JP4978277B2 - Catalyst for producing ethylene oxide, method for producing the same, and method for producing ethylene oxide - Google Patents

Description

  The present invention relates to a catalyst for producing ethylene oxide, a method for producing the same, and a method for producing ethylene oxide.

  The catalyst used for producing ethylene oxide from ethylene is mainly composed of silver (Ag), and Ag is supported on a carrier. Industrially, elements such as alkali metals and rhenium (Re) are added as co-catalysts to Ag, which is the main component of the catalyst, to improve the catalyst performance (Patent Document 1).

  Regarding the action effect of alkali metal, the effect of neutralizing the acid sites of the support existing on the support or the effect of modifying the catalytic action of Ag existing on the Ag surface has been reported, but details are unknown. . On the other hand, for Re, the location in the catalyst and the mechanism of action as a co-catalyst are unknown, but coexistence with an alkali metal is essential to act as a co-catalyst (Patent Document 2). ).

The carrier usually has α-alumina as a main component, and α-alumina is produced by firing a mixture of raw material powder, a binder, and a pore-forming agent. The carrier thus produced usually contains impurities such as silicon (Si) and sodium (Na) as impurities, and the content of Si is 0.1 to several tens wt% in terms of SiO ₂ and Na. the content is 0.01 number wt% in terms of Na ₂ O.

  It has been reported that the amount of Si and Na in the support is composed of Ag, an alkali metal, and the support, and has a great influence on the performance of the catalyst not containing Re (Patent Documents 3 and 4). Accordingly, it is necessary to control the amounts of Si and Na in the carrier by managing the amounts of Si and Na in the α-alumina raw material powder, the binder, and the pore forming agent. As Re-containing catalysts, catalysts having an Ag content of 20% by weight or more have been reported (Patent Documents 5 and 6).

Japanese Patent Laid-Open No. 9-150058 JP 63-126552 A JP 63-116743 A JP-A-1-123629 Japanese Patent Laid-Open No. 3-207447 WO2005-097318

  As a result of intensive studies aimed at providing an improved ethylene oxide production catalyst comprising at least Ag, Cs, Re and a support, the present inventors have obtained the following knowledge. That is, in the case of a catalyst comprising a high surface area support, Ag, Cs, and Re, it has been said that Si and Na components in the support usually do not affect the properties of Re as a promoter. However, if the ratio of the Si component to the Na component in the support is kept within a certain range, a catalyst having a remarkably improved selectivity can be obtained surprisingly by increasing the Re cocatalyst action.

  The present invention has been completed on the basis of the above findings, and consists of a group of related inventions. The gist of each invention is as follows.

The gist of the first invention is an ethylene oxide production catalyst used for producing ethylene oxide from ethylene, which is composed of at least silver (Ag), cesium (Cs), rhenium (Re) and a carrier, and is necessary for the carrier. As a pretreatment, it is obtained by supporting an alkali metal and then supporting Ag, Cs, and Re, and the carrier has a specific surface area of 0.6 to 3.0 m ² / g, Si and Na contents. Using a support having a weight ratio of ₂ to 50 in terms of SiO ₂ / Na ₂ O, and the Re content (support basis) is 170 to 600 ppm per 1 m ² / g of the specific surface area of the support, It exists in the catalyst for ethylene oxide manufacture characterized by the molar ratio of Cs / Re being 0.3-19.

The second invention has been made by further study based on the above knowledge, and the gist thereof is an ethylene oxide production catalyst used for producing ethylene oxide from ethylene, which is at least silver (Ag). ), Cesium (Cs), rhenium (Re), and a carrier, and the carrier is obtained by carrying an alkali metal as a pretreatment if necessary, and then carrying Ag, Cs, and Re. A carrier having a surface area of 0.6 to 3.0 m ² / g and having an acid point of pKa of 5.0 or less is used, and the Re content (carrier standard) is 1 m ² / g per specific surface area of the carrier. It is 170-600 ppm, and exists in the catalyst for ethylene oxide manufacture characterized by the molar ratio of said Cs / Re being 0.3-19.

