Preparation method of layered high-specific-surface-area hydroxyl alumina nano material and catalyst thereof

Abstract

The invention provides a preparation method of a layered high-specific-surface-area aluminum hydroxide nano material, which comprises the following steps: dissolving an aluminum salt in water, adding an ammonium salt, heating, stirring, carrying out suction filtration, and drying to obtain a target product aluminum hydroxide. The invention also provides a catalyst, the catalyst comprises a first component aluminum hydroxide and a second component active substance, the first component aluminum hydroxide is prepared by the method, and the second component is metal. The aluminum salt and the ammonium salt which are used as raw materials are cheap and easy to obtain, the preparation process is simple, the prepared hydroxyl alumina has a layered structure and abundant pore channels, the specific surface area is up to 428.7 m < 2 > / g, and the hydroxyl alumina is suitable for being used as a catalyst carrier. In addition, a good synergistic effect is achieved between the metal active component and the aluminum hydroxide in the catalyst, and the catalyst is good in catalytic activity and has a commercial application prospect.

Description

Technical Field

[0001] The invention relates to the technical field of aluminum oxyhydroxide, in particular to a method for preparing a layered aluminum oxyhydroxide nano material with a high specific surface area and a catalyst prepared by using the aluminum oxyhydroxide obtained by the invention as a carrier. Background Art

[0002] Aluminum oxyhydroxide (AlOOH) is a key industrial raw material, widely used as a catalyst support, adsorbent and coating material. Given its importance in multiple industrial fields, especially its application in the field of catalysts, it is crucial to develop a method for efficiently preparing high-purity, high-specific surface area aluminum oxyhydroxide. Although there are many technologies for preparing aluminum oxyhydroxide, including solution precipitation method, hydrothermal synthesis method, etc., these traditional methods still have some shortcomings. For example, the precipitation method usually obtains aluminum oxyhydroxide with a low specific surface area, and although the hydrothermal synthesis method can regulate the product properties, it often needs to be carried out under high temperature and high pressure, the process is complicated and it is difficult to expand the production scale.

[0003] In the patent literature, CN118307018A describes a method for preparing hydroxy aluminum oxide by precipitation, which utilizes aluminum salt and alkaline solution to react, and obtains the product through subsequent hydrothermal treatment, aging and purification steps. Although this method can adjust the reaction conditions to control the product characteristics, the whole process is cumbersome and energy-consuming, which limits its industrial application potential. CN112158866A uses sulfur-containing substances to treat aluminum oxide to prepare hydroxy aluminum oxide. This method can produce sulfur-containing hydroxy aluminum oxide, but the carrier is only suitable for specific catalytic reactions, such as phenylacetylene hydrogenation, and its application range is limited. CN116395724A shows a method for preparing flaky hydroxy aluminum oxide by Couette-Taylor eddy current reaction, but this method requires extremely special reaction conditions and is only effective under high temperature and high pressure, resulting in low production efficiency and difficulty in widespread application. In addition, CN106964348A introduces a method for preparing aluminum hydroxide with high specific surface area by calcining aluminum hydroxide at 300°C, which is suitable for the preparation of Pt / AlOOH catalysts. Although its specific surface area is improved compared with the prior art, it is still unsatisfactory and the calcination process is energy-consuming.

[0004] It can be seen that the existing preparation methods are not efficient in large-scale production of high specific surface area aluminum oxyhydroxide. Therefore, it is particularly urgent to develop a new method that can efficiently prepare high specific surface area aluminum oxyhydroxide under mild conditions, which can not only meet the needs of industrial production, but also significantly reduce costs. Summary of the invention

[0005] The purpose of the present invention is to provide a method for preparing layered aluminum hydroxide with high specific surface area to solve the technical problems existing in the background technology.

[0006] The solution of the present invention to solve the technical problem is:

[0007] The first aspect of the present invention provides a method for preparing a layered high specific surface area aluminum oxyhydroxide, comprising the following steps:

[0008] The aluminum salt is dissolved in water, and ammonium salt is added, heated, stirred, filtered and dried to obtain layered aluminum hydroxide with high specific surface area.

