JP2008229578A - Oil decomposing catalyst and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an oil decomposing catalyst whose activity to oil is high enough to decompose and remove oil fouling at a lower temperature with regard to the oil decomposing catalyst which decomposes and removes the oil fouling caused by lampblack and the like generated in cooking. <P>SOLUTION: The decomposing catalyst, wherein a noble metal, an alkali metal sulfate, and the oxide of a rare earth element are supported by an inorganic oxide. This allows the oil decomposing catalyst whose activity to oil is high enough to decompose and remove the oil fouling at a lower temperature to be provided, and the oil fouling caused by cooking and the like can be decomposed and removed by coating the inside of a ventilation flue in a range hood, an oil recovering filter, and the like with the catalyst. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an oil decomposition catalyst for decomposing and removing oil dirt caused by oily smoke and the like generated during cooking, and a method for producing the same.

  There has been a problem that oil smoke or the like generated during cooking contaminates the surroundings of the cooker and the ventilation path of the range hood and the ventilation fan installed in the cooking area with oil.

In order to solve such problems, a filter for a range hood has been proposed in which a photocatalyst composed of titanium dioxide and manganese oxide is supported on a filter, and oil dirt is decomposed and removed by ultraviolet irradiation (for example, Patent Document 1). ). In addition, an oil decomposition catalyst has been proposed in which a catalyst composed of manganese dioxide and manganese carbonate is provided in an exhaust passage of a cooking device such as a fish roaster to decompose and remove oil smoke by heat (for example, Patent Document 2).
Japanese Patent Laid-Open No. 10-5513 Japanese Patent No. 3424301

  Such conventional oil cracking catalysts have the following problems.

  In the method of decomposing and removing oil dirt by the above photocatalytic action, the catalyst activity is not so high that a large amount of adhered oil is decomposed in a short time. Moreover, in the method of decomposing and removing oil smoke by the above heat, the catalyst temperature needs to be 200 to 400 ° C. or higher.

  SUMMARY OF THE INVENTION The present invention solves such conventional problems, and an object of the present invention is to provide an oil decomposition catalyst having a high activity of a catalyst for oil and capable of decomposing and removing oil dirt at a lower temperature, and a method for producing the same. .

  In order to achieve the above object, the oil cracking catalyst of the present invention is characterized in that a noble metal, an alkali metal sulfate, and an oxide of a rare earth element are supported on an inorganic oxide.

  With this configuration, it is possible to provide an oil decomposition catalyst that has high activity of the catalyst for oil and that can decompose and remove oil dirt at a lower temperature.

  According to the present invention, since the noble metal, the alkali metal sulfate, and the rare earth element oxide are supported on the inorganic oxide, the catalyst exhibits high activity with respect to oil, and more An oil decomposition catalyst capable of decomposing and removing oil dirt at a low temperature can be provided.

  The invention according to claim 1 of the present invention is an oil decomposition catalyst characterized in that a noble metal, an alkali metal sulfate, and an oxide of a rare earth element are supported on an inorganic oxide.

  The invention according to claim 2 of the present invention is the oil cracking catalyst according to claim 1, wherein the noble metal is platinum.

  The invention according to claim 3 of the present invention is the oil cracking catalyst according to claim 1 or 2, wherein the alkali metal sulfate is cesium sulfate.

  The invention according to claim 4 of the present invention is the oil cracking catalyst according to any one of claims 1 to 3, wherein the rare earth element oxide is cerium oxide.

  By adopting the configuration according to any one of claims 1 to 4, the catalyst exhibits high activity with respect to oil, and oil stains can be decomposed and removed at a lower temperature.

  The invention according to claim 5 of the present invention is the oil decomposition catalyst according to any one of claims 1 to 4, characterized in that the inorganic oxide is alumina.

  Since γ-alumina and the like that are commercially available as a catalyst carrier have a large surface area, the catalyst component can be supported in a highly dispersed manner, and also has excellent heat resistance, so that it is actually used when producing a catalyst. It is thought that the coarsening of the catalyst due to the heat load at the time can be suppressed. Therefore, it is considered preferable for supporting the catalyst of the present invention.

  The invention according to claim 6 of the present invention is characterized in that the weight of cesium sulfate contained in the catalyst is 1 to 5% of the weight of the inorganic oxide. It is an oil cracking catalyst of description.

