DE1443906C3 - Process for the preparation of alkenyl esters - Google Patents

Description

A process for the preparation of alkenyl esters has been found which is characterized in that one monoolefins with oxygen and higher organic acids than acetic acid in the presence of a palladium metal catalyst, which is applied to supports containing silica or aluminum oxide, is converted at an elevated temperature.

Suitable olefins for the process according to the invention are aliphatic monoolefins, such as ethylene and propylene or butylenes. It is advantageous to use the olefins in high concentration, e.g. B. ethylene as 99% ethylene, but they can also z. B. used in a mixture with paraffinic hydrocarbons with which they often arise in petroleum refining processes.

Mono- or polybasic acids can be used as acids for the process according to the invention, z. B. propionic acid, butyric acids, adipic acid, but also aromatic acids such as benzoic acid or Phthalic acids, such as o-, m- or p-phthalic acid. Here too it is advisable to use the acids in concentrated form. The molar ratio of the acids to the Olefins or the alkylbenzenes is advantageously approximately 0.2 to 3.0: 1.

Examples of the organic esters obtained according to the invention are: vinyl propionate, vinyl butyrate, vinyl benzoate, Divinyl adipate, divinyl o-phthalate, divinyl pphthalate, Allyl propionate, allyl butyrate, allyl benzoate, di-allyl-m-phthalate, methallyl propionate, methallyl butyrate or di-methallyl-o-phthalate.

The palladium-metal catalyst used according to the invention is applied to a carrier. An aluminum oxide carrier is used as the carrier, expediently those in which the aluminum oxide is partially or completely in the form of spinel. Aluminum silicates or silicas can also be used as carriers. If aluminum oxide itself is used as a carrier, it is advisable to use carriers which have been produced from active aluminum oxide by thermal treatment and have internal surfaces between 1 and 100 m ² / g. preferably 10 and 80 m ² / g. In the spinel catalysts, the aluminum oxide is advantageously at least 20%, if possible 40% and more, as spinel.
Such carriers have proven to be very suitable,

ίο in which the aluminum oxide is practically completely present as spinel and which preferably have internal surfaces of 10 to 80 m ² / g. Lithium, beryllium and magnesium in particular have proven themselves as spinel-forming metals. Zinc, manganese, iron, cobalt and nickel, with lithium in the monovalent form and all others in the divalent form. The spinel catalysts can be produced in various ways. One can, for example, start from highly active aluminum oxide in lump form, which has an internal surface area of 200 to 350 m ² / g. This lumpy aluminum oxide, for example in the form of sausages, pills or balls, can be impregnated with an aqueous salt solution of the spinel-forming metal to be used or, in the case of lithium, with an aqueous hydroxide solution and the impregnated catalyst can be dried. it is advisable to convert these into oxides by heating them to 250 to 650 ° C., optionally with the addition of gases containing oxygen or water vapor 2 to 20 hours. When using lithium as the spinel-forming metal, you can soak several times with the hydroxide solution to bring about complete spinel formation with intermediate drying. If you have done the soaking with salts, you can also soak several times with the interposition of the decomposition stage for the salt. Another way of working is that of fine granular aluminum oxide with a large inner surface and this is mixed with the solution of the metal compound, whereby you can add as much solution of the metal compound as the beab- (.

corresponds to the later degree of conversion into spinels. After drying, you can use the mass deform suitable means, e.g. B. press into strands or pills, optionally with the addition of lubricants and - as far as salts were used - with the interposition of the decomposition stage as above described glow. Another manufacturing option is to use aqueous solutions of aluminum salts, for example sodium aluminate, by adding compounds of the spinel-forming metals to precipitate the metal aluminates, to free them from adhering soluble salts by washing and converting the obtained spinel intermediate product into spinel by the thermal treatment. It is it is also possible to produce mixing spindles by using several spinel-forming metal compounds. The amount of annealing temperatures and the duration of the annealing process are the same for the individual spinel precursors different, but it can easily be determined by preliminary tests which conditions must be met are in order to obtain the desired porosity of the finished catalyst support.

