MXPA97010025A - Process for olefi acetoxylation - Google Patents

Abstract

The present invention relates to a process for the production of vinyl acetate by reacting at high temperature, in a fluid bed reactor, ethylene, acetic acid and a gas containing oxygen, in the presence of a fluid bed catalytic material, characterized in that a liquid is introduced into the fluidized bed reactor in order to dissipate the heat thereof by evaporation of the liquid.

Description

PROCESS FOR OLEFIN ACETOXYLATION Field of the Invention The present invention relates generally to a fluid bed process for the acetoxylation of olefins or diolefins and, in particular, to a fluid bed process for the production of vinyl acetate from of ethylene, acetic acid and a gas containing oxygen, in the presence of a fluid bed catalyst. Description of the State of the Art Fluid bed processes for the production of vinyl acetate from ethylene, acetic acid and an oxygen-containing gas, in the presence of a fluid bed catalyst, are already known, for example, from EP-A-0685449, EP-A-0685451 and EP-A-0672453. EP-A-0685449 describes a process for the preparation of vinyl acetate in a fluid bed reactor comprising feeding ethylene and acetic acid into the fluid bed reactor through one or more inlets, feeding a gas containing oxygen to the fluid bed reactor through at least one other inlet, bring the gas containing oxygen, ethylene and acetic acid into the fluid bed reactor while coming into contact with a fluid bed catalytic material, to allow the ethylene, the Acetic acid and oxygen react to produce vinyl acetate, and recover the vinyl acetate from the fluid bed reactor. EP-A-0685451 describes a method for the preparation of a fluidizable catalyst having the formula Pd-MA wherein M comprises Au, Ba, Cd, Bi, Cu, Mn, Fe, Co, Ce, U or mixtures thereof. A, comprises an alkali metal or a mixture thereof and M is present in the range of 0 to 5% by weight approximately and A is present in the range from more than 0 to 10% by weight approximately whose process is useful in the acetoxylation of olefins and diolefins in a fluid bed reactor and comprises: (a) preparing a fluid bed catalyst precursor consisting mainly of Pd-M supported on a fixed bed catalyst support; (b) grinding the fixed bed catalyst precursor with a fluid bed catalyst binder to form a slurry; (c) drying the slurry to form microspheresidal particles of fluid bed solid catalyst precursor; and optionally (d) impregnating the microspherical particles of fluid bed catalyst precursor with a solution of an alkali metal salt to produce a fluid bed catalyst.

EP-A-0672453 describes a support for the preparation of a catalyst for vinyl acetate comprising a mixture of substantially inert microspheroidal particles having a pore volume between 0.2 and 0.7 cc / g, a surface area comprised between 100 and 200 m2 / g and where at least 50% of said particles are less than 100 microns. The preparation of vinyl acetate from ethylene, acetic acid and oxygen is an exothermic reaction and, therefore, it is necessary to provide means for cooling the fluid bed reactor and thus dissipating the heat released. In the event that this is not done, thermal overflows and loss of control of the reactor temperature will occur. In addition to the safety problems involved in a thermal overflow, there is a likelihood that the catalyst will be damaged / deactivated as a result of the high temperatures involved. A means for dissipating heat is described in the aforementioned EP-A-0685449, which consists of providing tubes / cooling coils within the fluidized bed reactor that facilitate the transfer of heat from the reactor. However, the use of this method imposes a physical limit on the amount of dissipatable heat due to the number and size of the cooling tubes / coils that can be adapted in the reactor without the fluidization characteristics being affected. Therefore, the problem to be solved resides in that the heat dissipation of the fluidized bed reactor must be carried out without affecting in a detrimental way to the operation of the fluidized bed process. It has been found that the solution to this problem is to introduce a liquid in the fluidized bed reactor in order to cool it by evaporation of the liquid, using with it the latent heat of vaporization of the liquid. The dissipation of the reaction heat by injection of liquid acetic acid in the fluidized bed reaction of acetylene and acetic acid, in the presence of zinc acetate supported on activated carbon, to produce vinyl acetate, has already been disclosed by the Patent. of the Soviet Union No. 384815. However, this process differs completely from