HU203292B - Catalyzer containing alkali metal of two kinds for dehydrogenating hydrocarbons and method for dehydrogenating hydrocarbons - Google Patents

Abstract

The present invention relates to a catalyst for the dehydrogenation of hydrocarbons, in particular paraffins, containing from 0.01 to 2.0% by weight of platinum group component, from 0.2 to 2.0% by weight of the IVA component of the periodic table, from 0.2 to 15% % halogen and two edges of alkali metal and are 0.05 to 2% by weight of lithium and 0.05 to 3% by weight of potassium. The invention also relates to the dehydrogenation process. Scope of the description: Page 8, Figure 2 EN 203 292 B -1-

Description

The present invention relates to the dehydrogenation of hydrocarbons which can be dehydrogenated in the presence of a hydrocarbon catalyst. In addition, the present invention relates to a novel catalyst composition.

The dehydrogenation of hydrocarbons is an important industrial hydrocarbon conversion process. due to the high demand for dehydrogenated hydrocarbon products for detergents, high octane gasoline, pharmaceuticals, plastics, synthetic rubbers, and other products well known in the art. Another such process is the dehydrogenation of isobutane to produce isobutylene, which polymerizes to provide an adhesive additive, a motor oil viscosity enhancer, and a plastic additive that is impact resistant and antioxidant.

Solid catalysts containing platinum group metals are well known among the catalysts used for the conversion of hydrocarbons. For example, U.S. Patent Nos. 2,479,109 and 2,479,110 disclose a catalyst comprising platinum and a halogen compound on an alumina support for various reactions, e.g. for the catalysis of reforming, hydrogenation, hydrocracking, oxidation and dehydrogenation. The term "reforming" in these patents refers to the simultaneous dehydrogenation, isomerization, cyclization, and cracking of abenzines. The halogen bound in the halogen compound plays a role in controlling the type of cracking effect in this catalyst. Excessive side effects, eg in order to avoid cracking reactions with excess gas evolution and low yielding liquid reformed product, it is advisable to keep the halogen content below 8% of the alumina content. These patents do not include alkali metal catalyst components.

U.S. Patent No. 2,930,763 discloses a two-step process for reforming hydrocarbons. In the first step, the hydrocarbon fraction containing the unsaturated compounds and / or nitrogen, sulfur or oxygen compounds is hydrogenated in the presence of a catalyst, the alumina catalyst used to hydrogenate and saturate the unsaturated compounds and / or reduce the nitrogen, sulfur or oxygen content of the hydrocarbon fraction. platinum and alkali metal components. The saturated hydrocarbon fraction from the first is contacted with a conventional reforming catalyst in the second step under reforming conditions, the catalyst used being platinum and bound halogen on an alumina support. Optionally, the catalyst used in the first step may also contain a bound halogen. Claim 2 of the present invention relates to a catalyst consisting mainly of alumina and 0.01% to 1% platinum, 0.1% to 1% bound halogen and 0.01% to 11% alkali metal.

This patent does not deal with the utilization of periodic system Group IVA elements as catalysts.

The hydrocarbon dehydrogenation process described in U.S. Patent 3,531,543 is performed with a catalyst comprising platinum and tin on a neutral metal oxide support. Preference is given to oxide carriers in which the internal acidity is neutralized with an alkali or alkaline earth metal. Pure alumina, for example, has a very internal acidity (see, for example, PInes and Haag, Journal of the American Chemical Society, 82, 2471, 1960). Aluminum oxide, for example, catalyzes the chain isomerization of olefins, dehydration of alcohols, and strongly binds amines. An increase in the amount of alkali metals also causes a reduction in the acidic nature of the alumina, and the catalysts are prepared from halogen-free compounds, which can be used in the manufacture of catalysts if the halogen residue is effectively removed from the finished catalyst composition.

U.S. Pat. No. 3,745,111 discloses a catalyst for reforming hydrocarbons comprising a platinum group component, a tin component, and a halogen component on a porous support. This patent also demonstrates that a platinum-tin-alkali or alkaline-earth metal composition is particularly effective in dehydrogenation of hydrocarbons. According to the patent, in dehydrogenation catalyst compositions containing an alkaline or alkaline earth metal, the amount of halogen, if not completely removed, should be kept to a minimum, due to the acidic nature of the alumina and the side reactions of the hydrocarbon cracking and isomerization. undesirable in industrial dehydrogenation processes) to keep or eliminate the amount of auxiliary halogen components.

