SU643071A3 - Method of reactivation of used silver catalyst for oxidation of ethylene to ethylene oxide - Google Patents

Description

due to its low boiling point and low cost. The amount of ode in the prepared impregnation solution is crucial. It should not exceed 10% of the total amount of the solution. Advantageously, the water concentration is between 0.2 and 5% by weight, especially when cesium nitrate or rubidium nitrate is used. The concentrations of the cesium compound, respectively, rubidium in the impregnation solution are limited by the solubility of the compound. However, in most cases it is advisable that the minimum concentration be 0.01 wt.%. A concentration of 0.05-0.4% by weight, calculated on the total amount of the solution, is particularly suitable. The treatment of the spent catalyst by the relevant invention with the impregnation solution can most easily be carried out by soaking the spent catalyst and draining the excess amount. solution. In large installations, the treatment is propez & o: t by pouring a reactor filled with a catalyst with a solution of a cesium or rubidium compound. After the separation of the excess solution, the alcohol remaining on the catalyst, and in some cases water, is removed by evaporation and, if desired, with additional product; nitrogen. Evaporation temperature is not. should be too high compared with the temperature of the applied alcohol. If distillation is carried out under reduced pressure, then evaporation can be carried out already at room temperature or, for example, at 50 s. But it is often advisable to choose a higher temperature, for example 50 -.

Oxidation of Ethylene in Oxyethylene In a particularly preferred embodiment of the invention, the spent catalyst is impregnated with an impregnating solution consisting of 0.2. 5% by weight of water, 0.05-0.4% by weight of cesium or rubidium nitrate and aliphatic alcohol containing 1-6 carbon atoms, and immediately thereafter the alcohol is evaporated at 70-120 seconds, preferably at 30-300, in some cases while blowing nitrogen. It is advisable that cesium nitrate, respectively, rubidium nitrate, be dissolved in the minimum amount of water necessary for complete dissolution, and then diluted with such amount of methyl, ethyl, propyl or isopropyl alcohol, preferably methyl alcohol, so that the concentration of water in the finished solution The flow rate was 0.2 - 5% by weight. The concentration of rubidium nitrate or cesium nitrate is 0.05 - 0.4% by weight, calculated on the total amount of solution. Both always and here. The necessary concentration of rubidium or cesium on the catalyst is 1.-1000, preferably 3-500 ppm. features 10.300 ppm-i, and it can be achieved by applying a solution of YLL impregnation of the appropriate concentration. . -. . . . . The properties of the catalyst before and after treatment are shown in the table. As can be seen from the table, thanks to the treatment of the spent catalyst with reduced activity according to the invention, its selectivity is greatly increased. In addition, the degree of conversion increases by 2-4 times, or with an equal degree of conversion, the reaction temperature can be lowered by 20-30 ° C.

Before processing After processing

The possibility of lowering the reaction temperature is another advantage of the proposed method 60 since the formation of undesirable by-products, such as carbon dioxide, formaldehyde and acetic aldehyde, decreases with decreasing temperature.

70

4-5 78 10-12

4-5

Claims (2)

