KR101649334B1 - Preparation method of porous copper-manganese oxide catalysts - Google Patents

Abstract

The present invention relates to a method for preparing a porous copper-manganese oxide catalyst capable of effectively removing harmful and odorous gases such as carbon monoxide, nitrogen oxides, ammonia, hydrogen sulfide, and volatile organic compounds. Manganese oxide in the presence of a swellable layered silicate colloid dissociated to a nano-thickness in an aqueous solution, thereby forming a composite structure of the copper-manganese oxide particles and the layered silicate lattice, thereby improving the porosity and ultimately improving the gas- This is a process for producing an improved porous copper-manganese catalyst. The porous copper-manganese catalyst is used as a catalyst for oxidative decomposition of carbon monoxide, nitrogen oxides, ammonia, and volatile organic compounds.

Description

Preparation of porous copper-manganese oxide catalysts < RTI ID = 0.0 >

The present invention relates to a method for preparing a porous copper-manganese oxide catalyst capable of effectively removing harmful and odorous gases such as carbon monoxide, nitrogen oxides, ammonia, hydrogen sulfide, and volatile organic compounds. Manganese oxide in the presence of a swellable layered silicate colloid dissociated to a nano-thickness in an aqueous solution, thereby forming a composite structure of the copper-manganese oxide particles and the layered silicate lattice, thereby improving the porosity and ultimately improving the gas- This is a process for producing an improved porous copper-manganese catalyst. The porous copper-manganese catalyst is used as a catalyst for oxidative decomposition of carbon monoxide, nitrogen oxides, ammonia, and volatile organic compounds.

Recently, as the public demand for a pleasant and harmless living environment has increased, legal regulations on the emission of harmful substances or odorous substances have been strengthened. Accordingly, deodorant, which can effectively control or remove odorous substances and harmful substances, Deodorization equipment has been urgently required and many researches have been carried out recently.

Generally, noxious gases and odors which are harmful or uncomfortable to humans are generated in various places such as daily living space, market and shopping center, automobile, chemical plant, industrial site, sewage disposal plant, landfill, incinerator, large power plant and boiler. Typical harmful gas and odor materials include carbon monoxide (CO), nitrogen oxides (NOx), ozone, ammonia, trimethylamine, acetaldehyde, methanethiol, methyl sulfide, methyl disulfide, hydrogen sulfide, nitrogen oxide, nitrogen dioxide, styrene, and volatile organic compounds (VOC).

Typically, materials such as activated carbon, activated alumina, zeolite, porous silica, and titanium dioxide photocatalyst are used for removing or reducing harmful gases or odors. Recently, a method for producing a carbon nanoball (Adv. Material 2002, 14, no. 1, January 4) having a porous carbon shell portion having a spherical hollow core portion has been proposed. There is an advantage that a malodor generating substance can be adsorbed. Conventional deodorization materials such as activated carbon and zeolite can be used in a honeycomb type produced by extrusion using alumina or silica oxide followed by firing, a cartridge type produced by extrusion molding mixed with a linear polymer, Block type, and the like. However, such conventional deodorants have a low specific surface area and a low content of effective deodorizing components, and the initial deodorizing ability is not rapid, and the removal efficiency is drastically decreased at room temperature or low temperature.