U.S. Pat. No. 3,892,657 discloses that indium acts as a potent promoter on platinum-containing catalysts when the atomic ratio of indium to platinum is in the range of 0.1: 1 to 1: 1. . This patent also discloses that elements comprising group IVA of the periodic system, e.g. germanium, tin and lead can also be added to the indium-containing catalysts used in acidic reforming processes. This acid form catalyst thus comprises a platinum group component, an IVA group component, an indium component, a halogen component, and an indium component, a halogen component, and a porous support. The acid catalysts used for reforming processes contain up to 3.51% halogen and the acid catalysts used for isomerization and cracking contain up to 10% halogen.

However, in the catalyst used in the patented dehydrogenation process containing an alkaline or alkaline earth metal, however, the halogen content should be kept to a minimum (about 0.11%).

U.S. Patent No. 3,909,451 discloses a novel process for the preparation of a dehydrogenation catalyst.

-2GB 203292Β contains a platinum component, a tin component, and an alkaline or alkaline earth metal component. IV. In Example 1A, a platinum-tin-potassium composition containing less than 0.2% bound chlorine is disclosed.

U.S. Patent Nos. 4,329,258 and 4,363,721 disclose a catalyst comprising a platinum group metal, tin, an alkaline or alkaline earth metal, and a bonded halogen element on a refractory mineral metal oxide support. The atomic ratio of the alkali metal or alkaline earth metal to the platinum group metal is 0.210. The patents show that adding a ppm amount of an alkali or alkaline earth metal to a platinum group metal, tin and halogen catalyst for reforming processes results in an increase in the yield of the hydrocarbon fraction greater than 5 carbon atoms.

British Patent No. 1,499,297 discloses a catalyst for use in a dehydrogenation process comprising at least one of platinum, gallium, indium and thallium, and an alkali metal, particularly lithium or potassium, and alumina as carrier. The patent also contains 0.011% to 0.11% halogen. It is desirable to keep the halogen content within this low t% range in order to increase the selectivity and stabilizing effect of the catalyst.

The catalysts primarily used in the art, as described above, contain a platinum group component, a group IVA component, and an alkaline or alkaline earth metal component, the catalyst having an atomic ratio greater than 10, the halogen component must be removed completely or kept as low as possible, generally less than 0,1% but in any case less than 0,2% on an elemental basis.

Starting with column 18, line 47 of U.S. Patent No. 3,996,304, a catalyst composition is disclosed which comprises an alumina-containing refractory inorganic oxide compound, a tin component, a rhodium component, a platinum or palladium component, and an alkali compound. or an alkaline earth metal component. Among the alkali metal components, potassium and / or lithium are known to be preferred. These catalysts can be specifically used as selective hydrogenation catalysts, in particular for the conversion of conjugated diolefin hydrocarbons to monoolefin hydrocarbons. Although it is disclosed in the patents that the alkali metal component may contain potassium and / or lithium, it does not disclose the specific catalyst of the present invention in which the alkaline component may contain 0.05% to 2% by weight of lithium and 0.05% by weight. -3% by weight of potassium based on the weight of the composition. As can be seen from the examples presented below, the novel catalyst compositions of the present invention have not been widely described in the catalysts used primarily in the hydrogenation process.

Surprisingly, it has been found that by adding two types of alkali metal, lithium and potassium components to the catalyst, a catalyst composition is obtained which gives better results.

Thus, the present invention relates to catalyst compositions which provide better results. In addition, the present invention relates to hydrocarbon conversion processes, especially dehydrogenation of hydrocarbons, which have improved results.

Accordingly, the present invention relates to widely used catalyst compositions comprising a platinum group component, a periodic system group IVA component and two alkaline components on a support, the catalyst composition having two alkaline components in the range of 0.051% to 21% by weight of the composition. lithium and 0.051% to 31% potassium.

