The method of producing vinyl acetate

 

(57) Abstract:

The invention relates to the production of vinyl acetate by contacting ethylene, acetic acid and oxygen-containing gas with palladium catalyst on a carrier. The preparation of the catalyst comprises the following stages: (a) impregnation of the catalytic media palladium compound, (b) the conversion of this palladium compound to almost metallic palladium and (C) sintering of palladium on the carrier at a temperature of 650 - 1000oIn the presence of a reducing gas selected from the group comprising nitrogen, carbon dioxide, helium, or in the presence of inert gas or mixture of gases. The reaction proceeds at a temperature of 145 - 195oC, a pressure of 1 to 20 ATM. Preferably as palladium compounds are used acetate, sulfate, nitrate, palladium chloride or haloesters palladium salt. The carrier is preferably selected from the group: silicon dioxide, aluminum oxide, silicon dioxide/aluminum oxide, titanium dioxide, zirconium dioxide or carbon. Effect: increased activity and lifetime of palladium catalyst. 12 C.p. f-crystals, 2 tab., 3 Il.

The present invention relates to a method of obtaining vinilla media.

Preparation of palladium catalysts on a carrier to obtain a vinyl acetate usually includes the impregnation of the corresponding media palladium connection with the subsequent conversion of the palladium compound to almost metallic palladium.

The methods of preparation of catalysts impregnated with shell is described, for example, in U.S. patents 3822308, 4048096, 5185308 and 5332710, Canada 2128162, USA 4087622, Canada 2128154 and 2128161 and USA 5422329.

The methods of preparation of catalysts pobelochnogo type described, for example, in U.S. patents 3743607, UK 1333449, USA 3939199 and 4668819, applications EP 330853, EP 403950 and EP 431478 and patent Canada 2071698.

In U.S. patent 5336803 described a method of pre-processing palladiumsilver catalysts in which the catalyst is kept in the presence of an oxidant, such as air, at a temperature at least sufficient for the partial oxidation of palladium; the oxidant is removed and injected inert gas, such as nitrogen, the catalyst is again maintained at a temperature up to 500oIn the presence of a reducing agent, such as hydrogen or ethylene. Described in this patent the method is illustrated on the example of the conventional catalyst, nominally containing 1% palladium and the vinyl acetate as the operation is reduced. If the catalytic activity, and hence the productivity of the process is reduced to a technically unacceptable level required regeneration and/or replacement of the catalyst. Decontamination acetate catalysts described Abel and others in Chem. Eng. Technol. 17 (1994), 112-118.

A simple increase in the amount of palladium in the catalyst to increase the service life of the catalyst is associated with a particular problem, consisting in the fact that the initial activity of the catalyst may be too high for secure and/or regulated process on an industrial scale, for example, because of the limited ability of the heat sink installation.

Therefore, there remains a need in the design that solves this problem of the method of preparation of the palladium catalyst on the media, aimed to produce vinyl acetate.

Thus, in accordance with the present invention features a method of producing vinyl acetate, in the exercise of which is provided by the contacting ethylene, acetic acid and oxygen-containing gas with palladium catalyst on a carrier prepared by the method comprising the following stages: (a) impregnation rode the ski palladium and (C) sintering of palladium on the carrier at a temperature above 500oC.

According to the present invention described above technical problem is solved due to the fact that palladium on the carrier is sintered at temperatures above 500oC.

Not based on any theory, I believe that this stage of sintering causes growth of metallic palladium, which reduces the initial activity of the catalyst. Thus, the proposed method enables the preparation of catalysts, characterized by a high concentration of palladium and technically acceptable initial activity, these catalysts have technically longer service life compared to known catalysts. This is the stage of sintering increases the average pore size kremmidiotis media. It was found that the catalysts of the present invention is less susceptible to undesirable effects of excess concentration of a promoter such as potassium acetate.