  The invention according to claim 7 of the present invention is characterized in that the weight of cerium oxide contained in the catalyst is 1 to 2% of the weight of the inorganic oxide. It is an oil cracking catalyst of description.

  With regard to the inventions of claims 6 and 7, it is considered that the addition effect of cesium sulfate and cerium oxide is not obtained even if the content is too small, and conversely if it is too much, the catalytic action of the noble metal is hindered. In addition, when adding the cerium to an alumina and improving the heat resistance of a catalyst, it is supposed that the addition amount is about 1 mol% with respect to an alumina.

  The invention according to claim 8 of the present invention is characterized in that a noble metal is supported after an alkali metal sulfate and a rare earth element oxide are supported on an inorganic oxide. Or an oil cracking catalyst according to any one of the above.

  As a result, the noble metal, which is the main active species, is supported on the surface of the catalyst, and the catalytic action of the noble metal can be sufficiently exhibited.

  The invention according to claim 9 of the present invention is a method for producing an oil cracking catalyst, wherein a noble metal, an alkali metal sulfate, and an oxide of a rare earth element are supported on an inorganic oxide. .

  The invention according to claim 10 of the present invention is characterized in that an aqueous solution in which cesium sulfate and cerium nitrate are dissolved is impregnated with an inorganic oxide, dried and fired. This is a method for producing an oil cracking catalyst.

  According to the eleventh aspect of the present invention, an aqueous solution in which cesium sulfate and cerium nitrate are dissolved is impregnated with an inorganic oxide, dried, and fired at a temperature at which cerium oxide is produced in the presence of oxygen. It is a manufacturing method of the oil-decomposition catalyst of Claim 9 or 10 characterized by the above-mentioned.

  The oil decomposition catalyst of the present invention can be produced by the production method according to any one of claims 9 to 11. Further, firing at a temperature at which cerium oxide is produced in the presence of oxygen described in claim 11 is, for example, firing at a high temperature of about 900 ° C. in an air atmosphere.

  The invention according to claim 12 of the present invention is characterized in that an inorganic oxide carrying cesium sulfate and cerium oxide is impregnated in a dinitrodiammine platinum nitric acid solution, dried and then fired. Item 12. The method for producing an oil cracking catalyst according to any one of Items 9 to 11.

  The invention according to claim 13 of the present invention is characterized in that an inorganic oxide carrying cesium sulfate and cerium oxide is impregnated in a dinitrodiammine platinum nitric acid solution, dried, and then fired in a reducing atmosphere. A method for producing an oil cracking catalyst according to any one of claims 9 to 12.

  The oil cracking catalyst of the present invention can be produced by the production method according to claim 12 or 13. Further, by firing in a reducing atmosphere according to claim 13, platinum is reduced, and a more active catalyst can be produced. In addition, the platinum particle size and the like can be controlled by appropriately setting the reducing conditions. Note that firing in a reducing atmosphere is, for example, firing at about 400 ° C. while flowing nitrogen gas containing about 4% by volume of hydrogen.

  Embodiments of the present invention will be described below.

(Embodiment 1)
An aqueous solution in which cesium sulfate and cerium nitrate are dissolved is impregnated with alumina, dried and fired to prepare alumina powder supporting cesium sulfate and cerium oxide. This powder is impregnated with a dinitrodiammine platinum nitric acid solution having an appropriate concentration, dried and fired to obtain an oil decomposition catalyst in which platinum, cesium sulfate, and cerium oxide are supported on alumina.

  As described above, an oil decomposition catalyst that exhibits high activity with respect to oil and can decompose and remove oil dirt at a lower temperature can be obtained.

  Here, platinum is shown as the noble metal, but palladium, rhodium, and ruthenium may be used in addition to this.

  Here, cesium sulfate is shown as the alkali metal sulfate, but sulfates of lithium, sodium, potassium, and rubidium may also be used.

  Here, cerium oxide is shown as the rare earth element oxide, but lanthanum oxide may be used in addition to this.

  Here, alumina is shown as the inorganic oxide, but various inorganic oxides known as catalyst carriers such as silica, titania, zirconia, etc. may be used.

  The weight of cesium sulfate contained in the catalyst is preferably 1 to 5% of the weight of alumina, and the weight of cerium oxide is preferably 1 to 2% of the weight of alumina.