the process that constitutes the object of the present invention, mainly with regard to the use of acetylene as a reactant instead of ethylene. As a result, the reaction exotherms differ considerably; the route from ethylene to vinyl acetate has approximately twice the heat of reaction of the acetylene route. Furthermore, since the catalysts for the ethylene-based processes differ substantially in their nature from the catalysts for the acetylene-based process, their response to the liquids in terms of wet cooling and defluidization is unpredictable. In the practice of the fixed-bed ethylene-based path to produce vinyl acetate, the acetic acid reactant has never been introduced as a liquid in the catalyst bed, since the belief was that such a measure would lead to deactivation of the catalyst. SUMMARY OF THE INVENTION Therefore, the present invention provides a process for the production of vinyl acetate by reacting at high temperature, in a fluid bed reactor, ethylene, acetic acid and a gas containing oxygen, in the presence of a catalytic material for fluidized bed, characterized in that a liquid is introduced into the fluidized bed reactor in order to dissipate the heat thereof by evaporating the liquid. The process of the present invention is advantageous in that it can reduce or totally eliminate the number of cooling tubes / coils in the reactor, thus facilitating the use of a smaller reactor, both features having cost advantages. The process also allows the elimination of a liquid vaporizing column and pre-heating gas exchangers, thereby improving the economic factors of the process. Detailed Description of the Invention It is essential that the liquid is vaporized within the fluidized bed reactor under the reaction conditions that are used for the production of vinyl acetate, so that the desired cooling effect is obtained and a substantial accumulation is avoided. of liquid inside the catalytic bed. Inevitably, during start-up using catalysts having an adsorbent component, for example silica, when the catalyst is "dry" it will adsorb a certain amount of the liquid feed. However, under steady-state operating conditions, virtually all of the liquid introduced into the fluidized catalyst bed evaporates therein such that any net accumulation of liquid within the fluidized catalyst bed is less than the wet-cooling limit of the bed. fluidized catalytic. The liquid introduced into the fluidized bed reactor can suitably be a reactant, an inert liquid or a product of the reaction, or a mixture of two or more of the above. In this way, at least a part of the acetic acid reactant can be fed to the fluidized bed reactor in liquid form. Alternatively, or in addition, at least part of the ethylene and / or oxygen can be introduced into the reactor in the form of a liquid, although in this case, to avoid damage to the catalyst, practically all of the ethylene and / or liquid oxygen should evaporating (for example in a feed pipe or in a heat exchanger) before it comes into contact with the fluidized bed catalyst. Alternatively, or in addition, an inert liquid may be employed, preferably one having a high latent heat of evaporation. Suitable inert liquids include, for example, liquid hydrocarbons, such as pentane and hexane. Alternatively, or in addition, the liquid may be a product of the reaction. A suitable product is water, which is formed as a byproduct of the reaction of ethylene, acetic acid and oxygen, because it has a relatively high latent heat of vaporization. The vinyl acetate product and / or the by-product acetaldehyde can be recycled and also introduced in liquid form in the fluidized bed reactor. The liquid can be introduced into the fluidized bed reactor by suitably arranged injection means. A single injection medium may be employed or a plurality of injection means may be disposed within the fluidized bed reactor. To introduce fluid in the fluidized catalytic bed, the number of injection means used is that number required to provide a sufficient penetration and dispersion of liquid in each injection medium, to achieve a good dispersion of the liquid through the fluidized catalyst bed. A preferred injection means consists of a nozzle or a plurality of nozzles that include gas-induced atomization nozzles in which a gas is used to promote the injection of the liquid, or nozzles of the liquid-only spray type. Alternatively, the liquid may be introduced with the ethylene and / or gas containing oxygen and / or recycle gas fed to the fluidized bed reactor, suitably by bubbling ethylene and / or gas containing oxygen and / or recycle gas through the liquid before its introduction into the