DE1542229A1 - Catalyst for the oxidation of olefins - Google Patents

Description

R e ctio n g "Catalyst for the oxidation of olefins" Priorities : May 18, 1965 and June 2, 1965-Great Britain The invention relates to catalysts and their manufacture. In particular, the invention relates to substrates applied or supported silver catalyst. Such catalysts are for the oxidation of ethylene su xthylene oxide using molecular Oxygen is particularly useful.

According to the invention comprises an applied to a carrier or supported silver catalyst supported silver with a Content of α-aminium oxide or silicon carbide, with at least 95% of the carrier has a pore diameter from 6 to 180 pi, at least 99% of the support have a particle size of 10 to 400 M and the porosity of the carrier is 35 to 65%. Preferably 95% of the support has a pore diameter from 20 to 180ju. It is also preferred that 50% by weight of the carrier have a particle size from 100 to 300 µ.

An Xrffiser with a porosity of 40 to 50% is advantageous.

According to a further feature of the invention, a method for Manufacture of one applied to an ériger or with a carrier provided silver catalyst dos impregnation of an α-aluminum oxide as defined above and the silicon carbide carrier with a bilber compound and the calciner, respectively of the resulting product at a temperature and for a time that is at least sufficient to replace the silver compound. Examples of useful silver compounds are the oxalate, lactate, carbonate and oxide.

The silver compound can come from a soling or a solution being separated or knocked down, although precaution is taken, a Solution to be used, since in this way more silver compound is generally deposited or can be knocked down. If in 1 treatment an inadequate The operation can be used to deposit or deposit the amount of silver be repeated. It is desirable to have a solution with a high content on the silver compound used to get the number of treatments that are required are to deposit or deposit the required amount of silver, su diminish. In general, it is preferred to 10 to 20% by weight Silver, based on the catalyst, should be provided, although with the help of multiple Impregnation procedure up to 50% silver can be achieved.

In a particularly preferred procedure according to the invention an aqueous solution of silver lactate is used. This can expediently by mixing ammonium lactate with silver nitrate and filling silver lactate be made with methanol. Ammonium lactate is opposite to alkali metal aotates prevents ammonium nitrate from being completely removed in the caicination stage, while oxides of alkali metals would tend to remain in the catalyst. These Oxides, especially sodium oxide, tend to be deleterious on the catalyst.

An accelerator or promoter, such as a barium, Tin, caloium or magnesium compounds can be used, barium lactate it is preferred if silver lactate is used. A useful concentration of barium lactate is the one containing 0.1 to 0.5% barium based on the weight of the total Catalyst results, but it was found that barium levels of only 0, 01% provide usable catalysts.

Caicinating is preferably carried out at a temperature of from 200 to 300 ° C, with a temperature of about 275 ° C being particularly preferred. Da3 calcining should be continued until the compound calcines to silver oxide and any volatile reaction products have been removed.

The invention is not to be construed as limiting with reference to the following Examples explained in more detail. All percentages are percentages by weight, unless otherwise is specified.

Example 1 116 g of ammonium carbonate and 280 g of 88% lactic acid were obtained reacted until the evolution of carbon dioxide ceased and then 340 g of silver nitrate added in 250 cm3 of water. 4 l of methanol were added and the silver lactate precipitate was filtered, washed with methanol and then dried at 70 ° C.

150 g of the silver lactate produced in this way were dissolved in 210 cents of water golbet and there were 2 g of a solution of barium lactate and then 50 cm3 15% hydrogen peroxide added. The solution was heated to 90 ° C and it 350 g of 7.94 mm spheres (5/16 inch spheres) of α-aluminum oxide (pore diameter 95% 20 to 180 µ, pore size 95% 10 to 400 µ and porosity 44 to 48%) added, the mixture for 15 minutes under periodic or discontinuous Stirring was kept at 90 ° C.

The catalyst was then filtered off, dried at 80 ° C. for 16 hours and finally clacinated for 4 hours at 275 ° C. This procedure was Repeated 2 times so that a total of 3 impregnations took place. The finished catalyst contained 11.4% by weight of silver and 0.12% by weight of barium, based on the total weight of the catalyst.

Example 2 There were 5 cm3 of 30% hydrogen peroxide and 350 g of 4.76 mm - spheres (3/16 inch spheres) of α-aluminum oxide (pore diameter su 99% 6 to 80 μ, particle size 95% 10 to 200 μ and porosity 49%) including a 63% by weight Solution of silver lactate was added and the mixture was stirred for 15 minutes under periodic Heated to 90 ° C or discontinuous stirring. The one so impregnated Carrier was then filtered off and dried at 90 ° C. for 24 hours. net. After 4 Calcining at 275 ° C. for hours, the resulting catalyst contained 10.8% by weight Silver based on the total weight of the catalyst. The catalyst had one Porosity from 44 to 48%.

