RU2223818C2 - Halogen-containing catalyst and a method for preparation thereof - Google Patents

Abstract

FIELD: organic synthesis catalysts. SUBSTANCE: catalyst used in production of aromatic hydrocarbons contains one or more halogen components with uniform quantitative distribution of halogen. Preparation of catalyst involves deposition of one or more halogen components on L-type zeolite followed by drying at the water vaporization rate 15 wt %/h or less. According to invention, catalyst can be prepared in such a way as to homogenously distribute halogen in order to reduce cracking power of catalyst. EFFECT: increased selectivity regarding aromatics. 7 cl, 2 dwg, 1 tbl, 5 ex

Description

 The invention relates to a catalyst used in the production of aromatic hydrocarbons, and to a method for producing such a catalyst. More specifically, the invention relates to a halogen-containing catalyst, such as one or more halogen components and platinum supported on an L type zeolite catalyst in which the halogen is evenly distributed, while the cracking activity of the catalyst can be reduced. The invention also relates to a method for producing a catalyst.

 To date, platinum-alumina catalysts have been used as a catalyst in the production of aromatic hydrocarbons by aromatizing non-aromatic hydrocarbons, such as aliphatic hydrocarbons. However, such catalysts have the disadvantage that hydrocarbons containing 6 or 7 carbon atoms could not be effectively converted to aromatic hydrocarbons.

 To solve this problem, Japanese Patent Application Publication No. 57408/1983 proposed a catalyst in which platinum is applied to an L type zeolite, and subsequently various methods for improving the activity, selectivity, catalyst life, etc., have been proposed for the L type zeolite, or simplified methods for producing a catalyst.

 For example, the following were proposed: (1) a catalyst in which type L zeolite bearing a Group VIII metal is oxychlorinated to improve catalytic activity and catalyst life (Japanese Patent Application Laid-Open No. 168539/1985); (2) a catalyst treated with a solution containing a solution of platinum and a non-platinum metal salt to uniformly distribute and deposit platinum (Japanese Patent Application Laid-Open No. 138539/1986); (3) a catalyst in which platinum is supported on a type L zeolite treated with a halogen-containing compound (Japanese Patent Application Laid-Open No. 57653/1987); (4) a catalyst in which platinum-bearing L type zeolite is treated with a halogen-containing compound (Japanese Patent Application Laid-open No. 91334/1988); and (5) a catalyst prepared using a simple process that involves simultaneously applying and treating a platinum component and one or more halogen components on type L zeolite (Japanese Patent Application Laid-Open No. 49936/1993).

 However, the above-mentioned catalysts (1) - (5) in practical application create a number of problems, and all these catalysts are characterized by high cracking activity. Therefore, the selectivity to aromatic compounds is insufficient.

 The present invention is designed to solve the above disadvantages. In other words, it is an object of the present invention to provide a catalyst for producing aromatic hydrocarbons in which the quantitative distribution of halogen in the catalyst is uniform, so that its cracking activity can be reduced.

 Another objective of the present invention is to provide a process for the preparation of the catalyst described above.

 The applicants of the present invention conducted extensive research to develop a practical catalyst for the production of aromatic compounds, which could solve the problems associated with the above catalysts, and the cracking activity of which can be reduced. As a result of the studies, it was found that if the evaporation rate of water is reduced at the drying stage of the catalyst preparation process, a catalyst can be obtained in which the halogen is evenly distributed so that the object of the present invention is effectively achieved. The present invention is based entirely on this conclusion.

In other words, the first object of the present invention is a halogen-containing catalyst that contains one or more halogen components and in which the halogen is evenly distributed. In particular, the invention relates to a halogen-containing catalyst for which, in the drawing, showing the relationship between the distance in the direction of the cross-sectional width (x: distance from one surface of the catalyst) and the x-ray intensity (I) obtained by evaluating the halogen atom in the cross-section of the catalyst using linear analysis in one direction by using a device with the electron-beam microanalytical probe (herein referred to as ELMAZ), the ratio α [{(FF ₀₎ / F} value (FF ₀₎ for integrated greatness e (F)] is 0.17 or less, wherein the value (FF ₀₎ is obtained by subtracting the value (F ₀₎ obtained by integrating the X-ray intensity (I ₀₎ of the tangent of the curve at the minimum and smallest value of the curve showing the intensity of X rays relative to x between one surface of the catalyst and another surface of the catalyst, from the value (F) obtained by integrating the above intensity I relative to the distance x between the surfaces.

