a valence of 2). (7)
A combination of one or more substances from the above groups.

The preferred refractory inorganic oxide for use in the present invention is alumina. A suitable alumina material is γ
-, Η-, θ-, crystalline alumina known as alumina, of which γ- and η-alumina give the best results. A preferred heat resistant inorganic oxide is about 0.3 to about 1.0.
It has an apparent bulk density of 1 g / cc, and its surface area characteristics are such that the average diameter of pores is about 20-300Å, the volume of pores is about 0.1-1 cc / g, and the surface area is about 100 to about 500 m ² / g
belongs to. A particularly preferred alumina is US Patent 3,852, as a by-product of the Ziegler higher alcohol synthesis reaction as described in Ziegler US Patent 2,892,858.
Its properties were elucidated in 190 and 4,012,313. For simplicity, such alumina is referred to below as "Ziegler's alumina". Ziegler Alumina is now a trademark of "Catapal" under the name Vista Chemical Co.
from mpany and also under the trademark "Pural" Condea Chemie GM
Available from BH. This material is an extremely high-purity pseudo-boehmite powder and has been shown to produce high-purity γ-alumina upon high temperature calcination.

This alumina powder can be molded into a suitable catalyst substance by a technique known to those skilled in the art of molding catalyst carriers. For example, spherical carrier particles are formed from this Ziegler alumina by the following method. (1) This alumina powder is converted into an alumina sol by reaction with an appropriate deflocculating acid and water, and then the resulting mixture of sol and gelling agent is put into an oil bath to form an alumina gel. To produce spherical particles. This can be easily converted into a γ-alumina carrier material by known methods. (2) The powder is extruded by an existing method, molded, and then rolled into a spherical particle by a spinning machine, and then dried and calcined to generate a desired spherical carrier material particle. (3) After moistening the powder with a suitable peptizer, the powder particles are rolled into a spherical material of the desired size. This alumina powder can be used as a carrier material for rods, pills, pellets, tablets, granules, extrudates, and other shapes and modalities known to those skilled in the art of similar shapes, if desired, as catalyst material. It can be molded by a method well known to those skilled in the molding technology.

A preferred form of carrier material suitable for the present invention is a cylindrical extrudate having a diameter of about 0.75 mm to 3.3 mm,
Especially, a diameter of about 1.6 mm is desirable. The length to diameter ratio is approximately 1: 1 to 5: 1, with 2: 1 being particularly desirable. Extrudates of carrier material are usually prepared by mixing alumina powder with water and a suitable peptizer such as nitric acid, acetic acid, aluminum nitrate, etc. until an extrudable dough is formed. It The amount of water added to produce this dough is usually 45-65% by weight, sufficient to make up for the loss of combustion (LOI) at 500 ° C.
Above all, 55% by mass is desirable. On the other hand, the addition ratio of the acid is usually sufficient to supply 2 to 7% by mass of the volatile-free alumina powder used in the mixture, and particularly preferably 3 to 4% by mass. The dough thus produced is extruded through a die of appropriate size to obtain shaped particles. The extrudate is dried at a temperature of about 150 to 200 ° C and then calcined at a temperature of about 450 to about 800 ° C for 0.5 to 10 hours to form the desired shape of the refractory inorganic oxide. At this time, the heat-resistant inorganic oxide has an apparent bulk density of about 0.6 to about 1 g / cc and about 150 to 280 m / g (desirably, about 0.
(185 to 235 m / g at a pore volume of 3 to 0.8 cc / g)
It is desirable to be composed of fairly pure γ-alumina, having a surface area of.

An integral part of this catalyst is the platinum group metal component of the surface layer. Of the platinum group, namely platinum, palladium, rhodium, ruthenium, osmium and indium, palladium is the preferred component, with platinum being particularly preferred. Mixtures of platinum group metals are also within the scope of the invention. This component is chemically bound within the final catalyst composite, as a compound such as an oxide, sulfide, halide, oxyhalide, etc., and chemically bound to one or more other composite components. Or, it may exist as a single metal. Best results are obtained when almost all of this constituent is present in the elemental state. This component may be present in the final catalyst composite in any catalytically effective amount, but relatively small amounts are desirable. In fact, the platinum group metal component of the surface layer usually contains 0.01 to 2% by weight of the final catalyst, calculated on an elemental basis. Excellent results are obtained when the catalyst contains about 0.05 to 1% by weight of platinum.