Additionally, the present invention relates to hydrocarbon dihydrogenation processes comprising contacting a hydrocarbon feedstock under a dehydrogenation condition with a catalyst comprising a platinum group component, a group IVA component, a two alkaline component and a support, It contains from 1% lithium and 0.051% to 31% potassium based on the weight of the catalyst composition.

The following description describes the invention in more detail.

Again, the present invention relates to a high performance catalyst composition and to the use of a catalyst. The field of application of the catalyst according to the invention is dehydrogenation.

As described above, a typical component of the catalysts of the present invention is a platinum group component. The platinum component may be selected from platinum, palladium, iridium, rhodium, osmium, ruthenium, or a mixture thereof. However, platinum is the most preferred element of the group. At present, all platinum group components are present in the catalyst in a metallic state.

The platinum group component should be thoroughly distributed throughout the catalyst. The amount of platinum group component present in the catalyst is from 0.011% to 51% based on the elemental base of the finished catalyst composition. Preferably, the catalyst contains 0.11% to 2.0% by weight of the platinum component, most preferably 0.11% to 0.01% of the platinum component.

The platinum group components may be used in any suitable manner, e.g. co-precipitation, co-gelling, ion exchange, impregnation, vapor phase or atomic material

203292Β by precipitation or by any known method, to the other catalyst compositions. A preferred mode of delivery of platinum group elements is by impregnating the carrier with a readily degradable suspension of platinum group metal. One way to do this is by example. mixing the carrier with an aqueous solution of hydrogen (hexachloroplatinate) (IV). To distribute or fix the platinum group element better in the catalyst composition, another acid, e.g. nitric acid or optionally another component may be added to the impregnating solution.

The component selected from Group IVA of the Periodic Table may be selected from the group consisting of germanium, tin, lead, and mixtures thereof. However, of the IVA group, tin is the most preferred. In our opinion, the components of the group IVA are present in the catalyst rather in the oxidized state than in the elemental state. Group IVA elements may be present e.g. in the form of oxide compounds or in combination with the support or the other catalyst component. Thorough distribution of the preferred IVA group components throughout the catalyst composition. The amount of the components in Group IVA is generally from 0.011% to 51% based on the elemental base of the finished composition. Preferably, the catalyst contains from 0.21% to 0.01% of the group IVA element, in particular from 0.21% to 0.01% of the tin.

Group IVA components may be administered by any suitable means, e.g. co-precipitation, co-gelling, ion exchange, impregnation, or any other known process, at the same time as the other catalyst components or later in the catalyst composition. A preferred way of introducing the tin component is by co-gelling during the preparation of the porous support. The mixing of the tin, e.g. the alumina support may be a soluble tin compound, e.g. by mixing stannous chloride or stannous chloride with alumina hydrosol, a gelling agent, e.g. addition of hexamethylenetetramine, and the resulting mixture is added dropwise to an oil bath to form spheres containing alumina and tin. A preferred method for introducing the germanium component is to use a catalyst carrier with a solution or suspension of a germanium degradable compound, e.g. impregnated with alcohol dissolved in germanium tetrachloride. Similarly, the lead component can be used to impregnate the support with a solution of lead nitrate in water.

Extremely good results have been achieved with the combination of the two types of alkaline components with lithium potassium, the molar ratio of potassium to lithium being in the range of 0.3-1.0, but similarly good results can be obtained if the atomic ratio is the same. In our view, the alkali component is present in the finished catalyst composition in oxidized rather than elemental form. The alkaline component may be present e.g. in the form of an oxide compound or in combination with a support or other catalytic component.

Thorough distribution of the alkali component in the catalyst composition is preferred. The alkali or alkaline earth metal component generally contains 0.05% to 2% by weight of lithium and 0.051% to 10.01% of potassium based on the elemental base of the finished catalyst composition. Preferably, the catalyst contains 0.05% -2.0% lithium and 0.051% -3.01% potassium.

The alkaline components may be used in some suitable manner, e.g. co-precipitation or co-gelling, ion exchange, impregnation, or any other known process, at the same time as the other catalyst components or later in the catalyst composition. A preferred mode of application of the alkaline component is to impregnate the carrier with a solution of potassium chloride and lithium nitrate.