reactor. According to another alternative, the liquid can be pumped to the area of the grid plate which is an essential component of the fluidized bed reactor where contact with the ethylene and / or gas containing oxygen and / or recycle gas input will drive the liquid ascending through the fluidized catalyst bed. According to another alternative, the liquid can be pumped into the reactor through a bar or spray bars, optionally with one or more of the gaseous feeds. In a preferred embodiment, the present invention comprises a continuous process for the preparation of vinyl acetate in a fluid bed reactor comprising: (i) feeding ethylene, acetic acid and a gas containing oxygen to the fluidized bed reactor, bringing together ethylene, acetic acid and gas containing oxygen at elevated temperature in the fluid bed reactor while in contact with a fluid bed catalytic material to allow ethylene, acetic acid and oxygen-containing gas to react to produce vinyl acetate, a normally liquid by-product comprising water and organic material and a gaseous by-product comprising carbon dioxide; (ii) separating from the reactor a gaseous effluent comprising ethylene, acetic acid and gas containing unreacted oxygen, vinyl acetate product, a normally liquid by-product and a gaseous by-product; (iii) separating from the effluent extracted from the reactor in (ii) a gaseous stream comprising ethylene, gas containing oxygen and gaseous by-product from a stream comprising unreacted acetic acid, vinyl acetate product and a normally liquid byproduct, and recycling the stream gaseous separated to the fluid bed reactor; (iv) separating, in one or more operations, the stream comprising unreacted acetic acid, vinyl acetate product and normally liquid byproduct separated from the reactor effluent in (iii) in a fraction comprising vinyl acetate product and one or more fractions comprising unreacted acetic acid, vinyl acetate and normally liquid by-product; and (v) recovering vinyl acetate product and recycling a fraction comprising unreacted acetic acid and optionally vinyl acetate and / or normally liquid by-product to the fluidized bed reactor; introducing as a liquid, in the fluidized-bed reactor, at least part or all of one or more of (a) the supply of acetic acid and (b) the recycled fraction comprising unreacted acetic acid and optionally vinyl acetate and / or normally liquid byproduct. In the continuous process described above reference is made to a normally liquid byproduct, by which expression it is intended to define a by-product which is liquid under the conditions of normal pressure and temperature, as opposed to a gas under such conditions. There is no intention to suggest that the product is separated from the reactor in the form of a liquid. To maintain a controllable and constant reaction temperature it is necessary to balance the heat dissipation with the generated heat. This can be done by adding enough liquid to provide all the net thermal separation required (ie, in excess of that obtained by extracting product and introducing feeds and / or recycles from the reactor or into the reactor, respectively). However, in practice it is recognized that this would be difficult to control and could lead to excessive cooling of the liquids being fed to the reactor. This would result in de-fluidification and loss of reaction. This represents a safety hazard since ethylene and oxygen could then be mixed to form an explosive mixture. To solve this potential problem it is desirable to use certain cooling tubes / coils to provide a "fine tuning" of the heat dissipation. Normally, about 70% of the heat dissipation can be achieved by adding liquid to the reactor. However, any suitable percentage comprised between 100 and more than 0% of the heat dissipation can be achieved by means of additions of liquid to the reactor without exceeding the safety margins of the installation being handled. It is a recognized fact that vinyl acetate suppresses the reaction rate. Therefore, in the production of vinyl acetate in a fixed bed, little or no amount of vinyl acetate is returned to the reactor. However, in a fluid bed operation, because the bed is completely mixed, the impact of any vinyl acetate recycled to the reactor is lower since vinyl acetate is present throughout the bed by virtue of the mixture. Accordingly, the separation (iv) into a fraction comprising vinyl acetate product and one or more fractions comprising unreacted acetic acid and normally liquid byproduct, (which is recycled to the reactor) need not be so rigorous, economizing with it in the costs derived from the separation plant. Ethylene, acetic acid and a gas