[0009] Preferably, the aluminum salt is at least one of sodium metaaluminate and sodium aluminate.

[0010] Preferably, the ammonium salt is at least one of ammonium bromide and ammonium chloride.

[0011] The ammonium salt used in the present invention can be at least one of an inorganic ammonium salt and an organic ammonium salt, wherein the inorganic ammonium salt includes but is not limited to ammonium fluoride, ammonium bromide, ammonium chloride, ammonium iodide, ammonium carbonate, ammonium bicarbonate, ammonium phosphate, ammonium hydrogen phosphate, ammonium nitrate, ammonium nitrite, ammonium sulfate, and ammonium hydrogen sulfate. The organic ammonium salt includes but is not limited to ammonium adipate, ammonium oxalate, ammonium formate, ammonium acetate, ammonium propionate, ammonium stearate, ammonium acrylate, ammonium benzoate, ammonium picrate, ammonium dodecylbenzenesulfonate, ammonium succinate, ammonium malate, ammonium phthalate, and ammonium hydrogen tartrate.

[0012] Preferably, the molar ratio of the aluminum salt to the ammonium salt is 1:(0.1-100).

[0013] Preferably, the heating temperature is (0-100)°C.

[0014] Preferably, the drying temperature is (50-200)°C

[0015] Aluminum oxyhydroxide, as an important inorganic chemical material, is widely used in the fields of catalyst carriers, adsorption materials, coating materials, etc. The layered high specific surface area aluminum oxyhydroxide nanomaterial prepared by the present invention can be used as polymer functional fillers, ceramic materials, adsorption materials, catalysts and their carriers, etc. In particular, the aluminum oxyhydroxide prepared by the present invention has the characteristics of rich pores, large specific surface area, high activity, etc., and is very suitable as a catalyst carrier, which can improve its application in the field of catalysis.

[0016] Another aspect of the present invention provides a catalyst, comprising a first component of aluminum hydroxide and a second component of an active substance, wherein the first component of aluminum hydroxide is prepared by any preparation method provided in the first aspect. The second component is a metal. The catalyst preparation comprises the following steps:

[0017] The aluminum hydroxide provided in the first aspect is dispersed in water, a metal salt solution is added, stirred, a mixed gas containing hydrogen is introduced and the mixed gas atmosphere is maintained, heated, stirred, filtered, and dried to obtain a catalyst.

[0018] Preferably, the metal salt solution is at least one of palladium and platinum.

[0019] The metal salts used in the present invention include but are not limited to gold, silver, platinum, palladium, rhodium, ruthenium, rhenium, iridium, copper, iron, cobalt, and nickel.

[0020] Preferably, the mass ratio of the aluminum oxyhydroxide to the metal is 1:(0.001-0.5).

[0021] Preferably, the heating temperature is (0-100)°C.

[0022] Preferably, the drying temperature is (50-200)°C.

[0023] Preferably, the mixed gas is a mixed gas of hydrogen and an inert gas, the volume ratio of hydrogen to the inert gas is 1:(0-99), and the pressure of the mixed gas is (0.05-1.0) MPa.

[0024] The present invention has the following beneficial effects:

[0025] 1. The raw materials for preparing layered high specific surface area aluminum hydroxide oxide in the present invention are cheap and easily available, the reaction conditions are mild, high temperature and high pressure are not required, the preparation process is simple, it is suitable for large-scale production, and the industrial application prospect is broad.

[0026] 2. The product yield obtained by the preparation method of the present invention is relatively high, basically greater than 80%, and the maximum is as high as 98%.

[0027] 3. The layered high specific surface area aluminum hydroxide prepared by the present invention has a mesoporous structure and a large specific surface area, up to 428.7 m 2 / g, suitable as a catalyst carrier.

