WO2009088040A1 - Catalyst for production of ethylene oxide, and process for production of ethylene oxide - Google Patents

Catalyst for production of ethylene oxide, and process for production of ethylene oxide Download PDF

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Publication number
WO2009088040A1
WO2009088040A1 PCT/JP2009/050146 JP2009050146W WO2009088040A1 WO 2009088040 A1 WO2009088040 A1 WO 2009088040A1 JP 2009050146 W JP2009050146 W JP 2009050146W WO 2009088040 A1 WO2009088040 A1 WO 2009088040A1
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Prior art keywords
catalyst
ethylene oxide
carrier
temperature
mass
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PCT/JP2009/050146
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French (fr)
Japanese (ja)
Inventor
Takaaki Hashimoto
Masahide Shima
Tadashi Sento
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Nippon Shokubai Co., Ltd.
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Priority to JP2009548948A priority Critical patent/JP5581058B2/en
Publication of WO2009088040A1 publication Critical patent/WO2009088040A1/en

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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D301/00—Preparation of oxiranes
    • C07D301/02—Synthesis of the oxirane ring
    • C07D301/03—Synthesis of the oxirane ring by oxidation of unsaturated compounds, or of mixtures of unsaturated and saturated compounds
    • C07D301/04—Synthesis of the oxirane ring by oxidation of unsaturated compounds, or of mixtures of unsaturated and saturated compounds with air or molecular oxygen
    • C07D301/08—Synthesis of the oxirane ring by oxidation of unsaturated compounds, or of mixtures of unsaturated and saturated compounds with air or molecular oxygen in the gaseous phase
    • C07D301/10—Synthesis of the oxirane ring by oxidation of unsaturated compounds, or of mixtures of unsaturated and saturated compounds with air or molecular oxygen in the gaseous phase with catalysts containing silver or gold
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
    • B01J23/54—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
    • B01J23/66—Silver or gold
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
    • B01J23/54—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
    • B01J23/66—Silver or gold
    • B01J23/68—Silver or gold with arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
    • B01J23/688—Silver or gold with arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium with manganese, technetium or rhenium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/30—Catalysts, in general, characterised by their form or physical properties characterised by their physical properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/02—Impregnation, coating or precipitation
    • B01J37/0201—Impregnation
    • B01J37/0203—Impregnation the impregnation liquid containing organic compounds
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/08—Heat treatment
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D303/00—Compounds containing three-membered rings having one oxygen atom as the only ring hetero atom
    • C07D303/02—Compounds containing oxirane rings
    • C07D303/04—Compounds containing oxirane rings containing only hydrogen and carbon atoms in addition to the ring oxygen atoms
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J21/00—Catalysts comprising the elements, oxides, or hydroxides of magnesium, boron, aluminium, carbon, silicon, titanium, zirconium, or hafnium
    • B01J21/02—Boron or aluminium; Oxides or hydroxides thereof
    • B01J21/04—Alumina
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/50—Improvements relating to the production of bulk chemicals
    • Y02P20/52—Improvements relating to the production of bulk chemicals using catalysts, e.g. selective catalysts

Definitions

  • the present invention relates to a catalyst for ethylene oxide production and a method for producing ethylene oxide.
  • the present invention relates to a catalyst capable of producing ethylene oxide with high selectivity over a long period of time, which has excellent catalytic activity, selectivity and catalyst life, and a process for producing ethylene oxide using this catalyst.
  • Catalytic gas phase oxidation of ethylene with a molecular oxygen-containing gas in the presence of a silver catalyst to produce ethylene oxide is widely practiced industrially.
  • the silver catalyst used for the catalytic gas phase oxidation many techniques have been proposed with regard to the support, the method of support, the type of the reaction accelerator and the amount thereof to be added, and the like.
  • an alkali metal is effective as a reaction promoter.
  • JP-A-63-126552 Example 1
  • JP-A-9-150058 and JP-A-2003-320255 the selectivity of the catalyst can be improved by using alkali metal and rhenium in combination. Techniques to improve are disclosed.
  • JP-A-63-126552 discloses a catalyst containing silver, rhenium and cesium, and shows an improvement in initial selectivity. However, there is no disclosure that selectivity is improved over a long period of time.
  • JP-A-9-150058 a carrier is pretreated with a solution containing an alkali metal compound (lithium compound) and a cesium compound, then impregnated with a solution containing a silver compound and a cesium compound, and then heat treated.
  • a carrier is pretreated with a solution containing an alkali metal compound (lithium compound) and a cesium compound, then impregnated with a solution containing a silver compound and a cesium compound, and then heat treated.
  • the art of producing catalysts is disclosed, and the improvement of the activity and selectivity is shown. However, there is no disclosure that selectivity is improved over a long period of time.
  • JP 2003-320255 A discloses a catalyst having an active component containing halogen, silver, alkali metal and rhenium supported on a carrier, and by adopting such a configuration, high selectivity can be achieved for a long time. It can be maintained. However, there is no description about how long the high selectivity is maintained for a specific period, and its durability can not be said to be sufficient.
  • the present invention has been made in view of the above-described prior art and the problems thereof, and has a catalyst which has excellent catalytic performance and can produce ethylene oxide with high selectivity over a long period of time and a catalyst therefor It is an object of the present invention to provide a process for producing ethylene oxide.
  • the inventors of the present invention conducted intensive studies to solve the problems described above. As a result, the two desorption peak temperatures observed by the O 2 -Temperature Programmed Desorption (hereinafter also simply referred to as “O 2 -TPD method”) satisfy a predetermined relationship.
  • O 2 -TPD method O 2 -Temperature Programmed Desorption
  • one embodiment of the present invention is a catalyst for producing ethylene oxide, which comprises an ⁇ -alumina-based support and a catalyst component containing silver and an alkali metal and / or rhenium supported on the support.
  • the first desorption peak temperature (T1 [° C.]) observed in the temperature range of 150 to 250 ° C. by the O 2 -TPD method is less than 215 ° C .;
  • 250 by the O 2 -TPD method In the catalyst for producing ethylene oxide, the ratio (T2 / T1) of the second desorption peak temperature (T2 [° C.]) to the above T1 observed in the temperature range of -400 ° C. is less than 1.7 is there.
  • a catalyst capable of producing ethylene oxide with excellent catalytic performance and capable of producing ethylene oxide with high selectivity over a long period of time and a process for producing ethylene oxide using this catalyst can be provided.
  • One embodiment of the present invention is a catalyst for producing ethylene oxide, which comprises an ⁇ -alumina-based support and a catalyst component containing silver and an alkali metal and / or rhenium supported on the support, 1)
  • the first desorption peak temperature (T1 [° C.]) observed in the temperature range of 150 to 250 ° C. by the O 2 -TPD method is less than 215 ° C .; (2) 250 to 400 by the O 2 -TPD method
  • It is a catalyst for ethylene oxide production characterized in that a ratio (T2 / T1) of the second desorption peak temperature (T2 [° C]) to the above T1 observed in a temperature range of ° C is less than 1.7.
  • the catalyst for ethylene oxide production of the present invention only needs to satisfy the predetermined relationship between the two desorption peak temperatures observed by the O 2 -TPD method of the catalyst, and other forms (shape of support And the specific form of the catalyst component etc.) is not particularly limited.
  • the temperature-programmed desorption method is a method of measuring a molecule (atom) that is desorbed as a function of temperature by heating a sample after adsorbing a specific molecule (atom) to the sample.
  • the TPD method is generally used to analyze the adsorption state (adsorption energy, adsorption amount, etc.) of the specific molecule (atom) in the sample and the reaction on the sample surface.
  • oxygen molecules (O 2 ) as the specific molecules (atoms) are adsorbed to the sample, and then a pure carrier gas such as helium gas is added to the flow type cell containing the sample. Distribute. Then, the sample is heated at a constant temperature rising rate. Then, the adsorbed O 2 is released into the carrier gas by heating.
  • the desorption characteristic is monitored using a thermal conductivity detector (TCD) and a thermometer (thermocouple) in the cell.
  • TCD thermal conductivity detector
  • thermometer thermocouple
  • a thermal desorption spectrum is obtained by plotting the signal intensity of O 2 desorption (vertical axis) against the sample temperature (horizontal axis).
  • the desorption peak temperature in the present invention means the peak temperature in this thermal desorption spectrum.
  • the first peak is observed (first peak desorption temperature)
  • the second peak is observed in the temperature range of 250 to 400 ° C. (second peak desorption temperature).
  • the first peak desorption temperature (T1 [° C.]) is less than 215 ° C., preferably less than 213 ° C., and more preferably less than 210 ° C. If T1 is 215 ° C. or higher, the effect of the present invention of maintaining high selectivity over a long period in the production of ethylene oxide can not be obtained.
  • the lower limit value of the first peak desorption temperature is not particularly limited, but is generally 180 ° C. or more, more preferably 185 ° C. or more.
  • the ratio of T2 to T1 is less than 1.7, preferably less than 1.68, more preferably less than 1.65. If the ratio of T2 to T1 (T2 / T1) is 1.7 or more, the effect of the present invention of maintaining high selectivity over a long period in the production of ethylene oxide can not be obtained.
  • the lower limit value of the ratio (T2 / T1) of T2 to T1 is not particularly limited, but is generally 1.3 or more, and more preferably 1.4 or more.
  • the absolute value of the second peak desorption temperature (T2 [° C.]) is not particularly limited, as long as T1 and T2 / T1 satisfy the above-described numerical range.
  • T2 is preferably 270 to 380 ° C., more preferably 280 to 370 ° C., and still more preferably 290 to 360 ° C. If T2 is a value within such a range, the effect of the present invention of maintaining high selectivity over a long period in the production of ethylene oxide can be more significantly exhibited.
  • the composition of the carrier is not particularly limited except that it is mainly composed of ⁇ -alumina.
  • the support is based on ⁇ -alumina means that the content of ⁇ -alumina in the support is 90% by mass or more based on 100% by mass of the total mass of the support.
  • the content of ⁇ -alumina in the carrier is preferably 95% by mass or more, more preferably 98% by mass or more.
  • the composition is not particularly limited as long as it has ⁇ -alumina as a main component, but the support may contain, for example, an oxide of an alkali metal or alkaline earth metal or an oxide of a transition metal.
  • the content thereof is also not particularly limited, but the content of the oxide of an alkali metal or alkaline earth metal is preferably 0 to 5% by mass in terms of oxide, and more preferably 0.01 to 4%. %.
  • the content of the transition metal oxide is preferably 0 to 5% by mass, more preferably 0.01 to 3% by mass in terms of the oxide.
  • the support also usually contains silica (silicon oxide).
