KR20020035402A - Oxidation catalysts for elimination of the ethylene gas - Google Patents

Abstract

PURPOSE: Provided is an oxidation catalytic material for effectively eliminating ethylene gas which is generated during the storage of fruits, vegetables and to prolong their freshness. The high concentration of ethylene gas accelerates the aging. The catalytic oxidation material eliminates the ethylene gas and bad odor as well as stopping decay by its fungicide activity, lengthening the storage period. CONSTITUTION: The oxidation catalytic material comprises: a catalyst consisting of compound or mixture of more than two metal components selected from the group consisting of Mn, Cu, Cr, V, Fe, Ti, Si, Ni, Co, Zr and Ce, the above transition metal compounds being prepared by coprecipitation, sol-gel method and impregnation, containing Ti mandatorily; one or more gas absorption material which is porous inorganic material, being selected from sepiolite, TiO2, zeolite, activated carbon and activated clay; and precious metals such as Pd, Pt and anti-fungi materials selected from ion, metal, hydroxide and oxide forms of Ag, Zn and Cu. The catalyst is made to different shapes by molding after adding more than one binders selected from sodium silicate, methylcellulose, CMC, polyvinyl alcohol, silica sol, titania sol, and alumina sol. It is also made into the coating slurry by adding the above binder including catalyst, some distilled water or ion-exchange water.

Description

Oxidation catalysts for elimination of the ethylene gas

After harvesting fruits and vegetables such as vegetables and fruits, if the storage facility maintains high quality, high freshness, and extends the storage period, economic benefits will be very significant not only for consumers but also for retailers.

Factors that may influence the freshness of fruits and vegetables include moisture, bacteria, oxygen, carbon dioxide and ethylene gas concentration. Among them, ethylene gas is a substance that is produced by the ripening process of fruit. Facilitation can lead to early degeneration of plants, so control is critical to maintaining freshness.

Therefore, the present invention can effectively remove the ethylene gas generated during the storage process and maintain its effect for a long time to maintain the freshness of vegetables and fruits for a long time, and at the same time to remove the bacteria and the odor gas generated therefrom during the storage. The purpose of the present invention is to prepare an ethylene gas oxidative decomposition catalyst material having a metal oxide having a multifunctional gas removal and antibacterial function as a main component.

Known leading materials such as vegetables and fruits are ethylene gas adsorption removal materials, antibacterial fungicides, moisture absorbents, coating agents and cool storage materials. Examples of the ethylene gas removing material include ethylene decomposition using an oxidation reaction of potassium permanganate, reactive decomposition of potassium bromide, and adsorption removal using an inorganic porous body such as sepiolite. Impregnated ethylene removers and methods of removing precious metals or transition metal oxides as catalysts have been known. Recently, there are also methods of removing them using photocatalysts. After all, the method of removing ethylene can be classified into adsorption methods such as activated carbon, chemical oxidative decomposition using potassium permanganate or potassium bromide, and oxidative decomposition using metal oxide catalysts.

For example, Japanese Patent Application Laid-Open No. Hei 8-86558 produced a molded body using activated carbon, palladium chloride, and transition metal oxide (manganese, copper, etc.) and used it as an ethylene removal catalyst. This catalyst contains 82 wt% of activated carbon, 17 wt% of binder, 0.2 wt% of manganese, and 0.1 wt% of copper.

As another example, a fruit and vegetable ripening control film for removing ethylene gas by attaching or kneading an inorganic porous material to a polymer film such as vinyl or PE is commercialized. In addition, a microporous film and water droplets through which gas or water vapor can pass This non-condensing bunro film, an antimicrobial film coated with an antimicrobial agent is already commercialized. Of course, ethylene gas adsorption or an oxidizing agent based on a catalyst is partially commercialized.

However, Japanese Patent Application Laid-Open No. 8-86558 has activated carbon as its main component, and the odor gas and ethylene gas are mainly removed by the adsorption action of activated carbon, so the life is limited. In case of high concentration of gas, the adsorption capacity is limited. have. In this case, the individual components are simply mixed, and thus the adsorption capacity of the malodorous gas or ethylene gas is slightly lowered and the catalytic decomposition capacity is not satisfactory.

