JPS6210485B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a method for producing oxygen-containing compounds such as acetic acid from synthesis gas. In particular, the present invention relates to a method of increasing the activity of a rhodium catalyst for producing a C2 oxygen-containing compound (an oxygen-containing organic compound having 2 carbon atoms) containing acetic acid by pre-treating a carrier on which rhodium is supported. (Prior Art) A method for producing an oxygen-containing compound mainly containing two carbon atoms, particularly an oxygen-containing compound containing acetic acid, acetaldehyde, and ethanol, from carbon monoxide and hydrogen is known. In this reaction, a heterogeneous catalyst consisting essentially of metallic rhodium is used (Japanese Patent Publication No. 41568/1983), and various improved methods are known for increasing the activity of the catalyst, such as by using a co-catalyst. As an improved method by treating the carrier, a vacuum evacuation method (for example, Japanese Patent Application Laid-Open No. 1983-1972) before impregnation with a catalyst metal component-containing liquid is
80806, 52-14706) and an oxalic acid cleaning method (for example, JP-A-56-8333, 56-8334). However, when focusing on the catalytic activity for producing acetic acid among C2 oxygen-containing compounds, sufficiently satisfactory results have not yet been obtained in terms of yield and selectivity. (Problems to be Solved by the Invention) In view of the above prior art, the present invention provides an improved method for obtaining a product containing an even higher amount of acetic acid in a method for producing C2 oxygenated compounds from synthesis gas. The purpose is to provide (Means for Solving the Problems) The present inventor has compared the case of using a pre-treated carrier in which an alkali metal salt is added and calcined and then washed with an acid aqueous solution compared to the case of using an untreated carrier. do
The present invention was completed based on the discovery that the activity of a rhodium catalyst for producing C2 oxygen-containing compounds is significantly enhanced. That is, the present invention relates to 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, which comprises supporting an alkali metal salt, calcination, and an aqueous acid solution. A pretreatment combined with washing reduced pores with a pore radius greater than 100 Å while leaving the mode of the pore radius in the range 40-100 Å virtually unchanged. This is a method for producing an oxygen-containing organic compound characterized by using a supported rhodium catalyst. The oxygen-containing compound targeted in the present invention is:
It refers to fatty acids, aldehydes, alcohols, esters thereof, etc., and typical examples include those with two carbon atoms, such as acetic acid, acetaldehyde, ethanol, and their esters, especially those containing two carbon atoms whose main component is acetic acid. It is an oxygen compound. When carrying out the present invention, the carrier material to be subjected to specific pretreatment before catalyst preparation is preferably a porous inorganic solid material having a specific surface area of 1 to 1000 m ² /g, such as silica, alumina, silica alumina, Examples include titanium oxide, zirconium oxide, thorium oxide, magnesium oxide, activated carbon, and zeolite, but silica-based carriers are particularly preferred. These carriers can be used in any shape, such as powder or pellet. These carrier materials are pretreated by the method exemplified below. i.e. from 0.01% to the weight of the untreated carrier material.
0.2%, preferably 0.03% to 0.1% of alkali metal salts, i.e. inorganic acid salts such as halides, halogenates, sulfates, nitrates, carbonates, hydroxides of lithium, sodium, potassium, rubidium, cesium; Impregnate with an aqueous solution containing organic acid salts such as acetate, formate, oxalate, etc. and air dry overnight. In this way, the carrier material carrying the alkali metal salt is
Calcinate at 200°C to 1500°C, preferably 400°C to 800°C. The atmosphere for the firing process may be air or an inert gas such as helium. Such a calcination treatment in the presence of an alkali metal salt reduces large pores with a radius of 100 Å or more present in the untreated carrier material and increases the uniformity of the pore distribution. At this time, 40~
The mode of the pore distribution in the 100 Å range remains virtually unchanged (Figure 1). After firing, alkali metal salts are removed by heating in an aqueous acid solution of 2% to 10% organic acids such as oxalic acid and acetic acid and inorganic acids such as nitric acid, sulfuric acid, and hydrochloric acid, and then boiled with a large amount of distilled water and decane. As for the method of producing a rhodium catalyst by supporting rhodium on a pretreated support by removing the acid remaining in the support by repeating the washing process, known techniques related to supported noble metal catalysts can be used. That is, 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; Rhodium chloride, or compounds commonly used in the preparation of precious metal catalysts such as ammine complex salts, clusters, rhodium carbonyl, and rhodium carbonyl acetylacetonate can be used, but rhodium chloride is particularly recommended because of its ease of handling. Other cocatalysts may be used in any form, but chlorides are particularly preferably used as compounds soluble in a suitable solvent such as water, as in the case of rhodium compounds. As a method for preparing the catalyst, conventional methods for preparing noble metal catalysts, such as an impregnation method, a dipping method, an ion exchange method, a coprecipitation method, a kneading method, etc., are used. As for the method of supporting the catalyst components on the carrier, all the catalyst components may be supported simultaneously, each component may be supported on the carrier sequentially, or each component may be subjected to reduction heat treatment, etc. as necessary. It is possible to use various means such as a method of sequentially or stepwise loading while carrying out the processing. To further explain the impregnation method as an example, a thermally decomposable inorganic rhodium compound and a compound of a cocatalyst component element are made into an aqueous solution in an amount of water according to the water absorption rate of the pretreated carrier, the carrier is added to the solution, and the mixture is stirred. After that, it is heated and dried to support it. Such a solid supporting rhodium and a cocatalyst component is usually further heat-treated to become an active catalyst supporting finely dispersed rhodium and a cocatalyst. The heat treatment is usually carried out by heating under reducing conditions, and the heat treatment converts the rhodium compound into an active rhodium catalyst. For example, rhodium chloride supported together with a co-catalyst component is heated in a hydrogen stream to change into a metal or a low valence state close to that of metal, and becomes active. The reduction treatment can be carried out in the presence of hydrogen 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°C to 600°C, preferably 150°C to 500°C. At this time, in order to maintain the optimum activation state of each component of the catalyst, the reduction treatment may be carried out 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 are no strict restrictions on the amount of each catalyst component used, but the surface area of the carrier (1 to 1000 m ² /g)
Determined by taking into consideration. Usually, the content of rhodium in the supported catalyst is between 0.01 and 15% by weight, preferably between 0.1 and 10% by weight.