  • silica silicon oxide
  • the content of silica in the carrier is also not particularly limited, but it is preferably 0.1 to 5% by mass, more preferably 0.3 to 3% by mass.
  • composition of the above-described carrier and the content of each component can be determined using a fluorescent X-ray analysis method.
  • the shape of the carrier is not particularly limited, and conventionally known findings can be appropriately referred to in addition to a ring, a sphere, a column, and a pellet.
  • the size (average diameter) of the carrier is also not particularly limited, and is preferably 3 to 20 mm, more preferably 5 to 10 mm.
  • the particle size of the carrier is also not particularly limited, but the primary particle diameter of the carrier is preferably 0.01 to 100 ⁇ m, more preferably 0.1 to 20 ⁇ m, and still more preferably 0.5 to 10 ⁇ m. And particularly preferably 1 to 5 ⁇ m.
  • the secondary particle diameter of the carrier is preferably 0.1 to 1,000 ⁇ m, more preferably 1 to 500 ⁇ m, still more preferably 10 to 200 ⁇ m, and particularly preferably 30 to 100 ⁇ m.
  • the specific surface area of the carrier is also not particularly limited, but is preferably 0.03 to 10 m 2 / g, more preferably 0.5 to 5.0 m 2 / g, and still more preferably 1.0 to 3. It is 0 m 2 / g. If the specific surface area of the carrier is 0.03 m 2 / g or more, the water absorption rate is sufficiently ensured, and the catalyst component can be easily supported. On the other hand, if the specific surface area of the support is 10 m 2 / g or less, the pore diameter of the support can be maintained to a certain large value, and the sequential oxidation of ethylene oxide at the time of ethylene oxide production using the produced catalyst can be suppressed. In addition, as a value of the specific surface area of a support
  • the pore volume of the carrier is also not particularly limited, but is preferably 0.2 to 0.6 mL / g, more preferably 0.3 to 0.5 mL / g, and still more preferably 0.35 to 0.45 mL. It is / g. If the pore volume of the support is 0.2 mL / g or more, it is preferable in terms of facilitating the loading of the catalyst component. On the other hand, if the pore volume of the carrier is 0.6 mL / g or less, it is preferable in that the strength of the carrier can be secured to a practical degree. As a value of pore volume of the carrier, the carrier deaerated at 200 ° C.
  • the size of the pores possessed by the carrier is also not particularly limited, but the average pore diameter is preferably 0.1 to 10 ⁇ m, more preferably 0.2 to 4.0 ⁇ m, and still more preferably 0.3 to 3 .0 ⁇ m. If the average pore diameter is 0.1 ⁇ m or more, the sequential oxidation of ethylene oxide accompanying retention of the product gas at the time of ethylene oxide production can be suppressed. On the other hand, if the average pore diameter is 10 ⁇ m or less, the strength of the carrier can be secured to a practical extent.
  • a value of an average pore diameter the value measured by the method similar to the method (mercury intrusion method) mentioned above as a measuring method of the pore volume of a support
  • the water absorption rate of the carrier is also not particularly limited, but is preferably 10 to 70%, more preferably 20 to 60%, and still more preferably 30 to 50%. If the water absorption rate of the carrier is 10% or more, the catalyst component can be easily supported. On the other hand, if the water absorption rate of the carrier is 70% or less, the strength of the carrier can be secured to a practical extent.
  • carrier the value obtained by the method as described in the Example mentioned later shall be employ
  • the catalyst of the present invention has a configuration in which a catalyst component is supported on the above-described carrier. And, first, the catalyst of the present invention essentially contains silver as a catalyst component. And, in addition to silver, at least one of alkali metal and rhenium which is a catalyst component generally used as a reaction promoter is further essentially contained. Specific examples of the alkali metal include lithium, sodium, potassium, rubidium and cesium. One of these alkali metals and / or rhenium (reaction accelerator) may be used alone, or two or more thereof may be used in combination. Among these, in the present invention, cesium and rhenium are suitably used as a reaction accelerator. In addition, conventionally well-known catalyst components other than the above-mentioned may be further used.
  • the loading amount of silver and the reaction promoter there is no particular limitation on the loading amount of silver and the reaction promoter, and it may be loaded in an amount effective for producing ethylene oxide.
  • the loading amount is 1 to 30% by mass, preferably 5 to 20% by mass, based on the mass of the catalyst for producing ethylene oxide.
  • the amount of the reaction accelerator supported is usually 0.001 to 2% by mass, preferably 0.01 to 1% by mass, and more preferably 0.1 to 0, based on the mass of the catalyst for ethylene oxide production. .7 mass%.
  • the amount of alkali metal supported when an alkali metal is used as a catalyst component Is preferably 0.03 to 1.0% by mass, more preferably 0.05 to 0.5% by mass, based on the mass of the catalyst.
  • the loading amount of rhenium when rhenium is used as the catalyst component is preferably 0.002 to 0.2 mass%, more preferably 0.01 to 0.1 mass%, based on the mass of the catalyst. is there.
  • the catalyst for ethylene oxide production according to the present invention is a catalyst for ethylene oxide production, except that the elimination peak temperature of the catalyst observed by the O 2 -TPD method is adjusted to satisfy the above-mentioned definition. It can be prepared according to the method.
  • the physical properties of the carrier can be controlled by adopting the following preparation method as a method for preparing the carrier. That is, 1) a method of adding a pore forming agent having a desired size and amount to a mother powder mainly composed of ⁇ -alumina, and 2) preparing at least two kinds of mother powders having different physical properties at a desired mixing ratio 3) a method of baking the carrier at a desired temperature for a desired time, and the like, and methods combining these are also known.
  • These preparation methods are described, for example, in "The nature of porous material and its application technology” supervised by Akira Takeuchi, published by Fuji Techno System, Ltd. (1999). Further, JP-A-5-329368, JP-A-2001-62291, JP-A-2002-136868, JP 2983740, JP 3256237, JP 3295433 and the like can also be referred to.
  • a solution for supporting the catalyst component (silver and alkali metal and / or rhenium) on the carrier is prepared. Specifically, a silver compound and a compound containing an alkali metal and / or a rhenium-containing compound are added to a solvent such as water. At this time, if necessary, a complexing agent for forming a complex may be further added to the solvent.
  • the silver compound include silver nitrate, silver carbonate, silver oxalate, silver acetate, silver propionate, silver lactate, silver citrate, and silver neodecanoate.
  • examples of compounds containing alkali metals include nitrates, carbonates, oxalates, halides, acetates, sulfates and the like of alkali metals
  • examples of rhenium-containing compounds include ammonium perrhenate and perrhenic acid Sodium, potassium perrhenate, perrhenic acid, rhenium chloride, rhenium oxide and the like can be mentioned.
  • the complexing agent for example, monoethanolamine, diethanolamine, triethanolamine, ethylenediamine, propylenediamine and the like can be mentioned.
  • One of these various compounds and complexing agents may be used alone, or two or more thereof may be used in combination.
  • the solution obtained above is then impregnated on the carrier also prepared above.
  • the reaction accelerator may be similarly dissolved in an aqueous solution in which silver ions are dissolved, and impregnated on the carrier simultaneously with the silver, or supported on the carrier before or after supporting silver.
  • a solution for loading for example, an aqueous solution
  • the carrier may be loaded on the solution.
  • the carrier is dried and fired. Drying is preferably performed at a temperature of 80 to 120 ° C. in an atmosphere of air, oxygen, or an inert gas (eg, nitrogen). In addition, firing may be performed at a temperature of 150 to 700 ° C., preferably 200 to 600 ° C., for about 0.1 to 100 hours in an atmosphere of air, oxygen, or an inert gas (eg, nitrogen). preferable. In addition, baking may be performed only in one step or may be performed in two or more steps. As preferable firing conditions, the first firing is performed at 150 to 250 ° C. for 0.1 to 10 hours in an air atmosphere, and the second firing is performed at 250 to 450 ° C. at 0.1 to 10 hours in an air atmosphere.
  • first firing is performed at 150 to 250 ° C. for 0.1 to 10 hours in an air atmosphere
  • the second firing is performed at 250 to 450 ° C. at 0.1 to 10 hours in an air atmosphere.
  • firing may be further performed at 450 to 700 ° C. for 0.1 to 10 hours in an inert gas (eg, nitrogen, helium, argon, etc.) atmosphere.
  • inert gas eg, nitrogen, helium, argon, etc.
  • a process for producing ethylene oxide comprising the step of gas phase oxidizing ethylene with a molecular oxygen-containing gas in the presence of the catalyst for ethylene oxide production of the present invention.
  • the process for producing ethylene oxide of the present invention can be carried out according to a conventional method except that the catalyst for producing ethylene oxide of the present invention is used as a catalyst.
  • reaction temperature 150 to 300 ° C. preferably 180 to 280 ° C.
  • reaction pressure 2 to 40 kg / cm 2 G preferably 10 to 30 kg / cm 2 G
  • reaction temperature 150 A space velocity of 1,000 to 30,000 hr -1 (STP), preferably 3,000 to 8,000 hr -1 (STP) is employed.
  • source gases to be brought into contact with the catalyst ethylene 0.5 to 40% by volume, oxygen 3 to 10% by volume, carbon dioxide gas 5 to 30% by volume, balance nitrogen, argon, inert gas such as water vapor, methane, ethane, etc.
  • the molecular oxygen-containing gas used in the production method of the present invention includes air, oxygen and enriched air.
  • Example 1 14.6 g of silver oxalate, 0.1444 g of cesium nitrate and 0.0246 g of ammonium perrhenate were dissolved in about 14 ml of water, and 6.8 ml of ethylenediamine was further added. After impregnating this solution with 52 g of an ⁇ -alumina carrier (specific surface area: 1.5 m 2 / g, silica content: 0.7% by mass, water absorption: 41.7%), in an air stream at 300 ° C. for 0.25 hours Heat treated. Then, heat treatment was further performed in a nitrogen stream at 550 ° C. for 3 hours to obtain catalyst A. The contents of cesium and rhenium in catalyst A were 0.158% by mass and 0.025% by mass, respectively, based on the mass of the catalyst.
  • Example 2 14.6 g of silver oxalate, 0.1313 g of cesium nitrate and 0.0246 g of ammonium perrhenate were dissolved in about 14 ml of water, and 6.8 ml of ethylenediamine was further added. After impregnating this solution with 52 g of an ⁇ -alumina carrier (specific surface area: 1.5 m 2 / g, silica content: 0.7% by mass, water absorption: 41.7%), in an air stream at 300 ° C. for 0.25 hours Heat treated. Next, heat treatment was further performed in a nitrogen stream at 550 ° C. for 3 hours to obtain catalyst B. The contents of cesium and rhenium in catalyst B were 0.143% by mass and 0.025% by mass, respectively, based on the mass of the catalyst.