containing oxygen are fed to the fluid bed reactor. A gaseous recycle stream comprising ethylene is also fed to the reactor., gas containing oxygen and gaseous by-product that has been separated from the effluent extracted from the reactor, and also a fraction comprising unreacted acetic acid and optionally vinyl acetate and / or normally liquid by-product, separated in (iv). At least part or all of one or more of (a) the acetic acid feed and (b) the recycled fraction comprising unreacted acetic acid and optionally vinyl acetate and / or normally liquid by-product, is introduced into the reactor at form of a liquid. The feed and recycle components can be introduced into the reactor by several different routes, including the fluid bed reactor grid, the spray bars and the liquid / gas feed nozzles. The components can be fed separately or in combination. Ethylene and acetic acid can be introduced into the reactor through one or more inlets and oxygen can be introduced through at least one other inlet. As indicated above, the liquid components can be introduced by means of gas-induced atomization nozzles where a gas is used to favor the injection of the liquid, or by nozzles of the liquid-only spray type. A suitable gas-induced atomization nozzle for use in the process according to the present invention comprises: (a) at least one inlet for a pressurized liquid; (b) at least one inlet for an atomizing gas, - (c) a mixing chamber for mixing said liquid with said gas; and (d) at least one outlet through which said mixture is discharged. The atomization gas may suitably be an inert gas, for example nitrogen or carbon dioxide. Preferably the atomization gas is the ethylene or oxygen feed or the recycle gas stream or a mixture of two or more thereof. An advantage derived from the use of the oxygen feed as atomizing gas is that the reactant causing the "heat source" is supplied with the liquid used to "dissipate the heat", ie the liquid refrigerant is supplied to the point where the need is maximum. Another advantage that arises from the use of oxygen as atomizing gas is that it eliminates the need to use a separate spray bar in the reactor bed to introduce oxygen, thus simplifying the design of the plant and improving fluidification due to the fact that there is less internal components in the reactor. Alternatively, ethylene feed or a combination of ethylene feed and oxygen feed may be used as the atomizing gas. Each of the nozzles may be provided with a plurality of outputs of suitable configuration. The outlets may comprise, for example, circular holes, slots, ellipsoids or other suitable configurations. Each nozzle may comprise a plurality of outputs of variable configuration. The size of the outlets is preferably such that there is little pressure drop through them. The outlets are preferably arranged symmetrically around the circumference of each nozzle, but may also be arranged asymmetrically therein. The supply of atomizing gas to each of the nozzles is maintained at a pressure sufficient to break the liquid into small droplets and to prevent the ingress of particles from the fluidized bed or blockage by particles of the nozzle outlets. The relative size of the mixing chamber is designed to achieve optimum atomization. The volume of the mixing chamber (atomizer) with respect to the volume of liquid passing through the chamber, expressed as: Volume of the mixing chamber (in ce) / liquid flow rate (cc / sec.) Is suitably order of 5 x 10"3 to 5 x 10" 1 seconds. The liquid velocity is preferably maintained at a sufficient rate to ensure that no particles, for example fines, are separated from the liquid stream. The weight ratio of atomizing / liquid gas supplied to each nozzle is usually in the order of 1:99 to 25:75. A suitable gas-induced atomization nozzle for use in the process of the present invention is described and illustrated in WO-A-94/28032. A single nozzle or a plurality of nozzles can be used. Preferably a plurality of nozzles is used. The nozzle or nozzles may be located on the reactor grid or on the walls of the reactor above the grid. A liquid-only spray nozzle, suitable for use in the process according to the present invention, comprises at least one inlet for liquid under pressure and at least one outlet for said liquid under pressure, maintaining sufficient liquid pressure inside the nozzle to ensure that the liquid exiting the outlet has the desired amount of movement to achieve adequate dispersion and penetration into the fluidized bed reactor. The pressure drop in each of the nozzles can be regulated, if desired, by the use of restrictive devices such as valves. The outlets