  Another gist of the present invention is a method for producing a catalyst according to the first invention comprising at least silver (Ag), cesium (Cs), rhenium (Re) and a support, wherein the above Ag loading operation is performed twice. The present invention is divided into the above, and the production method is characterized in that at least a part of the amount of Cs and Re contained in the catalyst is supported in the last supporting operation of Ag. Lies in a method for producing ethylene oxide, characterized in that ethylene is oxidized in the presence of the catalyst according to the first invention.

  Still another subject matter of the present invention is a method for producing a catalyst according to the second invention comprising at least silver (Ag), cesium (Cs), rhenium (Re), and a carrier, wherein the above-described Ag loading operation is performed in 2 steps. The production method is characterized in that at least a part of the amount of Cs and Re contained in the catalyst is supported at the time of the last support operation of Ag. The gist lies in a method for producing ethylene oxide, characterized in that ethylene is oxidized in the presence of the catalyst according to the second invention.

  According to the first invention or the second invention, there is provided a catalyst for producing ethylene oxide comprising at least Ag, Cs, Re, and a support, and having particularly improved selectivity.

  Hereinafter, the present invention will be described in detail.

<Catalyst according to the first invention>
The ethylene oxide production catalyst according to the first invention is composed of at least Ag, Cs, Re, and a carrier, and contains Li as a preferred embodiment.

Examples of the carrier include porous refractories such as alumina, silicon carbide, titania, zirconia, and magnesia, and those having a main component of α-alumina are particularly suitable. These porous refractories are manufactured by firing a mixture of raw material powder, a binder, and a pore-forming agent, and contain Si and Na components as impurities. The Si content is usually 0.5 to 7.0% by weight, preferably 1.8 to 7.0% by weight in terms of SiO ₂ , and the Na content is usually 0 in terms of Na ₂ O. 0.05 to 0.50% by weight, preferably 0.16 to 0.45% by weight. The range of the content of the Si component and the Na component is a value determined from the viewpoint of improving the selectivity of the catalyst.

In the first invention, the carrier having a high surface area and a constant ratio of Si component to Na component, that is, the specific surface area is 0.6 to 3.0 m ² / g, and the weight ratio of the contents of Si and Na is using the carrier 2 to 50 with SiO ₂ / Na ₂ O equivalent. When a carrier satisfying such conditions is used, a catalyst having a remarkably improved selectivity can be obtained by enhancing the Re-catalyst action.

The specific surface area of the support is preferably 0.8 to 2.0 m ² / g, more preferably 1.2 to 1.6 m ² / g, particularly from the viewpoint of catalyst life such as maintaining the selectivity of the catalyst. And the weight ratio (SiO ₂ / Na ₂ O converted value) of the content of Na is preferably 6 to 27, particularly from the viewpoint of improving selectivity. In addition, said specific surface area is B.I. E. T.A. It is a value measured by the method.

  Porous refractories for catalyst supports, particularly α-alumina, are commercially available in various grades having different specific surface areas and different impurity contents. Therefore, in the first invention, a commercially available porous refractory that satisfies the above physical properties can be selected and used as a carrier. The contents of the Si component and Na component in the carrier can be adjusted by washing the carrier with an acid aqueous solution having an appropriate concentration.

  The silver content is usually 5 to 40% by weight based on the total catalyst weight, but is preferably 15 to 30% by weight from the viewpoint of improving the catalyst life. The content of Cs is usually 10 to 10000 ppm, preferably 50 to 5000 ppm, based on the total catalyst weight, as in the conventionally known catalysts.

The Cs content depends on the Re content described later, and the Cs / Re molar ratio must be in the range of 0.3 to 19. The Cs / Re molar ratio is preferably 1.7 to 4.5, more preferably 2.2 to 4.5. In both cases where the Cs / Re molar ratio is less than 0.3 and exceeds 19, the effect of improving the selectivity of the catalyst is insufficient.

The content of Re depends on the specific surface area of the support used, and the specific surface area of the support (specific surface area as the support before being incorporated into the catalyst) is 170 to 600 ppm per 1 m ² / g, Preferably it is 200-500 ppm, More preferably, it is 250-450 ppm. If the content of Re exceeds 170 ppm / a (m ² / g) less than in the case and 600ppm / (m ² / g) becomes insufficient selectivity improving effect of the catalyst.

