DE1793481B2 - PROCESS FOR THE PRODUCTION OF VINYL ACETATE - Google Patents

Description

Vinyl acetate can be exhibited in a known manner after.

general equation This effect occurs already clearly with carrier materials

with grain sizes of about 1.5 mm in diameter and

2 CH ₂ = CH ₂ + 2 CH ₃ COOH + O ₂ 3 <> below it. The surprising increase

Pd compound of ^the catalyst performance, the vinyl acetate concentration

1 2 CH ₂ = CHOOCCH ₃ + 2 H ₂ O in the roll condensates and the acetic acid conversion

is in a fluidized bed with catalyst grain sizes of

from ethylene, acetic acid and molecular oxygen 0.1 to 0.5 mm in diameter particularly clear,

or air in the gas phase at an elevated temperature 35. B. vinyl acetate concentrations im

produce. It is of great importance that the raw condensate of about 45 percent by weight at a

Catalysts used have a high activity - performance of about 1000 g vinyl acetate per liter of catalyst

point to the use: the costly pallatizer and hour. It should be emphasized that especially

medium compounds, e.g. B. palladium oxide or acelate, the dissipation of the heat of reaction at the high

propionate, benzoate, sulfate, as low as possible to 40 catalyst performance in the fluidized bed no difficulty

keep. Furthermore, the reactor can be prepared in proportion to the capabilities.

higher catalyst outputs are reduced, so the invention now relates in detail to a further reduction in costs is achieved. Processes for the production of vinyl acetate have become known in the meantime, in the implementation of ethylene, acetic acid and molecular where the activity of the palladium oxygen used is increased in the gas phase, possibly in counter-bonds by special additives, to maintain inert gases Temperatures of 100 to get an economical process. 250 ⁰ C, preferably 150 to 220 ⁰ C, and pressures. B. the carboxylates, from 1 to 21 ata, preferably 5 to 11 ata, in contrast the acetates dos lithium, sodium, potassium, war a catalyst made of palladium compounds rubidium, cesium or alkaline earths (z. B. Mg, 50 and optionally called activators on a carrier, Ca). In addition, as activators, which are characterized in that the compounds of the metals copper, conversion in the presence of a catalyst through gold, zinc, cadmium, tin, lead, manganese, chromium, whose carrier material has a grain diameter of molybdenum, tungsten, uranium, were used , Iron, cobalt, nickel, about 0.1 to 1.5 mm, preferably 0.1 to 0.5 mm, niobium, vanadium or tantalum are listed. Has 55 as a carrier.

were silica, kieselguhr, silica gel, diatoms - Preferably the carrier material consists of silica

earth, aluminum oxide, aluminum silicate, aluminum (SiO ₂ ), especially in spherical form. Particularly advantageous

phosphate, pumice stone, silicon carbide, spinels, asbestos, the implementation of the implementation in the catalyst

or called activated carbon. Sator fluidized bed.

The known methods are generally used. However, within the scope of the present invention designed so that a starting gas mixture of the other carrier ethylene already mentioned, Acetic acid and oxygen are used via the catalysts. The same goes for those there sator at elevated temperature and elevated pressure called activators. Finally you can go to directs. The catalyst can be lumpy, preserving the activity of the catalyst granular or a similar gas mixture to be carried by the gas without a large 65 the supported catalyst Flow resistance passable form in one or more alkali acetates or alkali compounds, Be arranged tube, which is used to discharge the reac- the alkali acetates under the reaction conditions tion heat can be cooled. form, mix in such quantities that the

loss of vaporization of the hot supported catalyst Alkali acetates is replaced.

Instead of chemically pure acetic acid, the cheaper formic acid containing acetic acid can also be used, since the formic acid decomposes almost quantitatively into carbon dioxide over the supported catalyst and hydrogen, which however burns immediately with the oxygen, suffers.

Comparative example

4 liters of a silica carrier in spherical form with a diameter of 4 to 5 now were mixed with a solution which contained 40 g of palladium acetate, 76 g of cadmium acetate and 80 g of potassium acetate, soaked and then dried.

4 liters of the catalyst prepared in this way were placed in a technical circulation apparatus Filled catalyst furnace with a length of 5.6 m.