The essential feature of the catalyst of the present invention is that the platinum group metal component is concentrated on the surface layer of each catalyst particle. For the purposes of defining the invention, the components of the surface layer have a concentration of at least 1.5 times the concentration in the core of the catalyst grains in the fine layer. If possible, the concentration of the platinum group metal surface layer is
Desirably at least about twice the concentration in the core. As illustrated below, the surface layer may be 100 or 1
It is 50 microns thick and the core is 50% of the volume or 50% of the particle size. However, it does not exclude other quantitative criteria. “Layer” here (Laye
r) is a layer (Str) of catalyst particles having an essentially uniform thickness.
atum). Also, “Surface Layer”
r) refers to the layer of catalyst particles in contact with the surface of the particles. "Diameter" is defined as the shortest dimension that passes through the center of the catalyst particle, eg, this dimension is the cylindrical diameter of the extrudate. In the examples described below, the concentration of platinum is from the surface of the catalyst particles towards the center or along its radius,
Being measured. The "core" is defined in the present invention as a concentric cylindrical portion which occupies 50% of the volume or diameter of the catalyst particles, respectively. As illustrated as a preferred extruded product of the present invention, the core portion is a concentric cylindrical portion excluding the surface and ends of the particles. A feature of the platinum group metal component as a component of the surface layer is to form a gradient of the platinum group metal component on the surface and inside of the catalyst carrier. The concentration of the platinum group metal component decreases as it progresses from the surface of the catalyst particles to the center. The actual gradient of the platinum group metal component inside the catalyst particles will vary depending on the process used in preparing the catalyst. However, substantially most of the white metal component exists outside the inside of the core of the catalyst particles. As described above, the concentration of the platinum group metal component in the surface layer of the catalyst is at least 1.5 in the central part of the catalyst particles.
It is twice, preferably twice. The concentration gradient of the platinum group metal component is quantified by a scanning electron microscope (SEM).
The SEM data show the approximate metal content at one point in the catalyst pill based on a cross-sectional view of the metal distribution related to the level of alumina. Since the results of the individual analyzes are not based on the zero point, it is not possible to integrate the distribution curve, and the whole curve may move up and down, causing errors in the interpretation. However, this data is useful for making relative comparisons of metal distributions.

The reason for this surprising performance improvement is not fully understood, but it appears that one application of the catalysts of the present invention primarily to liquid phase processes.
Operating temperature necessary for isomerization of C ₄ -C ₇ alkane by improved catalyst as in the present invention, lower than before.
Also, the proportion of hydrogen in the feed stream has dropped significantly in modern isomerization units, as will be discussed later. Both a decrease in temperature and a decrease in the proportion of gas lead to an increase in the proportion of liquid reactants. Since the length of the diffusion path inside the catalyst appears to be more important for liquid reactants, the metal components of the surface layer provide a great deal of convenience in approaching the location of the catalyst. This notion is supported by the evidence that in the case of gas phase isomerization processes associated with existing technology, the platinum group metal components of the surface layer do not receive similar benefits.

Incorporating a platinum group metal component into the catalyst of the present invention is suitable for providing a surface layer composition such that the metal component concentration of each particle of the catalyst is at least 1.5 times the core of the particle. You may adopt the method. Best results are obtained when the surface is impregnated with a platinum group metal component. In order to impregnate the surface with the platinum group component, a low concentration acid impregnation method using a solution of a soluble and decomposable complex compound of the platinum group component is recommended. Usually, the solvent used in this impregnation step is selected on the basis of the ability to dissolve the desired degradable complex compound, which is a low concentration of acid, preferably an aqueous solution. As implied by the low concentration of acid, the impregnating solution usually has a normality of 2 or less. A hydrochloric acid solution is preferred, but nitric acids can also be used. Representative platinum group compounds used to prepare the catalysts of the present invention include chloroplatinic acid, ammonium chloroplatinate, bromoplatinic acid, platinum dichloride, platinum tetrachloride hydrate and platinum carbonyl dichloride. Examples include dichloride, dinitro, diaminoplatinum, palladium chloride, palladium chloride dihydrate, and palladium nitrate. Chloroplatinic acid is preferred as a source of particularly preferred platinum compounds. The platinum component of the surface layer can be impregnated onto the catalyst from a chloroplatinic acid solution without the presence of strong inorganic acids such as hydrochloric acid and nitric acid.