  In the first invention, an alkali metal can be supported on the carrier as a pretreatment if necessary. Such a pretreatment of the support is recommended from the viewpoint of further improving the catalyst performance. Here, the pretreatment refers to an alkali metal carrying treatment performed before carrying a silver compound. As the alkali used for the pretreatment, Li and / or Cs are usually used, and Li and Cs are preferably used. Cs in the above “Cs / Re molar ratio” means the Cs content supported on the catalyst in the post-treatment (treatment in which Ag, Re, and Cs are supported). Cs supported on the catalyst in the post-treatment is considered to be present on the surface of Ag together with Re.

  The usage-amount of Li and Cs is 100-1000 ppm normally as Li or Cs content in the support | carrier after a pretreatment. The Li content is preferably 400 to 1000 ppm, more preferably 550 to 1000 ppm, and particularly preferably 585 to 1000 ppm. The Cs content is preferably 100 to 500 ppm. When the content of Li and Cs in the support is less than 100 ppm, the effect of improving the catalyst life is insufficient, and when it exceeds 1000 ppm, the effect reaches a peak and is not economical. Cs used here is different from Cs in the post-treatment described above in that it is directly supported on the carrier. This is because, as described above, post-processing Cs is estimated to be attached to Ag together with Re.

  In the ethylene oxide production catalyst according to the first invention, from the viewpoint of improving the catalyst life, the Li / Re molar ratio is usually 6 to 63, preferably 25 to 63, more preferably 35 to 63, and particularly preferably. The weight ratio of Li / Ag is usually 0.0007 to 0.0073, preferably 0.0029 to 0.0073, more preferably 0.0040 to 0.0073, and particularly preferably 0.00. 0043-0.0073.

  The alkali metal (Li and Cs) can be supported in the pretreatment using a water-soluble alkali metal compound according to a conventionally known method. Examples of the alkali metal compound include nitrates, hydroxides, halides, carbonates, bicarbonates, oxalates, carboxylates, and the like, and carbonates are particularly preferable. These are used as an aqueous solution having an appropriate concentration according to the content.

  In the post-treatment, a catalyst impregnating solution obtained by dissolving a water-soluble Re compound, a water-soluble Cs compound and, if necessary, a water-soluble Li compound in an Ag amine complex solution is used. Is simple.

  Examples of the Ag compound used in the Ag amine complex solution include silver oxide, silver nitrate, silver carbonate, silver acetate, and silver oxalate. Examples of the amine include monoamines such as ammonia, pyridine, and butylamine, and alkanolamines such as ethanolamine. And polyvalent amines such as ethylenediamine and 1,3-diaminopropane. Examples of water-soluble Re compounds include rhenium halides, rhenium oxyhalides, rhenates, and perrhenates. Examples of the water-soluble Cs compound include the same compounds as in the pretreatment, but nitrates or hydroxides are preferable. The concentration of each component in the catalyst impregnating liquid is appropriately determined according to the content of each component.

  Examples of the impregnation method in the pretreatment step include a method of immersing the carrier in the solution, or a method of spraying the solution onto the carrier. As the drying treatment, after the impregnation treatment, the support and the excess solution are separated, followed by drying under reduced pressure or heat treatment. Examples of the heat treatment include a method using an inert gas such as air or nitrogen, or superheated steam, and the heating temperature is usually 100 to 300 ° C, preferably 130 to 270 ° C.

  Examples of the impregnation method in the post-treatment step include the same methods as described above. The heat treatment after impregnation is carried out by measuring the temperature and time required for Ag to precipitate on the support. It is preferable to select conditions under which Ag is deposited on the support so as to be as uniform and fine as possible. The heat treatment is performed using heated air (or an inert gas such as nitrogen) or superheated steam. The heating temperature is usually from 130 ° C to 300 ° C, and the heating time is usually from 5 to 30 minutes.