may comprise similar configurations as defined above for the gas-induced atomizing nozzles, a preferred configuration consisting of circular orifices. Additional information regarding the liquid only spray nozzles can be found in the aforementioned WO-A-94/28032. The introduction into the fluidized-bed reactor of a liquid may be the only means to dissipate heat from the reactor, or it can be supplemented by one or more different means to dissipate heat from the reactor. Other suitable means for dissipating heat from the reactor include the provision within the reactor of cooling tubes / coils and the passage of recycle gases and vapors from the reactor through external cooling tubes / coils or by an outdoor heat exchanger before its reintroduction into the reactor. Alternatively, or in addition, the liquid may be cooled (eg, using refrigeration techniques) before being introduced into the reactor. This allows an even higher cooling effect in the reactor than that provided solely by the evaporative effect of the liquid. Further cooling of the liquid can be achieved by the use of suitable cooling means, for example, a simple heat exchanger or refrigerator. Commercial ethylene and acetic acid with or without additional purification can be used in the process of the present invention. The gas containing oxygen may be a gas richer or poorer in molecular oxygen than air, but preferably it is substantially pure molecular oxygen. In the operation of the process should be considered the minimization of the risk of explosion associated with the use of a feed gas containing oxygen. In the process of the present invention, any fluid bed catalytic material, active for the conversion of ethylene, acetic acid and oxygen to vinyl acetate can be employed. Suitable fluid bed catalytic materials and methods for their preparation are described, for example, in the aforementioned EP-A-Nos. 672453 and 685451. A suitable catalyst comprises palladium and one or more promoters selected from alkali metals, alkaline earth metals, transition metals and metals of the lanthanides, supported on a suitable support, for example silica. Examples of promoter metals include potassium, sodium, barium, cadmium, antimony and lanthanum. The promoters are generally used as solutions of suitable salts of the metals, for example, carboxylate salts, usually acetates. For most promoters, for example potassium acetate, each of them should be maintained at a concentration between 0.1 and 30% by weight relative to the catalyst. In a fixed-bed process for the production of vinyl acetate, the acetic acid feed is vaporized with the gaseous feed. The catalyst bed releases promoter, eg, potassium acetate, during the reaction. Consequently, in the operation of a fixed-bed process, a small amount of promoter solution is sprayed into the inlet gas stream to vaporize and replenish the promoter on the catalyst bed. This can be difficult and can lead to an uneven distribution of the promoter which in turn can result in a non-optimal behavior of the catalyst. In the fluid bed process according to the present invention, it is preferable to dissolve the promoter in the liquid feed to the bed. Because the bed is in motion, fluidized, the catalyst and the promoter are mixed thus reaching a uniform concentration of promoter throughout the bed. This is clearly an improvement over the fixed-bed operation and should lead to improved productivity and selectivity since promoter levels can be controlled more easily. Samples of catalyst can be extracted from the reactor to control promoter levels and facilitate adjustment of the promoter feed levels in the liquid feed stream to maintain the proper level on the catalyst. Ethylene, acetic acid and oxygen-containing gas are suitably reacted at elevated temperature, conveniently within the range of 100 to 250 ° C, preferably within the range of 135 to 195 ° C. The pressure is suitably carried out at pressures within the range of 0 to 21 kg / cm2 gauge, preferably within the range of 5 to 10.5 kg / cm 2 gauge. The concentrations of the gaseous feed of ethylene, acetic acid and oxygen may vary. Generally, ranges useful in moles% are as follows: Ethylene - 30 to 70% preferably 35 to 65%, more preferably 40 to 60% Acetic acid - 10 to 25%, preferably 12 to 22%, more preferably 15 to 20%; and Oxygen - 0 to 25%, preferably 4 to 16%. The rest of the feed (up to a total of 100 mole%) comprises gaseous inerts, for example, carbon dioxide, ethane and argon, in the gaseous stream of recycle and by-product normally recycled liquid. The process of the present invention will now be illustrated by reference to the following examples.