Korean Patent No. 10-0118530 discloses an activated carbon containing at least one metal oxide such as iron, chromium, nickel, cobalt, manganese, copper, copper or magnesium or a cartridge type or block type Of deodorant. In addition, U.S. Patent No. 6319440 discloses a deodorant in which a copper or manganese metal catalyst is impregnated with powdered or granular, granular, or fibrous activated carbon, followed by acid treatment. However, in order to remove more effective odor due to limit of deodorizing capacity, it is required to develop a new deodorizing material economically having more powerful deodorizing power with a smaller weight and to develop various deodorant formulations having excellent applicability to other fields. In addition, it is also possible to use deodorant of various formulations such as a honeycomb type, a block type, a plate type, and the like using an activated carbon or a titanium dioxide for an air conditioner, an air purifier, a ventilator or a vacuum cleaner used for purifying the living environment and purifying the indoor air However, this also has a problem that the deodorizing effect is not quick and the deodorizing effect is insufficient. Korean Patent No. 10-0457699 relates to a deodorant using a porous adsorbent and a method for preparing the same. More specifically, the porous adsorbent and a metal salt solution are stirred, water evaporated, fired, and cooled to obtain various gas adsorption and oxidation A porous adsorbent carrying a metal is prepared and used for cleaning the air in a refrigerator, an air cleaner or an air-conditioner. Korean Patent No. 10-0330599 discloses a porous deodorization filter and a method of manufacturing the porous deodorization filter. More particularly, the present invention relates to a porous deodorization filter and a method for manufacturing the porous deodorization filter, and more particularly to a porous deodorization filter having a nanometer- A porous deodorizing filter configured to effectively remove the odor contained in the air by applying a powder of the system, and a manufacturing method thereof. Korean Patent No. 10-0413243 discloses that a white solid powder prepared by adding bentonite powder activated by an acid to gel-type aluminum phosphate is refluxed and stirred, and the pH is adjusted and then dried An odor removing agent is disclosed. Korean Patent No. 10-0424788 discloses a nanostructure deodorizer prepared by using bentonite, an organic cation, and a metal cation activated with an acid solution or an acid solution and an oxidizing agent mixed solution (activation solution). Korean Patent No. 10-0724288 discloses a resin composition capable of deodorizing and deodorizing, and provides a resin composition highly effective for deodorization and deodorization by prescribing a commercial activated carbon or a mixture of titanium oxide / zinc oxide. Korean Patent No. 10-0536259 discloses an additive comprising a zeolite powder having a foamed polymer foam and containing titanium oxide (TiO 2) on its surface and a silver activated carbon powder containing nano silver (Ag) A porous deodorizing filter prepared by impregnating a binder in a sol state onto a surface of a foamable polymer by forming a binder in a sol state by mixing an adhesive containing a casein solution mixed with water as a main material, Lt; / RTI > Korean Patent No. 10-0840735 discloses an activated carbon deodorant in which copper and a manganese compound are impregnated on the surface of an activated charcoal.

As a catalyst used for removing carbon monoxide at room temperature, Hopcalite composed of a mixture of manganese oxide and copper oxide is relatively economical and has an excellent effect of removing carbon monoxide, but its effect is reduced in the presence of water . (M.I. Brittan, H. Bliss, C. A. Walker, AIChE J. 1970, 16, 305). In addition, catalysts composed of gold nanoparticles (5) supported on metal oxide (GC Bond and DT Thompson, Gold Bulletin 2000, 33 (2), pp 41-51) have the ability to oxidize CO at room temperature However, a high technology is required to uniformly disperse and uniformly disperse metal particles into nano-sized particles. Precious metal catalysts such as Au, Pd, and Pt have excellent catalytic efficiency, performance consistency and durability, endotoxicity, and excellent performance as catalysts, but they still remain uneconomical. Japanese Patent No. 3321422 and Japanese Patent Application Laid-Open No. 2000-140577 disclose an apparatus for removing trace amounts of carbon monoxide, nicotine, acetaldehyde, ammonia, and sulfur dioxide present in a closed space. This apparatus removes carbon monoxide Cerium, palladium, magnesium, titanium or the like is supported on an oxide such as alumina, silica, iron oxide, titania, zirconia or zeolite in order to remove aldehyde and an adsorbent such as activated carbon, silica gel or titania is used An adsorbed activated carbon adsorbent is used to remove ammonia, and a catalyst in which manganese or copper is supported on an oxide such as titania, alumina, silica, or zeolite is used to remove sulfur dioxide. However, these catalysts have the disadvantage that they are required to separately heat the apparatus since each of the catalysts can remove toxic gases at a temperature higher than room temperature of 40 to 60 ° C. U.S. Patent No. 6,280,691 discloses a method for removing SOx, NOx, ozone and the like at room temperature by installing a low temperature oxidation catalyst such as platinum, palladium or silver in a device for removing toxic gases coexisting in a building at low temperature . In addition, U.S. Patent No. 6,187,276 discloses a method for removing aluminum oxide (VOC) contained in a room from a low temperature by adding aluminum oxide containing a precious metal such as platinum (Pt), palladium (Pd) . Japanese Patent Application Laid-Open Nos. 6-219,721 and 10-296,087 disclose that ceria, zirconia and titania are prepared by coprecipitation with precious metals such as silver (Ag), palladium (Pd), rhodium (Rh) Although the catalyst shows the ability to oxidize CO, it shows excellent performance at a high temperature of 150 to 200 ° C, but it is known that the activity decreases sharply at room temperature. U.S. Patent No. 6,492,298 discloses a method of preparing a catalyst for oxidation reaction exhibiting performance at room temperature and a catalyst formed by supporting a noble metal on a metal oxide such as ceria or zirconia having an oxygen vacancy site by reduction treatment Toxic gases such as CO, NOx, ethylene, formaldehyde, trimethylamine, methylmercaptan and acetaldehyde can be purified at 25 ° C. U.S. Patent No. 6,503,462 also discloses an apparatus for purifying CO, volatile organic compounds (VOC), ozone, and the like that coexist in the atmosphere, a noble metal such as platinum (Pt), palladium (Pd) Cobalt (Co), and iron (Fe) on an inorganic material such as alumina, silica, or titania having a large surface area is used to form an invention.