  Cesium sulfate and cerium oxide do not provide the effect of addition even if the content is too small, and conversely, if the content is too large, it is considered that the catalytic action of noble metals is hindered. In addition, when adding the cerium to an alumina and improving the heat resistance of a catalyst, it is supposed that the addition amount is about 1 mol% with respect to an alumina.

  Similarly, the platinum content is preferably about several percent of the weight of alumina. This is because even if the amount is too small, sufficient catalytic action cannot be obtained, and conversely, if the amount is too large, sufficient catalytic action is not obtained.

  When producing the catalyst, for example, a solution prepared by mixing cesium sulfate, cerium nitrate, and dinitrodiammine platinum nitric acid solution may be prepared, impregnated with alumina or the like, dried, and calcined. As described above, it is preferable to support platinum after supporting cesium sulfate and cerium oxide on alumina. This is because platinum, which is the main active species, is supported on the surface of the catalyst, and the catalytic action of platinum can be sufficiently exhibited. Moreover, in order to suppress the coarsening of platinum due to a heat load during production, the firing temperature after supporting platinum is preferably as low as possible. Therefore, it is considered preferable to support and fire components other than platinum in advance.

  Also, when impregnating alumina into an aqueous solution in which cesium sulfate and cerium nitrate are dissolved, and drying and firing, it is necessary to fire under conditions where cerium nitrate becomes cerium oxide. For example, about 900 ° C. in an air atmosphere Can be fired.

  Moreover, when impregnating alumina powder carrying cesium sulfate and cerium oxide in a dinitrodiammine platinum nitric acid solution, and drying and firing, it may be fired at, for example, about 400 to 600 ° C. in an air atmosphere. You may bake in atmosphere. By calcination in a reducing atmosphere, platinum is reduced and a more highly active catalyst can be produced. In addition, the platinum particle size and the like can be controlled by appropriately setting the reducing conditions. Note that “calcining in a reducing atmosphere” described here is, for example, firing at about 400 ° C. while flowing nitrogen gas containing hydrogen at a volume concentration of about 4%.

  Hereinafter, the present invention will be described in detail with reference to examples.

(Example 1)
Cesium sulfate 0.27g and cerium nitrate hexahydrate 0.43g were dissolved in ion exchange water 100g. While stirring this aqueous solution, 10 g of γ-alumina was added thereto to form a suspension. Water was removed from the suspension using an evaporator and further dried at 110 ° C. for 1 hour using a dryer to obtain a dry powder. This dry powder was fired at 900 ° C. for 5 hours in an air atmosphere using an electric furnace to obtain an alumina powder carrying cesium sulfate and cerium oxide. This is a precursor powder.

  The precursor powder was pulverized in a mortar to obtain a fine powder. On the other hand, 50 g of a dinitrodiammine platinum nitric acid solution with a platinum weight concentration of 0.77% was prepared, and 10 g of the pulverized precursor powder was added thereto to obtain a suspension. Water was removed from the suspension using an evaporator and further dried at 110 ° C. for 1 hour using a dryer to obtain a dry powder carrying platinum. This dry powder carrying platinum was calcined at 600 ° C. for 5 hours in an air atmosphere using an electric furnace to obtain an oil decomposition catalyst in which platinum, cesium sulfate and cerium oxide were carried on alumina. At this time, the content of each component calculated from the charged amount in the catalyst is 4.0% for platinum, 2.7% for cesium sulfate, and 1.7% for cerium oxide, based on the weight of alumina.

(Comparative Example 1)
50 g of a dinitrodiammine platinum nitric acid solution having a platinum weight concentration of 0.80% was prepared, and 10 g of γ-alumina was added to the suspension while stirring to prepare a suspension. Water was removed from the suspension using an evaporator and further dried at 110 ° C. for 1 hour using a dryer to obtain a dry powder. This dry powder was fired at 600 ° C. for 5 hours in an air atmosphere using an electric furnace to obtain a catalyst having platinum supported on alumina. At this time, the content of platinum in the catalyst calculated from the charged amount is 4.0% with respect to the weight of alumina.

(Evaluation example 1)
For the catalysts of Example 1 and Comparative Example 1, the following performance evaluation test was performed using a thermogravimetric analyzer.