When using silica or aluminum silicates as a catalyst carrier it is more advantageous-

3 4

wise from preliminary products with a large inner upper class participant, it is more advantageous to use concentrated

surface area (above 200 m ² / g) and leads this to work through titrated oxygen, expediently

mix treatment in products over with inner over 99%. As far as one works in the liquid phase,

Surface areas between 20 and 80 m ² / g. it is advantageous to use 0.5 to 30 mol

The palladium can be on the support in amounts of 5 oxygen per 100 mol of olefins used. By the Arvon z. B. 0.1 to 10 percent by weight, the oxygen content in the gas phase can be advantageous wise 0.5 to 5 percent by weight, are applied. gaseous mixture of olefins, acids and sour-das Palladium can be applied to the carrier z. B. 1 to 40 parts by volume, advantageous earth, by z. B. with an aqueous palladium as 2 to 30 parts by volume. Because im one time saline solution soaks and through reduction, for example only part of the gases, especially the olefins, wisely with hydrazine hydrate, which is reacted in an alkaline solution, it can be advisable to use the gases Palladium precipitates on the carrier. But you can after separation of the reaction products in the also the palladium, for example the nitrate, or recirculation.

the organic salts, for example the acetate, by The reaction temperatures are expedient

Reduction with hydrogen at an elevated temperature in the range from 50 to 250 ° C., advantageously

transfer into the metal. 100 to 180 ° C. The reaction can take place under normal pressure

In a particularly preferred embodiment or under increased pressure. At the you can carry out the reaction in the presence of alkali or work in the liquid phase, you can z. B. Ge alkaline earth salts the applied total pressures of 2 to 80 atm. use. At the the organic acids. Mainly 20 jobs in the gas phase are carried out more appropriately The lithium, sodium and potassium salts are wise at ordinary or slightly elevated levels of organic acids. As far as you can see the reaction in pressure.

When working in the liquid phase, it is advisable to use the mentioned organic salts in the work-up of the reaction products to be used in the following organic acid to dissolve. There are 0.2 to 25 ways to do it: If there are no salts in the reaction mixture 2 molar solutions of the organic salts in which are to be dissolved, the reaction mixture is separated by distillation turning acids. Insofar as one works in the gas phase, unreacted reactants are formed in the, you bring the salts to the finished with palladium th ester and any by-products, provided catalysts to in amounts of 0.5 to Insofar as dissolved salts were present in the reaction, 10 percent by weight, advantageously 1 to 5 percent, can be the low-boiling products initially weight percent, based on the carrier. It is expedient to separate off by distillation, if necessary with the aid of the salts in aqueous solution on the noble water vapor or other carrier gases, metal-provided catalyst to impregnate and on and can in the residue the separation of salt and. finally to dry. make higher-boiling products through extra

If the catalysts are used in a fixed arrangement with an organic solvent, for example in the reaction chamber, then pills, sausages and hydrocarbons can be used. When working in the gas or spheres with a size of 2 to 8 mm, the phase leaving the reactor can advantageously be 3 to 5 mm. When using the products to cool so that most of the columns of catalyst in the moving bed are chosen more advantageously and the reaction products are liquefied. The here wise the spherical shape of the catalyst, when working in the 4 ° non-condensed fractions of the reaction products, fluidized bed can, for. B. the microsphere shape with sizes for example the ester, one can use the con of 20 to 80 μ. If, with gases leaving densation, the process according to the invention is operated in the liquid, for example acids, higher-boiling esters, glyco phase with suitable means, 45 sion of gases to liquefy. The application of the Kommer can upwards or downwards through the catalysis of the gases has the advantage that the separation of the sator bed can be passed through, whereby the gaseous carbonic acid formed as a by-product from the moderate constituents - ie z. B. to facilitate the ethylene and the reaction gases. Liquid products can be conveyed from the condensates obtained by the oxygen - in cocurrent or in countercurrent with cooling or compression. The reaction can also be finely divided into the products, i.e. the organic esters, suspended from the water-liquid products and separated from the reaction product after the end of the reaction on the one hand and separated from the acids on the other hand. The acid can evaporate and in vapor form and lead back into the reaction chamber. The application 55 is to be returned to the reaction space as soon as one is working in the gas phase. .
a fixed catalyst particularly advantageous Example 1
detention. The reaction participants can be The preparation of the catalyst support was carried out in or downward flow through the catalyst bed in the following manner: 4 mm spheres. But it can z. B. also with a diameter of active aluminum oxide can be worked with a moving lumpy catalyst, 60 inner surface of 288 m ² / g were used at usual · h., The catalyst can be in the form of a moving temperature with such an amount of saturated bed through An aqueous solution of zinc nitrate is passed through the reaction chamber, which corresponds to a 40% formation of zinc spinel, or a fluidized bed can also be used. By heating the soaked and dried spheres in gaseous form, the reactants are passed through a bed in which 65 500 ⁰ C the zinc nitrate was decomposed to the oxide. This the catalyst is in a swirling state. The product was then heated to 1050 ^° C. for 12 hours