 A second aspect of the present invention relates to a method for producing a halogen-containing catalyst, which comprises the step of depositing one or more halogen components on a carrier, in particular a type L zeolite, and then drying it at a water evaporation rate of 15 wt.% / Hr or less.

 In FIG. Figure 1 shows the relationship between the distance in the direction of the cross section width (x) and the x-ray intensity (I) in the case when the halogen atom is subjected to linear analytical measurement using an ELMAZ device.

 In FIG. 2 shows a perspective view of one example of a catalyst based on type L zeolite used in measurements using ELMAZ.

 The halogenated catalyst of the present invention has such a uniform distribution of halogen as described above. Figure 1 shows the quantitative distribution of halogen in the halogen-containing catalyst of the present invention and shows the relationship between the distance in the direction of the cross-sectional width (x) and the x-ray intensity (I) in the case when the halogen atom is linearly analyzed using ELMAZ. In addition, in FIG. 2 is a perspective view showing one example of a catalyst based on type L zeolite, which was used in the above-mentioned measurement using ELMAZ.

 The present invention is further described in more detail by the example of FIGS. 1 and 2.

In the case where the catalyst of the present invention has, for example, such a cylindrical shape as shown in FIG. 2, a linear analysis using ELMAZ is carried out in a straight line shown in the drawing with respect to a sectional section parallel to the lower surface. Figure 1 presents the results of a linear analysis together with the ratio between the distance in the direction of the cross-sectional width (x: distance from one catalyst surface), which is the abscissa axis, and the x-ray intensity (I), which shows the concentration of halogen atoms, which is ordinate axis. In accordance with FIG. 1, in a halogen-containing catalyst of the present invention, the ratio of α ({(FF ₀ ) / F} of a quantity (FF ₀ ) to an integrated quantity (F)] is 0.17 or less, where the value (FF ₀ ) is calculated by subtracting the value (F ₀ ) obtained by integrating the x-ray intensity (I ₀ ) of the tangent curve with a minimum and the smallest value of the curve showing the x-ray intensity relative to the distance x between one catalyst surface (x = 0) and the other catalyst surface (x = x ₀ ), from the value (F), obtained oh referred to above by integrating the intensity I with respect to the distance x between the surfaces (x; x 0, _0). If the value α is more than 0.17, the cracking selectivity increases, and as a result, undesirable aromatization selectivity falls From this point of view, in the present invention. preferably, the value of α is 0.15 or less.

 In addition, the above linear analysis of the present invention can be applied to a catalyst having any shape, and as long as the catalyst has the above value α, a feature of the present invention can be implemented. Therefore, in the present invention there are no particular restrictions on the shape of the catalyst. In the present invention, however, a catalyst having a cylindrical shape may be preferred in terms of ease of molding and strength of the catalyst.

To obtain a new catalyst based on L type zeolite, a conventional L type zeolite is used as a starting material. In this case, the initial L type zeolite can be represented by the formula 0.9-1.3 M ₂ / _n O • Al ₂ O ₃ • 5.0-7.0 SiO ₂ • 0-9H ₂ O (where M is an alkali metal or alkaline earth metal), and n represents the valency of M). Typical examples of zeolite are disclosed on pages 9 and 10 of Japanese Patent Laid-open Application 133835/1983, as well as on page 5 of Japanese Laid-Open Patent Application 80333/1984.

 The new catalyst based on type L zeolite of the present invention can be obtained by applying one or more halogen components and metal-containing compounds, in particular a platinum-containing compound, to the aforementioned starting material, type L zeolite. By applying one or more halogen components and a metal component, such as a platinum-containing compound, excellent catalytic activity and excellent catalyst durability can be obtained, which have not been obtained to date.