The platinum group component is surface-impregnated by the compounded platinum group metal component compound being attracted to the heat-resistant oxide carrier, and the platinum group metal being retained mainly on the outer surface of the catalyst. A compound known as a complex with a desired platinum group component and a heat-resistant inorganic oxide carrier is
It can be used to prepare the catalyst of the present invention. It has been found that polydentate ligands are very useful in complexing platinum group metals and heat resistant inorganic oxide supports and impregnating platinum group metal components. A polydentate ligand is a compound that contains one or more adducts that can strongly bind to the oxide support. Such adducts typically include carboxylic acids,
It includes amino groups, thiol groups, phosphorus groups, or other highly polar chemical moieties. Further, the multidentate ligand has a high affinity for the platinum group metal component —SH or PR.
Containing a functional group such as ₂ (where R is a hydrocarbon), as well as another functional group consisting of a carboxylic acid or similar component that is strongly adsorbed to the metal oxide support, This is one aspect of the present invention. The preferable property of this multidentate compound is that it strongly binds to the platinum group metal, but also that the platinum group metal component does not penetrate the catalyst particles by binding quickly and firmly to the carrier. It is guaranteed. Some examples of useful polydentate ligands are: thio-malic acid, thiolactic acid, mercapto-propionic acid, thiodiacetic acid, thioglycolic acid,
Thio-propionic acid is included. It is also within the scope of this invention that the catalyst contains other metal components known to improve the effectiveness of platinum group metal components.
Such metal modifiers include rhenium, tin, germanium, lead, cobalt, nickel, indium, gallium, zinc, uranium, dysprosium, thallium, and mixtures thereof. A catalytically effective amount of such a metal modifier can be incorporated into the catalyst by methods known in the art. The composite is dried and calcined prior to addition to the Friedel-Crafts metal halide. This drying is carried out at a temperature of about 100 to 300 ° C., followed by sufficient conversion of the metal components to oxides at a temperature of about 375 to 600 ° C. in an air or oxygen atmosphere for about 0.5 to 10 hours. In order to oxidize and fire. In the preferred embodiment, the calcined composite is then subjected to a reduction step with hydrogen at similar temperatures and for similar times.

One of the essential components of the catalyst of the present invention is the Friedel-Crafts metal halide. Friedel-Crafts type compatible metal halides include aluminum chloride, aluminum bromide, ferric chloride, ferric bromide, zinc chloride, and similar compounds,
Of these, aluminum halides, especially aluminum chloride, usually give the best results. In general,
This component can be incorporated into the catalysts of the present invention by conventional methods of adding such metal halides. However, best results are usually obtained when subliming to the surface of a carrier according to the recommended method published in US Pat. No. 2,999,074. Halogenation of Friedel-Crafts due to the presence of chemically bonded hydroxyl groups in the refractory inorganic oxide during the preferred method in which the complex is impregnated with the Friedel-Crafts metal halide component. The reaction between the metal and the hydroxyl groups of the support takes place. For example, aluminum chloride reacts with the hydroxyl groups in a suitable alumina support to form active centers in the form of Al ... O ... AlCl ₂ , which enhances catalysis. Chloride and hydroxide ions occupy similar positions in the carrier, so that when the number of chlorides at the site is low, more hydroxide ions will form due to interaction with Friedel-Crafts metal halides. The site will be served. Therefore, when the chloride content of the carrier is in the low range of 0.1 to 10% by mass, it is possible to obtain a Friedel-Crafts type variety having a higher activity. The Friedel-Crafts metal halide can be sublimed and impregnated onto the composite under conditions such that the sublimed Friedel-Crafts metal halide will combine with the hydroxyl groups of the calcined support. Usually, Friedel, which reacts with the inorganic oxide carrier, accompanies this reaction.
About 0.5 to 2.0 moles of hydrogen chloride are removed per mole of Krafts metal halide. When subliming aluminum chloride that sublimes at about 184 ° C, a suitable impregnation temperature is about 19
0 to 700 ° C range, more preferably about 200 to 600 ° C
Is in the range. This sublimation can be carried out at atmospheric pressure or under pressure in the presence of a diluting gas such as hydrogen or light paraffinic hydrocarbons, or both. Friedel Crafts' metal halide impregnation
Although performed batchwise, the preferred method of impregnating the composite is to allow sublimed AlCl ₃ vapor to penetrate the composite layers as a mixture with a carrier gas such as hydrogen. According to this method, aluminum chloride is continuously deposited and reacted, and generated HCl is removed. The amount of Friedel-Crafts metal halide bound to the composite ranges from about 1 to 15% by weight, based on the Friedel-Crafts metal halide-free composite. In order to remove unreacted Friedel-Crafts metal halide from the final complex containing sublimed Friedel-Crafts metal halide, the complex was subjected to the sublimation temperature of Friedel-Crafts metal halide. Treat at the above temperature for a time sufficient to remove all unreacted Friedel-Crafts metal halide from the complex. For AlCl ₃ , temperatures of about 400 to 600 ° C. and about 1 to 48 hours are sufficient.