Example 1 Calculations showed that currents 1 and 2 of Table 1 were used in the production of a fluid bed of vinyl acetate by the catalyzed reaction of ethylene, acetic acid and oxygen, and the streams were added to the bed reactor. fluid in vapor phase at 8 bar gauge and 155 ° C, then for the stequio-metric reactions offered in Table 2 whose reactions are carried out in the degrees and conversions indicated in Table 3, approximately 8.7 MW of hot. (The degree of reaction is defined as the number of moles generated for any component divided by the stoichiometric ratio). However, if stream 1 were added to the reactor at 155 ° C and stream 2 was added so that 50% of the stream was in the liquid phase at 155 ° C, and the reactor was maintained at 155 ° C, the heat released would be reduced to approximately 3.7 MW. These two calculations show that part of the heat released in the reaction is used to vaporize the liquid feed thereby reducing the overall needs for heat dissipation by other means, for example by cooling tubes / serpentinei.

- - Table 1 - - Table 2 1. C2H4 + C2H402 + t2 02 ® C4H602 + H20 2. C2H4 + 3 02 ® 2C02 + 2H20 3. C2H4 + C2H402 • C4H802 4. C2H4 + C3H602 + Ti 02 ® C5H802 + H20 5. C2H4 + 2C2H402 + TÍ 02 ® C6H10O4 + H20 Table 3 REACTION DEGREE 1 128.89 DEGREE OF REACTION 2 8,03 DEGREE OF REACTION 3 0,0593 DEGREE OF REACTION 4 0,0146 DEGREE OF REACTION 5 0,1204 Comparative Test A fluid bed vinyl acetate reactor was operated at 8 bar gauge and at a bed temperature of 152 ° C with a gaseous hourly space velocity of 116 hr "1 (under the process conditions). of metals of 0.44 Pd, 0.36 Au and 2.5 K (% by weight) The total feed composition consisted of ethylene: acetic acid: oxygen: nitrogen, 52.9: 9.9: 7.6 : 29.6 as moles%, respectively Acetic acid was introduced into the reactor with the main gaseous inlet stream via a vaporizer at 150 ° C through the bottom of the reactor.The bed temperatures are offered in the following Table An on-line oxygen analyzer indicated that 45% of the oxygen had been converted to products This is not an example according to the present invention because none of the components was introduced into the reactor in the form of a liquid. This example has been included only for comparative purposes. Example 2 The Comparative Test was repeated except that the acetic acid was introduced into the reactor as a liquid at room temperature through a spray pipe located towards the reactor inlet within the catalytic bed. Bed temperatures are given in Table 4 below. An on-line oxygen analyzer indicated that 43% of the oxygen had been converted to products. This shows that the Comparative Test and Example 2 produced almost identical heats of reaction. Examination of Table 4 reveals the effect of introducing a cold liquid directly into the catalytic bed on the observed reaction exotherm. The reaction exotherm is taken as the temperature difference of the coils or heater oil between the system when operating with oxygen-free feed reagents and the system when operating with oxygen feed. When the acetic acid feed is vaporized, a reaction exotherm is observed throughout the bed. When the acetic acid is introduced as a liquid, the reaction exotherm is substantially reduced in the lower and intermediate sections of the bed. These results show that the direct addition of liquids to the reactor bed can dissipate part of the heat of reaction. The catalyst does not agglomerate or defluidify.

TABLE Item

Claims (13)

1. NOVELTY OF THE INVENTION Having described the present invention, it is considered as a novelty and, therefore, the content of the following is claimed as property: 1. A process for the production of vinyl acetate by reacting at elevated temperature, in a fluid bed reactor, ethylene, acetic acid and an oxygen-containing gas, in the presence of a fluid bed catalytic material, characterized in that a liquid is introduced into the fluidized bed reactor in order to dissipate the heat thereof by evaporation of the liquid .