Weight%. Catalysts such as those described above are used to convert synthesis gas, a mixture of carbon monoxide and hydrogen, into acetic acid-rich C2 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, in addition to carbon monoxide and hydrogen, carbon dioxide, nitrogen, argon, etc.
It may also contain other components such as 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 some cases, a liquid phase reaction may also be carried out, in which the catalyst is suspended in a suitable solvent and a raw material gas is introduced therethrough. Regarding the reaction conditions, various reaction condition factors can be varied over a wide range for the purpose of obtaining an oxygen-containing compound containing acetic acid as a main component in high yield and high selectivity. Typical ranges applicable to fixed bed flow reactors are shown below. The reaction pressure is 0 to 300Kg/cm ² G, preferably 20
It is carried out at a pressure of ~200Kg/cm ² G or less. The reaction temperature is
The temperature is 150-450°C, preferably 200-350°C. When the reaction temperature is high, the amount of hydrocarbon by-products increases, so it is possible to take measures such as increasing the raw material charging rate or diluting the catalyst with a carrier or the like in some cases. The charging rate of raw material gas per catalyst volume, that is, the space velocity, is calculated under standard conditions (0°C, 1 atm).
The rate is appropriately selected from the range of 10 ² to 10 ⁶ /hour, preferably 10 ³ to 5×10 ⁴ /hour, depending on the reaction pressure, reaction temperature, and raw material gas composition. The raw material gas composition is mainly a gas containing carbon monoxide and hydrogen, nitrogen,
It may contain an inert gas such as argon, helium, methane, carbon dioxide, or water. The molar ratio of carbon monoxide to hydrogen is from 20:1 to 1:5, preferably from 10:1 to 1:2. (Effects of the Invention) According to the present invention, a reaction result with a high space-time yield of acetic acid can be obtained, as specifically shown in the following examples. It is thought that the rhodium catalyst prepared using the carrier pretreated in this manner has a high surface concentration of catalyst components and exhibits high activity. The present invention will be explained below using specific examples. Catalyst Preparation Example 1 (Comparative Example with Untreated Support) 0.2122 g of zirconium tetrachloride (ZrCl ₄ ) was dissolved in 50 ml of distilled water, and then rhodium trichloride trihydrate was added.
Dissolve 1.9182g and add hydrochloric acid to completely dissolve. Furthermore, 0.4369 g of lithium permanganate trihydrate was dissolved to form a homogeneous solution. This catalyst precursor aqueous solution was mixed with silica gel (GR-
71111) 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 placed in a stream of steam (20N/hour).
It was held at 350°C for 2 hours to perform hydrogen reduction. The obtained catalyst is No. 1 in Table 1. Catalyst in Table 1 (No.1
~4) Metal composition (wt%) is rhodium 2.5, manganese 0.445, lithium 0.056, zirconium 0.277
It is.

【table】

[Table] Example 2 Support material used in Example 1 (silica gel GR-
71111) were pretreated in the order shown below. That is,
The untreated support material was impregnated with an aqueous lithium chloride solution containing 0.056% lithium and air dried overnight. After firing at 400°C for 2 hours in a blast firing furnace, the mixture was heated under reflux in a 5% oxalic acid aqueous solution for 5 hours, then boiled with a large amount of distilled water, and washed by repeated decantation. 110℃ in a blow dryer.