The Friedel-Crafts metal halide-containing composite thus obtained is subjected to a substantially water-free and hydrocarbon-free reduction step prior to its use in the conversion of hydrocarbons. Included within the scope of the present invention. The aim of this step is to ensure that the platinum group components are reduced to their respective metals and that the metal components are finely dispersed throughout the carrier. In this process, it is desirable to use virtually pure and dry (H ₂ O: 20 ppm by volume or less) hydrogen as a reducing agent. The reducing agent is contacted with the composite under conditions effective to reduce virtually all of the platinum group component to its metallic state, including temperatures of about 425 to 650 ° C. for about 0.5 to 2 hours. if,
If a prior measure is taken to pre-dry the plant in a virtually water-free state, and with hydrogen that is substantially free of water and hydrocarbons, this reduction process will be used as is. It can be implemented as part of the operating procedure. An organic polyhalogen component is used as an optional component of this catalyst. In this example, at least 2 composites containing Friedel-Crafts metal halide were prepared.
Contains methylene chloride atoms, methylene halides, haloforms, methylhaloforms, carbon tetrachloride, sulfur dihalides, sulfur halides. Thionyl halide. Treated with a polyhalogen compound selected from the group consisting of thiocarbonyl tetrahalide. Suitable polyhalogen compounds thus include methylene chloride, chloroform, carbon tetrachloride and the like. In each case, the polyhalogen compound must contain at least two chlorine atoms bonded to the same carbon atom. The recommended polyhalogen compound is carbon tetrachloride. The complex is preferably contacted with the polyhalogen compound in a state diluted with a non-reducing gas such as nitrogen, air or oxygen. In order to add at least 0.1% by mass of compound halogen to the complex, it is necessary to add about 0.2 to 5 at about 100 to 600 ° C.
Proper contact for time is an effective method. If the inorganic oxide support is first treated with a polyhalogen compound prior to incorporating the Friedel-Crafts metal halide, the improvement in catalyst performance is less than expected.

The catalyst of the present invention contains an additional halogen component. The halogen component is either fluorine, chlorine, bromine, iodine, or a mixture thereof. Of these, chlorine is the preferred component. This halogen component is generally present in a combined state with the inorganic oxide support. Although not essential to the invention, it is desirable that this halogen component be well dispersed throughout the catalyst. The content of halogen component is from 0.2 or more to about 15% by mass of the final catalyst, calculated on the basis of elements. The halogen component can be added to the catalyst either at the time of preparing the carrier of the inorganic oxide, at the time of adding the catalyst component, or before or after that. For example, the alumina sol used to form the desired alumina support material may contain halogen, at least some of which contributes to the final catalyst. The halogen component (or part thereof) can be added to the catalyst when the other catalyst component is incorporated into the support-for example when impregnating the platinum component with chloroplatinic acid. The halogen component (or a part thereof) is added to the catalyst by bringing the halogen or a solution, suspension, or dispersion containing the halogen into contact with the catalyst before and after blending the other catalyst component with the catalyst. You can also let it. Suitable halogen containing compounds are halogen containing acids such as hydrochloric acid. Alternatively, the halogen component (or part thereof) may be a halogen-containing compound, solution,
It is possible to mix with the catalyst by bringing the suspension and the dispersion into contact with the catalyst.