Stage sintering (C) is preferably carried out using a gaseous reducing agent, but it can be done in the presence of a gaseous oxidant or in inert gas. Acceptable gaseous reducing agents are hydrogen and carbon monoxide. Pickup is mi gases for use individually or in combination with gaseous oxidants or reductants are nitrogen, carbon dioxide and helium. Acceptable temperature for the sintering step and ranges from more than 500 to 1000oC, preferably from 650 to 1000oC. the Preferred duration of the stage of sintering is 1-24 hours In the case of gaseous oxidizer catalyst needed in the subsequent recovery. The catalyst may be purged with an inert gas prior to sintering during heating (for security), as well as during cooling to less than 100oC, more preferably to less than 60oC) to prevent any re-dispersion of palladium. Heating and cooling can be performed with any appropriate or real speed. Stage sintering () on an industrial scale can be carried out in the tower or the vessel that complies with the above conditions of the method. During the process, the catalyst can be mixed with the gas stream. You can use the oven with a rotating auger. In laboratory scale can be applied to the pipe, horizontally or vertically installed in the electric furnace, provided effective contact between the gas and the solid material (usually should take into account the ratio of length/diameter). You may need the m shorter than the required time. For specialists in the art it is obvious how to lead these parameters in accordance with the scale of the process. Generally, stage of sintering () causes growth of metallic palladium from 3-4 up to 8-15 nm in diameter.

The conversion of the palladium compound to almost metallic palladium on the stage (b) can be carried out by recovery, which can immediately precede the stage of sintering (in), and the implementation of both stages in the same equipment.

The method of preparation of the catalyst of the present invention can be applied for the preparation of homogeneously impregnated catalysts or catalysts impregnated with a shell designed for carrying out the processes of obtaining vinyl acetate in the fluidized bed or a fixed bed.

Proposed by the present invention a method of preparation of catalysts can be used to prepare catalysts having high concentration of palladium, for example, more than 0.5 wt.%, preferably more than 1 wt.% in terms of the total weight of the catalyst. The concentration of palladium can be up to 5 wt.% in the case of a fluidized bed or to reach 10 in the catalyst on the carrier, characterized by a high concentration of palladium, if it is prepared by a known method, and it could even be so high that it would be unsafe and/or unregulated in the case of application in industrial scale. However, in the preparation in accordance with the method of the present invention, the initial activity of the catalyst is reduced in comparison with the activity is usually prepared catalyst, while due to the high concentration of palladium is achieved technically acceptable activity for a longer service life of the catalyst.

Acceptable for cooking as catalysts impregnated with shell and evenly impregnated catalysts the catalytic media may include porous silicon dioxide, aluminum oxide, silicon dioxide/aluminum oxide, titanium dioxide, zirconium dioxide or carbon, preferably silicon dioxide. Acceptable specific pore volume of the carrier may be 0.2-3.5 ml/g of the carrier, the specific area of their surface may be 5-800 m2/g media, and the apparent or bulk density can range from 0.3 to 1.5 g/ml In the case of catalysts used in the process in a fixed bed, the size of the movable partition layer, the particles of the medium will usually be in the form of spheres, pellets, extrudate, pellets or any other suitable form. In the case of the use of catalysts in the processes carried out in the fluidized bed, the media generally can be characterized by such distribution of particle size that at least 60% of the catalyst particles have a diameter less than 200 μm, preferably at least 50% of particles have a diameter of less than 105 microns and not more than 40% of the catalytic particles have a diameter less than 40 microns.

At the stage of (a) the carrier is preferably impregnated with a palladium compound in an acceptable solvent. As such solvents may be used water, carboxylic acids, such as acetic acid, benzene, toluene, alcohols, such as methanol or ethanol, NITRILES, such as acetonitrile or benzonitrile, tetrahydrofuran or a chlorinated solvent such as dichloromethane. In a preferred embodiment, the solvent used water and/or acetic acid. The media is recommended to impregnate the acetate, sulfate, nitrate, palladium chloride or other galoidsodyerzhascikh salts of palladium such as H2PdCl4, Na2PdCl4or K2PdCl4. Preferred odorants compound is palladium acetate.