  • Example 3 14.6 g of silver oxalate, 0.0844 g of cesium nitrate and 0.0246 g of ammonium perrhenate were dissolved in about 14 ml of water, and 6.8 ml of ethylenediamine was further added. After impregnating this solution with 52 g of an ⁇ -alumina carrier (specific surface area: 1.5 m 2 / g, silica content: 0.7% by mass, water absorption: 41.7%), in an air stream at 300 ° C. for 0.25 hours Heat treatment was performed to obtain catalyst C. The contents of cesium and rhenium in catalyst C were 0.092% by mass and 0.025% by mass, respectively, based on the mass of the catalyst.
  • a TPD measurement apparatus manufactured by Nippon Bell Co., Ltd., catalyst analyzer, BEL-CAT
  • 0.5 g of the catalyst after reaction was put into a quartz glass TPD sample tube to make a catalyst layer, and the inside was replaced with helium gas.
  • a thermocouple was placed at the center of the catalyst layer. Then, the temperature was raised to 50 ° C. while supplying helium gas at a supply rate of 60 ml / min. Thereafter, the temperature was raised to 240 ° C. over 19 minutes while supplying oxygen (O 2 ) gas at a supply rate of 60 ml / min, and the temperature was kept at 240 ° C. for 60 minutes after the temperature rise.
  • O 2 oxygen
  • the temperature was lowered to 50 ° C. over 40 minutes while supplying oxygen (O 2 ) gas at a supply rate of 60 ml / min, and after the temperature drop, the supply was switched to the supply of helium gas (supply rate 60 ml / min).
  • the desorption peak temperature observed in the temperature range of 150 to 250 ° C. is taken as the first desorption peak temperature (T 1 [° C.]), and the desorption peak temperature observed in the temperature range of 250 to 400 ° C.
  • the desorption peak temperature (T2 [° C.]) was used.
  • the ratio (T2 / T1) with respect to T1 [degreeC] of T2 [degreeC] was computed combining these measurements. The results are shown in Table 1 below.
  • the catalyst obtained in each Example and each Comparative Example was pulverized to a particle size of 600 to 850 ⁇ m, and 0.3 g of each pulverized catalyst was pulverized to a particle size of 850 to 1180 ⁇ m , F24) together with 0.9 g, was filled into a heating type double-tubular stainless steel reactor (inner diameter 3 mm, tube length 300 mm) to form a packed bed.

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  • Chemical Kinetics & Catalysis (AREA)
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Abstract

Disclosed is a catalyst which has excellent catalytic performance and enables the long-term and highly selective production of ethylene oxide. Also disclosed is a process for producing ethylene oxide with the catalyst. Specifically disclosed is a catalyst for use in the production of ethylene oxide, which comprises a carrier mainly composed of α-alumina and a catalyst component comprising silver and an alkali metal and/or rhenium and supported on the carrier. The catalyst has: (1) a first desorption peak temperature (T1 [˚C]) that is observed in a temperature range between 150 to 250˚C of lower than 215˚C as measured by oxygen temperature-programmed desorption method (O2-TPD method); and (2) a ratio of a second desorption peak temperature (T2 [˚C]) that is observed in a temperature range between 250 to 400˚C as measured by oxygen temperature-programmed desorption method (O2-TPD method) to the T1 (i.e., a T2/T1 ratio) of less than 1.7.

Description

エチレンオキシド製造用触媒およびエチレンオキシドの製造方法Catalyst for producing ethylene oxide and method for producing ethylene oxide
　本発明は、エチレンオキシド製造用触媒およびエチレンオキシドの製造方法に関する。詳細には、本発明は、触媒活性、選択性および触媒寿命に優れ、長期に亘って高い選択率でエチレンオキシドを製造しうる触媒およびこの触媒を用いたエチレンオキシドの製造方法に関する。 The present invention relates to a catalyst for ethylene oxide production and a method for producing ethylene oxide. In particular, the present invention relates to a catalyst capable of producing ethylene oxide with high selectivity over a long period of time, which has excellent catalytic activity, selectivity and catalyst life, and a process for producing ethylene oxide using this catalyst.
　エチレンを銀触媒の存在下で分子状酸素含有ガスにより接触気相酸化してエチレンオキシドを製造することは工業的に広く行われている。この接触気相酸化に用いる銀触媒については、その担体、担持方法、反応促進剤の種類やその添加量などに関し、多くの技術が提案されている。 Catalytic gas phase oxidation of ethylene with a molecular oxygen-containing gas in the presence of a silver catalyst to produce ethylene oxide is widely practiced industrially. With regard to the silver catalyst used for the catalytic gas phase oxidation, many techniques have been proposed with regard to the support, the method of support, the type of the reaction accelerator and the amount thereof to be added, and the like.
　ここで、反応促進剤としては、アルカリ金属が有効であることが知られている。例えば、特開昭６３－１２６５５２号公報（実施例１）、特開平９－１５００５８号公報、特開２００３－３２０２５５号公報には、アルカリ金属とレニウムとを併用することにより、触媒の選択性を向上させる技術が開示されている。 Here, it is known that an alkali metal is effective as a reaction promoter. For example, in JP-A-63-126552 (Example 1), JP-A-9-150058 and JP-A-2003-320255, the selectivity of the catalyst can be improved by using alkali metal and rhenium in combination. Techniques to improve are disclosed.
　具体的には、特開昭６３－１２６５５２号公報には、銀、レニウム、セシウムを含有する触媒が開示されており、初期選択性の向上が示されている。しかしながら、長期間に亘って選択性が向上する旨の開示はない。 Specifically, JP-A-63-126552 discloses a catalyst containing silver, rhenium and cesium, and shows an improvement in initial selectivity. However, there is no disclosure that selectivity is improved over a long period of time.
　また、特開平９－１５００５８号公報には、アルカリ金属化合物（リチウム化合物）とセシウム化合物を含有する溶液で担体を前処理し、次いで銀化合物およびセシウム化合物を含有する溶液を含浸させた後に加熱処理して触媒を製造する技術が開示されており、活性および選択率の向上が示されている。しかしながら、やはり長期間に亘って選択性が向上する旨の開示はない。 Further, in JP-A-9-150058, a carrier is pretreated with a solution containing an alkali metal compound (lithium compound) and a cesium compound, then impregnated with a solution containing a silver compound and a cesium compound, and then heat treated. The art of producing catalysts is disclosed, and the improvement of the activity and selectivity is shown. However, there is no disclosure that selectivity is improved over a long period of time.
　さらに、特開２００３－３２０２５５号公報には、ハロゲン、銀、アルカリ金属およびレニウムを含む活性成分を担体に担持した触媒が開示されており、かような構成とすることで高い選択性を長期間維持することができるとしている。しかしながら、具体的にどの程度の期間に亘って高い選択性が維持されたかについての記載がなく、その耐久性は十分とは言い難い。 Further, JP 2003-320255 A discloses a catalyst having an active component containing halogen, silver, alkali metal and rhenium supported on a carrier, and by adopting such a configuration, high selectivity can be achieved for a long time. It can be maintained. However, there is no description about how long the high selectivity is maintained for a specific period, and its durability can not be said to be sufficient.
　銀触媒の触媒活性、選択性および触媒寿命はすでに高いレベルに達しているが、なおこれらの物性の向上が求められている。例えば選択率を例にとれば、エチレンオキシドの生産規模は大きいことから、選択率が僅か１％向上するだけでも、原料エチレンの使用量が著しく節約され、その経済的効果は大きい。このような事情から、より優れた触媒性能を有する銀触媒の開発が当該技術分野の研究者の継続的なテーマとなっている。 Although the catalyst activity, selectivity and catalyst life of silver catalysts have already reached high levels, there is still a need to improve their physical properties. For example, when the selectivity is taken as an example, since the production scale of ethylene oxide is large, even if the selectivity is improved by only 1%, the amount of use of the raw material ethylene is significantly saved, and the economic effect is large. For these reasons, the development of silver catalysts with better catalytic performance has become a continuing theme for researchers in the art.
　本発明は、上述した従来技術の技術およびその問題点に鑑みてなされたものであり、優れた触媒性能を有し、長期に亘って高選択率でエチレンオキシドを製造しうる触媒およびこの触媒を用いたエチレンオキシドの製造方法を提供することを目的とする。 The present invention has been made in view of the above-described prior art and the problems thereof, and has a catalyst which has excellent catalytic performance and can produce ethylene oxide with high selectivity over a long period of time and a catalyst therefor It is an object of the present invention to provide a process for producing ethylene oxide.
　本発明者らは、上述した課題を解決すべく鋭意研究を行った。その結果、酸素昇温脱離（Ｏ２－Ｔｅｍｐｅｒａｔｕｒｅ　Ｐｒｏｇｒａｍｍｅｄ　Ｄｅｓｏｒｐｔｉｏｎ）法（以下、単に「Ｏ２－ＴＰＤ法」とも称する）により観測される２つの脱離ピーク温度が所定の関係を満足するような触媒を採用することで、エチレンに対する活性が高く、かつエチレンオキシドを高選択率で製造可能なエチレンオキシド製造用触媒が提供されうることを見出し、本発明を完成させるに至った。 The inventors of the present invention conducted intensive studies to solve the problems described above. As a result, the two desorption peak temperatures observed by the O 2 -Temperature Programmed Desorption (hereinafter also simply referred to as “O 2 -TPD method”) satisfy a predetermined relationship. By employing a catalyst, it has been found that a catalyst for producing ethylene oxide that can be produced with high activity to ethylene and high selectivity to ethylene oxide can be provided, and the present invention has been completed.
　すなわち、本発明の一形態は、α－アルミナを主成分とする担体と、前記担体に担持されてなる、銀ならびにアルカリ金属および／またはレニウムを含む触媒成分とを含むエチレンオキシド製造用触媒であって、（１）Ｏ２－ＴＰＤ法により１５０～２５０℃の温度領域に観測される第１脱離ピーク温度（Ｔ１［℃］）が２１５℃未満であり；（２）Ｏ２－ＴＰＤ法により２５０～４００℃の温度領域に観測される第２脱離ピーク温度（Ｔ２［℃］）の前記Ｔ１に対する比（Ｔ２／Ｔ１）が１．７未満であることを特徴とする、エチレンオキシド製造用触媒である。 That is, one embodiment of the present invention is a catalyst for producing ethylene oxide, which comprises an α-alumina-based support and a catalyst component containing silver and an alkali metal and / or rhenium supported on the support. (1) The first desorption peak temperature (T1 [° C.]) observed in the temperature range of 150 to 250 ° C. by the O 2 -TPD method is less than 215 ° C .; (2) 250 by the O 2 -TPD method In the catalyst for producing ethylene oxide, the ratio (T2 / T1) of the second desorption peak temperature (T2 [° C.]) to the above T1 observed in the temperature range of -400 ° C. is less than 1.7 is there.
