DE1075613B - Column for carrying out organic chemical reactions in the presence of fine-grain catalysts - Google Patents

Description

Implementation column. organic-chemical reactions in the presence fine-grain catalysts Numerous organic-chemical reactions are known which are carried out in the presence of catalysts. With discontinuous Process, it is possible in most cases to implement the reaction in reaction vessels, which also contain the catalysts. In many cases it is but one strives to carry out the organic chemical reactions continuously. So far as it is about the implementation of liquid reactants like them z. B. are generally present in esterification reactions, you can do this Carry out reactions in columns continuously. But it causes difficulties to fix the catalysts in the columns.

It has now been found that columns for carrying out o ¢ ganisch-chemi3cher Reactions in the presence of fine-grain catalysts are particularly suitable if the fine-grained catalysts are in sieve baskets, which are in the column are arranged in the manner of packing.

Colons filled with Raschig rings are used for the implementation the organic-chemical reactions, so can the fine-grained catalysts in sieve baskets in the shape of Raschig rings. In the hollow inside this packing is then the fine-grained catalysts. It is also possible, To use ordinary Raschig rings and in their cavity the sieve baskets with the to attach fine-grained catalysts. One embodiment is for example the following; Fixed load-bearing metal frames, which are in the form of random packings, will be covered with a fine-meshed net. In these baskets the fine-grained Filler to be filled (Fig. I). It is also possible to use ordinary packing, z. B. Raschigringe to provide inside and / or outside with a network and in fill the space between the Raschig ring and the mesh with fillers (Fig. II).

Other embodiments are possible. It is essential that the pressure load the overlying filling from the strainer baskets or from other self-supporting Bodies or their Gertist is added, so that the fine-grained filler loose is and can be fully effective without pressure load in the column.

It is advisable to only half up the individual sieve baskets To fill two-thirds with the fine-grain fillers. This achieves that the individual particles of the filler are easily mobile. Also swell some fillers, e.g. ion exchange resins. The size of the sieve meshes depends on the particle size of the fillers used. ion exchangers often have one Grain size from about 0.3 to 0.8 mm. In this case the mesh size should be be about 0.2 mm. The sieves can be made depending on the intended use of the column Metals or plastics.

The size of the sieve baskets depends on the diameter of the column. The same guidelines apply for selection as for Raschig rings.

The fillers, e.g. ion exchange resins, can be used in the regeneration stay in the strainer baskets.

Also provided with bottoms columns, on the bottoms of which the fine-grained Catalysts are located, are suitable for carrying out organic chemical reactions, if the fine-grained catalysts are prevented from falling through the bottom tray. In this case, the fine-grained catalysts are prevented from falling through by that one provides the floor drains with inclined fine-meshed sieves through which the catalysts on the floors do not get through. The sieves can e.g. B. be designed as small roofs (Fig. III) or in a cone shape.

The steep arrangement of the sieves achieves that the ion exchange resin the sieve does not close, but rolls again and again on the floor. But it is also possible to convert the ion exchange resin used as an esterification catalyst into small Sieve containers that are about one-third to two-thirds full, or in Liquid and gas permeable bags fill and in this form the Bring soil or the entire soil with the exception of the inlet and outlet weir to be covered by a sieve bell that is sufficiently high and firmly attached to the floor surface, in the interior of which the exchanger is loosely filled. It is essential that a Falling of the fine-grained ion exchange resin onto the underlying floors is prevented. The mesh size of the sieves depends on the grain size of the Replacement resin. The ion exchange resin is created by the steam from the respective floor below whirled up or "dances" on the floor like a catalyst in a fluidized bed. The whirling up of the ion exchange resin can be supported by the fact that the weirs on the individual floors are set so that a high layer of liquid is created stops on the floors. Sedimentation takes place in this liquid layer the fine grains slower than in the gas or vapor space organic-chemical reactions, which can be carried out in the columns equipped according to the invention are for example esterifications, transesterifications, transacetalizations, the production of ethers or the elimination of water or hydrogen halide. Particularly beneficial esterifications can be carried out in the columns equipped according to the invention, z. B. the esterification of unsaturated acids or alcohols, which polymerize easily. It is Z. B. possible to esterify acrylic acid continuously with alcohols without that losses due to premature polymerization of the Acryi.-acid or the formed Acrylic acid ester enter.

The parts mentioned in the examples are parts by weight.

Example 1 A Raschig column is equipped with an ion exchanger which are in fine-meshed wire baskets in the shape of Raschig rings, filled.