Impregnation of the carrier can be made by contacting the carrier with a solution of palladium compounds by dipping, immersing, or spraying. This impregnation can be accomplished in one or several stages or ongoing process. The media can be subjected to contact with an impregnating palladium solution treatment in the drum, the rotation mode and the movement of the vortex or similar by achieving uniform impregnation. The impregnation is usually carried out at room temperature. In the case of palladium acetate in acetic acid can create elevated temperature, for example, reaching 120oWith, preferably 100oC, more preferably 60oC. Such impregnation is conducted carefully, avoiding destruction or abrasive wear of the media. Media, you can fill in an impregnating solution of 5-100% of the volume of its pores.

In addition to palladium compounds, the carrier can also be impregnated at the stage of (a) compounds of gold, copper and/or Nickel, preferably gold, which converts to metal together with palladium on stage (b) contained in the particles of metallic palladium in the form of mixtures and/or alloys with palladium. Acceptable connection Zolotaryova or acetate of gold, preferably ul4. These promoters can be used in an amount of 0.1-10 wt.% each metal promoter contained in the finished catalyst.

In addition to palladium and optional gold, copper and/or Nickel at any appropriate stage of the process of preparing the carrier may be impregnated with one or more salts of metals of group I, group II, lanthanide or transition metals, preferably of cadmium, barium, potassium, sodium, iron, manganese, Nickel, antimony and/or lanthanum, which are contained in the finished catalyst in the form of salts, usually acetates. Usually contains potassium. Acceptable salts of these compounds include acetates and chlorides, but you can use any soluble salt. These promoters can be used in an amount of 0.1-15 wt.%, preferably 3-9 wt.% each promoter salt included in the composition of the finished catalyst.

If you need to enter the palladium or the promoter in excess of the amount which is provided by the solubility of the salt in the solvent, the impregnated carrier is optional can be dried, and the stage of impregnation to repeat two or more times. Stage drying can be performed at a temperature of DOS is to carry out at room temperature and under reduced pressure. At the stage of drying, you can use air, nitrogen, helium, carbon dioxide or any acceptable inert gas. To facilitate drying of the catalyst can be treated in the drum, to bring the system into rotational motion or to mix with the gas stream.

For the preparation of catalysts impregnated with sheath carry out the contacting wet or dry impregnated carrier with a basic solution in the processing in the drum to give the system a whirl, rotational motion, with stirring or so on This basic solution can also be applied by spraying the impregnated carrier during processing in the drum into rotation, with stirring or similar Grounds can serve as hydroxides, carbonates or silicates of metals of groups I or II. Typical examples are sodium hydroxide, metasilicate sodium, potassium hydroxide, metasilicate potassium and barium hydroxide. Basically the solution can be applied in one or several stages with corresponding intervals of exposure between these stages of processing. Stage deposition is usually carried out at room temperature, but it can be increased to 100oC. you Can use any solvent, which is soluble basic Matricaria such a time interval, to permit the deposition of metal salts in the shell. This process usually lasts more than one hour, preferably from 8 to 24 hours For the deposition typically requires the optimal number of reasons and, as a rule, required its excess, and usually it is equal to 1.8 times the nominal quantity necessary for the formation of metal salts of hydroxides.

The impregnated carrier may be washed to remove anionic contaminants, such as nitrate, sulfate, and usually halide. Removal of chloride leaching with deionized water should hold up until the test of silver nitrate will not show the absence of any chlorides. The content of anionic impurities should be minimized. The content of cationic impurities should be minimized; for example, the amount of sodium in the dry catalyst should be less than 0.5 wt.%, preferably less than 0.2 weight. %. In such a low concentration is quite acceptable in the presence of such impurities and their concentration, absolute zero, no significant does not matter. On an industrial scale it is possible to conduct periodic washing process. To speed up the process you can use warm water. Cu is elitnye). Moreover, the reagents for preparation should be chosen in such a way as to avoid the application of chloride and sodium ions, using, for example, metasilicate potassium instead of sodium salt.