  In particular, a catalyst having a high Ag loading rate, for example, a catalyst having an Ag loading rate of 15 to 30% by weight (catalyst standard) is obtained by dividing the method for producing a catalyst according to the present invention, that is, the Ag loading operation into two or more times. In addition, at least a part of the amount of Cs and Re contained in the catalyst can be easily obtained by a production method characterized in that the catalyst is supported during the final supporting operation of Ag. From the viewpoint of catalyst performance, it is preferable that more than half of the amount of Cs and Re is supported in the last support operation of Ag. The amount of Cs and Re carried during the last loading operation of Ag is more preferably 3/4 or more of the amount of Cs and Re, and most preferably the total amount of Cs and Re. The same applies to the components other than Cs and Re. According to the method for producing a catalyst according to the present invention, Cs, Re and the like are supported together with Ag at the time of the last support operation of Ag. In the method of supporting Cs, Re and the like on the catalyst, the performance of the catalyst is lowered.

  The method for producing ethylene oxide using the catalyst for producing ethylene oxide according to the first invention can be carried out according to known conditions. The reaction pressure is usually 0 to 3.5 MPaG, and the reaction temperature is usually 180 to 350 ° C., preferably 200 to 300 ° C. As the composition of the reaction raw material gas, a mixed gas containing 1 to 40% by volume of ethylene and 1 to 20% by volume of molecular oxygen is generally used, and a diluent such as an inert gas such as methane or nitrogen is generally used. The gas can be present at a constant rate (for example, 1 to 70% by volume). As the molecular oxygen-containing gas, air or industrial oxygen is usually used. Furthermore, for example, by adding about 0.1 to 50 ppm of halogenated hydrocarbon as a reaction modifier to the reaction raw material gas, formation of hot spots in the catalyst can be prevented, and the performance of the catalyst, particularly the selectivity, can be greatly increased. It can be improved.

<Catalyst according to the second invention>
The ethylene oxide production catalyst according to the second invention is an ethylene oxide production catalyst used for producing ethylene oxide from ethylene, and includes at least silver (Ag), cesium (Cs), rhenium (Re) and a carrier. It is obtained by supporting an alkali metal as a pretreatment on a support as necessary, and then supporting Ag, Cs, and Re. The support has a specific surface area of 0.6 to 3.0 m ² / g. And a carrier having an acid point of pKa of 5.0 or less is used, the Re content (support basis) is 170 to 600 ppm per 1 m ² / g of the specific surface area of the carrier, and the molar ratio of Cs / Re Is 0.3-19. That is, the second invention differs from the first invention in that the acid point is defined instead of the SiO ₂ / Na ₂ O ratio defined for the carrier in the first invention. Then, the regulation of the acid point enhances the Re cocatalytic action as in the case of the regulation of the SiO ₂ / Na ₂ O ratio.

  The appropriate acid point defined in the second invention has a strength of pKa of 5.0 or less, and shows a color reaction using methyl red as an indicator. In addition, the acid point with a pKa of 3.2 or less does not affect the selectivity of the catalyst if it is in an amount of a weak color reaction, but if the amount increases so as to cause a strong color reaction, the selectivity of the catalyst is reduced. Since it lowers, it is not preferable. An acid point of pKa 3.2 or lower indicates a color reaction with methyl yellow. Further, a base point having a pKa of 7.3 or more is not preferable, and this shows a color reaction with bromothymol blue.

  The acid / basicity of the surface of the carrier can be easily determined by a color reaction by an indicator method (April 26, 1966, published by Sangyo Tosho Co., Ltd., Kozo Tabe and Tsuneichi Takeshita “Acid-base catalyst”) 161, May 1, 1986, published by Kodansha, edited by the Catalysis Society of Japan, "Catalyst Course Separate Volume Catalyst Experiment Handbook", page 170, published by Maruzen Co., Ltd., June 25, 1984, The Chemical Society of Japan, "Chemical Handbook Basics" 3rd edition, page II-342).

  The amount of acid sites can be determined by titrating a sample colored with the above indicator with a base such as n-butylamine. The determination of the end point of the color reaction with the indicator and the titration with the base is usually sufficient visually.