 In this case, examples of halogen-containing compounds are various compounds, and there are no particular restrictions. Typical examples of halogen-containing compounds are chlorine-containing compounds such as hydrogen chloride and ammonium chloride, fluorine-containing compounds such as hydrogen fluoride and ammonium fluoride, iodine-containing compounds such as hydrogen iodide and ammonium iodide, and bromine-containing compounds such as hydrogen bromide and ammonium bromide. As for halogen-containing compounds, the above compounds can be used separately or as a mixture of two or more compounds, and the combination of a chlorine-containing compound and a fluorine-containing compound is particularly preferred.

 Furthermore, it is preferable to use a compound containing platinum as the metal-containing compound, and there is no limitation on the platinum-containing compound as long as it is the source of platinum, but platinum salts are usually used. Typical examples of a platinum-containing compound are tetraminplatinum chloride, chloroplatinic acid, chlorplatinates, tetraminplatinum hydroxide and dinitrodiaminoplatin.

 In the method for producing a new catalyst based on L type zeolite of the present invention, there are practically no restrictions on the method of applying a metal component, such as a platinum-containing compound, and one or more halogen components, onto the initial L type zeolite. Any atmospheric impregnation method, vacuum impregnation method, osmotic method and ion exchange method can be used. In addition, when a metal-containing compound and one or more halogen-containing compounds are applied to an initial type L zeolite, they can be applied simultaneously, but after the initial metal application, halogen (s) can then be applied. On the other hand, the reverse procedure is also possible.

 There is practically no limit on the number of compounds to be applied at the application stage, but the amount of a metal-containing compound, such as a platinum-containing compound, is preferably usually in the range from 0.1 to 5.0 wt.% Metal based on the total weight of the catalyst . The range from 0.3 to 1.5 wt.% Is particularly optimal. In addition, the amount of one or more halogen-containing compounds to be supported on the catalyst is usually preferably in the range of 0.1 to 5.0% by weight of halogen based on the total weight of the catalyst. In the case where the amount of the metal-containing compound and the halogen-containing compound to be deposited on the catalyst deviates from the above ranges, the effect of improving the catalytic activity is sometimes not manifested.

In the present invention, there are practically no restrictions on the conditions of application, and they can usually be selected in accordance with the circumstances. Typically, L type zeolite can be brought into contact with one or more halogen-containing compounds and a metal-containing compound at a temperature of from room temperature to 90 ^{° C.} for 1 minute to 10 hours.

 In the preparation of the halogen-containing catalyst of the present invention, the treated L type zeolite is dried after applying one or more halogens and a metal or in the step between applying a metal to a halogen. At this time, either vacuum drying or atmospheric drying can be used as a drying method. In the present invention, rotary drying or vacuum rotary drying is preferred in terms of halogen distribution.

 Moreover, in the present invention, after applying the halogen, it is preferable to carry out relatively slow drying. In the case where the metal, such as platinum, and one or more halogen components are sequentially deposited in this order, it is preferable that the drying speed in the drying step after application of the halogen (s) is relatively low. On the other hand, in the case where one or more halogen components and the metal are sequentially deposited in this order, it is preferable that the drying speed in the drying step after applying the halogen (s), i.e. the drying rate at the drying stage between the halogen (s) deposition step and the metal deposition step was relatively low. In addition, it is preferable to slowly dry the zeolite, not only in the drying step between the steps of applying one or more halogen components and the metal sequentially in this order, but also in the drying step after applying the metal.

 On the other hand, in the case where the metal and one or more halogen components are applied simultaneously, it is preferable that after their application the drying speed at the drying stage is low.

 When carrying out the drying operation, first the drying is carried out at a low temperature for some time and then at a high temperature, or in the case when the drying is carried out at an elevated temperature, it is desirable to reduce the rate of temperature increase.