For the porous material, a porous absorption carrier having a surface area of at least 5-500 m ^z / g is preferred. The porous carrier material should be heat resistant relative to the hydrocarbon conversion temperature. In the present invention, carriers conventionally used in the conversion of hydrocarbons have been considered as carriers, e.g. 1. activated carbon, coke or charcoal; 2. silica or silica gel, silicon carbide, clay minerals, synthetic and natural silicates, which may or may not be acid-treated, such as swelling material, porcelain, silica, bentonite, kaolin, diatomaceous earth, etc .; 3. ceramics, porcelain, ground chamotte, bauxite; 4. refractory inorganic oxide compounds such as aluminum oxide, titanium dioxide, zirconia, chromium oxide, beryllium oxide, vanadium oxide, cerium oxide, hafnium oxide, zinc oxide, magnesium oxide, boric oxide, thorium oxide, silicon aluminum oxide, silicon magnesium oxide, chromium aluminum oxide, aluminum boron oxide, silicon zirconia, etc .; 5. crystalline zeolitic aluminosilicates, e.g. naturally occurring or synthetic mordenite and / or faujasite, e.g. in hydrogen or metal cation exchange form; 6. spinels, e.g. MgAl2O4, FeAl2O4, ZnAfeCX CaAl2O4 and similar compounds of formula MO-Al2O3, wherein M is a metal of 2; 7. a combination of materials derived from one or more of the foregoing groups. Preferably, the carrier used in the catalyst used is alumina, especially gamma or etha-alumina.

The preferred carrier material can be made from synthetic or natural materials by any suitable means. The carrier may be formulated in any desired form, e.g. spheres, pellets, presses, presses, powders or granules, etc. and can be used in any particle size. The preferred form of the alumina support is a spherical form. Preferred particle diameters are about 1.5 mm, but about 0.75 mm and smaller.

The alumina spheres are prepared by converting an aluminum metal into an alumina sol by reaction with an appropriate peptic acid and water, and then dropping a mixture of the resulting colloidal solution and a gelling agent into an oil bath to produce spherical aluminum gel granules such as those described. aging, drying and annealing can be readily converted to the preferred gamma or ETA alumina support. In the case of alumina cylinders, alumina powder is mixed

-4HU 203292Β with water and an adequate amount of peptic acid, e.g. nitric acid until it has a compressible hardness. The resulting solid is pressed on an appropriately sized press and then cut to size. Other forms of alumina support may be prepared by any conventional method. After forming the alumina particulate forms, the resulting carrier material is generally dried and annealed. The alumina support is also subjected to an intermediate treatment during its manufacture, e.g. water wash or aluminum hydroxide wash, these treatments are well known in the art.

The catalyst compositions of the present invention also contain a halogen component. The halogen component may be fluorine, chlorine, bromine or iodine or a mixture thereof. Preferred halogen components are chlorine and bromine. In our opinion, the halogen component is present in the bound state with the porous support and the alkaline component. Thorough distribution of the halogen component throughout the catalyst composition is preferred. The amount of halogen component is between 0.21% and 151%, based on the elemental base of the finished catalyst.

The catalyst component may be introduced into the catalyst by any suitable means, either during the preparation of the support or before, during or after the introduction of the other catalyst components. The alumina sol used to make the preferred alumina support is e.g. may contain halogen, thereby providing at least a portion of the halogen content of the finished catalyst composition. The halogen component, or a portion thereof, may also be introduced into the catalyst by combining the carrier and other catalyst components, e.g. when using a hydrogen hexachloroplatinate (TV) compound for impregnation with the platinum component. The balogen component or part thereof may also be introduced into the catalyst composition by contacting the catalyst with a halogen or a halogen compound, a solution, suspension or dispersion containing the halogen, before or after combining the other catalyst components and the carrier. Suitable halogen-containing compounds include halogen-containing acids, e.g. hydrochloric acid. The halogen component or a portion thereof may also be introduced into the catalyst by contacting the catalyst with a halogen-containing compound, solution, suspension or dispersion in a subsequent regeneration step. In the catalyst regeneration step, the carbon deposited on the catalyst in the form of coke during the conversion of the hydrocarbon is burnt off the catalyst and the platinum group component is redistributed on the catalyst, so that the efficiency of the regenerated catalyst is close to that of the fresh catalyst. The halogen component, either during carbon combustion or during redistribution of the platinum component, e.g. by contacting the catalyst with hydrogen gas to introduce the catalyst into the catalyst. The halogen component may also be added to the catalyst composition such that the halogen or halogen-containing compound, solution, suspension or dispersion, e.g. propylene dichloride is added to the carbohydrate gene feed stream or the recycled gas during the hydrocarbon conversion process.

