JPS6114130B2 - - Google Patents

Description

[Detailed description of the invention]

This invention relates to a method for producing oxygen-containing organic compounds such as acetic acid from synthesis gas. In particular, it relates to a process for obtaining _C2 oxygenates containing increased proportions of acetic acid using certain rhodium- and manganese-containing catalysts. BACKGROUND ART A method for producing an oxygen-containing organic compound containing mainly two carbon atoms from carbon monoxide and hydrogen, particularly an oxygen-containing compound containing acetic acid, acetaldehyde, and ethanol as components, is known. In this reaction, a heterogeneous catalyst consisting essentially of metal rhodium is used (Japanese Patent Publication No. 54-41568), and an oxygen-containing compound consisting of solid fine particles containing a combination of rhodium and manganese is used as a catalyst. Improved method for increasing the activity of the synthesized catalyst (Special Publication 1983-
43453) has been done. Furthermore, a method of suppressing the production of methane by combining lithium, potassium, cesium, rubidium, etc. is also known (Japanese Patent Application Laid-Open No. 8334-1983). In this way, a mixed gas of carbon monoxide and hydrogen (hereinafter referred to as synthesis gas) is reacted in the presence of a catalyst that combines rhodium, manganese, and potassium.
Methods for producing C ₂ oxygen-containing compounds are well known, and specific examples thereof are summarized in a table in the above-mentioned Japanese Patent Application Laid-open No. 8334/1983. This technology works to shift the distribution of the generated _C2 compounds toward the acetic acid side (lines 9 to 10 at the bottom right of p. 2 of the same publication).
When the proportion of acetic acid in the C ₂ oxygen-containing compounds was calculated, it was approximately 48% in the highest case (J) among the eight cases, which cannot be said to be sufficiently high. In view of this prior art, it is an object of the present invention to provide an improved process for the production of _C2 oxygenates from synthesis gas, in which a product containing a further increased proportion of acetic acid is obtained. . A method using a rhodium catalyst activated by heat treatment of a rhodium compound on a carrier in combination with an alkali metal, in which the heat treatment is performed in the presence of permanganate ions, and the coexisting alkali metal is potassium. It has been found that, only in the case of ions, the composition of the C ₂ oxygenate obtained by the reaction of synthesis gas is one with a significantly increased proportion of acetic acid. That is, the present invention involves reacting carbon monoxide and hydrogen in the presence of a catalyst containing rhodium and manganese,
In a method for producing an oxygen-containing compound containing acetic acid, acetaldehyde, and ethanol as components, an active rhodium catalyst obtained by heat treatment of a rhodium compound supported on a carrier together with permanganate ions and potassium ions are allowed to coexist. This is a method for producing an oxygen-containing organic compound characterized by using a catalyst. In known rhodium-manganese containing catalysts,
The source of manganese is specifically disclosed as manganese nitrate. However, in the present invention, permanganate ions are used instead of such manganese cations, and these are supported on a carrier together with a rhodium compound. As long as the permanganate ion compound is permanganate itself, it may be permanganate itself or its metal salts, such as alkali metal salts such as lithium and sodium. Such permanganate ions are supported on a carrier such as silica gel together with a rhodium compound such as rhodium chloride and activated by heat treatment. The method of the present invention uses this catalyst in the coexistence of potassium ions in a reaction to obtain a C ₂ oxygen-containing compound from synthesis gas. The coexisting potassium ions may be added after preparing the active rhodium-manganese-containing catalyst by the specific production method described above, but it is easier and more convenient to support them on the carrier together with the rhodium and manganese components during catalyst preparation. It is. When potassium permanganate is used