 In addition, in order to remove water from the system, vacuum drying is particularly preferred from the above drying methods. The vacuum depth during vacuum drying is optimal in the range in which the evaporation rate of water is satisfactory, but is preferably in the range of 5 to 750 mm Hg, more preferably in the range of 30 to 720 mm Hg.

Moreover, in the aforementioned drying step, drying is preferably carried out at a water evaporation rate of 15% w / h or less. If the evaporation rate of water is more than 15 wt.% / Hour, the halogen is applied to the catalyst unevenly, which is undesirable. From this point of view, it is preferable that the rate of evaporation of water is 10 wt.% / Hour or less. If the evaporation rate of water is 15 wt.% / Hour or less, drying can be carried out at a constant temperature or as the temperature rises. In the case when the drying is carried out with increasing temperature, the temperature can be increased stepwise or at a constant coefficient. In the present invention, it is particularly preferable to use a method in which drying is carried out at a temperature in the range from 25 to 60 ^{° C.} for 10 to 180 minutes, and then the temperature is raised to a level of 70 to 250 ^{° C.} for 5 to 120 minutes and this temperature is kept constant for 10 to 180 minutes, and rotary drying or rotary vacuum drying is carried out over the entire temperature range; or a method in which the temperature is raised from a level in the range from 0 to 60 ^{° C.} to a level in the range from 70 to 250 ^{° C.} for 100 to 180 minutes, and this temperature is kept constant for 10 to 80 minutes, and rotary drying or rotary vacuum drying is carried out over the entire temperature range. First of all, a preferred example of the drying step described above is a method in which drying is carried out at 40 ^{° C.} for 2 hours and then the temperature is raised to 100 ^{° C.} for 40 minutes and the temperature is maintained at 100 ^{° C.} for 30 minutes, and rotary or vacuum rotary drying is carried out over the entire temperature range, and a method in which the temperature is raised from 40 to 100 ^{° C.} for 2 hours and 30 minutes, and the temperature is maintained at 100 ^{° C.} for 30 minutes, wherein rotary drying or rotary vacuum drying is carried out in all temperature in tervale.

In addition, it is preferable that the catalyst is calcined at a higher temperature than the above drying temperature, for example, at a temperature of from 250 to 350 ^o C. In the case when the calcination temperature deviates from the specified interval, the catalytic activity of the catalyst is sometimes insufficient. In the present invention, there is no particular limitation on the atmosphere during calcination, but is usually carried out in air. In this case, the calcination can be carried out in a stream of air or it can be carried out without any stream or air.

 The halogen-containing catalyst of the present invention contains the above type L zeolite, but if necessary, a natural or synthetic inorganic oxide such as alumina, silica or aluminosilicate can be added as a binder. The amount of binder used is preferably in the range of 5 to 90% by weight based on the total weight of the catalyst.

 Examples of hydrocarbons as a starting material with which the halogen-containing catalyst of the present invention can be used are paraffin hydrocarbons, olefinic hydrocarbons, acetylene hydrocarbons, cycloparaffin hydrocarbons and cycloolefin hydrocarbons, and they can be used individually or as a mixture of two or more hydrocarbons.

 The paraffinic hydrocarbons mentioned above preferably contain from 6 to 10 carbon atoms and their typical examples are n-hexane, methylpentane, n-heptane, methylhexane, dimethylpentane and n-octane.

 In addition, the above olefinic hydrocarbons preferably contain from 6 to 10 carbon atoms and their typical examples are hexene, methylpentene, heptene, methylhexene, dimethylpentene and octene. The acetylene hydrocarbons mentioned above preferably contain from 6 to 10 carbon atoms and their typical examples are hexine, heptin and octin.

 The cycloparaffin hydrocarbons mentioned above preferably contain from 6 to 10 atoms and their typical examples are methylcyclopentane, cyclohexane, methylcyclohexane and dimethylcyclohexane.

 In addition, the above-mentioned cycloolefin hydrocarbons preferably contain from 6 to 10 carbon atoms and their typical examples are methylcyclopentene, cyclohexene, methylcyclohexene and dimethylcyclohexene.