Optionally, the catalyst of the present invention may also contain a sulfur component. The sulfur content may generally be from 0.01% to 2% by weight based on the elemental base of the finished catalyst composition. The sulfur component may be introduced into the catalyst composition by any suitable means. Preferably, the sulfur or a sulfur-containing compound, e.g. contacting the hydrogen sulfide or a low molecular weight mercaptan compound with the catalyst composition in the presence of hydrogen at a temperature of from about 100.10 ° C to about 540 ° C, preferably under anhydrous conditions, to introduce the sulfur.

Optionally, the catalyst may contain additional components or mixtures thereof, acting alone or in combination, as catalyst modifiers to improve the performance, selectivity or stability of the catalyst. Some of these well known catalyst modifiers are e.g. Antimony, arsenic, bismuth, cadmium, chromium, cobalt, copper, gallium, gold, indium, iron, manganese, nickel, rhenium, scandium, silver, tantalum, thallium, titanium, tungsten, uranium, zinc and zirconium. In our catalyst system we mainly use indium as a further modifier. These components may be added to the carrier in any suitable manner during or after the preparation thereof, or may be added to the catalyst composition in any suitable manner, either before, during or after the combination of the catalyst components.

The catalyst of the present invention is preferably non-acidic. As used herein, the term "non-acidic" means that the catalyst has very little effect on chain isomerization, meaning that the catalyst, when tested under dehydrogenation conditions, converts 1-butane to less than 10% by weight of isobutylene. conversion is preferably less than 1%. The acidity of the catalyst may be reduced if necessary, and the catalyst may be rendered non-acidic by increasing the amount of the alkaline component within the range of the claim or removing a portion of the halogen component by steam treatment of the catalyst.

After combining the catalyst components and the porous support, the resulting catalyst composition is typically dried at 100 ° C to 320 ° C for a typical drying period of from 1 to 24 hours, but may be chelated to 320 ° C and 600 ° C. At a temperature of about 1 ° C, the calcination period is about 0.510 hours, but may be more. Finally, the annealed catalyst composition is generally subjected to reduction prior to use in the hydrocarbon conversion process. The reduction is carried out at a temperature in the range of about 230 ° C to 650 ° C for a period of 0.5 to 10 hours or more, in a reduction environment, preferably dry hydrogen, and the reduction temperature and reduction period are selected such that the platinum group components of the catalyst in a quantity metallic.

In the process of the present invention, the dehydrogenable hydrocarbons are in the dehydrogenation zone

203292Β under dehydrogenation conditions in contact with the catalyst composition of the present invention. The contact may be in a fixed catalyst bed system, a fluidized bed or other system, or in a batch process. A fixed catalyst bed is preferred. In this fixed bed system, the hydrocarbon feed stream is preheated to the desired reaction temperature and then introduced into the fixed catalyst bed zone for contact with the catalyst. The dehydrogenation zone consists of one or more separate reaction zones, and the heater between the zones ensures that the desired reaction temperature is maintained at each entry into the reaction zone. The hydrocarbons may be contacted with the catalyst by lower, upper, or radial inlet. In industrial-scale reactors, radial hydrocarbon flow is preferred. The hydrocarbon at the time of contact with the catalyst may be liquid, boiled-liquid or vapor-phase. Vapor contact is preferred.

Dehydrogenating hydrocarbons include dehydrogenated hydrocarbons having from 2 to 30 carbon atoms or more and include paraffins, alkyl aromatic hydrocarbons, naphthenes and olefinic hydrocarbons. One group of hydrocarbons that can be dehydrogenated with a catalyst is paraffins having from 2 to 30 carbon atoms or more. The catalyst is particularly suitable for dehydrogenation of paraffins having 2 to 15 carbon atoms or more to the corresponding monoolefin hydrocarbons or dehydrogenation of 3 to 15 carbon atoms or monoolefin hydrocarbons into the corresponding diolefin hydrocarbons.