  EXAMPLES Hereinafter, although an Example demonstrates this invention still in detail, this invention is not limited to a following example, unless the summary is exceeded. In addition, the measuring method of the physical property used in the following examples is as follows.

(1) Specific surface area:
B. E. T.A. Measured by the method. Nitrogen adsorption was performed at 77K, and the specific surface area was calculated by the BET one-point method.

(2) Si and Na contents in the carrier:
The sample was pulverized and then pressure-molded and measured by fluorescent X-ray analysis.

(3) Cs, Re and Li contents in the pretreatment support and catalyst:
The above components were extracted with nitric acid, Cs and Li were measured by atomic absorption method, and Re was measured by ICP emission method.

(4) Ag content in the catalyst:
Ag was extracted with nitric acid and measured by potentiometric titration.

(5) Carrier acid and basicity:
The acid and basicity of the carrier were measured as follows. That is, the carrier was dried at 120 ° C. for 3 hours, cooled, and then poured into dried toluene. A few drops of an indicator (0.001 wt%) dissolved in toluene was added thereto, and the mixture was shaken well and allowed to stand. And the presence or absence of a color reaction is investigated for every indicator.

Example 1:
(1) Measurement of acid and basicity of carrier:
α- alumina carrier (surface area 1.0 m ² / g, water absorption rate 35.7 wt%, _SiO 2 3.0 _wt%, Na 2 O0.35 wt%, _{SiO 2} / Na 2 O weight ratio of 9, the shape 8 mm × The acidity and basicity were measured for a ring shape of 8 mm.

  Methyl yellow with a pKa of 3.2 or less did not show a red color reaction, but a methyl red with a pKa of 5.0 or less showed a red color reaction. Further, bromothymol blue having a pKa of 7.3 or more did not show a blue color reaction. From the above, it was found that the above carrier has an acid point of 3.2 <pKa ≦ 5.0, but no base point of pKa ≧ 7.3.

(2) Pretreatment of carrier:
100 g of the α-alumina carrier is immersed in 200 mL of an aqueous solution in which 0.156 g of cesium carbonate (Cs ₂ CO ₃ ) and 1.69 g of lithium carbonate (Li ₂ CO ₃ ) are dissolved, and then the excess liquid is cut. Was heated with superheated steam at 150 ° C. for 15 minutes at a flow rate of 2 m / sec to prepare a support impregnated with Li and Cs components. The Li content in the support was 500 ppm, and the Cs content was 230 ppm. Table 1 shows the physical properties of the carriers used.

(3) Preparation of silver amine complex solution:
322 g of silver nitrate (AgNO ₃ ) and 192 g of potassium oxalate monohydrate (K ₂ C ₂ O ₄ .H ₂ O) were dissolved in 1.4 L and 1.6 L of water, respectively, and then heated to 60 ° C. in a hot water bath. The mixture was gradually mixed while warming to obtain a white precipitate of silver oxalate (AgC ₂ O ₄ ). The precipitate was collected by filtration and washed with distilled water to obtain hydrous silver oxalate (water content: 23.3% by weight). 375 g of hydrous silver oxalate thus obtained was gradually added and dissolved in an aqueous solution consisting of 103 g of ethylenediamine, 28.1 g of 1,3-diaminopropane, and 133 g of water to prepare a silver amine complex solution.

(4) Preparation of Ag catalyst:
To 12.7 g of the silver amine complex solution obtained above, 0.6 mL of an aqueous solution having a cesium nitrate (CsNO ₃ ) concentration of 5.54 wt% and an aqueous solution having an ammonium perrhenate (NH ₄ ReO ₄ ) concentration of 3.05 wt% 6 mL and 2.1 mL of water were added to obtain an impregnation solution. The impregnation solution thus obtained was impregnated with 30 g of α-alumina support impregnated with Li and Cs by heating to 40 ° C. under reduced pressure in an evaporator. The impregnated support was heated with superheated steam at 200 ° C. for 15 minutes at a flow rate of 2 m / second to obtain a catalyst. The contents of Ag, Cs, Re, and Li (support basis) in the catalyst were 13.6% by weight (12.0% by weight on the catalyst basis), 980 ppm, 420 ppm, and 500 ppm, respectively.