 As described above, in the halogen-containing catalyst of the present invention, the quantitative distribution of halogen in the catalyst can be made uniform by slowing down the evaporation rate of water during the drying step of the catalyst preparation process, as a result a metal such as platinum becomes highly dispersed so that the cracking selectivity of the catalyst is reduced and increases its selectivity for aromatization. Therefore, cracking activity can be regulated.

 The present invention is described in more detail using examples and a comparative example.

Example 1
(1) Preparation of catalyst
To 100 wt. parts of zeolite L type (TSZ-500 KOA, manufactured by Toso Co., Ltd) add 20 wt. parts of a binder of silicon dioxide (Snow Tech, Nissan Chemicals Co., Ltd), then mixed and pressed. Next, annealing is carried out in air for 2 hours at a temperature of 500 ^{° C.} , type L zeolite bound with silica is obtained.

To obtain an impregnating solution, 0.086 g of tetramine platinum chloride, 0.088 g of ammonium fluoride, 0.019 g of ammonium chloride and 2.1 g of deionized water are mixed. The impregnation solution thus obtained is slowly added dropwise to 5 g of the above pressed L type zeolite with a binder of silica to deposit platinum and halogens on it. At the drying stage, drying is first carried out on a rotary evaporator in vacuum at 40 ^° C for 2 hours, then the temperature is increased to 100 ^° C for 40 minutes under conditions of a rotary evaporator, followed by drying in a vacuum rotary evaporator at 100 ^° C for 30 minutes. In this case, the vacuum level in the vacuum rotary evaporator is 40 mm Hg. Then, to obtain a catalyst, calcination is carried out in air at 320 ^{° C.} for 1 hour.

Comparative Example 1
(1) Preparation of catalyst
Zeolite L type (5 g), brought to the application step of Example 1, is heated in a vacuum rotary evaporator to 100 ^{° C.} for 60 minutes and a temperature of 100 ^{° C. is} maintained for 3 hours also under drying conditions in a vacuum rotary evaporator. Apply the same methodology as in Example 1, except for the drying stage. In this case, the vacuum level in the vacuum rotary evaporator is 40 mm Hg.

Example 2
(1) Preparation of catalyst
Zeolite L type (5 g), brought to the stage of application and processing of Example 1, is heated in a vacuum rotary evaporator from 40 to 100 ^o C for 2 hours 30 minutes and a temperature of 100 ^o C is maintained for 3 hours also under vacuum drying rotary evaporator. Apply the same methodology as in Example 1, except for the drying stage. In this case, the vacuum level in the vacuum rotary evaporator is 40 mm Hg.

Example 3
(1) Preparation of catalyst
Zeolite L type (5 g), brought to the stage of application and processing of Example 1, is heated under rotation from room temperature to 90 ^{° C.} for 2 hours at atmospheric pressure and a temperature of 90 ^{° C. is} maintained for 3 hours also in a rotary evaporator at atmospheric pressure pressure. Apply the same methodology as in Example 1, except for the drying stage.

Example 4
(1) Preparation of catalyst
Zeolite L type (5 g), brought to the stage of application and processing of Example 1, is heated in a vacuum rotary evaporator from 40 to 100 ^° C for 100 minutes and a temperature of 100 ^° C is maintained for 30 minutes also under drying conditions in a vacuum rotary evaporator . Apply the same methodology as in Example 1, except for the drying stage. In this case, the vacuum level in the vacuum rotary evaporator is 40 mm Hg.

Example 5
(1) Preparation of catalyst
Zeolite L type (5 g), brought to the stage of application and processing of Example 1, is heated by rotation from room temperature to 90 ^o C for 3 hours at atmospheric pressure and a temperature of 90 ^o C is maintained for 3 hours also in a rotary evaporator at atmospheric pressure. Apply the same methodology as in Example 1, except for the drying stage.