The dehydrogenation conditions include a temperature of 400 ° C to 900 ° C, a pressure of 0.01 bar10 bar and a liquid velocity of 0.1 h ¹ to 100 h ¹ . Generally, higher temperatures are required for comparable conversion of normal molecular paraffins of lower molecular weight. The pressure in the dehydrogenation zone is kept to the lowest practicable level, consistent with the size of the equipment, to achieve possible chemical equilibrium values.

The flow of material leaving the dehydrogenation zone generally contains unmodified dehydrogenated reaction products. The effluent stream is then cooled and then transferred to a hydrogen separation zone for hydrogen separation, whereby the hydrogen rich vapor phase is separated from the hydrocarbon rich liquid phase. Generally, the hydrocarbon-rich liquid phase is separated by means of a suitable selective adsorbent or selective solvent or by a selective reaction or reactions or by a suitable fractionation system. The unconverted dehydrogenable hydrocarbons are recovered and recycled to the reaction zone. Intermediates used in the manufacture of dehydrogenation reactions or intermediates or other compounds.

The dehydrogenable hydrocarbons introduced into the dehydrogenation zone may be mixed with a diluent before, during or after introduction. Diluents include hydrogen, steam, methane, ethane, carbon dioxide, nitrogen, argon and the like. The preferred diluent is hydrogen. Generally, when hydrogen is used as a diluent, the molar ratio of hydrogen to hydrocarbon used is (0.1: 1) to (40: 1), the best results are obtained when the molar ratio of (1: 1) to (10: 1) value. The dilution hydrogen stream passing through the dehydrogenation zone is generally recycled to the process, separated from the vapors leaving the dehydrogenation zone.

Water or substances which undergo dehydrogenation under water conditions, e.g. alcohols, aldehydes, ethers or ketones may be added to the dehydrogenation zone continuously or intermittently. such that the amount thereof in the hydrocarbon feed stream is in the range of 1 to 20,000 ppm by weight. If the dehydrogenable paraffins contain from 6 to 30 carbon atoms or more, the best result is obtained with a water content of from 1 to 10,000 mass ppm.

Industrially significant dehydrogenation catalysts are characterized by three main properties: high activity, high selectivity, and good stability. Activity is a measure of the conversion capacity of a catalyst that indicates the extent to which the catalyst converts the starting compounds to the final product under specific reaction conditions, such as the specified temperature, pressure, contact time, optionally diluent. , e.g. concentration of hydrogen. The activity of the dehydrogenation catalyst was determined by measuring the conversion or disappearance of the paraffins and the result was expressed as a percentage of the amount of paraffin fed. Selectivity is a measure of the converting capacity of a catalyst that indicates the extent to which the catalyst converts the starting compounds to the desired compound or compounds relative to the amount of starting compounds. The selectivity of the catalyst was determined by measuring the molar amount of olefinic hydrocarbons formed in the product relative to the molar amount of the total converted paraffins, giving the result in mol%. Stability is a measure of the change in activity and selectivity parameters over time - a smaller change in values means a greater degree of stability.

Since dehydrogenation of hydrocarbons is an endothermic reaction and the degree of conversion is limited by chemical equilibrium, high conversion and low hydrogen partial pressure are desirable to achieve higher conversion. Under these extreme conditions, the activity and selectivity of the catalyst over a long period of time are difficult to maintain. due to increased aromatization, cracking, isomerization and coke formation. Therefore, it is advantageous from time to time to replace the catalyst with a catalyst of appropriate activity, selectivity and stability.

The following examples illustrate the catalyst and process of the present invention in more detail. The following examples are provided by way of illustration only and are not intended to limit the claims which follow.