Copper-manganese oxide systems have shown excellent adsorption characteristics for carbon monoxide, volatile organic compounds (VOCs) at room temperature decomposition properties and odor sources such as ammonia and hydrogen sulfide. However, the catalytic activity of the copper-manganese oxide system is susceptible to crystallization, and when the catalyst is heat-treated for regeneration after a certain period of time, the catalytic properties of the copper-manganese oxide system deteriorate rapidly in accordance with the change of the crystallinity, Disadvantages were pointed out. In addition, there is a need to further improve the specific surface area required basically as a catalyst.

The present inventors have devised a method for maximizing the specific surface area required as a catalyst in order to improve the excellent deodorization and harmful gas catalytic decomposition properties of the copper-manganese metal oxide. That is, in the copper-manganese catalyst oxide manufacturing process, a method of improving the catalytic performance by improving the porosity of the material itself through copper-manganese catalyst particles and multi-repagination by forming the house-of-card structure of the layered silicate particles is completed .

The present invention relates to amorphous CuO-MnO ₂ , which is a catalyst for decomposing harmful gas and malodorous gas at room temperature, and is designed to improve the efficiency and durability of the catalyst.

The process for preparing the porous copper-manganese oxide catalyst in the present invention comprises the following steps.

A step of preparing a layer silicate colloid by swelling in an aqueous solution, a step of hydrolyzing a copper and manganese salt compound (copper acetate, copper nitrate, copper chloride, copper sulfate) in the presence of a layered silicate colloid, A step of preparing, separating and washing, and finally a step of drying and heat-treating a porous composite of a copper-manganese composite oxide and a layered silicate lattice.

The preparation of the layered silicate colloid is obtained by dispersing a layered silicate having excellent water swelling property in water. The layered silicate material is swellable, the lattice layer is negatively charged, and may be a natural clay suspension having a layered structure. Examples of natural clays include smectite-based clays such as montmorillonite, saponite, hectorite, nontronite, videllite and bentonite. Examples of synthetic clays include laponite, Smecton, And mica (Synthetic fluorine mica). In the swelling clay, the lattice layer is negatively charged, so that metal oxide particles having a cationic charge are combined with electrostatic attraction. The swelling clay suitable for the formation of the layered silicate colloid has a cation exchange capacity (CEC: cation exchange capacity, mequiv./100 g) preferably in the range of 60 to 120. When the cation exchange capacity is 60 or less, the swelling property due to hydration energy is lowered, which is not preferable for the formation of colloid. Conversely, when it is 120 or more, swelling in the aqueous solution does not occur effectively. The amount of the layer silicate added in the total reaction solution is preferably 0.5 wt% to 2.0 wt%. If the amount is less than 0.5 wt%, the effect of improving the porous structure is insufficient due to the presence of the layer silicate. If the amount is more than 2.0 wt%, the viscosity of the reaction solution is excessively increased.