　本発明によれば、優れた触媒性能を有し、長期に亘って高選択率でエチレンオキシドを製造しうる触媒およびこの触媒を用いたエチレンオキシドの製造方法が提供されうる。 According to the present invention, a catalyst capable of producing ethylene oxide with excellent catalytic performance and capable of producing ethylene oxide with high selectivity over a long period of time and a process for producing ethylene oxide using this catalyst can be provided.
　以下、本発明の実施の形態を説明する。 Hereinafter, embodiments of the present invention will be described.
　本発明の一形態は、α－アルミナを主成分とする担体と、前記担体に担持されてなる、銀ならびにアルカリ金属および／またはレニウムを含む触媒成分とを含むエチレンオキシド製造用触媒であって、（１）Ｏ２－ＴＰＤ法により１５０～２５０℃の温度領域に観測される第１脱離ピーク温度（Ｔ１［℃］）が２１５℃未満であり；（２）Ｏ２－ＴＰＤ法により２５０～４００℃の温度領域に観測される第２脱離ピーク温度（Ｔ２［℃］）の前記Ｔ１に対する比（Ｔ２／Ｔ１）が１．７未満であることを特徴とする、エチレンオキシド製造用触媒である。 One embodiment of the present invention is a catalyst for producing ethylene oxide, which comprises an α-alumina-based support and a catalyst component containing silver and an alkali metal and / or rhenium supported on the support, 1) The first desorption peak temperature (T1 [° C.]) observed in the temperature range of 150 to 250 ° C. by the O 2 -TPD method is less than 215 ° C .; (2) 250 to 400 by the O 2 -TPD method It is a catalyst for ethylene oxide production characterized in that a ratio (T2 / T1) of the second desorption peak temperature (T2 [° C]) to the above T1 observed in a temperature range of ° C is less than 1.7.
　本発明のエチレンオキシド製造用触媒は、上述した通り、触媒のＯ２－ＴＰＤ法により観測される２つの脱離ピーク温度が所定の関係を満足するものであればよく、その他の形態（担体の形状や触媒成分の具体的な形態など）は特に制限されない。 As described above, the catalyst for ethylene oxide production of the present invention only needs to satisfy the predetermined relationship between the two desorption peak temperatures observed by the O 2 -TPD method of the catalyst, and other forms (shape of support And the specific form of the catalyst component etc.) is not particularly limited.
　昇温脱離法（ＴＰＤ法）とは、試料に特定の分子（原子）を吸着させた後に加熱し、これにより脱離してくる分子（原子）を温度の関数として測定する手法である。ＴＰＤ法は通常、試料における上記特定の分子（原子）の吸着状態（吸着エネルギー、吸着量など）や試料表面での反応を解析する目的で用いられる。 The temperature-programmed desorption method (TPD method) is a method of measuring a molecule (atom) that is desorbed as a function of temperature by heating a sample after adsorbing a specific molecule (atom) to the sample. The TPD method is generally used to analyze the adsorption state (adsorption energy, adsorption amount, etc.) of the specific molecule (atom) in the sample and the reaction on the sample surface.
　詳細には、Ｏ２－ＴＰＤ法では、試料に上記特定の分子（原子）としての酸素分子（Ｏ２）を吸着させた後、試料を入れたフロー型セルにヘリウムガスなどの純キャリアガスを流通させる。そして、試料を一定の昇温速度で加熱する。すると、吸着していたＯ２が加熱によりキャリアガス中へ脱離してくる。この脱離特性を、熱伝導度検出器（ＴＣＤ；Ｔｈｅｒｍａｌ　Ｃｏｎｄｕｃｔｉｖｉｔｙ　Ｄｅｔｅｃｔｏｒ）およびセル内の温度計（熱電対）を用いてモニターする。そして最終的には、Ｏ２脱離の信号強度（縦軸）を試料温度（横軸）に対してプロットすることで、熱脱離スペクトルが得られるのである。本発明における脱離ピーク温度とは、この熱脱離スペクトルにおけるピーク温度を意味する。なお、熱脱離スペクトルを得るためのＯ２－ＴＰＤ法の具体的な手法としては、後述する実施例に記載の手法を採用するものとする。 Specifically, in the O 2 -TPD method, oxygen molecules (O 2 ) as the specific molecules (atoms) are adsorbed to the sample, and then a pure carrier gas such as helium gas is added to the flow type cell containing the sample. Distribute. Then, the sample is heated at a constant temperature rising rate. Then, the adsorbed O 2 is released into the carrier gas by heating. The desorption characteristic is monitored using a thermal conductivity detector (TCD) and a thermometer (thermocouple) in the cell. Finally, a thermal desorption spectrum is obtained by plotting the signal intensity of O 2 desorption (vertical axis) against the sample temperature (horizontal axis). The desorption peak temperature in the present invention means the peak temperature in this thermal desorption spectrum. As a specific method of the O 2 -TPD method for obtaining a thermal desorption spectrum, the method described in the examples to be described later is adopted.
　本発明のような、α－アルミナを主成分とする担体に銀ならびにアルカリ金属および／またはレニウムを含む触媒成分が担持されてなる触媒の熱脱離スペクトルにおいては、１５０～２５０℃の温度領域に１つ目のピークが観測され（第１ピーク脱離温度）、２５０～４００℃の温度領域に２つ目のピークが観測される（第２ピーク脱離温度）。 In the thermal desorption spectrum of a catalyst in which a catalyst component containing silver and an alkali metal and / or rhenium is supported on an α-alumina-based support as in the present invention, the temperature range of 150 to 250 ° C. The first peak is observed (first peak desorption temperature), and the second peak is observed in the temperature range of 250 to 400 ° C. (second peak desorption temperature).
　そして、本発明の触媒においては、第１ピーク脱離温度（Ｔ１［℃］）は２１５℃未満であり、好ましくは２１３℃未満であり、より好ましくは２１０℃未満である。Ｔ１が２１５℃以上であると、エチレンオキシドの製造において長期に亘って高選択率を維持するという本発明の作用効果が得られなくなってしまう。なお、第１ピーク脱離温度の下限値について特に制限はないが、一般的には１８０℃以上であり、より好ましくは１８５℃以上である。 And in the catalyst of the present invention, the first peak desorption temperature (T1 [° C.]) is less than 215 ° C., preferably less than 213 ° C., and more preferably less than 210 ° C. If T1 is 215 ° C. or higher, the effect of the present invention of maintaining high selectivity over a long period in the production of ethylene oxide can not be obtained. The lower limit value of the first peak desorption temperature is not particularly limited, but is generally 180 ° C. or more, more preferably 185 ° C. or more.
　また、本発明の触媒において、Ｔ２のＴ１に対する比（Ｔ２／Ｔ１）は１．７未満であり、好ましくは１．６８未満であり、より好ましくは１．６５未満である。Ｔ２のＴ１に対する比（Ｔ２／Ｔ１）が１．７以上であると、エチレンオキシドの製造において長期に亘って高選択率を維持するという本発明の作用効果が得られなくなってしまう。なお、Ｔ２のＴ１に対する比（Ｔ２／Ｔ１）の下限値について特に制限はないが、一般的には１．３以上であり、より好ましくは１．４以上である。 In the catalyst of the present invention, the ratio of T2 to T1 (T2 / T1) is less than 1.7, preferably less than 1.68, more preferably less than 1.65. If the ratio of T2 to T1 (T2 / T1) is 1.7 or more, the effect of the present invention of maintaining high selectivity over a long period in the production of ethylene oxide can not be obtained. The lower limit value of the ratio (T2 / T1) of T2 to T1 is not particularly limited, but is generally 1.3 or more, and more preferably 1.4 or more.
　なお、第２ピーク脱離温度（Ｔ２［℃］）の絶対値についても特に制限はなく、Ｔ１およびＴ２／Ｔ１が上述した数値範囲を満足するような値であればよい。一例を挙げると、Ｔ２は、好ましくは２７０～３８０℃であり、より好ましくは２８０～３７０℃であり、さらに好ましくは２９０～３６０℃である。Ｔ２がかような範囲内の値であれば、エチレンオキシドの製造において長期に亘って高選択率を維持するという本発明の作用効果がより一層顕著に発揮されうる。 The absolute value of the second peak desorption temperature (T2 [° C.]) is not particularly limited, as long as T1 and T2 / T1 satisfy the above-described numerical range. As an example, T2 is preferably 270 to 380 ° C., more preferably 280 to 370 ° C., and still more preferably 290 to 360 ° C. If T2 is a value within such a range, the effect of the present invention of maintaining high selectivity over a long period in the production of ethylene oxide can be more significantly exhibited.
　続いて、本発明の触媒の具体的な構成について説明する。ただし、本発明の技術的範囲は特許請求の範囲の記載に基づいて定められるべきであり、以下に記載する具体的な形態のみに制限されることはない。 Subsequently, the specific constitution of the catalyst of the present invention will be described. However, the technical scope of the present invention should be determined based on the description of the claims, and is not limited to only the specific embodiments described below.
　まず、担体の組成について、α－アルミナを主成分とすること以外は特に制限されない。ここで、担体が「α－アルミナを主成分とする」とは、担体におけるα－アルミナの含有量が、担体の全質量１００質量％に対して９０質量％以上であることを意味する。担体におけるα－アルミナの含有量は、好ましくは９５質量％以上であり、より好ましくは９８質量％以上である。α－アルミナを主成分とするものであればその他の組成は特に制限されないが、担体は、例えばアルカリ金属またはアルカリ土類金属の酸化物や遷移金属の酸化物を含有しうる。これらの含有量についても特に制限はないが、アルカリ金属またはアルカリ土類金属の酸化物の含有量は、酸化物換算で好ましくは０～５質量％であり、より好ましくは０．０１～４質量％である。また、遷移金属の酸化物の含有量は、酸化物換算で好ましくは０～５質量％であり、より好ましくは０．０１～３質量％である。 First, the composition of the carrier is not particularly limited except that it is mainly composed of α-alumina. Here, that the support is based on α-alumina means that the content of α-alumina in the support is 90% by mass or more based on 100% by mass of the total mass of the support. The content of α-alumina in the carrier is preferably 95% by mass or more, more preferably 98% by mass or more. The composition is not particularly limited as long as it has α-alumina as a main component, but the support may contain, for example, an oxide of an alkali metal or alkaline earth metal or an oxide of a transition metal. The content thereof is also not particularly limited, but the content of the oxide of an alkali metal or alkaline earth metal is preferably 0 to 5% by mass in terms of oxide, and more preferably 0.01 to 4%. %. In addition, the content of the transition metal oxide is preferably 0 to 5% by mass, more preferably 0.01 to 3% by mass in terms of the oxide.