Example 1. (comparative). 70 g of a catalyst containing 11.3% by weight of silver on a 7-Det alumina carrier are tested at a flow rate of 250 at 1 atm. Under these conditions, a temperature of 56% is required to achieve a conversion rate of 5%. The selectivity is 70.5%. Example 2. 50 g of the catalyst described in example 1, which for 7 years was used to produce ethylene oxide by directly oxidizing ethylene with oxygen, wastes (200 ml capacity of Erlenmeyer flask and 50 ml of solution , 5 g of cesium nitrate and 50 g of water per 1 kg of methyl alcohol and a lot of mass for 1 hour. Immediately after this, the excess impregnating solution is drained and the catalyst is dried for 0.5 h at a drying cabinet at. The concentration of cesium in the catalyst is loop. m per kg of catalyst. The catalyst treated with this method is brought into contact with the source gas under the same conditions as in comparative example 1 With 245 ° C and a conversion rate of 5%, a selectivity of 72% can be achieved. Example 3, 100 g the catalyst described in example 1 is placed in a glass tube with an internal diameter of 20 mm and a length of 500 mm. At room temperature for 1 hour, 500 g of an impregnating solution containing 9.2 g of acetic acid is pumped through the catalyst (bottom to top) cesium and 30 g of water per 1 kg zopropilovogo alcohol. Immediately thereafter, the solution is drained and the catalyst is dried for 0.5 hours at, and the catalyst is under vacuum. The cesium concentration on the catalyst is 800 mg per kg of catalyst. Processed by the method described in Example 1, the catalyst is brought into contact with the source gas. / At a conversion degree of 5%, a selectivity of 72% is achieved. PRI me R 4. 100 g of catalyst. described in example 1, is placed in a glass tube with an inner diameter of 20 mm and a length of 500 mm. From the Erlenmeyer flask, the catalyst, heated to 40c, is poured over the impregnating solution, which contains 3 mg of cesium sulfate in 10 g of water and 1000 g of ethanol. After draining the impregnating solution, the second and third times are treated with fresh solutions. Directly thereafter, the alcohol solution is allowed to drain and then dried for 1 hour in a stream of nitrogen flowing at a rate of 100 l / h, and the catalyst is heated to a heat transfer medium in the double jacket of the glass tube. The cesium concentration on the catalyst is 1 mg per 1 kg of catalyst. The catalyst treated in this way is placed in the reactor used in the experiments and, by the method described in comparative example 1, is brought into contact with the source gas. At 25iDc, with a conversion rate of 5%, a selectivity of 70.8% is achieved. Example 5, 100 g of the catalyst described in Example 1 is placed in a 250 ml round bottom flask, which is equipped with an addition funnel and connected to a vacuum line. The flask is evacuated to 200 mm Hg. From a dropping funnel, a 150 ml feed solution containing 0.44 g of cesium nitrate and 0.33 g of rubidi nitrate in 10 g of water and 1000 g of propyl alcohol is poured into the catalyst for 2 minutes. After equalizing the pressure with the atmospheric catalyst, it is kept in the impregnating solution for another 2 hours. Immediately after this, the solution is allowed to drain through a suction filter and the catalyst is dried for 5 hours at 100 ° C in a vacuum drying oven. The total concentration of cesium and rubidium on the catalyst is 100 mg / kg of catalyst. The catalyst treated using the method described above was brought into contact with the source gas in the reactor used in the experiments and in the method described in Example 1. At 240 ° C and a conversion of 5%, a selectivity of 75% is achieved. Example b. The experiment is repeated in accordance with that described in Example 4, however, in this case, the impregnation solution is changed, and it contains 0.44 g of cesium nitrate. O, 33g of rubidium nitrate and 100 g in: ode to 900 g of propyl alcohol {10% water calculated for the whole solution), With the subsequent implementation of the process in the reactor with the source gas at 245 sec, a conversion degree of 4% and a selectivity of 75% are achieved. DETAILED DESCRIPTION A method for reactivating spent silver catalyst for the oxidation of ethylene to ethylene oxide by treating the catalyst with a chemical reagent, so that, in order to increase the degree of reactivation of the catalyst, a chemical reagent is used a solution containing, in%. water: Water 0.2 - 10 Compound of cesium and / or rubidium 0, OB - 0.4 Al | Matic alcohol. containing 1-6 carbon atoms of the remainder, and the treatment with the specified reagent is carried out to the final content of the cesium and / or rubidium catalysts in 1-1000 hours. in a million 64307 in Sources of information taken into account for the expert 1. Romanian patent 53012, cl. B 01 J 11/10, 1971. 2. USSR author's certificate 144839, cl. B 01 J 11/10, 1961.