Example 3 5 cm 3 of hydrogen peroxide and 1 cm 3 of barium lactate solution were obtained and 350 g of 4.76 mm (3/16 inch spheres) spheres of silicon carbide (porosity 38% and 95% pore size 6 to 80 μ) was added to a 60% by weight solution of silver lactate and the mixture was mixed for 15 minutes under periodic and discontinuous, respectively Stir heated to 90 ° a. The so impregnated carrier turo de filtered off and 16 hours dried at 85 ° C and then oalinated at 260 ° C for 4 hours. The procedure was then repeated with the resulting catalyst and after calcining If the catalyst contained 19.0% bilber and 0.1% barium, based on the total weight of the catalyst.

The catalyst thus prepared was to induce oxidation from Ethylene to xethylene oxide using molecular oxygen is particularly good suitable and it can be used with inhibitors such as organic halogen compounds will. He has due to the amount of silver that is deposited on the carrier or can be precipitated, a high effectiveness and a high selectivity in Regarding ethylene oxide and the silver adheres well to the carrier and the impregnation with it is uniform so that the catalyst is easier to handle and in Use its effective life for a long period of time maintains.

Example 4 A gas mixture with a content of 5.8% oxygen, 5% ethylene, 0.00002% (0.2 p.p.m.) ethylene dichloride and nitrogen as the remainder duroh a layer or a bed of one produced as described in Example 1 Catalyst passed. The catalyst layer or the catalyst bed was maintained at a temperature of 264 ° C and the contact time was 3.4 seconds. The ethylene conversion was 30%, based on the ethylene fed in, and the ethylene oxide yield was 72%, related to the converted ethylene.

Example 5 A gas mixture with a content of 599% oxygen, 3% ethylene, 0.00003% (0.3 p. P. M.) Ethylene dichloride and nitrogen as Remainder by a layer or a bed of one as described in Example 3 produced catalyst passed. The catalyst layer or that Catalyst bed was maintained at a temperature of 262 ° C and the contact time was 3.6 seconds. The ethylene conversion was 54%, based on the feed Ethylene, and the ethylene oxide yield was 71% based on the ethylene converted.

Claims (13)

Claims catalyst for the oxidation of olefins with a Silver content on a carrier, characterized in that the carrier is α-aluminum oxide or silicon carbide, with at least 95% of the rigers having a pore diameter from 6 to 180 M, at least 95% of the trigger have a part size of 10 to Have 400 μ and the porosity of the carrier is 35 to 65%. 2.) Catalyst according to claim 1, characterized in that zß the particle size distribution is such that 50 wt .-% of the carrier has a particle size (pore diameter) of 100 up to 300 µ. 3.) Catalyst according to claim 1 or 2, characterized in that 95% of the carrier have a pore diameter of 20 to 180 µ. 4.) Catalyst according to claim 1 to 3, characterized in that the carrier rias has a forosity of 40 to 50%. 5.) Catalyst according to claim 1 to 4, characterized in that it also contains a barium, Zi, calcium or magnesium compound. 6.) Catalyst according to claim 1 to 5, characterized in that Barium in an amount of 0.1 to 0.5% by weight, based on the weight of the silver, is present. 7.) Catalyst according to claim 1 to 6, characterized in that or contains 10 to 20 wt.% silver. 8. A method for producing the catalyst according to claim 1 to 7, characterized in that a carrier with a content of α-aluminum oxide or silicon carbide, of which at least 95% have a pore diameter of 6 to 180m µ and at least 95% have a particle size of 10 to 400 µ and the porosity of which is 35 to 65%, impregnated with a silver compound and then resulting product at a temperature and for a time that is at least suffice, us decompose the silver compound, calcined. 9. procedural approach to claim 8, characterized in that as Silver compound an oxalate, carbonate, oxide or Laotat is used. 10.) The method according to claim 8 or 9, characterized in that da8 the silver compound is used in the form of a solution. 11.) The method according to claim 8 to 10, characterized in that daduroh an aqueous solution of silver lactate is used as the solution for the silver compound, preferably yins those obtained by reacting ammonium lactate with silver nitrate wu turns. 12.) The method according to claim 8 to 11, characterized in that one calcining at a temperature of 200 to wa performs. 13. The method according to claim 8 to 12, characterized in that the impregnation and calcination treatments are repeated at least once.