　担体はまた、シリカ（酸化ケイ素）を通常含有する。担体におけるシリカの含有量についても特に制限はないが、好ましくは０．１～５質量％であり、より好ましくは０．３～３質量％である。 The support also usually contains silica (silicon oxide). The content of silica in the carrier is also not particularly limited, but it is preferably 0.1 to 5% by mass, more preferably 0.3 to 3% by mass.
　なお、上述した担体の組成や各成分の含有量は、蛍光Ｘ線分析法を用いて決定されうる。 The composition of the above-described carrier and the content of each component can be determined using a fluorescent X-ray analysis method.
　担体の形状は特に制限されず、リング状、球状、円柱状、ペレット状のほか、従来公知の知見が適宜参照されうる。また、担体のサイズ（平均直径）についても特に制限はなく、好ましくは３～２０ｍｍであり、より好ましくは５～１０ｍｍである。 The shape of the carrier is not particularly limited, and conventionally known findings can be appropriately referred to in addition to a ring, a sphere, a column, and a pellet. Further, the size (average diameter) of the carrier is also not particularly limited, and is preferably 3 to 20 mm, more preferably 5 to 10 mm.
　担体の粒径に関しても特に制限はないが、担体の一次粒子径は、好ましくは０．０１～１００μｍであり、より好ましくは０．１～２０μｍであり、さらに好ましくは０．５～１０μｍであり、特に好ましくは１～５μｍである。また、担体の二次粒子径は、好ましくは０．１～１，０００μｍであり、より好ましくは１～５００μｍであり、さらに好ましくは１０～２００μｍであり、特に好ましくは３０～１００μｍである。 The particle size of the carrier is also not particularly limited, but the primary particle diameter of the carrier is preferably 0.01 to 100 μm, more preferably 0.1 to 20 μm, and still more preferably 0.5 to 10 μm. And particularly preferably 1 to 5 μm. The secondary particle diameter of the carrier is preferably 0.1 to 1,000 μm, more preferably 1 to 500 μm, still more preferably 10 to 200 μm, and particularly preferably 30 to 100 μm.
　担体の比表面積についても特に制限はないが、好ましくは０．０３～１０ｍ２／ｇであり、より好ましくは０．５～５．０ｍ２／ｇであり、さらに好ましくは１．０～３．０ｍ２／ｇである。担体の比表面積が０．０３ｍ２／ｇ以上であれば、吸水率が充分に確保され、触媒成分の担持が容易となる。一方、担体の比表面積が１０ｍ２／ｇ以下であれば、担体の細孔径がある程度大きい値に維持され、製造された触媒を用いたエチレンオキシド製造時のエチレンオキシドの逐次酸化が抑制されうる。なお、担体の比表面積の値としては、後述する実施例に記載の手法により得られる値を採用するものとする。 The specific surface area of the carrier is also not particularly limited, but is preferably 0.03 to 10 m 2 / g, more preferably 0.5 to 5.0 m 2 / g, and still more preferably 1.0 to 3. It is 0 m 2 / g. If the specific surface area of the carrier is 0.03 m 2 / g or more, the water absorption rate is sufficiently ensured, and the catalyst component can be easily supported. On the other hand, if the specific surface area of the support is 10 m 2 / g or less, the pore diameter of the support can be maintained to a certain large value, and the sequential oxidation of ethylene oxide at the time of ethylene oxide production using the produced catalyst can be suppressed. In addition, as a value of the specific surface area of a support | carrier, the value obtained by the method as described in the Example mentioned later shall be employ | adopted.
　担体の細孔容積も特に制限されないが、好ましくは０．２～０．６ｍＬ／ｇであり、より好ましくは０．３～０．５ｍＬ／ｇであり、さらに好ましくは０．３５～０．４５ｍＬ／ｇである。担体の細孔容積が０．２ｍＬ／ｇ以上であれば、触媒成分の担持が容易となるという点で好ましい。一方、担体の細孔容積が０．６ｍＬ／ｇ以下であれば、担体の強度が実用的な程度に確保されうるという点で好ましい。なお、担体の細孔容積の値としては、水銀圧入法により、２００℃にて少なくとも３０分間脱気した担体をサンプルとし、測定装置としてオートポアＩＩＩ９４２０Ｗ（株式会社島津製作所製）を用い、１．０～６０，０００ｐｓｉａの圧力範囲及び６０個の測定ポイントで測定される値を採用するものとする。 The pore volume of the carrier is also not particularly limited, but is preferably 0.2 to 0.6 mL / g, more preferably 0.3 to 0.5 mL / g, and still more preferably 0.35 to 0.45 mL. It is / g. If the pore volume of the support is 0.2 mL / g or more, it is preferable in terms of facilitating the loading of the catalyst component. On the other hand, if the pore volume of the carrier is 0.6 mL / g or less, it is preferable in that the strength of the carrier can be secured to a practical degree. As a value of pore volume of the carrier, the carrier deaerated at 200 ° C. for at least 30 minutes by mercury intrusion method is used as a sample, and Autopore III 9420 W (manufactured by Shimadzu Corporation) is used as a measuring device, 1.0. We shall adopt values measured at a pressure range of ~ 60,000 psia and at 60 measuring points.
　担体の有する細孔のサイズも特に制限されないが、平均細孔直径は、好ましくは０．１～１０μｍであり、より好ましくは０．２～４．０μｍであり、さらに好ましくは０．３～３．０μｍである。平均細孔直径が０．１μｍ以上であれば、エチレンオキシド製造時の生成ガスの滞留に伴うエチレンオキシドの逐次酸化が抑制されうる。一方、平均細孔直径が１０μｍ以下であれば、担体の強度が実用的な程度に確保されうる。なお、平均細孔直径の値としては、担体の細孔容積の測定方法として上述した手法（水銀圧入法）と同様の手法により測定される値を採用するものとする。 The size of the pores possessed by the carrier is also not particularly limited, but the average pore diameter is preferably 0.1 to 10 μm, more preferably 0.2 to 4.0 μm, and still more preferably 0.3 to 3 .0 μm. If the average pore diameter is 0.1 μm or more, the sequential oxidation of ethylene oxide accompanying retention of the product gas at the time of ethylene oxide production can be suppressed. On the other hand, if the average pore diameter is 10 μm or less, the strength of the carrier can be secured to a practical extent. In addition, as a value of an average pore diameter, the value measured by the method similar to the method (mercury intrusion method) mentioned above as a measuring method of the pore volume of a support | carrier shall be employ | adopted.
　担体の吸水率についても特に制限はないが、好ましくは１０～７０％であり、より好ましくは２０～６０％であり、さらに好ましくは３０～５０％である。担体の吸水率が１０％以上であれば、触媒成分の担持が容易となる。一方、担体の吸水率が７０％以下であれば、担体の強度が実用的な程度に確保されうる。なお、担体の吸水率の値としては、後述する実施例に記載の手法により得られる値を採用するものとする。 The water absorption rate of the carrier is also not particularly limited, but is preferably 10 to 70%, more preferably 20 to 60%, and still more preferably 30 to 50%. If the water absorption rate of the carrier is 10% or more, the catalyst component can be easily supported. On the other hand, if the water absorption rate of the carrier is 70% or less, the strength of the carrier can be secured to a practical extent. In addition, as a value of the water absorption rate of a support | carrier, the value obtained by the method as described in the Example mentioned later shall be employ | adopted.
　本発明の触媒は、上述した担体に触媒成分が担持されてなる構成を有する。そして、本発明の触媒は、まず、触媒成分として銀を必須に含有する。そして、銀に加えて、一般に反応促進剤として用いられる触媒成分であるアルカリ金属およびレニウムの少なくとも一方をさらに必須に含有する。アルカリ金属として具体的には、リチウム、ナトリウム、カリウム、ルビジウム、セシウムが挙げられる。これらのアルカリ金属および／またはレニウム（反応促進剤）は、１種のみが単独で用いられてもよいし、２種以上が併用されてもよい。これらのうち、本発明においては、反応促進剤としてセシウム、レニウムが好適に用いられる。なお、上述した以外の従来公知の触媒成分がさらに用いられてもよい。 The catalyst of the present invention has a configuration in which a catalyst component is supported on the above-described carrier. And, first, the catalyst of the present invention essentially contains silver as a catalyst component. And, in addition to silver, at least one of alkali metal and rhenium which is a catalyst component generally used as a reaction promoter is further essentially contained. Specific examples of the alkali metal include lithium, sodium, potassium, rubidium and cesium. One of these alkali metals and / or rhenium (reaction accelerator) may be used alone, or two or more thereof may be used in combination. Among these, in the present invention, cesium and rhenium are suitably used as a reaction accelerator. In addition, conventionally well-known catalyst components other than the above-mentioned may be further used.
　銀や反応促進剤の担持量については特に制限はなく、エチレンオキシドの製造に有効な量で担持すればよい。例えば、銀の場合、その担持量はエチレンオキシド製造用触媒の質量基準で１～３０質量％であり、好ましくは５～２０質量％である。また、反応促進剤の担持量は、エチレンオキシド製造用触媒の質量基準で、通常０．００１～２質量％であり、好ましくは０．０１～１質量％であり、より好ましくは０．１～０．７質量％である。より詳細には、本発明の作用効果をより一層発揮させるという観点から、触媒成分としてアルカリ金属が用いられる場合のアルカリ金属の担持量（２種以上のアルカリ金属が用いられる場合の合計担持量）は、触媒の質量基準で、好ましくは０．０３～１．０質量％であり、より好ましくは０．０５～０．５質量％である。また、触媒成分としてレニウムが用いられる場合のレニウムの担持量は、触媒の質量基準で、好ましくは０．００２～０．２質量％であり、より好ましくは０．０１～０．１質量％である。 There is no particular limitation on the loading amount of silver and the reaction promoter, and it may be loaded in an amount effective for producing ethylene oxide. For example, in the case of silver, the loading amount is 1 to 30% by mass, preferably 5 to 20% by mass, based on the mass of the catalyst for producing ethylene oxide. The amount of the reaction accelerator supported is usually 0.001 to 2% by mass, preferably 0.01 to 1% by mass, and more preferably 0.1 to 0, based on the mass of the catalyst for ethylene oxide production. .7 mass%. More specifically, from the viewpoint of further exhibiting the function and effect of the present invention, the amount of alkali metal supported when an alkali metal is used as a catalyst component (total amount of support when two or more alkali metals are used) Is preferably 0.03 to 1.0% by mass, more preferably 0.05 to 0.5% by mass, based on the mass of the catalyst. The loading amount of rhenium when rhenium is used as the catalyst component is preferably 0.002 to 0.2 mass%, more preferably 0.01 to 0.1 mass%, based on the mass of the catalyst. is there.