as the permanganate ion compound, potassium ions already coexist in the catalyst obtained by supporting this together with rhodium and then heating it. However, when other permanganate ion compounds such as lithium permanganate are used, the effects of the present invention can only be achieved by using a catalyst to which potassium ions are separately added. The catalyst used in the present invention and its preparation method will be explained in more detail below. Rhodium compounds used for catalyst preparation include, for example, inorganic acid salts such as rhodium chloride, rhodium bromide, rhodium iodide, rhodium nitrate, and rhodium sulfate; organic acid salts such as rhodium acetate, rhodium formate, and rhodium oxalate; Any of the compounds commonly used in the preparation of noble metal catalysts, such as rhodium oxide or ammine complex salts, clusters, rhodium carbonyl, and rhodium carbonyl acetylacetonate, can be used, but chloride is particularly recommended for ease of handling. These rhodium compounds are not in an active state (referring to the activity of synthesizing an oxygen-containing organic compound such as acetic acid from carbon monoxide and hydrogen; the same applies hereinafter) before heat treatment. The carrier for supporting these rhodium and manganese components preferably has a specific surface area of 1 to 1000 m ² /g, and includes silica, alumina, silica alumina, titanium oxide, zirconium oxide, thorium oxide, magnesium oxide, activated carbon, Although zeolite and the like can be used, silica-based carriers are particularly preferred.
These carriers can be used in any form such as powder or pellets. Potassium ion compounds to be added and allowed to coexist include halides such as potassium chloride, halogen oxygen salts such as potassium chlorate, inorganic acid salts such as sulfates, nitrates, and carbonates, hydroxides, acetates, formates, and sulfates. Organic acid salts such as acid salts can be used regardless of whether or not the anion component is stable during heat treatment. In order to facilitate loading onto a carrier, a compound soluble in a suitable solvent such as water is preferably used. Although the present invention is characterized by the use of specific manganese sources and alkali metals, conventional methods for preparing noble metal catalysts can be applied to the catalysts used therein.
For example, an impregnation method, a dipping method, an ion exchange method, a coprecipitation method, a kneading method, etc. are used. More specifically, the catalyst can be obtained by dissolving the above catalyst component in water or an organic solvent such as n-hexane or alcohol, adding a porous inorganic carrier to this solution to support the solution, and then subjecting the solution to a reductive heat treatment. The catalyst components may be supported on the carrier by simultaneously supporting all the catalyst components, by sequentially supporting each component, or by subjecting each component to reduction heat treatment as necessary. It is possible to use various methods such as a method of carrying the data sequentially or in stages while performing processing such as the following. To further explain the impregnation method as an example, a thermally decomposable inorganic rhodium compound, permanganate, and potassium salt are made into an aqueous solution in an amount of water depending on the water absorption rate of the carrier, the carrier is added to the solution, and after stirring and mixing, heating is performed. Dry and support. Such a solid supporting a compound of rhodium and manganese is further heated to become an active catalyst supporting finely dispersed rhodium and manganese. The heat treatment is performed by heating the rhodium compound supported on the carrier together with permanganate ions to a temperature of 150°C or higher, usually under reducing conditions.This heat treatment converts the rhodium compound into an active rhodium catalyst. become. For example, rhodium chloride supported together with permanganate ions is heated in a hydrogen stream to become a metal or a low valence state close to it, and becomes active. The rhodium-based catalysts disclosed in the prior art are also described as being obtained by heating a supported rhodium compound under reducing conditions, and that the rhodium deposited is typically in