Depending on the reagents at the stage (b), the palladium compound can be converted into metal before or after the described optional stage of leaching. You can apply liquid reducing agents such as water, hydrazine, formaldehyde, sodium formate, methanol or alcohols, preferably aqueous hydrazine. Recovery can also be performed using gases such as carbon monoxide, hydrogen and ethylene. They can be diluted with an inert gas, such as nitrogen, carbon dioxide or helium. As a rule, the restoration of the gases is carried out at elevated temperatures of the order of 100-500oWith the restoration of the material. Recovery is usually carried out in a liquid reducing agent and at room temperature, but can be performed at temperatures up to 100oC.

After conversion of the palladium compound to metal is sintered according to the method presented in this description. This stage of sintering (in) can be performed after stage (b) followed by heating the catalyst in the gaseous bossano above.

Contacting ethylene, acetic acid and oxygen-containing gas with palladium catalyst on a carrier prepared in accordance with the method of preparation of the catalyst of the present invention, can be made by methods known in the art. For example, the contacting of the reactants with the catalyst can be carried out in a fixed or fluidized bed at a temperature in the range of 145-195oC and under a pressure in the range of 1-20 ATM. Get the vinyl acetate can be distinguished by conventional methods known in the art.

Below the invention is illustrated with reference to Fig. 1-3, examples and experiments. In Fig. 1 schematically shows some of the possible methods of preparation of catalysts in accordance with the present invention. In Fig. 2 shows a graph that compares the performance of the catalyst prepared in accordance with the invention, performance of the catalyst prepared in accordance with the invention, depending on the operating time. In Fig. 3 presents a graph that compares the effect of the promoter of potassium acetate on the activity of cat is undertaken in accordance with the invention.

As shown in Fig. 1, the homogeneous catalysts of the type (neoborochnye) can be prepared by the implementation stages of impregnation of the carrier palladievye salts and optional promoters with subsequent drying and recovery of metals. Further, such a material can be subjected to an optional washing and drying before sintering in accordance with the present invention and the final impregnation optional promoters, such as the acetates of potassium, sodium, cadmium, or barium.

For the preparation of catalysts shell-type carrier impregnated with palladium and optional promoters, such as gold, can be subjected to an optional drying. Then precipitated metals. Further, such material may be sent either (I) on the recovery of metals, washing and drying, or (II) rinsing and drying with subsequent recovery of metals. The material is then subjected to sintering in accordance with the present invention with subsequent impregnation promoters, such as potassium acetate, sodium, cadmium, or barium.

Example 1

The catalyst As prepared in accordance with the present invention so that it was characterized by the following nominal composition (i.e., without Rapida media

15 g of spherical particles of silicon dioxide KA 160 as a carrier (4-6 mm, firm SudChemie) was injected into the solution 1,0264 g three-hydrate of tetrachloropalladate sodium (Johnson Matthey) and 0,2655 g three-hydrate soloconsolidation acid (Aldrich company) in 9.1 g of deionized water. The material was added in one portion and the mixture was stirred in a vortex mode up until evenly had not absorbed the entire solution. Then the impregnated carrier was left to stand in the closed position for two hours at room temperature.

2. The precipitation of the compounds of palladium and gold on the media.

A solution of 1.7 g of the pentahydrate sodium metasilicate (company Fisons) in 18 g of water was added to the impregnated carrier with stage 1. The mixture was briefly a few times was stirred in a vortex mode in total for 15 minutes, preventing the formation of "zones", and then left to stand over night.

3. Recovery of palladium and gold to almost metallic state

The aqueous phase of the above material from step 2 was treated with 5 g of 55% hydrazine hydrate is added (company Aldrich).

4. Flushing connections on the media

The aqueous phase decantation and the material from stage 3 were washed four times approx najednou shutoff valve, and then washed with deionized water with a flow rate of approximately 1 l for 12 h before until the test of silver nitrate gave a negative result. The material was dried at 60oWith over night in an oven with forced convection and cooled.