Dry for 4 hours to obtain a pretreated carrier. 30 g of the above pretreated carrier was impregnated with an aqueous catalyst precursor solution prepared in the same manner as in Example 1, and air-dried overnight. This was dried and reduced in the same manner as in Example 1 to obtain catalyst No. 2 in Table 1. Example 3 A carrier material (silica gel GR-
71111) to obtain a pretreated carrier. Example 2 below
A catalyst was prepared in the same manner as above to obtain catalyst No. 3 in Table 1. The results of measuring the pore distribution of this pretreated carrier are shown in FIG. 1 in comparison with the pore distribution of an untreated carrier material. In the case of untreated support materials, pores with a mode of pore radius of ±10% (77±8%) account for only 46% of the pore volume; As a result of acid washing, the number of pores with a radius of 100 Å or more decreased, and the proportion of pores with a mode ±10% of the pore volume increased to 64%. Example 4 A carrier material (silica gel GR-
71111) and prepared a catalyst in the same manner as in Example 2 below to obtain catalyst No. 4 in Table 1. Example 5 (Comparative example using untreated carrier) Potassium chloride 0.0136g, lithium chloride 0.0206
g, terbium chloride dihydrate 0.0274g, iridium tetrachloride monohydrate 0.1026g, rhodium trichloride trihydrate
Completely dissolve 1.919 g in 25 ml of distilled water. This catalyst precursor aqueous solution was impregnated into 15 g of silica gel (GR-71111 manufactured by Fuji Davison Chemical Co., Ltd.) and air-dried overnight. After drying in a blow dryer at 40°C for 20 hours, it was filled into a quartz glass reduction tube and held at 600°C in a hydrogen stream (20 Nl/hour) for 2 hours to perform hydrogen reduction. The obtained catalyst is No. 5 in Table 2. Second
The metal composition (wt%) of the catalysts (Nos. 5 to 8) in the table is 5 rhodium, 0.048 potassium, 0.023 lithium, 0.096 terbium, and 0.374 iridium. Example 6 Aqueous catalyst precursor solution prepared in the same manner as Example 5 was added to Example 3
It was impregnated with 15 g of the pretreated carrier used in , and air-dried overnight. After drying in a blow dryer at 40°C for 20 hours, the mixture was filled into a quartz glass reduction tube and held at 450°C in a hydrogen stream (20 Nl/hour) for 2 hours to perform hydrogen reduction. The obtained catalyst is No. 6 in Table 2. Example 7 (Comparative example using untreated carrier) A catalyst precursor aqueous solution prepared in the same manner as in Example 5 was mixed with silica gel (GR-70513 manufactured by Fuji Davison Chemical Co., Ltd.) 15
g and air-dried overnight. Thereafter, drying and hydrogen reduction were carried out in the same manner as in Example 5. The obtained catalyst is shown in Table 2.
It is No.7. Example 8 Untreated carrier material used in Example 7 (silica gel GR
-70513) was pretreated in the same manner as in Example 2. However, the firing temperature for supporting lithium chloride is 600°C.
Below, 15g of the catalyst precursor aqueous solution of Example 5 was added to the pretreated carrier.
and air-dried overnight. Thereafter, drying and hydrogen reduction were performed in the same manner as in Example 6. The obtained catalyst is shown in Table 2.
It is No.8. Activity evaluation method and results In Examples 1 and 2, 3 ml of catalyst and 7 ml of carrier were used. In Example 3, 2 ml of catalyst and 8 ml of carrier were used. In Example 4, 4 ml of catalyst was used.
and 6 ml of carrier were uniformly filled into a stainless steel U-shaped reaction tube, and the raw material gas (CO/H ₂
= 2/1) at a rate of 100 Nl/hour, the reaction was carried out at a reaction pressure of 80 Kg/cm ² G and a reaction temperature of 300°C. In Examples 5 to 8, 10 ml of the catalyst was packed into a stainless steel U-shaped reaction tube, and the raw material gas (CO/H ₂ =
9/1) at a rate of 100Nl/hour, and the reaction pressure
The reaction was carried out at 80 Kg/cm ² G and at a reaction temperature of 300°C. The reaction results obtained by gas chromatography analysis of the liquid product and reaction gas collected by pressure cooling are shown in Tables 1 and 2. Here, the selection rate (%) is
It is the percentage of moles of carbon monoxide converted to specific products relative to moles of carbon monoxide consumed.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the pore distribution with the pore radius on the horizontal axis and the differential pore volume on the vertical axis, where the solid line shows the distribution for the pretreated carrier and the broken line shows the distribution for the untreated carrier material.

Claims (1)

[Claims] 1 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 rhodium-containing catalyst, which includes supporting an alkali metal salt, calcination, and washing with an aqueous acid solution. Depending on the combined pretreatment, 40~
It is characterized by using a rhodium catalyst supported on a porous inorganic solid material carrier in which pores with a pore radius larger than 100 Å are reduced while the mode of the pore radius in the range of 100 Å is virtually unchanged. A method for producing oxygen-containing organic compounds.