  10 mg of the catalyst was placed in an aluminum sample container, and 2 mg of oleic acid, which is the main component of cooking oil, was added dropwise thereto, and the change in weight over time was observed. As test conditions, air was circulated in the sample chamber at a flow rate of 100 ml / min, and the temperature was raised from room temperature to 500 ° C. at a heating rate of 10 ° C./min. The oil residual ratio was defined as the weight at 500 ° C. when the oleic acid was completely burned. The test results are shown in FIG. For comparison, a plot when only oleic acid is heated is also shown.

  As shown in FIG. 1, when the catalyst of Example 1 or Comparative Example 1 and oleic acid were heated in contact with oleic acid as compared with the case of oleic acid alone, the weight gradually decreased from the start of temperature increase, Compared to the case of oleic acid alone, the combustion progressed rapidly, and it was confirmed that the combustion of oleic acid was promoted by the catalytic action.

  In addition, it can be seen that the catalyst of Example 1 is burning oleic acid clearly faster than the catalyst of Comparative Example 1. For example, in the catalysts of Example 1 and Comparative Example 1, abrupt combustion occurs from around points A and B in FIG. 1, but a clear time difference can be confirmed between A and B. From this, it was found that the catalyst of Example 1 can exhibit high activity against oil. Moreover, the sample temperature in the point A in FIG. 1 is 180-190 degreeC, It has confirmed that the catalyst of Example 1 started the combustion of oil at comparatively low temperature.

  Although the detailed mechanism by which the catalyst of Example 1 can exhibit high activity with respect to oil is unknown, the addition of a small amount of cesium sulfate and cerium oxide improved the combustion activity for oil compared to the case of platinum alone. It is considered a thing.

  The oil cracking catalyst of the present invention is characterized in that a noble metal, an alkali metal sulfate, and an oxide of a rare earth element are supported on an inorganic oxide. Thereby, the activity of the catalyst with respect to oil is high, and an oil decomposition catalyst that can decompose and remove oil dirt at a lower temperature can be provided. By applying this catalyst to the inside of the ventilation passage of the range hood, the oil collecting filter, etc. Oil stains derived from cooking and the like can be decomposed and removed.

The figure which shows the result of the performance evaluation test of the oil decomposition catalyst of Example 1 of this invention

Claims (13)

An oil cracking catalyst characterized in that a noble metal, an alkali metal sulfate, and an oxide of a rare earth element are supported on an inorganic oxide. 2. The oil cracking catalyst according to claim 1, wherein the noble metal is platinum. The oil decomposition catalyst according to claim 1 or 2, wherein the alkali metal sulfate is cesium sulfate. The oil cracking catalyst according to any one of claims 1 to 3, wherein the rare earth element oxide is cerium oxide. The oil decomposition catalyst according to any one of claims 1 to 4, wherein the inorganic oxide is alumina. The oil decomposition catalyst according to any one of claims 1 to 5, wherein the weight of the cesium sulfate contained in the catalyst is 1 to 5% of the weight of the inorganic oxide. The oil decomposition catalyst according to any one of claims 1 to 6, wherein the weight of the cerium oxide contained in the catalyst is 1 to 2% of the weight of the inorganic oxide. The oil cracking catalyst according to any one of claims 1 to 7, wherein a noble metal is supported after an alkali metal sulfate and a rare earth element oxide are supported on an inorganic oxide. A method for producing an oil decomposition catalyst, comprising supporting a noble metal, an alkali metal sulfate, and an oxide of a rare earth element on an inorganic oxide. The method for producing an oil cracking catalyst according to claim 9, wherein an aqueous solution in which cesium sulfate and cerium nitrate are dissolved is impregnated with an inorganic oxide, dried, and then fired. The aqueous solution in which cesium sulfate and cerium nitrate are dissolved is impregnated with an inorganic oxide, dried, and calcined at a temperature at which cerium oxide is formed in the presence of oxygen in the presence of oxygen. Of producing an oil cracking catalyst. The oil decomposition catalyst according to any one of claims 9 to 11, wherein an inorganic oxide carrying cesium sulfate and cerium oxide is impregnated in a dinitrodiammine platinum nitric acid solution, dried and fired. Manufacturing method. The inorganic oxide carrying cesium sulfate and cerium oxide is impregnated in a dinitrodiammine platinum nitric acid solution, dried, and then fired in a reducing atmosphere. Of producing an oil cracking catalyst.

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