-6HU 203292Β

Brief Description of the Drawings:

Figures 1 and 2 show the performance of catalyst A according to the invention and catalyst B other than the present invention in the dehydrogenation process of paraffins. Figure 1 shows the weight conversion of normal paraffins as a function of time measured in hours. Figure 2 depicts the catalyst selectivity, expressed as a percentage of the normal olefin hydrocarbon formed, as a percentage of the normal paraffin conversion. Figures 3 and 4 show the performance of the two additional catalysts in the dehydrogenation process of paraffins. In Figures 3 and 4, catalyst "C" is a catalyst other than the present invention, catalyst "D" being a catalyst according to the invention. Figure 3 shows the conversion in% of normal paraffins versus hours of measurement. Figure 4 illustrates the catalyst selectivity, expressed as a percentage of the normal olefin hydrocarbons produced, as a function of the normal paraffin conversion expressed as a percentage.

Example I

30.2 g of tin alumina support were impregnated with 4.6 g of 2.54% hydrogen hexachloroplatinate (IV) solution and 16.43 g of 0.8% lithium nitrate solution, 1.44 g of a 71% solution of nitric acid in water, 59.6 g, were added to the two solutions. The catalyst was dried in an oven at 150 ° C for 2 hours 20 minutes. In the next step, the catalyst was then annealed at 540 ° C for 2.5 hours in an air stream. The resulting composition (29.5 g) was then impregnated in a mixture of 6.7 g of 3.4% potassium chloride and 88.6 g of water. The composition was then heated with steam for 2 hours, in an oven at 150 ° C for 2 hours, and then heated at 540 ° C for 2.5 hours. The catalyst is then reduced by needles. The resulting catalyst A contains 0.391% platinum, 0.5% tin, 0.771% potassium, 0.44% lithium, and 0.75% chloride ion.

II. example

The second catalyst was prepared with a single alkaline component. The catalyst was prepared essentially according to the procedure of Example 1, except that impregnation with potassium and subsequent steam and furnace drying and annealing were omitted. Thus, the alkali component of the catalyst contained only lithium. The resulting catalyst composition "B" contained 0.381% platinum, 0.51% tin, 0.61% lithium and 0.11% chloride. It should be noted that despite the different percentages by weight of the alkali metals in the A and B catalysts, the two catalysts generally contain the same molar number of alkali components. Catalysts A, A 'and' B 'contain 8.4.10' 'and 8.5.10' 'moles of alkali metal, respectively, per 100 g of catalyst.

III. example

The third catalyst was prepared essentially as described in Example 2. Accordingly, this catalyst was not prepared by the process of the present invention and contains only one alkaline component. The resulting "C" catalyst contains 0.371% platinum, 0.51% tin, 0.61% lithium and 0.11% chloride.

ARC. example

The fourth catalyst was prepared essentially as described in Example 1. However, for this catalyst, the potassium chloride solution was replaced by a potassium nitrate solution. The resulting catalyst composition "D" contains 0.38 wt% platinum, 0.5 wt% tin, 0.761 wt% potassium, 0.451 wt% lithium and 0.19 wt% chlorine. In this way, this catalyst corresponds to the catalyst of the present invention.

Example V

In this example, the catalytic activity of catalysts A, and B for dehydrogenation of normal paraffins is shown. These evaluation studies were performed in a pilot plant consisting of a reactor and equipment for separating the product. The amount of raw material required for the batch was introduced into the reaction zone with 5 cm ^{3 of} catalyst. The product leaving the reaction zone was then separated and analyzed. The introduced feedstock contained par 3 carbon paraffins. A pressure of 138 kPa was maintained in the reaction zone.

The raw material is fed to the reaction zone per hour to 350 ml in 70 hours corresponding to a ^'one liquid space velocities. The specific gravity of the raw material was 0.7531 ml / g and its molecular weight was 166, so the molar feed was 1.59 mol / h. Hydrogen was added to the reaction zone at a rate of 11.2 g / h, resulting in a 4: 1 molar ratio of hydrogen to hydrocarbon. The reactor inlet temperature was maintained at 495 ° C. After two hours in the dehydrogenation operation, the exit temperature was 473 ° C for catalyst A and 481 ° C for catalyst B.

The results of the assay are shown in Figures 1 and 2. Figure 1 shows the weight conversion of normal paraffins as a function of reaction time in hours. Normal paraffin conversion is determined by dividing the mass of the feedstock converted during the reaction by the weight of the total feedstock. Figure 1 shows that after 20 hours, catalyst A gave a higher conversion than catalyst B.