[0028] 4. The layered high specific surface area aluminum hydroxide oxide prepared by the present invention is used as a carrier, and its catalytic activity is higher than other commercially available carriers and higher than commercial palladium carbon. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 XRD spectra of aluminum oxyhydroxide obtained at different synthesis temperatures in Example 1;

[0030] Figure 2 is a transmission electron microscope image of AlOOH-80 in Example 1;

[0031] Figure 3 The pore size distribution diagram of AlOOH-80 and the isothermal adsorption-desorption curve diagram of nitrogen in Example 1;

[0032] Figure 4 This is the transmission electron microscopy of the Pd / AlOOH-80 sample in Example 1;

[0033] Figure 5 It is a comparison chart of the activity of the Pd / AlOOH-80 sample and other catalysts in Example 1;

[0034] Figure 6 This is a comparison chart of the activity of the Pd / AlOOH-80 sample and commercial palladium carbon in Example 1; DETAILED DESCRIPTION

[0035] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention clearer and more understandable, the technical solutions in the embodiments of the present invention are clearly and completely described in combination with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0036] The first aspect of the present invention provides a method for preparing a layered high specific surface area aluminum hydroxide oxide nanomaterial, comprising the following steps: dissolving aluminum salt in water, adding ammonium salt, heating, stirring, filtering, and drying to obtain a layered high specific surface area aluminum hydroxide oxide.

[0037] According to an embodiment of the present invention, the aluminum salt is selected from at least one of sodium metaaluminate and sodium aluminate.

[0038] According to an embodiment of the present invention, the ammonium salt is selected from at least one of an inorganic ammonium salt and an organic ammonium salt.

[0039] According to an embodiment of the present invention, the inorganic ammonium salt includes but is not limited to ammonium fluoride, ammonium bromide, ammonium chloride, ammonium iodide, ammonium carbonate, ammonium bicarbonate, ammonium phosphate, ammonium hydrogen phosphate, ammonium nitrate, ammonium nitrite, ammonium sulfate, and ammonium hydrogen sulfate.

[0040] According to an embodiment of the present invention, the organic ammonium salt includes but is not limited to ammonium adipate, ammonium oxalate, ammonium formate, ammonium acetate, ammonium propionate, ammonium stearate, ammonium acrylate, ammonium benzoate, ammonium picrate, ammonium dodecylbenzenesulfonate, ammonium succinate, ammonium malate, ammonium phthalate, and ammonium hydrogen tartrate.

[0041] According to an embodiment of the present invention, the molar ratio of the aluminum salt to the ammonium salt substance is 1:(0.1-100).

[0042] According to an embodiment of the present invention, the heating temperature is (0-100)°C.

[0043] According to the embodiment of the present invention, the drying temperature is (50-200)°C

[0044] A second aspect of the present invention provides a catalyst comprising a first component of aluminum oxyhydroxide and a second component of an active material.

[0045] According to an embodiment of the present invention, the first component aluminum oxyhydroxide is prepared by any preparation method provided in the first aspect.

[0046] According to an embodiment of the present invention, the second component is a metal.

[0047] According to an embodiment of the present invention, the catalyst preparation comprises the following steps:

[0048] The aluminum hydroxide provided in the first aspect is dispersed in water, a metal salt solution is added, stirred, a mixed gas containing hydrogen is introduced and the mixed gas atmosphere is maintained, heated, stirred, filtered, and dried to obtain a catalyst.

[0049] According to an embodiment of the present invention, the metal salt solution is at least one of palladium and platinum.

[0050] According to an embodiment of the present invention, the metal salt used in the present invention includes but is not limited to gold, silver, platinum, palladium, rhodium, ruthenium, rhenium, iridium, copper, iron, cobalt, and nickel.

[0051] According to an embodiment of the present invention, the mass ratio of aluminum oxyhydroxide to metal is 1:(0.001-0.5).

[0052] According to an embodiment of the present invention, the heating temperature is (0-100)°C.

[0053] According to an embodiment of the present invention, the drying temperature is (50-200)°C.

[0054] According to an embodiment of the present invention, the mixed gas is a mixed gas of hydrogen and an inert gas, the volume ratio of hydrogen to the inert gas is 1:(0-99), and the pressure of the mixed gas is (0.05-1.0) MPa

[0055] The present invention also provides an application of the above catalyst, which is applied to alkyne hydrogenation reaction. The method comprises the following steps: adding an alcohol solvent into a reactor, dispersing the catalyst in the solvent, adding a reaction substrate alkyne, the molar ratio of metal to substrate being 1:(500-10000), replacing hydrogen, and maintaining the hydrogen pressure at (0.1-1) MPa, heating the temperature at (20-70)°C, stirring, and starting the alkyne hydrogenation reaction.