　本発明のエチレンオキシド製造用触媒は、触媒のＯ２－ＴＰＤ法により観測される脱離ピーク温度が上述した規定を満足するように調節される点を除けば、従来公知のエチレンオキシド製造用触媒の製造方法に従って調製されうる。 The catalyst for ethylene oxide production according to the present invention is a catalyst for ethylene oxide production, except that the elimination peak temperature of the catalyst observed by the O 2 -TPD method is adjusted to satisfy the above-mentioned definition. It can be prepared according to the method.
　以下、本発明のエチレンオキシド製造用触媒を製造する手法の一例を説明するが、本発明の技術的範囲は特許請求の範囲の記載に基づいて定められるべきであり、下記の手法のみに限定されるわけではない。 Hereinafter, although an example of the method of manufacturing the catalyst for ethylene oxide production of this invention is demonstrated, the technical scope of this invention should be defined based on description of a claim, and it is limited only to the following method. Do not mean.
　まず、担体を準備する。担体の調製方法としては、次のような調製方法を採用することで、担体の物性が制御されうることが知られている。すなわち、１）α－アルミナを主成分とする母粉体に、所望のサイズおよび量の気孔形成剤を添加する方法、２）物性の異なる少なくとも２種の母粉体を所望の混合比で調合する方法、３）担体を所望の温度にて所望の時間焼成する方法、などが知られており、これらを組み合わせた手法も知られている。これらの調製方法については、例えば、「多孔質体の性質とその応用技術」竹内雍監修、株式会社フジ・テクノシステム発行（１９９９年）に記載されている。また、特開平５－３２９３６８号公報、特開２００１－６２２９１号公報、特開２００２－１３６８６８号公報、特許第２９８３７４０号公報、特許第３２５６２３７号公報、特許第３２９５４３３号公報なども参照されうる。 First, prepare the carrier. It is known that the physical properties of the carrier can be controlled by adopting the following preparation method as a method for preparing the carrier. That is, 1) a method of adding a pore forming agent having a desired size and amount to a mother powder mainly composed of α-alumina, and 2) preparing at least two kinds of mother powders having different physical properties at a desired mixing ratio 3) a method of baking the carrier at a desired temperature for a desired time, and the like, and methods combining these are also known. These preparation methods are described, for example, in "The nature of porous material and its application technology" supervised by Akira Takeuchi, published by Fuji Techno System, Ltd. (1999). Further, JP-A-5-329368, JP-A-2001-62291, JP-A-2002-136868, JP 2983740, JP 3256237, JP 3295433 and the like can also be referred to.
　次いで、担体に触媒成分（銀並びにアルカリ金属および／またはレニウム）を担持させるための溶液を調製する。具体的には、銀化合物と、アルカリ金属を含有する化合物および／またはレニウム含有化合物とを、水などの溶媒に添加する。この際、必要に応じて、錯体を形成するための錯化剤をさらに溶媒に添加してもよい。銀化合物としては、例えば、硝酸銀、炭酸銀、シュウ酸銀、酢酸銀、プロピオン酸銀、乳酸銀、クエン酸銀、ネオデカン酸銀などが挙げられる。また、アルカリ金属を含有する化合物としては、アルカリ金属の硝酸塩、炭酸塩、シュウ酸塩、ハロゲン化物、酢酸塩、硫酸塩などが挙げられ、レニウム含有化合物としては、過レニウム酸アンモニウム、過レニウム酸ナトリウム、過レニウム酸カリウム、過レニウム酸、塩化レニウム、酸化レニウムなどが挙げられる。さらに、錯化剤としては、例えば、モノエタノールアミン、ジエタノールアミン、トリエタノールアミン、エチレンジアミン、プロピレンジアミンなどが挙げられる。これらの各種化合物や錯化剤は、それぞれ、１種のみが単独で用いられてもよいし、２種以上が併用されてもよい。 Then, a solution for supporting the catalyst component (silver and alkali metal and / or rhenium) on the carrier is prepared. Specifically, a silver compound and a compound containing an alkali metal and / or a rhenium-containing compound are added to a solvent such as water. At this time, if necessary, a complexing agent for forming a complex may be further added to the solvent. Examples of the silver compound include silver nitrate, silver carbonate, silver oxalate, silver acetate, silver propionate, silver lactate, silver citrate, and silver neodecanoate. Further, examples of compounds containing alkali metals include nitrates, carbonates, oxalates, halides, acetates, sulfates and the like of alkali metals, and examples of rhenium-containing compounds include ammonium perrhenate and perrhenic acid Sodium, potassium perrhenate, perrhenic acid, rhenium chloride, rhenium oxide and the like can be mentioned. Furthermore, as the complexing agent, for example, monoethanolamine, diethanolamine, triethanolamine, ethylenediamine, propylenediamine and the like can be mentioned. One of these various compounds and complexing agents may be used alone, or two or more thereof may be used in combination.
　次いで、上記で得られた溶液を、同じく上記で準備した担体に含浸させる。この際、反応促進剤は、上述したように銀イオンが溶解した水溶液に同様に溶解させて銀と同時に担体に含浸させてもよいし、銀を担持する前または銀を担持した後に担体に担持してもよい。銀とは別に担持させる場合には、担持用の溶液（例えば、水溶液）を別途準備し、これに担体を担持させればよい。 The solution obtained above is then impregnated on the carrier also prepared above. At this time, as described above, the reaction accelerator may be similarly dissolved in an aqueous solution in which silver ions are dissolved, and impregnated on the carrier simultaneously with the silver, or supported on the carrier before or after supporting silver. You may In the case of loading separately from silver, a solution for loading (for example, an aqueous solution) may be separately prepared, and the carrier may be loaded on the solution.
　続いて、上記担体を乾燥し、焼成する。乾燥は、空気、酸素、または不活性ガス（例えば、窒素）の雰囲気中で、８０～１２０℃の温度で行うことが好ましい。また、焼成は、空気、酸素、または不活性ガス（例えば、窒素）の雰囲気中で、１５０～７００℃の温度で、好ましくは２００～６００℃の温度で０．１～１００時間程度行うことが好ましい。なお、焼成は、１段階のみ行われてもよいし、２段階以上行われてもよい。好ましい焼成条件としては、１段階目の焼成を空気雰囲気中で１５０～２５０℃にて０．１～１０時間行い、２段階目の焼成を空気雰囲気中で２５０～４５０℃にて０．１～１０時間行う条件が挙げられる。さらに好ましくは、かような空気雰囲気中での焼成後にさらに、不活性ガス（例えば、窒素、ヘリウム、アルゴンなど）雰囲気中で４５０～７００℃にて０．１～１０時間、焼成を行うとよい。 Subsequently, the carrier is dried and fired. Drying is preferably performed at a temperature of 80 to 120 ° C. in an atmosphere of air, oxygen, or an inert gas (eg, nitrogen). In addition, firing may be performed at a temperature of 150 to 700 ° C., preferably 200 to 600 ° C., for about 0.1 to 100 hours in an atmosphere of air, oxygen, or an inert gas (eg, nitrogen). preferable. In addition, baking may be performed only in one step or may be performed in two or more steps. As preferable firing conditions, the first firing is performed at 150 to 250 ° C. for 0.1 to 10 hours in an air atmosphere, and the second firing is performed at 250 to 450 ° C. at 0.1 to 10 hours in an air atmosphere. The conditions performed for 10 hours are mentioned. More preferably, after firing in such an air atmosphere, firing may be further performed at 450 to 700 ° C. for 0.1 to 10 hours in an inert gas (eg, nitrogen, helium, argon, etc.) atmosphere. .
　本発明の他の形態によれば、本発明のエチレンオキシド製造用触媒の存在下で、エチレンを分子状酸素含有ガスにより気相酸化する段階を有する、エチレンオキシドの製造方法が提供される。 According to another aspect of the present invention, there is provided a process for producing ethylene oxide comprising the step of gas phase oxidizing ethylene with a molecular oxygen-containing gas in the presence of the catalyst for ethylene oxide production of the present invention.
　本発明のエチレンオキシドの製造方法は、触媒として本発明のエチレンオキシド製造用触媒を使用する点を除けば、常法に従って行われうる。 The process for producing ethylene oxide of the present invention can be carried out according to a conventional method except that the catalyst for producing ethylene oxide of the present invention is used as a catalyst.
　例えば、工業的製造規模における一般的な条件、すなわち反応温度１５０～３００℃、好ましくは１８０～２８０℃、反応圧力２～４０ｋｇ／ｃｍ２Ｇ、好ましくは１０～３０ｋｇ／ｃｍ２Ｇ、反応温度１５０～３００℃、好ましくは１８０～２８０℃、空間速度１，０００～３０，０００ｈｒ－１（ＳＴＰ）、好ましくは３，０００～８，０００ｈｒ－１（ＳＴＰ）が採用される。触媒に接触させる原料ガスとしては、エチレン０．５～４０容量％、酸素３～１０容量％、炭酸ガス５～３０容量％、残部の窒素、アルゴン、水蒸気等の不活性ガスおよびメタン、エタン等の低級炭化水素類からなり、さらに反応抑制剤としての二塩化エチレン、塩化ジフェニル等のハロゲン化物を０．１～１０容量ｐｐｍ含有するものが挙げられる。本発明の製造方法において使用される分子状酸素含有ガスとしては、空気、酸素および富化空気が挙げられる。 For example, general conditions in industrial production scale, ie reaction temperature 150 to 300 ° C., preferably 180 to 280 ° C., reaction pressure 2 to 40 kg / cm 2 G, preferably 10 to 30 kg / cm 2 G, reaction temperature 150 A space velocity of 1,000 to 30,000 hr -1 (STP), preferably 3,000 to 8,000 hr -1 (STP) is employed. As source gases to be brought into contact with the catalyst, ethylene 0.5 to 40% by volume, oxygen 3 to 10% by volume, carbon dioxide gas 5 to 30% by volume, balance nitrogen, argon, inert gas such as water vapor, methane, ethane, etc. And lower hydrocarbons, and further containing 0.1 to 10 ppm by volume of a halide such as ethylene dichloride or diphenyl chloride as a reaction inhibitor. The molecular oxygen-containing gas used in the production method of the present invention includes air, oxygen and enriched air.
