MXPA97009067A - Catalyst and procedure for preparing acetatode vin - Google Patents

Abstract

A catalyst is described a process and a catalyst for producing vinyl acetate in the gas phase from ethylene, acetic acid and oxygen or oxygen-containing gases on a catalyst containing palladium and / or its compounds, cadmium compounds and compounds of alkali metal on a substrate, the invention is characterized in that the catalyst also contains at least one rhenium compound and / or a zircon compound

Description

CHILLER AND PROCEDURE TO PREPARE VINILQ ACETATE DESCRIPTIVE IIEIIORIñ '> It can be reacted in the gaseous phase with pyridic acid and oxygen or oxygen-containing gases on a bed with a palladium / eadmium / alkaline-containing bed to give vinyl acerate .. Ein this In this procedure, a performance in space time of more than 200"j / lh (U <> fV3 939 9, US-tt-4 ñfi? 019, US-fl-'i 902 Ü23, EP-fl) is obtained. 0 403 950, Uf-fl -5 225 08, HP-ñ-O 5F 95 952, KP-tt-0 b34 208, EP-nQ 634 209, EP-fl-0 634 214) 5e has now surprisingly found that said catalysts are considerably improved by the addition of at least one cornp? Est or rowing and / or at least one zirconium compound, ie, clan a superior performance in spacetime at the same selectivity or higher selectivity (ie the synthesis of vinyl acetate) and consequently, the invention provides a reliable process to prepare vimlo acetate in the gas phase from ethylene, acetic acid and oxygen or oxygen containing gases on a catalyst comprising palladium and / or its compounds. compounds, cadmium compounds and alkali metal compounds on a Support, wherein the catalyst additionally contains at least one oar compound and / or at least one zir oon compound. I read invoncion also provides a catalyst that I understand palladium and / or its compounds, cadmium compounds and alkali metal compounds on a support, where the catalyst 1 contains adi cíonalmont e at least one compound of volume and / or fior at least one compound of ..ircomo. Suitable supports are known inert support materials, such as silica, aluminum oxide, aluminum oxide, silicas, titanium oxide, zirconium oxide, titanium, silicon carbide and cay bon.