The second step is the preparation of a copper-manganese mixed oxide (or hydroxide) using copper and manganese salts. Examples of the copper salt include copper acetate (Cu (CH ₃ COO) ₂ ), copper nitrate (Cu (NO ₃ ) ₂ ), copper chloride (CuCl ₂ ), copper sulfate (CuSO ₄ ) . Manganese as, for example, manganese acetate _{(Mn (CH 3 COO) 2} ), manganese nitrate _{(Mn (NO 3) 2)} , manganese chloride (MnCl _2), manganese sulfate (MnSO _4), potassium permanganate (KMnO ₄ ) Or their hydrates may be used. These metal salts are weighed at a desired molar ratio and dissolved in distilled water and added to the layered silicate colloid solution. The base is then titrated with a precipitant to induce a precipitation reaction by hydrolysis. At this time, the base for increasing the pH of the aqueous solution may be used without limitation of the base surface for increasing the pH of the solution such as sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, urea, etc. However, sodium hydroxide, potassium hydroxide and sodium carbonate aqueous solution are most preferably used . Also, the pH of the solution for hydrolysis may be somewhat varied depending on the type of anions to be inserted between the layers, but the pH is usually controlled within the range of 3 to 8. When the pH is less than 3, a basic layered compound by hydrolysis is not formed, and when the pH is 8 or more, the yield of the reactant may be lowered due to some redissolving. The reaction temperature and time are not particularly limited.

In the third step, if a metal oxide precipitate is obtained as a result of the hydrolysis reaction in the presence of the layered silicate colloid, the separation and washing are repeated to remove unreacted materials and impurities.

In the fourth step, the metal (oxide) -layer silicate complex on the washed gel is dried and then heat-treated to obtain a porous copper-manganese metal oxide composite catalyst. The drying of the gel can be carried out without particular limitation by using a conventional drying apparatus. The heat treatment for obtaining the porous metal composite oxide catalyst is preferably carried out in a temperature range of 150 to 500 ° C. When the temperature is lower than 150 ° C, the dehydration reaction is insufficient and conversion to an oxide may be insufficient, and formation of a porous structure is not preferable. On the other hand, when the heat treatment temperature is 500 ° C or higher, the reaction between the constituent metal oxides is promoted to form a crystalline composite metal oxide, for example, spinel CuMn ₂ O ₄ , and the porous structure is reduced in sintering between particles It may be a cause of deteriorating the catalyst characteristics. The reaction time can be selected in the range of 0.5 to 24 hours. If the reaction time is less than 0.5 hour, the dehydration reaction may not occur completely. If the reaction time is more than 24 hours, the partial crystallization or sintering between particles is not economically advantageous.

The amorphous porous copper-manganese oxide catalyst obtained through the above process has many micropores formed between the two-dimensional layered silicate particles and the metal oxide particles as copper-manganese particles are formed in the presence of the nanometer-thick plate-like particles, Can be greatly improved and ultimately can be effectively applied to the adsorption and decomposition removal of harmful or odorous gases.

The amorphous porous copper-manganese composite metal oxide catalyst obtained through the present invention is useful as a catalyst in the field of industrial, automobile, chemical plants, power plants, incinerators, boilers, underpasses and tunnels, underground shopping malls, underground parking lots, , Nitrogen oxides, sulfur oxides, ammonia, volatile organic compounds, and the like.

Figure 1. Diagram of porous copper-manganese composite metal oxide catalyst manufacturing process
Figure 2. Results of X-ray diffraction analysis according to layered silicate content
Figure 3. Nitrogen adsorption-desorption isotherm curves of porous copper-manganese metal oxides synthesized by heat treatment at 280 ℃.

A specific example of the present invention is presented through examples. However, the following examples are intended to illustrate specific examples of the invention, but the scope of the invention should not be construed as being limited by the examples.

Example 1

A process diagram of the preparation of the porous copper-manganese mixed metal oxide catalyst is shown in Fig. First, a synthetic product, Laponite-RD, was used as a layered silicate. 1 g of laponite powder was slowly added to 200 g of distilled water with stirring to prepare a colloid by water swelling. Manganese chloride tetrahydrate (MnCl ^_2. 4H ₂ O) and 54.4g of copper chloride dihydrate (CuCl _^2. 2H ₂ O) was dissolved in 15.3g water 200g preparing a metal solution, and the mixed metal solution to the layered silicate colloid solution . 15.2 g of Na ₂ CO ₃ was slowly added thereto in powder form, and the temperature of the reaction solution was raised to 60 ° C and the hydrolysis reaction was carried out with stirring for 4 hours. When the hydrolysis reaction was completed, solid-liquid separation was carried out by centrifugation and unreacted material and impurities were removed by washing three times with distilled water. The precipitate thus obtained was dried at 120 DEG C for 2 hours to prepare a powdered copper-manganese composite. Followed by heat treatment at 280 DEG C for 2 hours to prepare a porous copper-manganese composite metal catalyst.

Example 2

A porous copper-manganese composite metal catalyst was prepared in the same manner as in Example 1, except that the addition amount of laponite was changed to 1.0 wt% and the rest was the same.