In the process of the present invention, a crackable hydrocarbon feedstock is mixed with hydrogen and contacted with a bed of catalyst particles of the type described above in the reaction zone of hydrocarbon isomerization. This contact can be carried out with the catalyst in a fixed bed, moving bed, fluidized bed system, or in a batch process. It is desirable to employ a fixed bed system in view of the risk of attrition of expensive catalysts and operational advantages. In this system, the hydrogen rich gas and feedstock are preheated to the desired reaction temperature by a suitable heating method and then flowed into an isomerization reaction zone containing a fixed bed of catalyst particles having the above characteristics. The isomerization reaction zone is in a single reactor,
Or in two or more separate reactors equipped with appropriate means to maintain the desired isomerization temperature at the entrance of each reaction zone. Two
The method of arranging more than one reactor is desirable for the purpose of allowing the isomerization to be improved by controlling the temperature of each reactor, and also for the purpose of partially replacing the catalyst without stopping the process. The reactants can be contacted with the bed of catalyst particles by any mode of flow, from above, from below, or radially. The reaction substance may be in a liquid phase, a gas-liquid mixed phase, or a gas phase at the time of contact with the catalyst particles, but when the present invention is applied to the liquid phase process, excellent results can be obtained. Alkanes having 4 to 7 carbon atoms in each molecule in the group of isomerizable hydrocarbons compatible with the feed to the process of the present invention (C ₄ -C ₇₎ is preferable. These include streams of straight-run light naphtha from petroleum refining or synthetic fuel production, light natural gasoline, light reformed gasoline, light raffinate cracking light naphtha from aromatic extraction, positive butane concentrate, field butane, etc. Included in. A particularly desirable feedstock is light straight run naphtha containing greater than 50% C ₅ and C ₆ paraffins with high concentrations of low octane normal paraffins. This feedstock is particularly susceptible to octane number improvement due to isomerization. Straight run light naphtha and other feedstocks also contain naphthenes, aromatics, olefins and hydrocarbons heavier than C ₆ . Up to 10% olefin content and C for efficient control of hydrogen consumption, cracking reaction, heat of reaction, and catalyst activity
Hydrocarbons heavier than ₆ should be limited to 20%.
It is generally known that high chloride platinum alumina catalysts of this kind are very sensitive to sulfur and oxygen containing compounds. Therefore, the feedstock should be free of these compounds and the concentration of sulfur should generally be below 0.5 ppm. The presence of sulfur in the raw material acts to temporarily deactivate the catalyst due to platinum poison. The activity of the catalyst can be recovered by removing sulfur from the catalyst compound with high temperature hydrogen or by reducing the concentration of sulfur in the inflowing raw material to 0.5 ppm or less to remove the sulfur adsorbed on the catalyst by hydrocarbons. It is possible. Moisture has the function of permanently deactivating the catalyst by removing highly active chloride from the catalyst and replacing it with inert aluminum hydroxide. Therefore, water and oxygenates that decompose to form water are only tolerated at very low concentrations. To that end, it is necessary to limit the concentration of oxygenates in the source material to usually less than 0.1 ppm. Sulfur can be removed from the feed stream by hydrotreating. Absorption systems for removing sulfur and moisture from hydrocarbon streams are known to those skilled in the art. Hydrogen is mixed with an isomerizable hydrocarbon feedstock such that the molar ratio of hydrogen to hydrocarbon feedstock is about 0.01: 5. Hydrogen is supplied entirely from the outside of the process, or is supplemented by hydrogen recovered as a raw material after being separated from the reaction effluent. Light hydrocarbons as well as small amounts of inert gases such as nitrogen and argon may be present in this hydrogen. It is desirable to remove water from the hydrogen supplied from outside the process using an absorption system known in the prior art. There is no net consumption of hydrogen in the isomerization reaction, but it is generally consumed in various side reactions such as cracking, disproportionation and saturation of aromatic and olefinic materials. Such hydrogen consumption is usually