The mesh size of the sieve baskets is chosen so that the ion exchanger can't fail. 100 parts by volume per hour are continuously fed into the column an esterification mixture of 55% acetic acid and 45% methanol. This The feed is heated to 550.degree. C. and the bottom of the column is heated to 90.degree. Over the head the column distilled at 540 C hourly about 300 parts by volume of the azeotropic Ethanol / methyl acetate mixture, of which about 200 parts by volume per hour be returned as reflux to the column. The column bottom becomes running all the water of esterification with a little methanol, acetic acid and methyl acetate taken. This column bottom can in a second column in methanol, methyl acetate and water are separated. The methanol containing methyl acetate is fed back to the first column. During the esterification, about 100 fall every hour Parts by volume of 800% ester.

The yield, based on the volume of acetic acid used, is 94 to 96 ° / o.

Example 2 The outlet openings are in a bubble-cap tray column concealed in the lower floors by wire mesh nets. The wire mesh nets are so fine that the ion exchanger on the lower floors does not penetrate the meshes can fall. First about 600 parts by weight of glacial acetic acid are put into the column given and heated to 1200 C in the bottom of the column. Then it will be on top Soil that the Catalyst contains a mixture of 220 parts of secondary per hour Amyl alcohol and 214 parts of 70% aqueous acetic acid added. At the head of the column the azeotropic amyl acetate-water mixture is distilled off, some of it again is returned to the top of the column. The rest of this azeotropic mixture separates on cooling in water and about 97% amyl acetate. Man receives about 330 parts by weight of amyl acetate per hour. The yield is 980/01 based on the weight of acetic acid.

Example 3 72 parts of acrylic acid are mixed with 133 parts of methanol, preheated to 650 C and in a column as described in Example 1, introduced. A temperature of 950 ° C. is maintained in the bottom of the column. At the The entire ester passes at the top of the column at 62.50 C as an azeotropic mixture of methanol and methyl acrylate above. All of the esterification water runs in the sump, with very few by-products contains, continuously from. The atl yield of acrylic acid methyl ester is 980/0, based on the weight of the acrylic acid used. From the methanol-acrylic acid methyl ester - Mixture, the ester can be separated off in a known manner.

Example 4 72 parts by weight of acrylic acid are combined with 176 parts by weight Ethanol mixed, preheated to 800 C and in a column according to Example 1 and 2 given.

The ternary ester-water-alcohol mixture goes at the top of the column at 770 with a proportion of about 35 percent by weight of ethyl acrylate. The yield is 96 to 97 percent by weight, based on the acrylic acid used.

Example 5 In a bubble-cap tray column as described in Example 2 a mixture of 144 parts by weight preheated to 950 is continuously produced Acrylic acid and 222 parts by weight of butanol introduced. Distilled at the top of this column the ternary, azeotropic mixture of about 15 percent by weight of butyl acrylate, 35 weight percent water and 50 weight percent butanol with a boiling point of 920 C. This mixture separates after the condensation in one after the cooler built-in separator in an aqueous layer with about 6 percent by weight butanol and little ester and a second layer, mainly butanol and ester contains little water. This upper layer is fed back into the column as reflux. In the bottom of the column, the anhydrous ester formed falls with non-esterified one Acrylic acid and with excess butanol at a bottom temperature of 1300 C. The bottom of the column, which contains about 75 to 80 percent by weight of butyl acrylate, is washed using the water discharged from the separating vessel can be. The pure ester is obtained in a second column. The recovered Butanol is fed back into the esterification process. The yield of butyl acrylate is 90 to 93 percent by weight, based on the weight of the acrylic acid used.

Example 6 In a bubble-cap tray column there is fine-grained, Activated charcoal dried at 1800 C. The activated carbon was at 1800 Charge C to saturation with dry hydrogen chloride gas. In this column 300 doughs about 95% of the above 1,4-butene-2-diol are passed. The dwell time in the Column takes about 3 hours. The feed temperature is kept at 150 to 1600.degree. At the top of the column, 195 to 196 parts per hour of 2,5-dihydirofuran are used as an azeotrope Mixture with 7 percent by weight of water at a boiling point of 64 to 650 C is distilled off.

Further areas of application for these columns are, for example the production of methyl acetate by transesterification of amyl acetate with methanol, using an acidic ion exchanger, or the production of hexyne-1, with the aid of a basic ion exchanger made from dibron? hexane-1,2 Splits off hydrogen bromide.

PATENT CLAIMS: 1. Kolorme for carrying out organic-chemical Reactions in the presence of fine-grain catalysts, characterized in that the fine-grained catalysts are in sieve baskets, which are in the column are arranged in the manner of packing.

Claims (1)

2. Column according to claim 1, characterized in that the screen baskets Raschig rings are whose base and top surfaces with sieves of suitable mesh size are locked. 3. Column according to claim 1, characterized in that the fine-grain fillers are located on the bottoms of a tray column, their processes are provided with inclined fine-meshed sieves.