　本発明の効果を、以下の実施例および比較例を用いて説明する。ただし、本発明の技術的範囲が以下の実施例のみに制限されるわけではない。なお、本実施例において、担体の各種パラメータの測定は以下の手法により行われた。 The effects of the present invention will be described using the following examples and comparative examples. However, the technical scope of the present invention is not limited to the following examples. In the present example, measurement of various parameters of the carrier was performed by the following method.
　＜担体の比表面積の測定＞
　担体を粉砕した後、０．８５～１．２ｍｍの粒径に分級したもの約０．２ｇを正確に秤量した。秤量したサンプルを２００℃にて少なくとも３０分間脱気し、ＢＥＴ（Ｂｒｕｎａｕｅｒ－Ｅｍｍｅｔ－Ｔｅｌｌｅｒ）法により測定した。 <Measurement of specific surface area of carrier>
After the carrier was crushed, about 0.2 g of the material classified to a particle size of 0.85 to 1.2 mm was accurately weighed. The weighed sample was degassed at 200 ° C. for at least 30 minutes and measured by the BET (Brunauer-Emmet-Teller) method.
　＜担体中のシリカ含有量の測定＞
　蛍光Ｘ線分析法により測定した。 <Measurement of silica content in carrier>
It was measured by fluorescent X-ray analysis.
　＜担体の吸水率の測定＞
　日本工業規格（ＪＩＳ　Ｒ　２２０５（１９９８年度））に記載の方法に準拠して、以下の手法により測定した。 <Measurement of water absorption rate of carrier>
It measured by the following methods based on the method as described in Japanese Industrial Standard (JIS R 2205 (fiscal year 1998)).
　ａ）破砕前の担体を、１２０℃に保温した乾燥機中に入れ、恒量に達した際の質量を秤量した（乾燥質量：Ｗ１（ｇ））。 A) The carrier before crushing was placed in a dryer kept at 120 ° C., and the mass when constant weight was reached was weighed (dry mass: W1 (g)).
　ｂ）上記ａ）で秤量した担体を水中に沈めて３０分間以上煮沸した後、室温の水中にて冷却し、飽水サンプルとした。 B) The carrier weighed in the above a) was immersed in water and boiled for 30 minutes or more, and then cooled in water at room temperature to obtain a water saturated sample.
　ｃ）上記ｂ）で得た飽水サンプルを水中から取り出し、湿布ですばやく表面を拭い、水滴を除去した後に秤量した（飽水サンプル質量：Ｗ２（ｇ））。 C) The water-saturated sample obtained in the above b) was taken out from water, the surface was quickly wiped with a wet cloth, and after removing water droplets, it was weighed (water-saturated sample weight: W2 (g)).
　ｄ）上記で得られたＷ１およびＷ２を用い、下記数式１に従って、吸水率を算出した。 D) Using the W1 and W2 obtained above, the water absorption was calculated according to the following formula 1.
Figure JPOXMLDOC01-appb-M000001
Figure JPOXMLDOC01-appb-M000001
　（実施例１）
　シュウ酸銀１４．６ｇ、硝酸セシウム０．１４４４ｇ、過レニウム酸アンモニウム０．０２４６ｇを約１４ｍｌの水に溶解し、さらにエチレンジアミン６．８ｍｌを添加した。この溶液をα－アルミナ担体（比表面積１．５ｍ２／ｇ、シリカ含有量０．７質量％、吸水率４１．７％）５２ｇに含浸した後、空気気流中３００℃で０．２５時間、熱処理を施した。次いでさらに窒素気流中５５０℃で３時間、熱処理を施し、触媒Ａを得た。触媒Ａにおけるセシウムおよびレニウムの含有量は、触媒の質量基準でそれぞれ０．１５８質量％および０．０２５質量％であった。 Example 1
14.6 g of silver oxalate, 0.1444 g of cesium nitrate and 0.0246 g of ammonium perrhenate were dissolved in about 14 ml of water, and 6.8 ml of ethylenediamine was further added. After impregnating this solution with 52 g of an α-alumina carrier (specific surface area: 1.5 m 2 / g, silica content: 0.7% by mass, water absorption: 41.7%), in an air stream at 300 ° C. for 0.25 hours Heat treated. Then, heat treatment was further performed in a nitrogen stream at 550 ° C. for 3 hours to obtain catalyst A. The contents of cesium and rhenium in catalyst A were 0.158% by mass and 0.025% by mass, respectively, based on the mass of the catalyst.
　（実施例２）
　シュウ酸銀１４．６ｇ、硝酸セシウム０．１３１３ｇ、過レニウム酸アンモニウム０．０２４６ｇを約１４ｍｌの水に溶解し、さらにエチレンジアミン６．８ｍｌを添加した。この溶液をα－アルミナ担体（比表面積１．５ｍ２／ｇ、シリカ含有量０．７質量％、吸水率４１．７％）５２ｇに含浸した後、空気気流中３００℃で０．２５時間、熱処理を施した。次いでさらに窒素気流中５５０℃で３時間、熱処理を施し、触媒Ｂを得た。触媒Ｂにおけるセシウムおよびレニウムの含有量は、触媒の質量基準でそれぞれ０．１４３質量％および０．０２５質量％であった。 (Example 2)
14.6 g of silver oxalate, 0.1313 g of cesium nitrate and 0.0246 g of ammonium perrhenate were dissolved in about 14 ml of water, and 6.8 ml of ethylenediamine was further added. After impregnating this solution with 52 g of an α-alumina carrier (specific surface area: 1.5 m 2 / g, silica content: 0.7% by mass, water absorption: 41.7%), in an air stream at 300 ° C. for 0.25 hours Heat treated. Next, heat treatment was further performed in a nitrogen stream at 550 ° C. for 3 hours to obtain catalyst B. The contents of cesium and rhenium in catalyst B were 0.143% by mass and 0.025% by mass, respectively, based on the mass of the catalyst.
　（実施例３）
　シュウ酸銀１４．６ｇ、硝酸セシウム０．０８４４ｇ、過レニウム酸アンモニウム０．０２４６ｇを約１４ｍｌの水に溶解し、さらにエチレンジアミン６．８ｍｌを添加した。この溶液をα－アルミナ担体（比表面積１．５ｍ２／ｇ、シリカ含有量０．７質量％、吸水率４１．７％）５２ｇに含浸した後、空気気流中３００℃で０．２５時間、熱処理を施し、触媒Ｃを得た。触媒Ｃにおけるセシウムおよびレニウムの含有量は、触媒の質量基準でそれぞれ０．０９２質量％および０．０２５質量％であった。 (Example 3)
14.6 g of silver oxalate, 0.0844 g of cesium nitrate and 0.0246 g of ammonium perrhenate were dissolved in about 14 ml of water, and 6.8 ml of ethylenediamine was further added. After impregnating this solution with 52 g of an α-alumina carrier (specific surface area: 1.5 m 2 / g, silica content: 0.7% by mass, water absorption: 41.7%), in an air stream at 300 ° C. for 0.25 hours Heat treatment was performed to obtain catalyst C. The contents of cesium and rhenium in catalyst C were 0.092% by mass and 0.025% by mass, respectively, based on the mass of the catalyst.
　（比較例１）
　シュウ酸銀１４．６ｇ、硝酸セシウム０．０９３８ｇ、過レニウム酸アンモニウム０．０２４６ｇを約１４ｍｌの水に溶解し、さらにエチレンジアミン６．８ｍｌを添加した。この溶液をα－アルミナ担体（比表面積１．５ｍ２／ｇ、シリカ含有量０．７質量％、吸水率４１．７％）５２ｇに含浸した後、空気気流中３００℃で０．２５時間、熱処理を施した。次いでさらに窒素気流中５５０℃で３時間、熱処理を施し、触媒Ｄを得た。触媒Ｄにおけるセシウムおよびレニウムの含有量は、触媒の質量基準でそれぞれ０．１０２質量％および０．０２５質量％であった。 (Comparative example 1)
14.6 g of silver oxalate, 0.0938 g of cesium nitrate and 0.0246 g of ammonium perrhenate were dissolved in about 14 ml of water, and 6.8 ml of ethylenediamine was further added. After impregnating this solution with 52 g of an α-alumina carrier (specific surface area: 1.5 m 2 / g, silica content: 0.7% by mass, water absorption: 41.7%), in an air stream at 300 ° C. for 0.25 hours Heat treated. Then, heat treatment was further performed in a nitrogen stream at 550 ° C. for 3 hours to obtain catalyst D. The contents of cesium and rhenium in catalyst D were 0.102% by mass and 0.025% by mass, respectively, based on the mass of the catalyst.
　（比較例２）
　シュウ酸銀１４．６ｇ、硝酸セシウム０．１８７６ｇ、過レニウム酸アンモニウム０．０３１５ｇを約１４ｍｌの水に溶解し、さらにエチレンジアミン６．８ｍｌを添加した。この溶液をα－アルミナ担体（比表面積１．５ｍ２／ｇ、シリカ含有量０．７質量％、吸水率４１．７％）５２ｇに含浸した後、空気気流中３００℃で０．２５時間、熱処理を施した。次いでさらに窒素気流中５５０℃で３時間、熱処理を施し、触媒Ｅを得た。触媒Ｅにおけるセシウムおよびレニウムの含有量は、触媒の質量基準でそれぞれ０．２０５質量％および０．０３２質量％であった。 (Comparative example 2)
14.6 g of silver oxalate, 0.1876 g of cesium nitrate and 0.0315 g of ammonium perrhenate were dissolved in about 14 ml of water, and 6.8 ml of ethylenediamine was further added. After impregnating this solution with 52 g of an α-alumina carrier (specific surface area: 1.5 m 2 / g, silica content: 0.7% by mass, water absorption: 41.7%), in an air stream at 300 ° C. for 0.25 hours Heat treated. Next, heat treatment was further performed in a nitrogen stream at 550 ° C. for 3 hours to obtain catalyst E. The contents of cesium and rhenium in catalyst E were 0.205% by mass and 0.032% by mass, respectively, based on the mass of the catalyst.
　（ＴＰＤ法による脱離ピーク温度の測定）
　上記の実施例１～３並びに比較例１および２で得た触媒Ａ～Ｅについて、以下に説明するＴＰＤ法を用いて、脱離ピーク温度を測定した。 (Measurement of desorption peak temperature by TPD method)
The desorption peak temperatures of the catalysts A to E obtained in the above Examples 1 to 3 and Comparative Examples 1 and 2 were measured using the TPD method described below.