The oxygen can be supplied in the form of air and heated, whereby the spinel formation took place. The so

will. Particularly in the case of circulation, the reac- obtained carrier has an inner surface of

36 m ² / g- To produce the catalyst, it was impregnated with palladium chloride solution. The palladium was then finely dispersed onto the support using an alkaline hadrazine hydrate solution. The palladium content of the finished catalyst was

2 percent by weight. 4.7 parts by weight of sodium propionate per 100 cm ^{3 of} the finished catalyst were impregnated as an aqueous solution on this catalyst. It was then ^{dried at 110 °} C. in vacuo. 500 cm ^{3 of} this catalyst were introduced into a tube of 22 mm inside diameter and 1500 mm in length. A mixture of 4.5 mol of ethylene, 1.45 mol of propionic acid and 0.85 mol of oxygen was passed hourly in vapor form over this catalyst, which was fixedly arranged in the reaction chamber. The reaction temperature was 145 ° C. Work was carried out at ordinary pressure. 8.8% of the carbon used as ethylene was converted. From the implemented. Carbon was obtained 80.6% as vinyl propionate and 19.4% as carbon dioxide.

Example 2

For the preparation of the catalyst, one obtained by heating active alumina was obtained Aluminum oxide with an inner surface of

3 m ² / g used. This carrier was impregnated with palladium chloride, then the palladium was finely dispersed on the carrier using an alkaline hydrazine hydrate solution. The palladium content of the finished catalyst was 2 percent by weight. A horizontal autoclave was used, in which 250 cm ^{3 of} the described catalyst were placed in a wire mesh. When the wire mesh was rotating in the autoclave, the catalyst was alternately in the liquid and gas phase, corresponding to the continuous work in the trickle phase. 99 g of propionic acid and 34 g of propylene (94.5%) were used in the 700 cm ^{3 autoclave.} Then 49 atmospheres of air were injected, corresponding to 5.0 g of oxygen. While the wire mesh was rotating, the autoclave was heated to 120 ° C. and left at this temperature for 12 minutes. 18% of the carbon used as propylene had converted. 66.2% of the converted carbon was obtained as allyl propionate, 17.6% as acetone and 5.5% as carbon dioxide.

Example 3

In the same arrangement as in Example 2 and with the same catalyst were in the autoclave introduced 98 g of butyric acid, 35 g of ethylene, and pressurized air to a total pressure of 50 atm., Corresponding to 5.7 g oxygen. The autoclave was heated to 122 ° C. while the wire mesh was rotating and leave at this temperature for 10 minutes. Of the carbon introduced as ethylene 4.6% implemented. 48.9% of the converted carbon was obtained as vinyl butyrate and 48.3% as carbon dioxide.

Claims (5)

Patent claims: 1. Process for the production of alkenyl esters, characterized in that one monoolefins with oxygen and higher organic Acids as acetic acid in the presence of a palladium metal catalyst based on silicic acid or aluminum oxide-containing carriers is applied, reacted at elevated temperature. 2. The method according to claim 1, characterized in that the catalyst support to be used internal surface area from 1 to 100 rrr / g. preferably 10 to 80 mm / g. 3. The method according to claim 1 and 2, characterized in that there is an aluminum oxide Carrier used in which the alumina partially or completely as spinel is present. 4. The method according to claim I to 3, characterized in that the reaction is carried out in the presence of alkali or alkaline earth salts of the organic acids used. 5. The method according to claim I to 4, characterized in that the process in the liquid Phase or in the gas phase.