JP2007130634A - Deodorization catalyst and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a catalyst which can efficiently decompose an odor component or a harmful gas component by oxidation even at a low temperature. <P>SOLUTION: In this deodorization catalyst, a composite oxide composed of CeO<SB>2</SB>and Fe<SB>3</SB>O<SB>4</SB>is provided as a carrier, and Mn is supported as a catalyst component on the carrier. The deodorization catalyst can efficiently decompose an odor component or a harmful gas component by oxidation even at a low temperature, can realize an enhanced performance of the catalyst, can reduce the deterioration of the catalyst, and has prolonged service life. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention is for decomposing and removing body odor, architectural odor, pet odor, cigarette odor, other odor components, carbon monoxide, and other harmful gas components that are generated in stores, homes, offices, etc. in the air. The present invention relates to a deodorizing catalyst and a method for producing the same, and can be used for an air cleaning device, an air conditioner, a garbage disposal machine, an exhaust treatment machine, and the like.

  In recent years, as represented by highly airtight and highly heat-insulating houses and buildings, bad smells and harmful gas components often become a problem as the confidentiality of buildings increases, and interest in removing odors and harmful gases is increasing. Is high. That is, the gas components to be removed include ammonia, acetaldehyde, trimethylamine, and methyl mercaptan, which are the four major odors in daily life, and harmful gas components such as carbon monoxide and formaldehyde.

Adsorbents such as activated carbon and zeolite are often used to remove these odors and harmful gases, but there is a problem in terms of the life of the adsorbent itself because there is no effective means for treating adsorbed odor components. . On the other hand, a method for oxidatively decomposing odor components and the like with a catalyst to make them harmless is a so-called clean process and has been attracting attention because of its long life, and various studies have been conducted. For example, Patent Document 1 describes a method of oxidizing and decomposing odor components at a high temperature using a catalyst. In addition, although decomposition by a catalyst at a low temperature has been proposed, it takes time to sufficiently decompose and remove various odor components and the like, and there is a problem in the oxidative decomposition rate.
Japanese Patent Laid-Open No. 61-8116

  As described above, in the conventional catalyst, in order to satisfy the requirement of oxidative decomposition and removal of odorous components or harmful gas components in a short time, an amount that uses the catalyst at a high temperature and a large amount of catalyst is required. . Therefore, the present invention provides a catalyst and a method for producing the same that can solve such problems as insufficient capacity, problems of apparatus configuration and upper temperature limit, and high cost.

  Regarding the structure of the catalyst for oxidatively decomposing the above-mentioned odor components or harmful gas components present in the living space, the catalyst metal component, carrier component, additive component, and production method will be described below.

  That is, the catalytic metal component can be in the form of a Mn metal, an alloy containing the metal or an oxide of the metal, or a mixture of two or more selected from the metal, alloy and metal oxide, Furthermore, these can be mixed with Co, Ni or the like.

As the carrier component, a complex oxide of CeO ₂ and Fe ₃ O ₄ is used, and the catalyst component is supported on this. As the additive component, Pr ₂ O ₃ , La ₂ O ₃ , Bi ₂ O ₃ , MgO, CoO, NiO, CuO, ZnO or the like can be employed.

  Such a catalyst can be prepared using a coprecipitation method, a precipitation method, or the like. That is, when using the coprecipitation method, prepare a raw material solution obtained by dissolving a metal compound for forming the composite oxide support and a metal compound for forming the catalyst component in a solvent, By mixing the raw material solution and the alkaline solution, the metal for forming the support is precipitated as a hydroxide as a precursor of the support, and at the same time, the metal for forming the catalyst component is added to the catalyst. What is necessary is just to co-precipitate as the hydroxide which is a precursor of a component, and to dry and bake the obtained precipitate. In addition, the catalyst may be subjected to reduction treatment as necessary after calcination.

  About the said addition component, it may add by making it precipitate as a hydroxide simultaneously with the said coprecipitation, or may be added as a hydroxide after the said coprecipitation, and the said baking etc. may be given.

  In the case of using the precipitation method, a raw material solution prepared by dispersing the composite oxide carrier and dissolving the metal compound for forming the catalyst component is prepared. By mixing, the catalyst component metal is precipitated as a precursor hydroxide on the composite oxide support, and the resulting solid is dried and fired, and subjected to reduction treatment as necessary. What should I do?

  In the case of this precipitation method, the additive component can be added by precipitation as a hydroxide simultaneously with the precipitation of the catalyst component, or the additive component is supported on the composite oxide support by the precipitation method. Alternatively, after the catalyst component is supported by the impregnation method, the catalyst component may be supported by the precipitation method.