(5) Ethylene oxidation reaction:
The Ag catalyst prepared above is crushed into 6-10 mesh, 3 mL of the catalyst is filled into a SUS reaction tube having an inner diameter of 7.5 mm, and reaction gas (ethylene 30%, oxygen 8.5%, vinyl chloride 1.5 ppm, carbon dioxide). Carbon 6.0%, remaining nitrogen) was flowed at GHSV 4300 hr-1 and pressure 0.7 MPaG to carry out the reaction. The reaction temperature was adjusted so that the production volume (STY) of ethylene oxide per unit volume of catalyst and unit time was 0.25 kg-EO / h · L-cat. The selectivity to ethylene oxide improved as the evaluation time increased and then decreased. Tables 3 and 4 show the catalyst components and catalyst performance. The selectivity to ethylene oxide was expressed on an ethylene basis. In Tables 3 and 4, Cs * in “Cs * / Re” means the content of Cs supported on the catalyst in the post-treatment. Further, the “degradation rate” of the catalyst performance represents a decrease in selectivity per cumulative ethylene oxide (EO) 1000 kg-EO / L-cat, and the unit is “% / EO1000”.

Examples 2-12 and Comparative Examples 1-11:
Except for changing the amount of lithium carbonate and cesium carbonate so as to obtain Li and Cs contents during pretreatment as shown in Tables 3 and 4 using the physical properties of the carriers shown in Tables 1 and 2. The same pretreatment as in Example 1 was performed. Next, a “silver amine complex solution” having the same composition as in Example 1 was prepared, and during the “preparation of Ag catalyst” in Example 1, the concentrations of cesium nitrate and ammonium perrhenate were changed, and Cs and Re Catalysts with content rates shown in Tables 3 and 4 were obtained. Note that the content of Ag (based on the carrier) is 13.6% by weight for all the catalysts. Subsequently, the oxidation reaction of ethylene was performed in the same manner as in Example 1 using each catalyst. Tables 3 and 4 show the catalyst components and catalyst performance.

  The following is understood from Tables 1 to 4 above.

(1) In a catalyst composed of Ag, Cs, Re and a carrier, the carrier used has a SiO ₂ / Na ₂ O weight ratio of 2 to 50 (or an acid site having a pKa of 5.0 or less), Re content (carrier In Examples 1 to 12 where the standard) satisfies 170 to 600 ppm per 1 m ² / g of the specific surface area of the support and the Cs * / Re molar ratio is 0.3 to 19, the maximum selectivity is 84.7 to 86.5%. .

(2) Especially in the case of Examples 1 to 8 where the SiO ₂ / Na ₂ O weight ratio of the carrier used is 6 to 27 and the Cs * / Re molar ratio is 2.2 to 4.5, the highest selectivity Is as high as 85.7 to 86.5%, and it is understood that the above range is more preferable.

(3) In Comparative Examples 1 to 3, in which the SiO ₂ / Na ₂ O weight ratio of the support is outside the range of 2 to 50, the maximum selectivity is 80.8 to 83. 8 as compared with Examples 1 to 12. It is understood that the SiO ₂ / Na ₂ O weight ratio of the support needs to be within the above range in order to increase the selectivity of the catalyst as low as 4%. The selectivity difference between the inside and outside the range of the SiO ₂ / Na ₂ O weight ratio of 2 to 50 of the support was as large as 3.1% when compared at the maximum value.

(4) In Comparative Example 4 in which the Re content (based on the support) is outside the range of 170 to 600 ppm per 1 m ² / g of the specific surface area of the support, the maximum selectivity is 81.9 compared to the cases of Examples 1 to 12. % Was low. From this, it is understood that the Re content must be in the above range in order to increase the selectivity of the catalyst.