Particularly suitable are supports of this type having a specific surface area of 40 to 350 rn2 / g (measured by the 1JET method) and an average pore radius of 50 to 2000 ñ (measured using the mercury porosirnetpa), especially silicas (1Q2) and mixtures of ÍO2 / AI2O3. These supports are used in the form of spheres, pellets, rings, strips or particles of another shape whose diameter or length and thickness is generally from 3 to 9 mrn. The total pore volume of the support is preferably 0.4 to 1.2 ml / g, and less than 10% of this volume must be formed by "micropores" (they have a pore diameter of less than 30 fi (fingstrorns). supports can be prepared from the aerobic S1O2 or an aerogenic mixture of Ti 1.02 01203 which is in the form of vitreous fungicides which can be prepared, for example, by flame hydrolysis of silicon tetrachloride or a mixture of tetrudoride of aluminum chloride in a hydrogen / oxygen system "US-fl-3 939 199). These arenas are commercialized under the names of ROeros? It is preferred to par cular the use of a support comprising S O2 or a mixture of S O2 / OI2O3 having a surface area of 50 to 250 m2 / g and a pore volume of 0"A 1 , .2 ml / g and pressed to part * of said icros using organic fillers U'Pf-1 0 403 950), The particles of this The support has a particle size of 4 to 9 min, with 5 to 20% of the pore volume of the support being formed by * pores having radii of 200 to 3000 f ?, and 50 to 90% of the volume of pore being formed by * pores having radii of 70 to 100 fi_ It is particularly advantageous if these support particles are prepare by means of tableting or extrusion with the addition of one or more C2-C20 carboxylates of Li, Mg, 01, 7n, fe or end as binders and with the addition of organic fillers (such as sugar, urea, higher fatty acids, for relatively long chain inas, cellulose stainless steel) and lubricants (such as kaolin, graphite, metal-based soaps) (US-R-5 225 388). Subsequently, the particles are ignited in gases containing O2 at about 500 to 900 ° C for about 0.25 to 5 hours. ? The catalytically active substances can be applied to the support in a customary manner, for example, by means of individual or multiple impregnation of the support with a solution of the active substances, subsequent drying and, if desired, reduction. However, lac * active substances can be applied also to the support, for example, by single or multiple spraying, deposition < *? ? n or immersion in steam, or by precipitation on or l < port. Suitable solvents for the catalytically active substances are, in particular, water or non-subsumed carboxylic acids having from 2 to 1 carbon atoms, for example acetic acid, propiome acid, acid and isobutyl alcohol, and the different Valiant acids. Due to their physical properties and also for economic reasons, preference is given to using acetic acid as carboxylic acid. The additional use of an inert solvent is when the carboxylic acid used is one in which the substances are not sufficiently soluble. For example, palladium chloride can dissolve only nicer in aqueous acetic acid than in glacial acetic acid. Other suitable solvents are those which are inert and crosslinkable with the carboxylic acid, for example, water or ethers such as tetrahydrofluoride or dioxane, but also hydrocarbons such as benzene. Catalyst can be prepared-it is fully impregnated in which the catalytically active metallic compounds have penetrated the core of the support particles, or also impregnated surface catalysts in which the metal salts have not penetrated the core, but only in a outer part - more or less dense of the support particles ?, that is, the surface area of the particles. In both cases, the elements to be applied can be applied individually to ia (urine of solutions of their compounds, or also in any combination.) Preference is given to using solutions containing at least one compound of each of the elements ( It is given paricular preference to use an individual solution that contains exactly one compound of each of the elements to be applied.If "the solution" -referred to as follows, this means a solution that with at least one compound of one of the elements Pd, alkaline metal, Cd, Re, Zr, or a solution containing at least one compound of each of two or more of these elements To prepare fully impregnated catalysts The procedure is preferably as follows (US-0-4 902 823, US-FL-393 190, US-FI-4 660 019): The impregnation of the catalyst support with the solution of the active components is carried out out in such a way that the support material is covered with the solution and any excess solution is poured or filtered afterwards. Considering the solution losses, it is advantageous to use * only the amount of solution (according to the integral pore volume of the catalyst support *) and mix carefully, so that the particles of the support material are wetted together by +. to carry out the impregnation process, the mixing at the same time, for example, in a drum or a dryer by stirring, it being possible to apply the drying immediately, it is generally advantageous obtain the composition of the solution used to impregnate the catalyst support *, so that the desired amount of active subsizes *, and apply by means of an individual impregnation, However, this can also be applied by a plurality of impregnations, preferably drying is carried out after each impregnation Par * to prepare * impregnated surface catalysts, preference is given to proceed according to one of the following three methods, where a solution of at least one compound of at least one of the elements Pd, alkali metal, Cd, Re and / or Zr is always used. * that have a dynamic viscosity of at least () .. 003 Pa-s, preferably from 0.005 to 0.009 Pa-s :: 1.- The sopor-te particles are sprayed, while they are mixed in imam, once or a plurality of times with the solution in the form of droplets having an average diameter of at least 0.3 nm, or in the form of liquid jets, and dried immediately after each spray. The "immediate" drying means here that the drying of the sprayed particles has to start immediately. This is generally sufficient if the drying of the particles starts at most within a few minutes of a spray. In v aspersion, the volume of solution is from h to 00% of the pore volume of the support particles. This method is described broadly in EP-0 634 214, which is expressly incorporated in the present invention as (eroncia, 2 .-- The supporting particles are impregnated, while they are mixed in imamen , once or a plurality of times with the "elution", or dry immediately after each nnprognation. "Immediate" drying here means the same as in the first method, and the volume of solution in each impregnation it is from 5 to 00% of the pore volume of the support particles This method is described extensively in FP-0-0 634 209, which is expressly incorporated in the present invention as reference 3.- The support particles are impregnated once or a plurality of times with the solution and dried after each impregnation but, in contrast to the second method, no upper limit is set on the volume of solution: it is now more than 80% of the pore volume in each impregnation due to the larger volume of the solution n, intimate mixing is not absolutely necessary, although generally useful. Rather, the duration of each impregnation and the time until the subsequent drying starts, that is, the time from the beginning of each impregnation to the start of subsequent drying, must now be sufficiently short that, after The last drying period is a surface area of 5 to 80% of the pore volume of the support particles with -nqa the catalytically active elements. The duration of this time that has to be selected for this purpose can be easily determined by preliminary experiments. This method is described broadly in L-P- -0 634 208, which is likewise incorporated herein by reference in the present invention as r "e foronda. A suitable method for determining the thickness of the surface area achieved in the prepared impregnated surface catalysts comprises opening with a cut a representative number of dried and impregnated support particles, and measuring the thickness of the surface area under the microscope. Alternatively, preferably less than 5% of the particles must have * a surface area thickness * that deviates by more than 15% (the desired value) The drying of the sprayed or impregnated catalyst support is preferably carried out under reduced pressure (from 0.1 to 0.8 bar), both in the case of fully impregnated catalysts, as in the case of impregnated surface catalysts The temperature during drying should generally be 50 to 80 ° C, preferably 50 to 70 ° C C. In addition, it is generally advisable to carry out drying in a stream of inert gas, for example, in a stream of nitrogen or carbon dioxide. after drying, it should preferably be less than 0% by weight, in particular less than 20% by weight. The finished catalysts must contain the following amounts of the catalytically active elements: Fl content of palladium? is generally from 0.6 to 3.5% by weight, preferably from 0.0 to 3.0% by weight, in particular from 1.0 to 2.5% by weight, The content of alkaline element is generally 0.3 J 0% by weight. The preference is to use potassium, generally in a quantity of 0.5 to 4.0% by weight, preferably 1.0 to 3.0% by weight, in particular * 1.5 to 2.5% by weight. The content of cadmium is generally from 0.1 to 2.5% by weight, preferably from 0.4 to 2.5% by weight, in particular * from 1.3 to 2% by weight. The content of the rowing or zirconium is generally from 0.05 to 3% by weight, preferably from 0.05 to J% by weight, in particular from 0.05 to 0.5% by weight, and rowing and zirconium can also be present together in the catalyst. *, in which case the total content of the two elements is within the specified scales.The indicated percentages always refer to the quantities of the elements Pd, alkaline element, Cd, Zr and / or Re present in the catalyst, based on the total mass of the catalyst (active elements plus anions more material (Je support).