Carbides that improve the stability of the catalyst by a hydrocarbon to feed molar ratio ranging from about 0.03 to 0.1 and compensate for variations in feedstock composition to maintain the conversion reaction and at the same time interfere with the function of catalyst particles. In order to suppress the formation of compounds (commonly called coke), more hydrogen than necessary to supplement consumption is retained in the reaction zone. In a preferred embodiment, the molar ratio of hydrogen to hydrocarbon in the reaction effluent is 0.05:
1 or less. Generally, molar ratios of 0.05 or less do not require the recycling of hydrogen from the reaction effluent to the feed. It is known that the amount of hydrogen required to suppress coke formation does not have to exceed the level of dissolved hydrogen. In a normal state reaction effluent, the amount of hydrogen in the solution is usually in a ratio of about 0.02: 1 to less than 0.01: 1. The amount of hydrogen above the amount required to replenish the consumption needed for good stability and conversion is measured in the effluent of the isomerization reaction zone, and the ratio of hydrogen to hydrocarbon is 0.01: 1 to 0.05: It is in the range of less than 1. If the ratio of hydrocarbon to hydrogen in the effluent is 0.05: 1 with the addition of dissolved hydrogen and excess hydrogen, these requirements are met for most feedstocks. The catalyst particles of the present invention have a effluent hydrogen to hydrocarbon molar ratio of 0.
Excellent results mainly in liquid phase processes with a ratio of less than 05: 1. The reactor temperature is usually in the range of about 40 to 250 ° C. Lower reaction temperatures are generally preferred because equilibrium favors relatively higher concentrations of isoalkanes over normal alkanes. Since low temperatures favor equilibrium mixtures containing the highest concentrations of high octane, highly branched isoalkanes,
When the raw material mixture consisting of alkanes C ₅ and C ₆ are primarily C ₅ and C ₆ alkanes, temperatures in the range of about 40 to 0.99 ° C. is preferred. If a significant amount of butane isomerization is desired, about 140 to 2 to maintain the activity of the catalyst.
Higher reaction temperatures in the range of 25 ° C are required. The operating pressure of the reaction is generally in the range of 1 to 100 atm, preferably 20 to 35 atm. Hourly liquid hourly space velocities range from about 0.25 to about 12 isomerized hydrocarbons per hour feed volume of catalyst.
The range of about 0.5 to 5 / hour is preferable. Also, the isomerization process requires the presence of small amounts of organic chloride cocatalysts. Since low levels of active chloride are constantly released from the catalyst particles with the feed of hydrocarbons, this organic chloride co-catalyst has been shown to retain high levels of active chloride in the catalyst particles. Contribute. The concentration of the co-catalyst in the mixed raw material is maintained at 30 to 300 mass ppm. The preferred cocatalyst compound is carbon tetrachloride. Only a few other suitable cocatalyst compounds are oxygen-free decomposable organic chlorides such as propyl dichloride, butyl chloride, chloroform. The presence of organic chlorides, some of which may be converted to hydrogen chloride, increases the need to dry the reaction. As long as the hydrocarbon feed and hydrogen are dry as described above, the presence of small amounts of hydrogen chloride will not have the opposite effect. Isomerization products from light naphtha feedstocks that are considered particularly suitable contain low octane normal paraffins and medium octane methylhexane, as well as the desired highest octane isopentane and dimethylbutane. It is within the scope of the present invention to subject the relatively low octane portion of the liquid product obtained in the same process to a step aimed at separation and recycling for the isomerization reaction. Generally, low-octane normal paraffin is separated and recovered to increase the octane number of the final product. Low-branch C ₆ and C ₇ paraffins are separated along with a small amount of hydrocarbons that are difficult to recover and separate,
Be recovered. Techniques for achieving this separation are well known and include fractional distillation methods and molecular sieve adsorption methods and the like. The catalyst and process of the present invention reduces the above-mentioned recycle appeal by achieving higher conversions to the desired product than when applying the prior art without recycle. The following examples are provided to illustrate the catalysts and processes of the present invention. These examples are presented as illustrative examples and should not be construed as limiting the scope of the claims.