2.5 m ³ / h starting gas having the composition: 62 volume percent ethylene, 21 volume percent acetic acid, 6.5 volume percent oxygen and 10.5 percent by volume CO ₂ were passed through the catalyst zone 8 ata inlet pressure and 190 ⁰ C reaction temperature. It. The result was a residence time of 5.7 seconds, a gas ^{loading of 2.9 Nm 3} starting gas mixture per liter of catalyst and hour and a flow rate of 95 cm / sec. The reaction products were removed from the reaction gas by condensation, unconverted acetic acid was distilled off and added back to the cycle gas after the converted products had been replaced. The vinyl acetate yield was 90.3%, based on an ethylene conversion of 6%. A catalyst output of 380 g of vinyl acetate per liter of catalyst per hour was obtained. Under these conditions, the vinyl acetate content in the condensate was 20.4 percent by weight and the acetic acid conversion was 16.2%.

example

3 liters of a silica carrier with a particle size of 0.1 to 0.2 mm were mixed with a solution which contained 30 g of palladium acetate, 57 g of cadmium acetate and 60 g of potassium acetate, soaked and then dried.

2.5 liters of the catalyst prepared in this way were used in a fluidized bed reactor. The fluidized bed reactor consisted of a 3 m long steam-heated one

υ Tube made of V4A steel with an inner diameter of 50 mm.

In order to avoid loss of contact due to the discharge of dust, an extended " A tube with a diameter of 125 mm is attached.

A gas with 65 percent by volume of ethylene, 16 percent by volume of acetic acid, 8 percent by volume of oxygen and 1 percent by volume of CO _{2 was passed} through the 2.5 liter catalyst used at an inlet ^{pressure of 8 ata and a temperature of 185 0} C ΙΟ Nm ³ Zh. The gas loading was 4 Nm ³ per liter of catalyst and hour, the residence time was 4.2 seconds, based on the bulk volume of the catalyst, and the flow rate was 34 cm / sec.

5700 g per hour of a condensate with 44 percent by weight of vinyl acetate, 45 percent by weight, were obtained Acetic acid and 11 percent by weight water. A catalytic converter output of 1000 g vinyl acetate per liter of catalyst per hour. 41% of the acetic acid used had been converted been. The yield of vinyl acetate was 90.5%,

based on an ethylene conversion of 11%.

Of course, small proportions of the carrier material can also have a grain diameter outside the have mentioned limits of 0.1 to 1.5 mm. It is sufficient if at least 80%, for example 85%, of the carrier material lie within these limits without thereby departing from the scope of the present invention weather'.

Claims (2)

From the reaction as leaving the reactor Claims- men by cooling under pressure the out- entitlement to rent. condensable fractions are removed from 1 Ve-drive for the production of vinyl acetate formed vinyl acetate, unreacted acetic acid by ύ ^ ϋΐ vSSÄ ΜΑ »« and 5 ^^^^^ ί ^^ Ύ? ™ ** molecular oxygen in the gas phase, given increased. Pressure door Auskondensaion the Reaknenfalls in the presence of inert gases at temperature tionspro-iukte economy, "* he da ^ ed.cn of doors from 100 to 250 ⁰ C, preferably 150 to particularly low Temperaturn. ^ Au expensive nd. The 220 ⁰ C, and pressures of 1 to 21 ata, preferably condensate w.rd m known manner dist.llat.v to -5 to 11 ata, worked in the presence of a catalyst from xo, while the reaction gas consumed palladium compounds and, if necessary, active agents after replacement Amounts of ethylene, acetic acid and catalysts on a carrier, characterized by oxygen and possibly after previous separation, that the reaction is carried out in the presence of carbonic acid formed in the reactor again as a catalyst, the carrier of which is fed. The incurred in the condensing material has a grain diameter of about 0.1 to ₅ i containing the crude condensate recovered vinyl acetate. 1.5 mm. From the point of view of a more economical reconditioning 2. The method according spoke 1, characterized in that the highest possible vinyl acetate content is shown. that the implementation in the presence of speaking a high Ess.gsaureumsatz - m the of a catalyst whose carrier material crude condensates is desired. Open a grain diameter of 0.1 to 0.5 mm * ° It has been found, surprisingly, that high _we j _st Vinyiacelatkonzentrationen in the Rohkondensaien or high acetic acid conversions as well as increased catalyst performance, expressed in g vinyl acetate per liter Catalyst and hour, can be achieved, though 25 a carrier is used whose grains have a small diameter within certain limits