Suitable compounds to be applied to the ion support are all pallate compounds, cadmium, an alkali metal, oar and zirconium that are only sulfur and do not contain constituents that poison the catcher, for example, sulfur; The acetates and chlorides are given. However, in the case of chlorides, it must be ensured that the chloride ions are removed beforehand (using the catalyst for the synthesis of vinyol acetate.) This is achieved by washing the impurified support, by * < * je? N With water, for example, palladium applied as a chloride has become an insoluble form, for example, by reduction and / or by hydroxylation, particularly suitable palladium compounds are carboxylates, preferably the salts of nitonocarboxylic acids all (tices having from 2 to 5 carbon atoms, for example acetate, propionate or butyrate) Other examples of suitable compounds are nitrate, nitrite, hydrated oxide, oxalate, acetylacetonate, acetoacetate Due to its adequate solubility and availability, palladium acetate is the palladium compound paricularly preferred, as is composed of alkali metal, preference is given to using at least one compound of K, Rb or Cs, in particular * at least one compound of K. Particularly suitable compounds are carboxylates, in particular acetates and propionates. Also suitable are the compounds which are converted to the acetate under the reaction conditions, for example, the drug, the lido or the carbonate. Since it is composed of cadmium, acetate is an appropriate part of the tree. Particularly suitable zirconium compounds are acet to and acet i l cet o at o. Particularly suitable rowing compounds are: If the reduction of the compound is carried out, which is sometimes l, a gaseous reducing agent can be used for this purpose Suitable propellant agents are, for example, hydrogen, methanol , dense form, ethylene, propylene, isobutylene, but full and other fine The reduction temperature is generally between 40 and 2 ('') 0 ° C, preferably at 70 and 200 ° C. It is generally advantageous to use a reducing agent diluted with inert gas and containing from 0.01 to 50% by volume, preferably from 0.5 to 20% by volume, of reducing agent The inert gases which can be used are, for example, nitrogen, dioxide The amount of the reducing agent depends on the amount of oil, the reduction equivalent must be * at least 1 to 1.5 times the oxidation equivalent, but larger amounts of reducing agent * do not cause problems The reduction is carried out after ués of drying. The preparation of vinyl acetate is carried out by passing * acetic acid, ethylene and oxygen or oxygen-containing gases, at temperatures of 100 to 220 ° C, preferably (12G to 20 ° C), and at pressures of 25 bar, preferably from 1 to 20 bars, on the finished catcher, it being possible to circulate the components that have not reacted, the "oxygen uptake is advantageously below 10% by volume (based on the It is advantageous, however, that dilution with inert gases such as nitrogen or carbon dioxide is advantageous.Carbon dioxide is particularly suitable for dilution in the case of a circulation process. V, which is formed in small KJades during the reaction With the catalysts of the invention, it achieves a higher performance in spacetime and a selectivity equal to or greater than a longer operating life of the catalyst than with catalysts which or contain oar or z rconium. The following examples describe the invention. The percentages of the elements Pd, Cd, Z \ -, Re and K are percentages by weight based on the total mass of the catalyst *. As a catalyst support, S1O2 was used in the form of pellets having a diameter of 6 rnin and a height (Je 6 in. The pellets had been pressed from powder (Je ROerosil with the aid of magnesium stearate as a binder, as described in FIG. US-fi-5 255 388. The surface area of the support was 120 rn2 / g, its pore volume was 0.784 rnl / g and its overall density was 500 g / L. The pore volume of a liter of support it was 392 rnl.