2. 2. - A process according to claim 1, characterized in that the liquid introduced into the reactor is a reactant, an inert liquid, a product of the reaction or a mixture of the above.
3. 3. - A process according to claim 2, characterized in that the liquid is liquid ethylene, liquid oxygen, a liquid hydrocarbon, liquid acetic acid, water, vinyl acetate or acetaldehyde.
4. 4. - A process according to any of the preceding claims, characterized in that the liquid is introduced into the fluidized bed through injection means.
5. 5. - A process according to claim 4, characterized in that the injection means is a gas-induced atomization nozzle.
6. 6. - A process according to claim 5, characterized in that the atomizing gas is nitrogen, carbon dioxide, ethylene, oxygen feed, gaseous recycle stream or a mixture of the above.
7. 7. - A process according to any of the preceding claims, characterized in that the catalyst comprises palladium and one or more promoters selected from alkali metals, alkaline earth metals, transition metals and metals of the lanthanides, supported on a support.
8. 8. - A process according to claim 7, characterized in that the promoter is chosen from potassium, sodium, barium, cadmium, antimony and lanthanum.
9. 9. - A process according to claim 7 or 8, characterized in that the concentration of promoter is between 0.1 and 30% by weight with respect to the catalyst.
10. 10. - A process according to any of claims 7 to 9, characterized in that the promoter is dissolved in the liquid feed.
11. 11. A process according to any of the preceding claims, characterized in that it is carried out at a temperature of 100 to 250 ° C and a pressure of 0 to 21 kg / cm 2 gauge.
12. 12. - A process according to any of the preceding claims, characterized in that the concentration of ethylene feed is 30 to 70 mol%, the concentration of acetic acid feed is 10 to 25 mol% and the oxygen concentration is 0 to 25 moles%.
13. 13. A process according to claim 1, characterized in that the process is continuous and comprises: (i) feeding ethylene, acetic acid and a gas containing oxygen to the fluid bed reactor, bringing together ethylene, acetic acid and oxygen-containing gas at elevated temperature in the fluid bed reactor while in contact with a fluid bed catalytic material to allow ethylene, acetic acid and oxygen-containing gas to react to produce vinyl acetate, a normally liquid by-product comprising water and material organic and a gaseous by-product comprising carbon dioxide; (ii) separating from the reactor a gaseous effluent comprising ethylene, acetic acid and gas containing unreacted oxygen, vinyl acetate product, a normally liquid by-product and a gaseous by-product; (iii) separating from the effluent extracted from the reactor in (ii) a gaseous stream comprising ethylene, gas containing oxygen and gaseous by-product from a stream comprising unreacted acetic acid, vinyl acetate product and a normally liquid byproduct, and recycling the stream gaseous separated to the fluid bed reactor, - (iv) separating, in one or more operations, the stream comprising unreacted acetic acid, vinyl acetate product and normally liquid byproduct separated from the reactor effluent in (iii) in a fraction that comprises vinyl acetate product and one or more fractions comprising unreacted acetic acid, vinyl acetate and normally liquid by-product; and (v) recovering vinyl acetate product and recycling a fraction comprising unreacted acetic acid and optionally vinyl acetate and / or normally liquid by-product to the fluidized bed reactor; introducing as a liquid, in the fluidized-bed reactor, at least part or all of one or more of (a) the supply of acetic acid and (b) the recycled fraction comprising unreacted acetic acid and optionally vinyl acetate and / or normally liquid byproduct. MBOTMBH A process for the production of vinyl acetate by reacting at high temperature, in a fluid bed reactor, ethylene, acetic acid and an oxygen-containing gas, in the presence of a fluid bed catalytic material, in which a liquid is introduced into the fluid bed. the fluidized bed reactor in order to dissipate the heat thereof by evaporating the liquid