5. Sintering of palladium (and gold)

Palladium material on the carrier with stage 4 is moved in a horizontal furnace and filled them a Central part of the quartz tube insert fill free space with quartz wool and the carrier 160 KA (after thorough preliminary drying). This quartz tube insert was placed inside a steel tube and was connected to the gas sources. The temperature in the furnace was increased up to 150oWith a speed of 10oC/min, and this temperature was maintained for 2 h at a constant current of nitrogen. Was introduced a stream of hydrogen at an average hourly feed rate of 60/h, and the flow of nitrogen was stopped. The temperature in the furnace was increased to 800oWith speed 30oC/min, and this temperature was maintained for 11 hours after this period, the obtained material was allowed to cool to room temperature in a stream of hydrogen. Before unloading the material flow of nitrogen was resumed, and the flow of bodoro the underwater potassium acetate (Aldrich company), dissolved in 8.8 g of water. The mixture is gently stirred in a vortex mode to fluid absorption. The resulting material was again dried overnight at 60oC.

Example 2 (comparative)

Catalyst B was prepared in accordance with the method described in example 1, except that the stage of sintering 5 did not.

Example 3 (comparative)

The catalyst was prepared in accordance with the method described in example 1, except that the stage of sintering 5 is not carried out and the metal content was reduced so that to achieve the same initial activity as the catalyst, prepared according to example 1.

Testing of the catalyst in the microreactor

The catalysts prepared by the above methods were tested in a microreactor using the following General methods. The tests were carried out under an absolute pressure of 7.8 bar and 150oWith the use of pelletized catalyst (prepared according to the above method and in the amount indicated in table 1), diluted with 60 ml of glass beads of diameter 1 mm and loaded into a stainless steel tube with an inner diameter of 10-11 mm Catalyst was preparing to rabotat ethylene. Next couple of acetic acid was mixed with ethylene was passed over the catalyst for at least 50 minutes In the source gas was gradually added a mixture of 21% oxygen in helium, while maintaining the maximum temperature of the catalytic layer 150oC. the Temperature of the hot spot of the catalyst was maintained at a level of 150oC. the Final composition of the mixture of reagents was expressed in volumetric ratio of ethylene:acetic acid:oxygen:helium, equal 53,1: 10,4: 7,7: 28,6, and the total hourly average gas flow rate was 3850 h-1. The flow of the product was analyzed in the vapor phase at hourly intervals using assembled on the production line gas chromatograph.

The catalyst activity was calculated in grams of the obtained vinyl acetate per liter of catalyst per hour (volumetric capacity, ODA), and the selectivity of the catalyst was calculated as the percentage of converted ethylene contained in the product. Data cited in terms of arithmetic average activity and selectivity, which was determined in the range from 17 to 22 hours after reaching full flow of oxygen.

Results of comparison of the activity of catalysts a, B and PR is t, what stage of sintering (stage 5) induced a decrease in the activity of the catalyst A. This corresponds to an increase of the particle size of palladium and reduction of specific surface area of particles of metallic palladium. The catalyst was prepared with a lower metal content than catalysts a and B, and the metal content was chosen so that the initial activity was the same as that of catalyst A. Thus, from catalysts a and b, one would expect the same initial technological behavior. However, it was expected that the catalyst And will maintain its performance over a longer period in comparison with the catalyst, if the increasing size of palladium particles and a reduction in the specific surface area of particles of palladium metal will cause a decrease in the initial activity, as illustrated in examples 7 and 8.

Testing of catalysts in larger reactors.