I. Fully impregnated catalysts Comparative example 1 I was impregnated with silica supports at 60 ° C with a solution of 24.3 g of palladium acetate, 21.3 g of cadmium acetate and 23.0 g of potassium acetate in 392 ml of glacial acetic acid (volume of solution - 100 % of the pore volume of the support) ,. Sul > seeuontemen < The solids were placed in a drying oven at 200 mbar under nitrogen until the residual acetic acid content was 6% by weight; the drying temperature was 65 ° C. The finished catalyst contained 2.3% by weight (Je Pd, 1.0% by weight of Cd and 1.9% by weight of K. It was completely impregnated, ie, in the core 50 rnl of this catalyst was placed in a reaction tube having an internal diameter of 8 rnrn and a length of 1.5 rn.After, at a pressure of R barias (reactor inlet) and at a catalyst temperature * of 150 ° C, the gas intended to be reacted was passed over the catalyst For several days, this gas consisted of 27% by volume of ethylene, 55% by volume of nitrogen, 12% by volume of acetic acid and 6% by volume of oxygen.The results are shown in Table 1. In this Table, The "relative rate of decrease in yield" is the quotient of the yield decrease (= initial yield (jel experiment minus final yield of the experiment) and the duration of the experiment, with respect to the quotient? of the catalyst used in comparative example 1. This catalyst * has thus the <ocente (- relative rate of decrease (Jel yield) 1.

Example the The procedure was as in the comparative example 1, except that the solution additionally con- tains .5 g of zircon acetyl cordonate and the amount of glacial acetic acid was 309 ml. The results are shown in the Table 1" Example Ib One liter of the catalyst prepared as in comparative example 1 was impregnated at room temperature with a solution of 4.2 g of Re207 in 308 rnl of water (volume of solution - 100% (Jel pore volume of catalyst *). Subsequently as in comparative example 1, until a residual water content of 6% by weight was reached, the catalyst was tested as in comparative example 1. The results are shown in Table 1.