Figure 2 shows the% selectivity for all normal olefin hydrocarbons versus t% normal paraffin conversion. The selectivity for all normal olefinic hydrocarbons was determined in% by dividing the mass of the amount of raw material used for the batch converted to the desired normal olefinic hydrocarbons by the weight of the feedstock fed to the batch. Figure 2 shows that catalyst A according to the present invention exhibits greater or comparable selectivity in the formation of the desired normal olefin hydrocarbons than catalyst B. In summary, during the last 60 hours of the 80 hour reaction time, catalyst A showed a higher conversion than

-7H 203292Β catalyst "B" and was more selective in the formation of the desired normal olefin hydrocarbons.

VI. example

In the previous example it should be emphasized that catalyst A contained 0.75% chloride ion and catalyst B contained 0.1% chloride ion. Two additional catalysts, "C" and "D", were also investigated to confirm that the better performance of catalyst A was not due to the higher amount of chloride chloride. In III. and IV. Examples 1 to 4 show that catalysts "C" and "D" contained 0.1% and 0.19% chloride chloride, respectively, so that these catalysts essentially contained the same amount of halogen.

The assays of the present invention were essentially as described in Example V. In this case, however, the raw material was C11-C13 normal paraffin with a molecular weight of 171. In addition, the reaction zone contained 10cnr of catalyst. Further, the catalyst was subjected to pre-sulfidation by the following process. The catalyst was reduced in the reaction zone at 495 C under a stream of hydrogen for 5 hours. Subsequently, hydrogen sulfide was added to the flowing hydrogen so that the gas mixture contained 99% hydrogen and 1% hydrogen sulfide. This mixture was then passed through the catalyst for an additional 5 hours at 495 ° C. After 5 hours, the flow of hydrogen and hydrogen sulfide mixture was stopped, and the raw material and diluent hydrogen were introduced. The test conditions were then set.

During the experiment the amount of feed was 700 ml / hour of from 20 ° C, as in Example V, this corresponds to 70 hours ^one liquid space velocities. The feed rate of 700 ml / h corresponds to a molar feed of 3.09 mol / h using a 171 molar mass of 0.775 ml / g feedstock. The hydrogen feed rate was 25 g / h, so the molar ratio of hydrogen to hydrocarbon was 4: 1. The reactor inlet temperature was carefully maintained at 495 ° C. The exit temperature of the six-hour dehydrogenation operation is 483 C for catalyst "C" and also 483 C for catalyst D.

The test results of the catalysts are shown in Figures 3 and 4. Figure 3 shows the conversion of% normal paraffins as a function of the hours of reaction time tested. Figure 3 shows that the catalyst "D" of the present invention results in a higher conversion than the catalyst of the present invention in the last 70 hours of the 80 hour study. Figure 4 shows the selectivity for all normal olefin hydrocarbons versus t% normal paraffin conversion. Figure 4 shows that catalyst "D" of the present invention resulted in improved selectivity in the production of standard olefinic hydrocarbons.

Therefore, it can be said that the better results obtained with the catalyst according to the invention in Example V are not due to the different halogen contents of the catalysts A and B. Figures 3 and 4 show that catalyst "D" of the present invention exhibited better conversion and selectivity properties than catalyst "C", despite having a comparable amount of halogen.

Claims (4)

Catalyst composition for the dehydrogenation of hydrocarbons, especially paraffins, comprising 0.012.0% by weight of a platinum group component, 0.22.0% by weight, a periodic system group IVA component, 0.2-15% by weight of a halogen component and two alkali metal components. on a support, characterized in that the two types of alkali metal components are 0.05 to 2% by weight of lithium and 0.05 to 3% by weight of potassium by weight of the composition. 2. The catalyst composition of claim 1, wherein the platinum group component is platinum, the periodic system group IVA component is tin, and the support is alumina. 3. A process for dehydrogenating hydrocarbons, in particular paraffins, under dehydrogenation conditions, characterized in that the paraffinic feedstock is dehydrogenated in the presence of a catalyst according to claim 1 or 2. 4. A method according to claim 3, characterized in that the dehydrogenation is 400 to 900 ° C takes place at a liquid space velocity of ¹ h and a pressure from 0.1 to 100 0.1 to 10 bar.