　まず、触媒の前処理として、８５０～１１８０μｍの粒径に粉砕した触媒３ｇを、内径７．５ｍｍ、管長３００ｍｍのステンレス製反応器に充填して充填層とした。次いで、この充填層にエチレン２３容量％、酸素６．７容量％、塩化エチレン６．４容量ｐｐｍ、残余が窒素からなるガスを導入し、反応圧力０．５ｋｇ・Ｇ、空間速度５５００ｈｒ－１の条件で、エチレン転化率が４．６容量％となるようにして、１０時間反応を行った。 First, as a pretreatment of the catalyst, 3 g of the catalyst pulverized to a particle diameter of 850 to 1180 μm was filled in a stainless steel reactor having an inner diameter of 7.5 mm and a tube length of 300 mm to form a packed bed. Then, a gas consisting of 23% by volume of ethylene, 6.7% by volume of oxygen, 6.4% by volume of ethylene chloride and the balance of nitrogen is introduced into this packed bed, reaction pressure 0.5 kg · G, space velocity 5500 hr -1 The reaction was carried out for 10 hours under the conditions such that the ethylene conversion rate was 4.6% by volume.
　一方、ＴＰＤ測定装置（日本ベル株式会社製、触媒分析装置、ＢＥＬ－ＣＡＴ）を準備した。反応後の触媒０．５ｇを石英ガラス製ＴＰＤ試料管に入れて触媒層とし、内部をヘリウムガスで置換した。その際、触媒層の中心に位置するように熱電対を設置した。次いで、ヘリウムガスを６０ｍｌ／分の供給速度で供給しながら５０℃まで昇温させた。その後、酸素（Ｏ２）ガスを６０ｍｌ／分の供給速度で供給しながら１９分間かけて２４０℃まで昇温させ、昇温後６０分間２４０℃に保持した。次いで、酸素（Ｏ２）ガスを６０ｍｌ／分の供給速度で供給しながら４０分間かけて５０℃まで降温させ、降温後はヘリウムガスの供給（供給速度６０ｍｌ／分）に切り替えた。 On the other hand, a TPD measurement apparatus (manufactured by Nippon Bell Co., Ltd., catalyst analyzer, BEL-CAT) was prepared. 0.5 g of the catalyst after reaction was put into a quartz glass TPD sample tube to make a catalyst layer, and the inside was replaced with helium gas. At this time, a thermocouple was placed at the center of the catalyst layer. Then, the temperature was raised to 50 ° C. while supplying helium gas at a supply rate of 60 ml / min. Thereafter, the temperature was raised to 240 ° C. over 19 minutes while supplying oxygen (O 2 ) gas at a supply rate of 60 ml / min, and the temperature was kept at 240 ° C. for 60 minutes after the temperature rise. Next, the temperature was lowered to 50 ° C. over 40 minutes while supplying oxygen (O 2 ) gas at a supply rate of 60 ml / min, and after the temperature drop, the supply was switched to the supply of helium gas (supply rate 60 ml / min).
　その後、１０℃／分の昇温速度で５００℃まで昇温させ、この際の酸素の脱離量を熱伝導度検出器（ＴＣＤ；Ｔｈｅｒｍａｌ　Ｃｏｎｄｕｃｔｉｖｉｔｙ　Ｄｅｔｅｃｔｏｒ）を用いて検出した。そして、１５０～２５０℃の温度領域に観察される脱離ピーク温度を第１脱離ピーク温度（Ｔ１［℃］）とし、２５０～４００℃の温度領域に観察される脱離ピーク温度を第２脱離ピーク温度（Ｔ２［℃］）とした。また、これらの測定と併せて、Ｔ２［℃］のＴ１［℃］に対する比（Ｔ２／Ｔ１）を算出した。結果を下記の表１に示す。 Thereafter, the temperature was raised to 500 ° C. at a temperature rising rate of 10 ° C./min, and the amount of oxygen released at this time was detected using a thermal conductivity detector (TCD). The desorption peak temperature observed in the temperature range of 150 to 250 ° C. is taken as the first desorption peak temperature (T 1 [° C.]), and the desorption peak temperature observed in the temperature range of 250 to 400 ° C. The desorption peak temperature (T2 [° C.]) was used. Moreover, the ratio (T2 / T1) with respect to T1 [degreeC] of T2 [degreeC] was computed combining these measurements. The results are shown in Table 1 below.
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
　（触媒の選択率の測定：加速試験）
　各実施例および各比較例において得られた触媒について、以下の手法により加速試験を行い、触媒の耐久性を評価した。 (Measurement of catalyst selectivity: accelerated test)
The accelerated test was performed by the following method about the catalyst obtained in each Example and each comparative example, and the durability of the catalyst was evaluated.
　まず、各実施例および各比較例において得られた触媒を、それぞれ６００～８５０μｍの粒径に粉砕し、粉砕後の各触媒０．３ｇを、８５０～１１８０μｍの粒径に粉砕したイナート（ノープロ製、Ｆ２４）０．９ｇとともに、外部が加熱型の二重管式ステンレス製反応器（内径３ｍｍ、管長３００ｍｍ）に充填して充填層を形成した。次いで、当該充填層に、エチレン２５容量％、酸素７．６容量％、二酸化炭素６．０容量％、二塩化エチレン３容量ｐｐｍ、残余はメタンと、微量の窒素、アルゴンおよびエタンからなるガスを導入し、反応圧力２５ｋｇ・Ｇ、空間速度２２０００ｈｒ－１の条件で、エチレン転化率が５容量％となるようにして、反応を行った。反応開始から１０日目に選択率および反応温度を測定した。また、反応開始から５０日目に選択率を測定した。測定結果を下記の表２に示す。なお、エチレンオキシド製造時の転化率および選択率は、それぞれ下記の数式２および数式３に従って算出される。 First, the catalyst obtained in each Example and each Comparative Example was pulverized to a particle size of 600 to 850 μm, and 0.3 g of each pulverized catalyst was pulverized to a particle size of 850 to 1180 μm , F24) together with 0.9 g, was filled into a heating type double-tubular stainless steel reactor (inner diameter 3 mm, tube length 300 mm) to form a packed bed. Then, in the packed bed, a gas consisting of 25% by volume of ethylene, 7.6% by volume of oxygen, 6.0% by volume of carbon dioxide, 3% by volume of ethylene dichloride, the remainder being methane, and trace amounts of nitrogen, argon and ethane The reaction was carried out under the conditions of a reaction pressure of 25 kg · G and a space velocity of 22000 hr −1 with an ethylene conversion of 5% by volume. The selectivity and reaction temperature were measured 10 days after the start of the reaction. Moreover, the selectivity was measured 50 days after the start of the reaction. The measurement results are shown in Table 2 below. In addition, the conversion rate and selectivity at the time of ethylene oxide manufacture are calculated according to following Numerical formula 2 and Numerical formula 3, respectively.
Figure JPOXMLDOC01-appb-M000003
Figure JPOXMLDOC01-appb-M000003
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000004
　上記表２に示す結果から、各比較例において得られた触媒と比較して、各実施例において得られた触媒では、より低い反応温度でも高い選択率が得られる。また、かような高い選択率が長期に亘って維持されうる。従って、本発明によれば、優れた触媒性能を有し、長期に亘って高選択率でエチレンオキシドを製造しうる触媒が提供されうる。そして、当該触媒を用いたエチレンオキシドの製造方法によれば、長期に亘って高収率でエチレンオキシドを製造することが可能となる。 From the results shown in Table 2 above, compared with the catalyst obtained in each comparative example, high selectivity can be obtained with the catalyst obtained in each example even at a lower reaction temperature. Also, such high selectivity can be maintained for a long time. Therefore, according to the present invention, a catalyst having excellent catalytic performance and capable of producing ethylene oxide with high selectivity over a long period can be provided. And according to the manufacturing method of ethylene oxide using the said catalyst, it becomes possible to manufacture ethylene oxide with a high yield over a long period of time.

Claims (5)

  1. 　α－アルミナを主成分とする担体と、
    　前記担体に担持されてなる、銀ならびにアルカリ金属および／またはレニウムを含む触媒成分と、
    を含むエチレンオキシド製造用触媒であって、
    　（１）酸素昇温脱離法（Ｏ２－ＴＰＤ法）により１５０～２５０℃の温度領域に観測される第１脱離ピーク温度（Ｔ１［℃］）が２１５℃未満であり；
    　（２）酸素昇温脱離法（Ｏ２－ＴＰＤ法）により２５０～４００℃の温度領域に観測される第２脱離ピーク温度（Ｔ２［℃］）の前記Ｔ１に対する比（Ｔ２／Ｔ１）が１．７未満である；
    ことを特徴とする、エチレンオキシド製造用触媒。     a carrier mainly composed of α-alumina,
    A catalyst component comprising silver and an alkali metal and / or rhenium supported on the carrier;
    A catalyst for producing ethylene oxide containing
    (1) The first desorption peak temperature (T1 [° C.]) observed in the temperature range of 150 to 250 ° C. by oxygen temperature-programmed desorption method (O 2 -TPD method) is less than 215 ° C .;
    (2) The ratio (T2 / T1) of the second desorption peak temperature (T2 [° C]) to the above T1 observed in the temperature region of 250 to 400 ° C by the oxygen temperature-programmed desorption method (O 2 -TPD method) Is less than 1.7;
    A catalyst for ethylene oxide production characterized in that
  2. 　前記Ｔ２が２９０～３６０℃である、請求項１に記載のエチレンオキシド製造用触媒。 The catalyst for ethylene oxide production according to claim 1, wherein T2 is 290 to 360 属 C.
  3. 　前記Ｔ１が１８０℃以上２１０℃未満である、請求項１または２に記載のエチレンオキシド製造用触媒。 The catalyst for ethylene oxide production according to claim 1 or 2, wherein T1 is 180 ° C or more and less than 210 ° C.
  4. 　前記Ｔ２の前記Ｔ１に対する比（Ｔ２／Ｔ１）が１．６５未満である、請求項１～３のいずれか１項に記載のエチレンオキシド製造用触媒。 The catalyst for ethylene oxide production according to any one of claims 1 to 3, wherein the ratio (T2 / T1) of T2 to T1 is less than 1.65.
  5. 　請求項１～４のいずれか１項に記載のエチレンオキシド製造用触媒の存在下で、エチレンを分子状酸素含有ガスにより気相酸化する段階を有する、エチレンオキシドの製造方法。 A process for producing ethylene oxide, comprising the step of gas phase oxidizing ethylene with a molecular oxygen-containing gas in the presence of the catalyst for ethylene oxide production according to any one of claims 1 to 4.
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Publication number Priority date Publication date Assignee Title
JP2013202592A (en) * 2012-03-29 2013-10-07 Mitsubishi Chemicals Corp Catalyst for ethylene oxide production and method for production of ethylene oxide

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