(2) Evaluation of the catalytic properties
Determination of water content
In each of the above examples and comparative example, a catalyst sample was taken during drying and the water content was determined using a TG-DTA device. 10 mg of the catalyst in the form of a molded product is weighed and then placed in the device. The temperature is raised from room temperature to 1000 ^{° C.} in an air stream of 70 cm ³ / min. The rate of temperature increase is 20 ^o C / min. The reduction in catalyst weight achieved at 500 ^{° C.} is considered to be water content. Calculate the rate of evaporation of water. The results are shown in the table.

Measurement with ELMAZ
Each of the catalysts obtained above is coated with a resin (PMMA: polymethylmethacrylate), and the resin containing the catalyst is cut parallel to the lower plane so as to open such a measurement surface as shown in FIG. 2. Using a conventional device with ELMAZ, the value of α is measured at an acceleration voltage of 15 kV, a beam size of 1 μm and a current in the sample of 0/05 μA. The results are shown in the table.

Evaluation of the periodic (impulse) reaction
Each of the resulting catalysts is ground to a size of 32 to 65 mesh, 50 mg of ground catalyst is weighed and placed in a reactor. After installing the reactor in the device, the temperature was raised from room temperature to 540 ^{° C.} for 35 minutes at a hydrogen flow rate of 100 cm ³ / min and hydrogen reduction was carried out at 540 ^{° C.} for 1 hour. After completion of the hydrogen reduction, a temperature of 460 ^° C. is set. N-C ₆ is used as a reagent. The pulse size (load) is changed to 0.5 μl, 1.0 μl, 2.0 μl, 3.0 μl to change the conversion. The results are shown in the table. The lower the C _1-4 selectivity, the better the catalyst. In this case, for each catalyst, selectivity is calculated as follows:
Selectivity C _1-4 = [mas.C /(mas.C _{1-4 1-5} + benzene)] • 100.

 Thus, the halogen-containing catalyst and the method for its preparation in accordance with the present invention can be widely and effectively used in the petrochemical industry in the production of aromatic hydrocarbons, as well as in the oil industry in the production of high-octane fuel, etc.

Claims (7)

1. Halogen-containing catalyst for the production of aromatic hydrocarbons, which contains one or more halogen components and platinum deposited on an L-type zeolite with a uniform quantitative distribution of halogen, in which the ratio α [{FF ₀ ) / F} of the value (FF ₀ ) to the integrated value (F)] is 0.17 or less, where the quantity (FF ₀₎ is obtained by subtracting the value (F ₀₎ obtained by integrating the X-ray intensity (I ₀₎ of the tangent of the curve at the minimum and smallest value of the curve showing the intensities x-rays with respect to x between one surface of the catalyst and another surface of the catalyst, from the value (F) obtained by integrating the indicated intensity I relative to the distance x between the surfaces, the amount of platinum included in the catalyst is from 0.1 to 5% and the amount of halogen-containing the compound is in the range from 0.1 to 5.0% for halogen based on the total weight of the catalyst. 2. A method of producing aromatic hydrocarbons from hydrocarbons of a number of paraffins using a halogen-containing catalyst according to claim 1 at a temperature of about 460 ° C. 3. A method of producing a halogen-containing catalyst, which includes the step of applying one or more halogen components and platinum to an L-type zeolite, and then the drying step at a water evaporation rate of 0.15 wt.% / H or less and the calcination step at 250-350 ° With a dried product. 4. The method of obtaining a halogen-containing catalyst according to claim 3, in which the rate of evaporation of water is 10 wt.% / H or less. 5. A method of producing a halogen-containing catalyst according to claim 3 or 4, in which drying is carried out at a temperature below 60 ° C, and then at a temperature above 70 ° C. 6. A method of obtaining a halogen-containing catalyst according to any one of claims 3 to 5, in which vacuum drying is carried out. 7. A method of producing a halogen-containing catalyst, which includes the step of applying one or more halogen components to an L-type zeolite, a drying step at a water evaporation rate of 15 wt.% / H or less, an annealing step at 250-350 ° C. of the dried product, and then the step of applying platinum to the carrier.

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