[0056] According to an embodiment of the present invention, the alcohol solvent is selected from at least one of methanol, ethanol, propylene glycol, ethylene glycol, n-butanol and isobutanol. Preferably, the solvent is ethanol.

[0057] In a specific embodiment of the present invention, the reaction substrate is phenylacetylene.

[0058] Example 1

[0059] S1: Dissolve sodium aluminate in water, add ammonium bromide, control the molar ratio of sodium aluminate and ammonium bromide to be 1:1, and a precipitate will be produced. Heat the mixed solution containing the precipitate to 80°C and stir for 3 hours. After the temperature of the mixed solution drops to room temperature, perform suction filtration. Add some deionized water to the filter cake during the suction filtration process to remove residual ions attached to the filter cake, and dry it at 60°C for 12 hours to obtain a layered high specific surface area hydroxy aluminum oxide nanomaterial (preparation temperature is 80°C, denoted as AlOOH-80). The hydroxy aluminum oxide prepared at different temperatures is determined by an X-ray diffractometer to determine their physical phases. Figure 1 The XRD spectra of aluminum oxyhydroxide prepared at room temperature 25°C and 80°C are shown in the spectra. From the spectra, we can see that the samples prepared by the preparation method of the present invention are all pure phase aluminum oxyhydroxide (AlOOH, JCPDS: 21-1307). We observed the morphology of AlOOH-80 by transmission electron microscopy. Figure 2 Figure 1 is a transmission electron microscope image of AlOOH-80. From the image, we can see that the AlOOH-80 sample prepared by the present invention has an obvious layered structure. We characterized the pore structure and specific surface area of ​​the AlOOH-80 sample by physical adsorption instrument. Figure 3 The pore size distribution diagram and nitrogen isothermal adsorption-desorption curve of AlOOH-80 sample are shown in the figure. From the figure, we can see that the nitrogen isothermal adsorption-desorption curve of AlOOH-80 has an obvious hysteresis loop, indicating that AlOOH-80 has a mesoporous structure. Its pore size distribution curve shows that its pores are mainly concentrated at 2.8nm. At the same time, the specific surface area of ​​AlOOH-80 is as high as 428.7m 2 / g.

[0060] Example 2

[0061] Sodium aluminate was dissolved in water, ammonium bromide was added, and the molar ratio of sodium aluminate and ammonium bromide was adjusted to prepare AlOOH of different experimental groups. Precipitation was produced in each experimental group. The mixed solution containing the precipitate was heated to 80°C and stirred for 3 hours. After the temperature of the mixed solution dropped to room temperature, it was filtered and filtered. Some deionized water can be added to the filter cake during the filtration process to remove the residual ions attached to the filter cake. It was dried at 60°C for 12 hours to obtain a layered high specific surface area aluminum hydroxide nanomaterial. Table 1 is a comparison of the yield of aluminum hydroxide prepared at different molar ratios of sodium aluminate and ammonium bromide. It can be seen that different molar ratios of sodium aluminate and ammonium bromide will not affect the physical phase of the product, and the products are all aluminum hydroxide. But it will affect the yield of the product. When the molar ratio is 1:0.7, 1:1 and 1:1.5, the yields are 81.6%, 96.2% and 98.0%, respectively. It can be seen that different molar ratios of sodium aluminate and ammonium bromide can be used to prepare layered high specific surface area aluminum hydroxide, and the yield is greater than 80%.