Catalysts a and b was tested in a larger tubular reactors as follows. of 77.5 g of catalyst a (example 7) and 77.5 g of catalyst b (example 8, comparative) were loaded into separate ones for each of them 6-foot reactor tube. These two tubes in the second tube was supplied with its own supply system gaseous/liquid raw materials and implementation of tampering with the product. Started feeding a stream of nitrogen with a flow rate 1106 ml/min (at standard temperature and pressure) and the flow of ethylene with consumption 2590 ml/min (at standard temperature and pressure). The sand bath and the tube was heated to 150oC and the pressure in the reactor was raised to 115 pounds per square inch. In the evaporator started feeding a stream of acetic acid (containing 2 weight. % water) with a flow rate of 155 g/h and the pair was mixed with nitrogen and ethylene. A small amount of acetic acid (2 wt.% water 0,0285 wt.% potassium acetate) with a flow rate of 13 g/h was introduced into the pre-heating zone with the aim of evaporation together with the main gas stream. After a few hours began to apply the oxygen with a flow rate of 153 ml/min (at standard temperature and pressure). The product stream was analyzed using assembled on the production line gas chromatograph, and then are condensed to obtain a crude liquid product consisting of vinyl acetate, acetic acid and water, and the remaining gases are discharged into the atmosphere, selecting the sample using a mounted on the line gas chromatograph. Monitored the progress of the receipt of vinyl acetate using both catalysts. Since the catalysts were deaktivirovana, constantly productive is 425 ml/min (at standard temperature and pressure). At full flow rate of the oxygen composition of the gas expressed in volumetric ratio of ethylene:acetic acid:water:oxygen:nitrogen, equal 49,7:19,6:1,3:8,2: 21,2, and the total hourly average gas flow rate was 2261 -1(at standard temperature and pressure). After reaching the full flow rate of the oxygen raw material consistent performance of the catalyst And further supported by the gradual increase in the temperature of the sand bath from approximately 150 to 160oC. Since both tubes were in the same sand bath, the performance of the catalyst was lowered to a level lower than that of the catalyst And, because he was deaktivirovana faster. In Fig. 2 presents the normalized daily performance of catalysts a and b depending on the number of days of operation. In Fig. 2 shows that although the initial performance of both catalysts was the same, after five days of operation, the comparative performance of the catalyst, i.e. a catalyst, were below the performance of the catalyst according to the invention, i.e., catalyst A. the study of the angular coefficients of the curves for the performance of both catalysts shows that the catalyst of time slowly decreased, reaching the end of 0.7. By the end of the experiment were tested catalyst And the performance in comparison with the catalyst by controlling the flow rate of the oxygen raw material and/or the temperature of the sand bath. It is seen that the performance is alternately increased and decreased in accordance with Fig. 2, and it should be noted that the performance of the catalyst And always exceeded the catalyst C. Catalyst And showed a lower rate of deactivation compared to catalyst, even though its initial activity they were very similar.

Example 9. Additional tests of the catalysts with the use of microreactor

Two additional portion of catalyst was prepared in accordance with the method described in example 1, except that the quantities of reagents used were increased 9 times. Upon completion stage of washing and drying each portion of the catalyst is accurately divided into 9 equal parts and soaked the target number (in wt.%) potassium acetate (see table 2). These catalyst samples were tested in accordance with test methods of examples 1-3. In Fig. 3 shows the activity that was achieved with ispolzovanie USA 5179056 (this activity was determined by extrapolation in accordance with the model, described in U.S. patent 5179056). In Fig. 3 shows that for the efficient operation of the catalyst in accordance with the present invention requires a minimum amount of potassium, about 1.5 weight. % while the catalyst according to the U.S. patent 5179056 to achieve maximum activity necessary additive of potassium approximately 2.5 weight. %. In the case of the catalyst in accordance with the present invention the effect of potassium remains approximately constant when the content of this promoter from approximately 1.5 to 5 wt.%. In the case of the catalyst in accordance with U.S. patent 5179056 with increase in the concentration of promoter activity begins to fall.

From the above data shows that the catalyst prepared in accordance with the present invention is less sensitive to excessive content caliacelacel promoter.

1. The method of producing vinyl acetate by contacting ethylene, acetic acid and oxygen-containing gas with palladium catalyst on a carrier prepared by the method comprising the following stages: (a) impregnation of the catalytic media palladium compound, (b) the conversion of this palladium compound to almost metallic palladium and (C) speco of a reducing gas, inert gas or mixture.