  Further, the catalyst component may not be supported at a time but may be supported in two portions. That is, the method prepares a raw material solution obtained by dissolving a metal compound for forming the composite oxide support and a Pd metal compound for forming the catalyst component in a solvent, By mixing with an alkaline solution, the metal for forming the carrier is precipitated as a hydroxide that is a precursor of the carrier and simultaneously coprecipitated as a Pd hydroxide, and the resulting precipitate is dried. The calcined product and the obtained calcined product are loaded with a metal for forming a second catalyst component that is the same as or different from the Pd metal by an impregnation method or a precipitation method. Also in this case, a reduction process can be performed thereafter.

With respect to the specific surface area of the catalyst, it is preferable that the specific surface area is 100 m ² / g or more by adjusting the conditions of the coprecipitation method or by using a carrier having a high specific surface area. This is advantageous in obtaining high activity even at low temperatures in the oxidative decomposition reaction of components and harmful gas components.

  The weight ratio of the catalyst metal component may be in the range of 0.1 to 30 wt%, and more preferably in the range of 2 to 15 wt% from the viewpoint of performance.

  The deodorization catalyst thus produced can be used particularly effectively in an air cleaning device, an air conditioner, a garbage treatment machine, an exhaust treatment machine, and the like. In addition, the catalyst structure is prepared using a particle shape, fiber shape, etc., and combined with a heater. The effect is expressed and the deodorization of the living space becomes possible. Also, after adsorbing the odor component etc. to the adsorbent, the adsorbent component is desorbed by heating it to regenerate the adsorbent, while the desorbed odor component etc. is oxidized and decomposed by the catalyst. Can be.

According to the catalyst of the present invention, Mn is supported as a catalyst component on a composite oxide support of CeO ₂ and Fe ₃ O ₄ , so that odorous components or harmful gas components can be efficiently oxidized and decomposed even at low temperatures. As a result, the catalyst performance can be improved and the deterioration of the catalyst can be reduced to extend its life.

  In addition, according to the method for producing a catalyst according to the present invention, a catalyst having the excellent characteristics as described above can be produced.

  Below, this invention is demonstrated by the comparison with an Example and a comparative example.

<Catalyst type>
An Example is the following invention catalyst, and a comparative example is three types of the following comparative catalysts 1-3. Here, in each of the following catalysts, the left side of “/” indicates a catalyst component, and the right side indicates a carrier component.

Invention catalyst Mn / CeO ₂ —Fe ₃ O ₄
Comparative catalyst 1 Ni / Al ₂ O ₃
Comparative catalyst 2 Ag / Al ₂ O ₃
Comparative catalyst 3 Ru / Al ₂ O ₃

<Preparation of catalyst>
Invention catalyst An aqueous solution of manganese nitrate was prepared as a manganese compound, cerium nitrate was added as a cerium compound, and a predetermined amount of iron nitrate was further added to prepare solution A. On the other hand, a liquid B was prepared by dissolving an alkaline solution in water as a precipitation reagent. Then, while the B liquid was stirred, it was poured into the A liquid to produce a coprecipitate. Thereafter, through the steps of aging, washing, drying, firing, and reduction for 1 hour, the catalyst in which Mn was supported on the support mainly in the form of MnO ₂ was completed.

Comparative catalyst 1, 2, 3
For the comparative catalyst 1, nickel was deposited on the aluminum oxide powder by an impregnation method, and the catalyst was completed through the steps of aging, drying, washing, firing and reduction.

  Comparative catalyst 2 was prepared in the same manner as comparative catalyst 1 using silver nitrate. Comparative catalyst 3 was prepared in the same manner as comparative catalyst 1 using ruthenium chloride.

<Evaluation of catalyst>
Each catalyst of the invention catalyst and comparative catalysts 1 to 3 was incorporated in a fixed bed flow reactor, and after this catalyst was subjected to hydrogen reduction treatment, a mixed gas of 20% oxygen and 80% helium containing 200 ppm trimethylamine was added. The odor oxidative degradation characteristics of each catalyst were evaluated by passing the product at a temperature of 30000 ml / h / g at 0 ° C. and measuring the product. The results are listed in Table 1.

According to Table 1, it can be seen that the inventive catalyst has very high activity. In addition, it was confirmed that for each catalyst, only three kinds of harmless gases of CO ₂ , N ₂ , and N ₂ O were generated, and a clean oxidation reaction in which no harmful gas was generated occurred.

Claims (2)

A deodorization catalyst for decomposing odor components or harmful gas components,
A deodorizing catalyst characterized in that Mn is supported as a catalyst component on a composite oxide support of CeO ₂ and Fe ₃ O ₄ . It is a manufacturing method of the deodorizing catalyst described in Claim 1,
A raw material solution prepared by dissolving a Ce compound, an Fe compound and a Mn compound in a solvent;
By mixing the raw material solution and the alkali solution, the Ce and Fe are precipitated as the precursor hydroxide, and at the same time, the Mn is co-precipitated as the precursor hydroxide. A method for producing a deodorizing catalyst, which comprises calcining a precipitate.