the metallic form; To obtain the catalyst used in the present invention, the same heat treatment as in the prior art can be applied, except that the catalyst is in the presence of permanganate ions. Since active rhodium compounds are thought to be mainly metallic or slightly positively charged, if a rhodium salt with a high valence is supported, the heat treatment will involve reduction. However, when a low valence rhodium compound such as rhodium carbonyl is supported, heat treatment without reduction may be sufficient. The heat treatment for converting the rhodium compound into an active state may be heating to the reaction temperature under reaction conditions, that is, in the presence of hydrogen in a mixed gas of carbon monoxide and hydrogen supplied as a raw material to the reaction system. , it is desirable to activate it by carrying out a heat treatment accompanied by reduction in a hydrogen stream before using it in the reaction. The reduction treatment can be performed in the presence of hydrogen gas or a mixed gas of carbon monoxide and hydrogen. Depending on the case, it may be partially diluted with an inert gas such as nitrogen, helium, or argon. The reduction treatment temperature is 100 to 600°C, preferably 150 to 500°C. At this time, in order to maintain the activation state of each component of the catalyst in an optimal state, the reduction treatment may be performed while raising the temperature gradually or stepwise from a low temperature. Further, the reduction can also be carried out chemically using a reducing agent such as methanol, hydrazine, or formalin. There is no strict limit on the amount of each catalyst component used, but the surface area of the carrier (1 to 1000 m ² /
g). Usually the content of rhodium in the supported catalyst is 0.01-15% by weight, preferably 0.1
-10% by weight, the content of manganese is 0.001-10% by weight, preferably 0.01-5% by weight. The ratio of potassium to rhodium is in the range of 0.001 to 2, preferably 0.01 to 1 in terms of atomic ratio. Catalysts such as those described above are used to convert synthesis gas, a mixture of carbon monoxide and hydrogen, into acetic acid-rich C ₂ oxygenates. The reaction is usually carried out in the gas phase, for example, a raw material gas containing carbon monoxide and hydrogen is passed through a fixed bed reactor packed with a catalyst. In this case, the raw material gas may contain other components other than carbon monoxide and hydrogen, such as carbon dioxide, nitrogen, argon, helium, methane, and water vapor. Further, the catalytic reactor is not limited to a fixed bed type, but may be of other types such as a moving bed type or a fluidized bed type. In addition, depending on the case, a liquid phase reaction may also be carried out in which the catalyst is suspended in a suitable solvent and the raw material gas is passed therethrough for the reaction. Although reaction conditions can be varied within a wide range,
The preferred range is the molar ratio of carbon monoxide and hydrogen.
20:1 to 1:5, preferably 10:1 to 1:
2. Reaction temperature is 200-400℃, preferably 220-350℃
°C, pressure 1 to 30 atm, preferably 20 to 200
Atmospheric pressure and space velocity are converted to standard conditions (0°C, 1 atm)
at 10 ² to 10 ⁶ Hr ^-1 , preferably 10 ³ to 5X10 ⁴ Hr ^-1
It is. The combination of a specific rhodium-manganese-containing catalyst and a specific alkali metal (K) in the present invention is C ₂ synthesized directly from carbon monoxide and hydrogen through a catalytic reaction.
The unexpected effects of increasing the proportion of acetic acid in oxygen-containing compounds will be explained using practical examples. Example 1 shows that when a rhodium-manganese-containing catalyst prepared using lithium permanganate was used in the coexistence of potassium ions added as potassium chloride, acetic acid accounted for more than 63% of the _C2 oxygenated compounds. The ratio of acetic acid is increased compared to the case of Example 2 in which potassium chlorate is used and the comparative example (Example 3) in which potassium ions do not coexist. Addition of other alkali metals does not have such an effect (Examples 4 to 6). Examples 7-10 are proportioned to Example 12 without additives using various amounts of potassium chlorate under other conditions. Example 13 uses potassium permanganate.

