DE1568400C - Process for the production of vinyl acetate - Google Patents

Description

The catalyst (125 parts by weight) was placed in a reactor consisting of a vertical stainless steel tube with an internal diameter of 2.54 cm. Acetic acid (500 parts / hour) was passed from top to bottom through the catalyst bed in countercurrent to an ethylene-oxygen mixture (100: 6 parts by volume) flowing from bottom to top. The reactor was kept at 120 ^° C. and the gas pressure at 10 atm.

The vinyl acetate was used in an amount of 0.22 and the acetaldehyde in an amount of 0.36 mol / l of catalyst volume / hour. educated. Neither carbon dioxide nor carbon dioxide nor high-boiling compounds could be proven.

Example 2

In the manner described above, a catalyst consisting of palladium on aluminum was prepared which contained t part by weight of palladium per 100 parts of aluminum oxide, which ^{had been heated to 1000 °} C. for 22 hours and had a surface area of 48 m ² / g. When this catalyst was used under the conditions mentioned in Example 1, the following yields were obtained: 0.3 mol of vinyl acetate / 1 / hour; 0.003 mol acetaldehyde / 1 / hour and 0.004. Moles of carbon dioxide / 1 / hour This illustrates the technical improvement achieved by the method according to the invention.

Example 3

A catalyst containing 0.6 percent by weight palladium on activated carbon was prepared by impregnating granular activated carbon with a. Palladium chloride solution and subsequent reduction in flowing hydrogen at 120 ⁰ C produced.

This catalyst was used under the conditions mentioned in Example 1. Here was ίο vinyl acetate in a space-time yield of 0.42 mol / l / Hours formed. The following selectivities (based on ethylene) were achieved: vinyl acetate 81.8; acetaldehyde 5.5; Ethylidene diacetate 11.5; Carbon dioxide 1.1%.

B e i s ρ i e 1 4

A catalyst comprising the 0.6 parts by weight of palladium ■ and 0.15 parts by weight of vanadium on activated carbon was prepared by addition of palladium as palladium chloride, reduction with hydrazine hydrate in the manner described in Example 1, followed by impregnation of the combination of palladium-carbon with a solution made from sodium metavanadate in boiling water.

When using this catalyst under the conditions mentioned in Example 1, the yield was at Vinyl acetate 0.3 mol / 1 / hour The selectivities (related on ethylene) were as follows: vinyl acetate 80.8; Acetaldehyde 12.4; Ethylidene diacetate ■ 5,6 and carbon dioxide 1.1%.

Claims (2)

1 2 solution of a palladium compound, ζ. Β. Palladium (II) claims: chloride, to be impregnated. The latter is then reduced to palladium metal, e.g. B. by treatment 1. Process for the preparation of vinyl acetate with hydrogen or hydrazine, expediently in the form by converting ethylene in the liquid phase 5 of hydrazine hydrate, which is in an alkaline solution, with molecular oxygen and acetic acid in z. B. a sodium hydroxide solution is dissolved. the The presence of an elemental platinum group-impregnated carbon is then caused, for example, by tall isolated on a support containing catalyst filtration, washed with water and down Overpressure and at elevated temperature, then dried. Vanadium, chrome, manganese, characterized in that the i ° iron, cobalt, nickel or copper or their salts Reaction in the presence of 0.1 to 10 Ge can be incorporated into the catalyst or in the percent by weight, based on the sum of the acetic acid used. weight from metal and carbon carrier of a platinum The activated carbon serving as carrier can be used in any group metal, on activated carbon with an upper biger suitable way. Suitable area of more than 50 m ² / g as catalyst 15 is, for example, granular charcoal or sugar charcoal performs. or coal obtained from hard coal, which in any 2. The method according to claim 1, characterized in that it is activated in a suitable manner, e.g. B. by steam shows that one is the implementation with an active treatment. The activated carbon preferably has a carbon surface area in the range of surface area in the range from 400 to 1200 m ² / g, in particular 400 to 1200 m ² / g, preferably more than 20, in particular more than 500 m ² / g. 500 m ² / g carried out as a carrier. When carrying out the procedure is located the catalyst applied to the activated carbon in a standing pipe. The acetic acid is on top Introduced at the end of the catalyst bed. In countercurrent 25 or in cocurrent with the liquid acid becomes a Mixture of ethylene and gaseous oxygen passed through the pipe. The heat of reaction can be in Processes for the production of esters are carried away in an unusual manner. The reaction pro- saturated alcohols, e.g. B. vinyl acetate, through oxides are at least partially carried by the gas stream tion of olefins with molecular oxygen in 30 and can by cooling or washing a mixture that contains carboxylate and carbonate ions after leaving the reactor, contains acid, in the presence of a platinum group metal The remaining gas mixture is then as a catalyst have already been proposed. The gate returned. A small amount is dispensed Platinum group metal can be drawn alone or on a carrier in order to remove impurities such as paraffins. which has a surface area of less than 50 m ² / g. When the gas is at high speed in the be turned. Cycle may vary depending on the temperature The invention relates to a process for and the pressure at which the reactor is maintained, the production of vinyl acetate by reacting, to be carried out in such a way that the gas discharges all of the reactive ethylene in the liquid phase with molecular acid products. The reactor material and acetic acid is preferably kept in the presence of an elemental 40 at constant gas pressure, and fresh ethylene and oxygen containing platinum group metal on a carrier are supplied to the extent that the catalyst is supplied under excess pressure and at an elevated temperature as it is from the reaction medium with formation of the temperature, which is characterized by the fact that the ducts are absorbed. The acetic acid, the catalyst bed is passed over reaction in the presence of 0.1 to 10 by weight, is for catalyst per cent, based on the sum of the weight of ¹ 45 recirculated bed, ie, is allowed an enrichment of metal and carbon support a platinum group metal, of the ester and other products take place. The on activated carbon with a surface area of more than the maximum permissible concentration of the ester depends on 50 m ² / g as the catalyst performs. depends on the temperature at which the reaction The process can be carried out at elevated temperatures. For the production of vinyl acetate from the range of 50 to 15O ⁰ C, preferably above 50, the concentrations of ethylene in an in 100 ⁰ C, are carried out. Overpressures of at -10.5 atmospheres and 100 ⁰ C carried out reaction up to for example 1 to 50 atmospheres, expediently from about 10 atmospheres, 30% vinyl acetate with 6% water. The Rea- can be applied. tion products can be removed from the reactor The amount of molecular oxygen, based on a side stream being withdrawn, the amount of olefin used, can be fractionated within a moderate 55 to remove the products. The wider limits are. Oxygen-containing acetic acid can then be partly or wholly returned to the concentration of up to 7 percent by volume, based on the reactor.
Volume of olefin. Preferably, concentrations of about 5 percent by volume are used. example 1 Under the term "platinum group metal" are 60 the metals platinum, palladium, ruthenium, rubidium, a catalyst that means 1 percent by weight palladium-osmium or iridium. Preferred as the metal contained, was made by impregnation of grain catalyst is palladium. The amount of platinum group metal retained in the catalyst containing activated carbon with a palladium chloride solution can lie within and subsequent reduction with an alkaline half-moderately wide limits. The catalyst 65 produced hydrazine hydrate solution. The catalyst can be prepared in any suitable manner and washed with distilled water until the. serving as a carrier charcoal are applied. Wash water was free of chloride ions and then with the example, coal with an aqueous 110 ⁰ C can be dried.