2. The method according to p. 1, characterized in that the ethylene, acetic acid and oxygen-containing gas in contact with the catalyst at a temperature within 145-195oC and a pressure of 1-20 atmospheres.

3. The method according to p. 1, characterized in that the catalyst carrier is impregnated with the palladium compound in the solvent selected from the group comprising water, carboxylic acid, benzene, toluene, alcohols, NITRILES, tetrahydrofuran and chlorinated solvents.

4. The method according to p. 3, characterized in that the solvent is water and/or acetic acid.

5. The method according to any of the preceding paragraphs, wherein the palladium compound is an acetate, sulfate, nitrate, palladium chloride or haloesters palladium salt.

6. The method according to p. 5, wherein the palladium compound is a palladium acetate.

7. The method according to any of the preceding paragraphs, characterized in that stage (b) is performed by contacting a palladium compound with a liquid or gaseous reducing agent selected from the group comprising aqueous hydrazine, formaldehyde, sodium formate, alcohol, carbon monoxide, hydrogen and ethylene.

9. The method according to any of the preceding paragraphs, wherein the palladium catalyst comprises at least 0.5 weight. percent palladium, calculated on the total weight of the catalyst.

10. The method according to any of the preceding paragraphs, characterized in that the catalytic carrier is a porous silicon dioxide, aluminum oxide, kranidioti/aluminiumoxid, titanium dioxide, zirconium dioxide or carbon.

11. The method according to any of the preceding paragraphs, characterized in that the carrier stage (a) is additionally impregnated with gold, copper, Nickel, and preferably additionally impregnated with one or more salts of elements of groups I or II, lanthanide or transition metals.

12. The method according to any of the preceding paragraphs, characterized in that the sintering time on the stage (in) is in the range between 1 and 24 hours.

13. The method according to any of the preceding paragraphs, characterized in that the sintering stage (in) causes growth of metallic palladium from 3-4 nm in diameter up to 8-15 nm in diameter.

 

Same patents:
The invention relates to a new and improved method of producing vinyl acetate ("VA") by reaction of ethylene, oxygen and acetic acid

The invention relates to the production of vinyl acetate from acetic acid, ethylene and oxygen or oxygen-containing gases

The invention relates to the technology of producing vinyl acetate

The invention relates to methods of automatic control and management of the process of obtaining a vinyl acetate ethylene and can be used in the chemical and petrochemical industry

The invention relates to joint receipt of acetic acid and/or vinyl acetate in the two reaction zones

The invention relates to a technology for production of vinyl acetate with ethylene acetoxysilane

The invention relates to the production of catalysts and, in particular, to obtain palladium and palladium/gold catalyst for the synthesis of vinyl acetate from ethylene, acetic acid and oxygen-containing gas, and to a method for producing vinyl acetate

The invention relates to catalytic chemistry, in particular to a method for preparing a catalyst for vapor-phase synthesis of vinyl acetate from acetylene and acetic acid
The invention relates to a new and improved method of producing vinyl acetate ("VA") by reaction of ethylene, oxygen and acetic acid

The invention relates to the production of vinyl acetate from acetic acid, ethylene and oxygen or oxygen-containing gases

The invention relates to joint receipt of acetic acid and/or vinyl acetate in the two reaction zones

The invention relates to the field of organic synthesis, namely the selective acetoxysilane 1,3-cyclopentadiene (CPD) in CIS-3,5-diacetoxyscirpenol (DACP)

The invention relates to the primary organic synthesis, and in particular to catalysts for diacetoxybiphenyl S-CIS-1,3-pen - tadiene in diacetoxybiphenyl

The invention relates to the production of vinyl acetate from acetic acid, ethylene and oxygen or oxygen-containing gases

The invention relates to the field of electrical engineering, namely, catalysts for fuel cells

The invention relates to the production of catalysts and, in particular, to obtain palladium and palladium/gold catalyst for the synthesis of vinyl acetate from ethylene, acetic acid and oxygen-containing gas, and to a method for producing vinyl acetate
The invention relates to a process for the preparation of catalysts and can be used to remove CO from the exhaust
Up!