[Table] The reaction results in these specific examples are summarized in Table 1. Selectivity (%) is defined by the following formula. Number of moles of CO converted to a specific product x 100/Number of moles of CO consumed The number of esters was calculated by dividing each into acid and alcohol. Example 1 Completely dissolve 0.9591 g of rhodium trichloride trihydrate, 0.2186 g of lithium permanganate, and 0.0272 g of potassium chloride in 25 ml of distilled water, then add 15 g of silica gel (ID type silica gel manufactured by Fuji Davison Chemical Co., Ltd., the same applies hereinafter). and air-dried overnight. After drying in a blow dryer at 110℃ for 4 hours, it was filled into a quartz glass reduction tube and heated in a hydrogen stream (201/
After heat treatment at 350°C for 2 hours, the temperature was immediately changed to a nitrogen stream and allowed to cool. 10ml of this catalyst was packed into a SUS-316 U-shaped reaction tube, and raw material gas (CO: _H2 = 2:1) was fed at a rate of 100Nl/hour at a pressure of 50Kg/ ^cm2G and a temperature of 278℃. The reaction is carried out to select _C2 oxygenated compounds with a selectivity of 67
Obtained in %. The main product, acetic acid, accounts for more than 63% of the total selectivity to these three _C2 oxygenated compounds. The analysis was conducted by directly introducing the reaction gas into a gas chromatograph. Example 2 Potassium chlorate 0.0447g instead of potassium chloride
A reaction was carried out under the same conditions using a catalyst prepared in the same manner as in Example 1 except that . _C2 from syngas
Selectivity to oxygenates is 72%, more than 63% of which is acetic acid. Examples 3 to 6 These are comparative examples in which no potassium ion compound is used (reaction conditions are the same as Examples 1 to 2). Example 3 had the same conditions as Example 1 except that potassium chloride was not used. Examples 4-6
are equivalent moles of LiCl instead of potassium chloride,
This is the case when NaCl and CsCl are used, and there is no effect of increasing the ratio of acetic acid in C ₂ oxygen-containing compounds such as potassium ion compounds. Examples 7 to 12 Example 9 is an example in which the same catalyst as in Example 2 was used, but the reaction was carried out under different conditions. i.e. 1/3 for rhodium
5 ml of a catalyst prepared using twice the molar amount of lithium permanganate and 1/10 times the molar amount of potassium chlorate was diluted with 5 ml of silica gel and filled into a similar reaction tube, and the pressure was 100 Kg/cm ² G and the temperature was 300°C. feedstock gas under the conditions of
The reaction was carried out by feeding at a rate of 100 Nl/hour. In Examples 7, 8, and 10, the amount of potassium chlorate used was changed, and in Example 11, 1/25 times the amount of potassium sulfate was used. Example 12, like Example 3, is a comparative example using a catalyst that does not use potassium salt. Examples 7-12 used the same reaction conditions as Example 9. Examples 13, 14 After completely dissolving 1.9182 g of rhodium trichloride trihydrate and 0.3839 g of potassium permanganate in 50 ml of distilled water, the catalyst was impregnated with silica gel and the following was carried out in the same manner as in Example 1. 13), compared with the case where the same molar amount of permanganic acid was used instead of potassium permanganate (Example 14). The reaction was carried out by filling 15 ml of the catalyst into a U-shaped reaction tube made of Hastelloy B and using the raw material gas (CO:H ₂ = 2:1) at a pressure of 50 Kg/cm ² G and a temperature of 277°C.
was fed at a rate of 50 Nl/hour. Example 15 (Example) 1.9194 g of rhodium trichloride trihydrate and 0.3849 g of potassium permanganate were completely dissolved in 50 ml of distilled water, and then impregnated with 30 g of silica gel. I got a catalyst. The metal composition of this catalyst was Rh: 2.5%, Mn: 0.44%, and K: 0.32%. 15 ml of this catalyst was packed into a Hastelloy B U-shaped reaction tube, and the raw material gas (CO:H ₂ = 2:1) was fed at a rate of 50 Nl/hour under the conditions of a pressure of 50 Kg/cm ² G and a temperature of 269°C. and the activity was evaluated. Example 16 (comparative example) 1.9184 g of rhodium trichloride trihydrate, 0.6922 g of manganese nitrate hexahydrate, and 0.2488 g of potassium nitrate,
Completely dissolve in 50ml of distilled water, then add silica gel.
A catalyst was obtained in the same manner as in Example 1. The metal composition of the catalyst was the same as Example 15 (Example). Activity evaluation was performed in the same manner as in Example 15. The results are summarized in Table 2.

[Table] As is clear from Table 2, Example 15 and Example 16
Although the metal composition of the catalyst is the same, when permanganate is used as the manganese raw material (Example 15), when nitrate is used (Example 16)
Compared to this, the production ratio of acetic acid in C2 oxygenated compounds is significantly larger.

Claims (1)

[Claims] 1 In a method for producing an oxygen-containing compound containing acetic acid, acetaldehyde, and ethanol by reacting carbon monoxide and hydrogen in the presence of a catalyst containing rhodium and manganese, the compound is supported on a carrier together with permanganate ions. an active rhodium catalyst obtained by heat treatment of a rhodium compound;
A method for producing an oxygen-containing organic compound, characterized by using a catalyst coexisting with potassium ions.