[0062] Table 1 Comparison of the yields of aluminum hydroxide prepared with different molar ratios of sodium aluminate and ammonium bromide

[0063] Experimental Group Molar Ratio product Yield 1 1:0.7 AlOOH 81.6％ 2 1:1 AlOOH 96.2％ 3 1:1.5 AlOOH 98.0％

[0064] Example 3

[0065] Sodium aluminate was dissolved in water, and different ammonium salts were added to prepare products of different experimental groups. The molar ratio of sodium aluminate to ammonium salt was 1:1. Precipitation was produced in each experimental group. The mixed solution containing the precipitate was heated to 80°C and stirred for 3 hours. After the temperature of the mixed solution dropped to room temperature, it was filtered and filtered. Some deionized water can be added to the filter cake during the filtration process to remove residual ions attached to the filter cake. It was dried at 60°C for 12 hours to obtain layered high specific surface area aluminum hydroxide nanomaterials. Table 2 is a comparison of the yields of aluminum hydroxide prepared by different ammonium salts. It can be seen that different ammonium salts will not affect the physical phase of the product, and the products are all aluminum hydroxide. At the same time, we also see that the use of different ammonium salts has little effect on the yield of AlOOH, and the yield of AlOOH is greater than 90%.

[0066] Table 2 Comparison of the yield of aluminum hydroxide prepared by different ammonium salts

[0067] Experimental Group Ammonium salt product Yield 1 Ammonium chloride AlOOH 94.6％ 2 Ammonium bromide AlOOH 96.2％ 3 Ammonium Nitrate AlOOH 93.5％ 4 Ammonium formate AlOOH 92.0％ 5 Ammonium benzoate AlOOH 93.7％ 6 Ammonium adipate AlOOH 91.5％

[0068] Example 4

[0069] Sodium aluminate is dissolved in water, and ammonium bromide is added. The molar ratio of sodium aluminate and ammonium bromide is controlled to be 1:1. At this time, a precipitate is produced. The mixed solution containing the precipitate is heated to 25°C-100°C and stirred for 3 hours. After the temperature of the mixed solution drops to room temperature, it is filtered and filtered. Some deionized water can be added to the filter cake during the filtration process to remove residual ions attached to the filter cake. Dry it at 60°C for 12 hours to obtain a layered high specific surface area hydroxy aluminum oxide nanomaterial. Table 3 is a comparison of the specific surface areas of the products prepared at different temperatures. From Table 3, we can see that the products prepared at different temperatures are all hydroxy aluminum oxide, but the specific surface area of ​​hydroxy aluminum oxide is affected. Overall, the specific surface area of ​​AlOOH prepared at different temperatures is relatively large, among which the specific surface area is the largest at 80°C, up to 428.7m 2 / g.

[0070] Table 3 Specific surface area of ​​the products obtained by preparing aluminum hydroxide at different temperatures

[0071] Experimental Group Preparation temperature product <![CDATA[Specific surface area / (m 2 / g)]]> 1 25℃ AlOOH 320.1 2 60℃ AlOOH 274.5 3 80℃ AlOOH 428.7 4 100℃ AlOOH 375.5

[0072] Example 5

[0073] Sodium aluminate was dissolved in water, and ammonium bromide was added. The molar ratio of sodium aluminate to ammonium bromide was controlled to be 1:1. At this time, a precipitate was produced. The mixed solution containing the precipitate was heated to 80°C and stirred for 3 hours. After the temperature of the mixed solution dropped to room temperature, it was filtered and filtered. Some deionized water can be added to the filter cake during the filtration process to remove the residual ions attached to the filter cake. It was dried at 30°C, 60°C, 90°C, 120°C and 150°C for 12 hours to obtain layered high specific surface area hydroxy aluminum oxide nanomaterials. Table 4 shows the specific surface area of ​​the products prepared by preparing hydroxy aluminum oxide at different drying temperatures. From Table 4, we can see that the products prepared at different drying temperatures are all hydroxy aluminum oxide, but the specific surface area of ​​hydroxy aluminum oxide is affected. Overall, the specific surface area of ​​AlOOH prepared at different temperatures is relatively large, among which the specific surface area is the largest at 80°C, up to 428.7m 2 / g.