(5) Comparative Examples 5 to 11 show that for catalysts not containing Re, the SiO ₂ / Na ₂ O weight ratio of the carrier has little effect on the selectivity of the catalyst. That is, in Comparative Examples 5 and 6 in which the SiO ₂ / Na ₂ O weight ratio of the support was in the range of 2 to 50, ie 11, the maximum selectivity was 81.9% as a result of optimizing the Cs content. It was. In contrast, the highest selectivity of Comparative Examples 7 and 8 _SiO 2 / Na ₂ O weight ratio of the carrier is 0.6 As a result of optimizing the Cs content is 80.8% of the carrier _SiO 2 / In Comparative Examples 9 to 11 in which the Na ₂ O weight ratio is 68, the result of optimization of the Cs content was 81.6%, and the catalyst had a SiO ₂ / Na ₂ O weight ratio of the support outside the range of 2 to 50. The selectivity was 80.8-81.6%. That is, the selectivity difference within the range of the SiO ₂ / Na ₂ O weight ratio of the support within the range of 2 to 50 is 0.3% as compared with the maximum value, which is 1/10 or less of the catalyst containing Re. It is understood that it is very small and has little effect.

Claims (13)

A catalyst for producing ethylene oxide used to produce ethylene oxide from ethylene, which comprises at least silver (Ag), cesium (Cs), rhenium (Re) and a carrier, and an alkali as a pretreatment if necessary. It is obtained by supporting a metal and then supporting Ag, Cs, and Re. As the above support, the specific surface area is 0.6 to 3.0 m ² / g, and the Si content in the support is in terms of SiO ₂ . 0.5 to 7.0% by weight, using a support in which the weight ratio of the content of silicon (Si) and sodium (Na) is ₂ to 50 in terms of SiO ₂ / Na ₂ O, the above Re content rate The catalyst for ethylene oxide production, wherein (support basis) is 170 to 600 ppm per 1 m ² / g of the specific surface area of the support, and the molar ratio of Cs / Re is 0.3 to 19. The catalyst of claim 1 Na content in the carrier is 0.05 to 0.50 wt% in terms of Na ₂ O values.   The catalyst according to claim 1 or 2, wherein the molar ratio of Cs / Re is 1.5 to 4.5.   The catalyst according to any one of claims 1 to 3, wherein the alkali metal used for the pretreatment of the carrier is lithium (Li), and the Li content in the carrier after the pretreatment is 100 to 1000 ppm. The catalyst according to any one of claims 1 to 3 , wherein the alkali metal used for the pretreatment of the carrier is cesium (Cs), and the Cs content in the carrier after the pretreatment is 100 to 1000 ppm.   The catalyst according to any one of claims 1 to 5, wherein the silver content is 5 to 40% by weight based on the total catalyst weight.   A method for producing ethylene oxide, comprising oxidizing ethylene in the presence of the catalyst according to claim 1. A catalyst for producing ethylene oxide used to produce ethylene oxide from ethylene, which comprises at least silver (Ag), cesium (Cs), rhenium (Re) and a carrier, and an alkali as a pretreatment if necessary. It is obtained by supporting a metal and then supporting Ag, Cs, and Re. As the above-mentioned support, the specific surface area is 0.6 to 3.0 m ² / g, and the Na content in the support is a Na ₂ O equivalent value. 0.05 to 0.50 wt%, using a support having a silicon (Si) and sodium (Na) content weight ratio of ₂ to 50 in terms of SiO ₂ / Na ₂ O, and containing the above Re A catalyst for ethylene oxide production, characterized in that the rate (based on support) is 170 to 600 ppm per 1 m ² / g of the specific surface area of the support, and the molar ratio of Cs / Re is 0.3 to 19.   The catalyst according to claim 8, wherein the molar ratio of Cs / Re is 1.5 to 4.5.   The catalyst according to claim 8 or 9, wherein the alkali metal used for the pretreatment of the carrier is lithium (Li), and the Li content in the carrier after the pretreatment is 100 to 1000 ppm. The catalyst according to claim 8 or 9 , wherein the alkali metal used for the pretreatment of the carrier is cesium (Cs), and the Cs content in the carrier after the pretreatment is 100 to 1000 ppm.   The catalyst according to any one of claims 8 to 11, wherein the silver content is 5 to 40% by weight based on the total catalyst weight.   A method for producing ethylene oxide, comprising oxidizing ethylene in the presence of the catalyst according to any one of claims 8 to 12.