Example 1 A prior art controlled catalyst was prepared to demonstrate the benefits of this catalyst. In order to obtain a masticated rebase material with a platinum to substrate ratio of about 0.9 to 1, 3.5% chloroplatinic acid, 2% of prior art extruded alumina base (particle size: about 1600 microns) was used.
It was vacuum impregnated in a solution of hydrochloric acid and 3.5% nitric acid (both by mass) so that the volume ratio was 9 solution to 10 base. Cold rolling the resulting mixture for about 1 hour,
Evaporated to dryness. Next, this composite was oxidized and contacted with a 1 M hydrochloric acid solution at 525 ° C. at a rate of 45 cc / hour for 2 hours to adjust the content of chloride. After that, this was subjected to reduction treatment in electrolytic hydrogen at 565 ° C for about 2 hours.
The content of chloride was about 1 to 25. After sublimating aluminum chloride with hydrogen, the catalyst was contacted with sublimed aluminum chloride at 550 ° C. for about 45 minutes to impregnate the active chloride to a level of about 5.5% by mass. This catalyst was named "Catalyst A". The catalyst contained approximately 0.247 of platinum and 5.5 (mass%) of chloride.

Example 2 "Catalyst B" containing approximately the same level of platinum as catalyst A was prepared according to the present invention for the purpose of evaluating the effect of platinum in the surface layer. The preparation of Catalyst B was done from the same prior art extruded alumina base used for Catalyst A of Example I. The extruded base was added to 3.5% (mass%) chloroplatinic acid solution (containing no effective concentration of hydrochloric acid and nitric acid to prevent uniform penetration of platinum into the carrier), and chloroplatinic acid 9 to base 10
A catalyst B was prepared by vapor deposition impregnation at a volume ratio of. The resulting mixture was cold rolled for about 1 hour and evaporated to dryness. Next, this mixture was oxidized and contacted with a 1 M hydrochloric acid solution at 525 ° C. at a rate of 45 cc / hour for 2 hours to adjust the content of chloride. Then, when this was subjected to reduction treatment in electrolytic hydrogen at 565 ° C. for about 2 hours, it contained about 1% of chloride to about 0.25% by mass of platinum. After subliming aluminum chloride with hydrogen, the catalyst is sublimed into aluminum chloride.
A treatment of impregnating the active chloride to a level of about 5.5% by mass was performed by contacting at 550 ° C. for about 45 minutes. This catalyst B contained approximately 0.242 of platinum and 5.8 (mass%) of chloride.

Example 3 In order to evaluate the effect of platinum in the surface layer on the platinum required for the catalyst, the "catalyst C" was used according to the present invention with the platinum content being about half that of catalyst A. Prepared. The preparation of catalyst C was done from the same prior art extruded alumina base used for catalyst A of Example I. Catalyst C
Was prepared by vapor deposition impregnation of a 3.5% (mass%) extruded chloroplatinic acid solution (without effective concentrations of hydrochloric acid and nitric acid) in a volume ratio of 9 chloroplatinic acid to 10 bases. The resulting mixture was cold rolled for about 1 hour and evaporated to dryness. The mixture is then oxidized to 1M
The content of chloride was adjusted by contacting with the hydrochloric acid solution of (2) at 525 ° C at a rate of 45 cc / hour for 2 hours. Thereafter, when this was subjected to reduction treatment in electrolytic hydrogen at 565 ° C. for about 2 hours, it contained about 0.125 mass% of platinum and about 1 chloride. After subliming aluminum chloride with hydrogen, the catalyst was contacted with the sublimed aluminum chloride at 550 ° C. for about 45 minutes to impregnate active chloride to a level of about 5.5% by mass. This catalyst C contained approximately 0.129 of platinum and 5.5% (mass%) of chloride.

Example 4 Catalyst Particles A, B and C were Scanned Electron Microscope (SEM)
It was evaluated by. The purpose of this analysis is to obtain catalyst particles A, B,
It is a confirmation of the distribution of platinum on the radius of C. 6 A and B particles each to derive a reliable average data
Each C particle and 3 C particles were evaluated. SEM as above
Data show the approximate metal content at any point within the catalyst particles based on the relationship between the content level of alumina and the metal distribution diagram. This data is useful for making relative comparisons of metal distributions. FIG. 1 shows the relative distribution of platinum levels over a radius of 800 microns from the surface of the catalyst particles to the center as a function of the average concentration of the core which accounts for 50% of the volume of the individual particles. The catalyst A showed a relatively uniform distribution of platinum, and the variation within the range of the catalyst was not so much observed between the surface layer and the core. Catalysts B and C clearly showed a relatively high platinum concentration in the surface layer, with the platinum concentration near the surface being up to about 2.5 times near the center of the catalyst particles. In order to quantify the differences between the catalysts according to both the invention and the prior art, the platinum concentration in the 100 micron and 150 micron surface layers was calculated from the data shown in Figure 1 as a function of the core platinum concentration. In addition, a core portion of 50% of the volume of the catalyst particles (both ends of the extruded product are considered as "surface layers") and a core portion of 50% of the particle diameter were considered. The ratio of the concentrations in the surface layer and the core is as follows. Margin Catalyst A Catalyst B Catalyst C 100-micron surface layer: 50% -volume core 1.26 1.88 1.67 50% -diameter core 1.31 2.02 1.87 150-micron surface layer: 50% -volume core 1.27 1.55 1.70 50%- Diameter core 1.32 1.66 1.91