FIGURE 1 Fully impregnated catalysts * Initial yield (grams of acetate Jo vin per liter (Je catalyst * and hour) II. Impregnated surface catalysts Comparative example 2 At 65 ° C, 25.3 g of palladium acetate, 25 g of cadmium acetate and 25.3 g of potassium acetate were dissolved in 130.0 rnl of anhydrous acetic acid (glacial acetic acid) (solution volume = 33% of the pore volume). ), and the highly viscous solution (7 inPa-s) was placed in a pre-heated glass at 65 ° C. At the same time, one liter of catalyst supports was heated to 65 ° C, and placed in a flask. All of the impregnation solution was then poured onto the support particles, and the particles intimately mixed until the solution had been completely absorbed by the particles. This procedure concluded after 3 minutes.

The catalyst was subsequently dried as in comparative example 1. 1-1 catalyst finished with 2.3% by weight of Pd, 1.8% by weight of Cd and 1.9% by weight of K. C-1 thickness of the surface area was 0.8 mm. The test was carried out as in comparative example L. The results are shown in Table 2. 11"relative index of decrease in yield" is -fi e as in comparative example 1, that is, again with respect to . ai zador * u here.

Example 2a The procedure was as in the comparative example 2, except that the solution contained additional 7.0 g of zirconium acetalidet. The thickness of the surface area was 0.8 rnrn. The results are shown in the Square or " Example 2b One liter of the catalyst prepared as in comparative example 2 was impregnated at room temperature with a solution of 3.5 g of Rβ207 in 300 rnl of water (volume of solution - 100% of the pore volume of the catalyst). The catalyst was subsequently dried as in comparative example 1, until a residual water content of 6% was reached. 1: 1 c t li dor put on? Ruol > as in the comparative example 1 .. The results are shown in Table 2.

CUflDRO 2 (impregnated surface catalysts) * Initial yield (grams of acetate of mine vi per liter of catalyst- and hour)

Claims (9)

1. Líí
2. NOVELTY OF THE INVENTION
4. i.- A process for preparing acetone to vi (asses gaseous from ethylene, acetic acid and oxygen or gases containing oxygen on a catalyst comprising palladium and / or its compounds, cadmium compounds and metal compounds alkali is a support, wherein the catalyst additionally contains at least one compound and / or at least one compound. The process as described in claim 1, wherein the catalyst - contains at least one potassium compound 3. The process as described in claims 2, wherein the catalyst contains 0.05% by weight to 3% by weight (Je oar and / or zircomo, based on 4. The process as described in any of claims 1 to 3, wherein the catalyst * contains 0.05 wt.% to 1 wt.% of oar and / or zircomo, based on in the total mass of the catalyst 5.- The procedure as described e in any of claims 1 to 4, wherein the catalyst contains from 0.05% by weight to 0.5% by weight of oar and / or zircomo, based on the total mass of the catalyst.
5. JO
6. (i) A catalyst comprises palladium and / or its compounds, cadmium and alkali metal compounds on a support, wherein the catalyst additionally contains at least one oar compound and / or at least one zircomo compound. and, if the catalyst comprises palmitate and / or its compounds, cadmium and at least one compound of * * mo, the alkali metal compound has to be a compound of pota. -, 10.
7. 7,. catalyst as described in claim h, wherein the catalyst contains at least one potassium compound.
8. 8. A catalyst as described in claim 7, wherein the catalyst contains 0.05 wt. 3% by weight of oar and / or zircomo, based on the total mass of the catalyst
9. 9. A catalyst as described in any of claims 6 to 8, wherein the catalyst * contains 0.05% by weight to 1. % by weight of rowing and / or zirco or, based on the total mass of the catalyst 10.- A catalyst as He writes in any of claims 6 to 9, wherein the catalyst contains from 0.05% by weight to 0.5% by weight of oar and / or zirconium, based on the total mass of the catalyst.