[0074] Table 4 Specific surface area of ​​the products obtained by preparing aluminum hydroxide at different drying temperatures

[0075] Experimental Group Preparation temperature product <![CDATA[Specific surface area / (m 2 / g)]]> 1 30℃ AlOOH 410.2 2 60℃ AlOOH 428.4 3 90℃ AlOOH 415.7 4 120℃ AlOOH 395.5 5 150℃ AlOOH 364.1

[0076] Example 6

[0077] Sodium aluminate was dissolved in water, and ammonium bromide was added. The molar ratio of sodium aluminate and ammonium chloride was controlled to be 1:1. At this time, a precipitate was produced. The mixed solution containing the precipitate was heated to 80°C and stirred for 3 hours. After the temperature of the mixed solution dropped to room temperature, it was filtered. Some deionized water can be added to the filter cake during the filtration process to remove the residual ions attached to the filter cake. It was dried at 60°C for 12 hours to obtain a layered high specific surface area aluminum oxide hydroxy nanomaterial. After analysis, the product was pure phase AlOOH with a yield of 88.5% and a specific surface area of ​​355.2m 2 / g.

[0078] Example 7

[0079] Sodium aluminate was dissolved in water, ammonium bromide was added, and the molar ratio of sodium metaaluminate and ammonium chloride was controlled to prepare products of different experimental groups. At this time, a precipitate was produced. The mixed solution containing the precipitate was heated to 80°C and stirred for 3 hours. After the temperature of the mixed solution dropped to room temperature, it was filtered and filtered. Some deionized water can be added to the filter cake during the filtration process to remove the residual ions attached to the filter cake. It was dried at 60°C for 12 hours to obtain a layered high specific surface area hydroxy aluminum oxide nanomaterial. Table 5 is a comparison of the yield of hydroxy aluminum oxide prepared at different molar ratios of sodium aluminate and ammonium bromide. It can be seen that different molar ratios of sodium aluminate and ammonium bromide will not affect the physical phase of the product, and the products are all hydroxy aluminum oxide. But it will affect the yield of the product. When the molar ratio is 1:0.7, 1:1 and 1:1.5, the yields are 80.1%, 86.4% and 83.7%, respectively. It can be seen that different molar ratios of sodium aluminate and ammonium bromide can be used to prepare layered high specific surface area hydroxy aluminum oxide, and the yield is greater than 80%.

[0080] Table 5 Comparison of the yields of aluminum hydroxide prepared with different molar ratios of sodium aluminate and ammonium bromide

[0081] Experimental Group Molar Ratio product Yield 1 1:0.7 AlOOH 80.1％ 2 1:1 AlOOH 86.4％ 3 1:1.5 AlOOH 83.7％

[0082] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0083] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a layered high specific surface area aluminum oxyhydroxide nanomaterial, characterized in that: The following steps are involved: Aluminum salt is dissolved in water, ammonium salt is added, heating, stirring, suction filtering and drying are performed to obtain the target product, layered aluminum oxide nanomaterial with high specific surface area.

2. The preparation method according to claim 1, characterized in that: The aluminum salt is at least one of aluminate and aluminate.

3. The preparation method according to claim 1, characterized in that: The inorganic ammonium salt is selected from at least one of ammonium fluoride, ammonium bromide, ammonium chloride, ammonium iodide, ammonium carbonate, ammonium bicarbonate, ammonium phosphate, ammonium hydrogen phosphate, ammonium nitrate, ammonium nitrite, ammonium sulfate and ammonium hydrogen sulfate.

4. The preparation method according to claim 1, characterized in that: The organic ammonium salt is selected from at least one of ammonium oxalate, ammonium adipate, ammonium formate, ammonium acetate, ammonium propionate, ammonium stearate, ammonium acrylate, ammonium benzoate, ammonium picrate, ammonium dodecylbenzenesulfonate, ammonium succinate, ammonium malate, ammonium phthalate and ammonium hydrogen tartrate.

5. The preparation method according to claim 1, characterized in that: The heating temperature is (0-100)°C.

6. The preparation method according to claim 1, characterized in that: The molar ratio of the aluminum salt to the ammonium salt is 1:(0.1-100).

7. The preparation method according to claim 1, characterized in that: The drying temperature is (50-200)°C.

8. A catalyst, characterized in that The invention comprises a first component of aluminum oxyhydroxide and a second component of active material, wherein the first component of aluminum oxyhydroxide is prepared by the preparation method according to any one of claims 1 to 7.

9. The catalyst according to claim 7, characterized in that The second component is a noble metal.

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