Example 3

The porous copper-manganese composite metal catalyst was prepared in the same manner as in Example 1, except that the addition amount of laponite was 1.5 wt% and the rest was the same.

Comparative Example 1

The copper-manganese metal oxide catalyst was prepared in the same manner as in Example 1 except that no layered silicate was added, and the influence of the layered silicate was confirmed. FIG. 2 shows X-ray diffraction analysis results of the copper-manganese metal oxide catalyst powder synthesized through Comparative Example 1 and Examples 1 to 3. The copper-manganese mixed metal oxide obtained from the X-ray diffraction analysis showed amorphous characteristics. FIG. 3 shows the nitrogen adsorption-desorption isotherms of copper-manganese metal oxide catalyst powders synthesized through Comparative Example 1 and Examples 1 to 3. Nitrogen adsorption - desorption isotherms were measured at liquid nitrogen temperature (77K) and all samples were pretreated for 2 hours under vacuum at 200 ℃. The specific surface area (S _BET ) calculated from the nitrogen adsorption-desorption isotherm is shown in Table 1. As can be seen from FIG. 3 and Table 1, when the layered silicate is included, the specific surface area is improved according to the development of the porous structure.

[Table 1] Specific surface area analysis results by nitrogen adsorption-desorption isotherm analysis

Example 4

The carbon monoxide removal efficiency of the copper-manganese metal oxide catalyst powder synthesized through Comparative Example 1 and Examples 1 to 3 was evaluated at room temperature. The carbon monoxide removal efficiency was evaluated by adding 1.5 g of copper-manganese oxide sample to a 5 L tether bag and measuring the change of concentration with time after injecting 50 ppm of carbon monoxide by using a compound gas detector (Q-RAE Plus) The efficiency was compared. Table 2 compares the carbon monoxide removal rate measurement results. It was confirmed that the porous characteristics of the catalyst were improved and the carbon monoxide removal efficiency was greatly improved by the presence of the layered silicate particles.

[Table 2] Evaluation results of carbon monoxide removal rate

Example 5

200 g of a 1.0 wt% layered silicate colloid solution was prepared by using Laponite-RD, which is a synthetic product of a layered silicate, in the same manner as in Example 2. [ To the solution, 7.1 g of potassium permanganate was added and dissolved, and a solution of 16.5 g of manganese acetate and 45 g of distilled water was titrated. Then, a mixture of 5.6 g of copper acetate and 84 g of distilled water was added to form a precipitate. The reaction was completed by stirring at room temperature for 4 hours. When the reaction was completed, solid-liquid separation was carried out by centrifugation. Followed by drying at 120 DEG C for 2 hours to prepare a powdery copper-manganese composite. The heat treatment was carried out at 280 ° C for 2 hours to prepare a porous copper-manganese composite metal catalyst.

Claims (8)

Cation exchange capacity (CEC) is the swelling of the layered silicate powder of 60-120 mequiv./100g in an aqueous solution of 0.5-1.5 wt% to prepare the colloidal phase layered silicate aqueous solution,
Preparing a copper-manganese mixed metal oxide or oxide by mixing and reacting a copper and manganese salt compound, separating and washing with water, drying and heat treatment to prepare an amorphous porous copper-manganese mixed metal oxide catalyst And the heat treatment is carried out at 150 to 500 ° C for 0.5 to 24 hours. The method of claim 1, wherein the swellable layered silicate is selected from the group consisting of natural or synthetic montmorillonite, bentonite, hectorite, saponite, beidellite, characterized in that at least one of nontronite, laponite, smecton, leucentite or swelling mica is selected. delete delete The method according to claim 1, wherein at least one of copper acetate, copper nitrate, copper chloride, copper iodide, copper bromide or copper sulfate is selected as the copper salt compound. The method according to claim 1, wherein the manganese salt compound is at least one selected from the group consisting of manganese nitrate, manganese nitrate, manganese chloride, manganese iodide, manganese bromide, manganese sulfate and potassium permanganate. delete 6. The method according to claim 1, wherein the harmful gas is selected from at least one of ammonia, hydrogen sulfide, aldehyde, carbon monoxide or nitrogen oxides, The amorphous CuO / CuMn ₂ O ₄ porous catalytic oxide for removing harmful gases, characterized in that the concentration of gas is reduced.

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