Example 5 The relative performance of catalysts A, B and C when used for isomerization was tested. The same feedstock was used for each catalyst test, ie hydrotreated straight run naphtha having the following composition (wt%): A transient isomerization test was conducted under conditions of 450 psig, 1.0 hourly liquid hourly space velocity, 0.3 molar ratio of hydrocarbon to hydrocarbon, and continuous temperature. The results are shown in FIG. 2 as a curve of the mass ratio of isopentane in the total pentane and the mass ratio of 2,2-dimethylbutane (“2,2-DMB”) in the total hexane. These ratios are higher in sensitivity than the measured octane number as a catalyst performance test, and it is said that the reproducibility of isooctane and dimethylbutane isomers, which have the highest octane number in the product, is low in the reproducibility of the measured octane. In contrast, it shows a high degree of accuracy.

A comparison of the relative performance of catalysts A and B
Thus, the advantages of surface layer platinum are demonstrated. Catalyst B is the best
It represents a 1-2% advantage over the tan isomer and is superior to others.
At all low temperatures (more favorable equilibrium is obtained)
Reach the peak. Even the catalyst C with low surface layer platinum concentration is high
Compared with catalyst A whose platinum concentration is controlled,
Therefore, the present invention requires expensive platinum in the isomerization method.
It is demonstrated to reduce the amount. The result is as follows
To be summarized.Research method Peak pure octane Reactor outlet peak temperature (℃)  Catalyst A 82.7 149 Catalyst B 83.0 132 Catalyst C 82.8 138 Research method octane peak temperature
Due to the influence of other product isomers in the
Body C_FiveAnd C₆Does not necessarily match the temperature reached by.
However, the conclusions regarding catalyst performance are consistent.

[0030]

INDUSTRIAL APPLICABILITY As described above, the catalyst of the present invention is a useful catalyst for reducing the amount of platinum required which is expensive in the isomerization method of alkane, and a method using the catalyst.

[Brief description of drawings]

FIG. 1 shows the platinum concentration gradient of the catalyst particles of the present invention.

FIG. 2 shows the distribution of isomers produced by the isomerization of a light naphtha stream using platinum-enriched catalyst particles in the surface layer, in comparison with catalyst particles containing uniformly dispersed platinum.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Mark Earl. Ford United States, 60089 Illinois, Buffalo Grove, Claret Drive 414 (72) C. Inventor. David Row United States, 60532 Illinois, Rail, Troubridge Way 2342 (72) Frank H. Inventor. Adams United States, 84121 Utah, Salt Lake City, South 2200 East 6590 (56) References Japanese Patent Publication Sho 38-132 (JP, B1) Hattori Ei and 4 others "New Catalytic Chemistry" (sho 63-4-15) Sankyo Publishing P. 145

Claims (2)

[Claims] 1. A combination of 1 to 15% by weight of Friedel-Crafts metal halide and a refractory inorganic oxide support containing 0.01 to 2% by weight, based on the element, of the platinum group metal component. In the alkane isomerization catalyst particles, the concentration of the platinum group metal component in the surface layer of the catalyst particles is at least 1.
5 times, the depth of this surface layer is 150 microns,
Further, the diameter of the core portion is 50% of the volume diameter of the catalyst particles, which is an alkane isomerization catalyst. 2. In an alkane isomerization catalyst particle composed of a combination of 1 to 15% by mass of aluminum chloride and alumina containing 0.01 to 2% by mass of platinum component based on the element, the platinum concentration in the surface layer of the catalyst particle. Is at least 1.5 times the value of the platinum concentration in the core, the depth of this surface layer is 150 microns, and the diameter of the core is 50% of the volume diameter of the catalyst particles. Isomerization catalyst.