On the other hand, when potassium permanganate and potassium bromide are used, they are mainly mixed with porous inorganic oxides such as sepiolite and zeolite, and used as ethylene gas adsorption decomposition agents. It is exhausted and has a problem that needs to be replaced, that is, a short lifespan. In addition, the film form of the packaging material of vegetables or fruits and vegetables has a problem that it is difficult to easily process a large amount of products at the same time during storage and transport as a characteristic to be individually packaged.

Therefore, in the present invention, the adsorption capacity of the malodorous gas and ethylene gas is kept constant, and the components of the adsorbed gas are rapidly oxidatively decomposed to maintain the oxidative decomposition capacity of the gas and to prolong the lifetime. In the present invention, by adsorbing catalyst components such as activated carbon, zeolite, and sepiolite for adsorption capacity and oxidative decomposition of adsorbed malodorous gas, metal oxides are prepared by using a copricipitation method to increase the oxidation resolution of ethylene gas. Was synthesized as a multicomponent compound, and the resolution was further improved by impregnating precious metals. In addition, Ag, Zn, Cu components were impregnated or substituted on the porous inorganic material to give an antibacterial action.

In order to effectively extend the freshness of a large amount of vegetables or fruits stored or transported in a certain space, it is to provide an excellent deodorizing performance, semi-permanent use and excellent antibacterial ethylene gas removal catalyst material.

1 is a removal characteristic of ethylene by the oxidation catalyst material of the present invention

2 is a removal characteristic of methyl mercaptan by the oxidation catalyst of the present invention

3 is a removal characteristic of hydrogen sulfide by the oxidation catalyst material of the present invention

The present invention relates to an adsorption oxidative decomposition type catalyst material capable of quickly and long-term removal of ethylene gas generated during the ripening process so as to extend the storage period for fruits and vegetables such as vegetables and fruits.

This catalyst consists mainly of a catalyst material in which a transition metal oxide and a noble metal component are combined, and is composed of a mixture of activated carbon and sepiolite and an antibacterial metal component on which a metal catalyst component is loaded.

As a result of measuring the decomposition and removal ability of ethylene gas using the oxidation catalyst of the present invention, the catalyst was manufactured in the form of honeycomb having a width of 70 mm, a length of 70 mm, a thickness of 30 mm and a thickness of 200 cpsi, and a size of 300 mm, 500 mm, and 300 mm in height. The reactor was fabricated using an acrylic sheet, and the oxidation catalyst was placed at the center of the reactor with 115 ppm of ethylene gas, 66.4 ppm of methyl mercaptan (CH3SH) and 186 ppm of hydrogen sulfide (H2O) as the initial concentration. The results of the measurement of the gas concentrations at intervals of 2 hours using a detector tube (manufactured by Gastec, Japan) are shown in Figs. 1, 2 and 3, respectively. Figure 1 shows the change of concentration with the change of ethylene gas over time, and the oxidative decomposition of ethylene suddenly occurred for about 5 hours, and the removal rate was about 90%. Figure 2 shows the removal characteristics of methyl mercaptan, a kind of malodorous gas, by the catalyst of the present invention. After about 8 hours of operation, 90% of the original gas concentration (66.4ppm) was removed. In the case of Figure 3, the reaction to hydrogen sulfide shows the characteristics of oxidative decomposition at a much faster rate than the previous two gases, and it can be seen that about 80% is removed within about 2 hours.

The characteristic of this catalyst is that the ability to remove ethylene gas is semi-permanent, and in addition to the ability to remove ethylene, it can simultaneously remove bacteria generated during storage and odor gas generated therefrom. The freshness retaining material of the present invention is an energy-low consumption type odor gas oxidative decomposition metal oxide catalyst including a catalyst material capable of absorbing or absorbing malodorous gas and easily oxidatively decomposing adsorption-absorbed gas components even at a relatively low temperature. .

Specifically, at least two of transition metals such as Mn, Cu, Cr, V, Fe, Ti, Si, Ni, Co, Ce, Ag as catalyst materials are composed of an oxidized compound or an oxidized mixture, and Pt, Pd Precious metals, such as metals or oxides, are added to form a main component, and sepiolite, TiO ₂ , zeolite, activated carbon, activated clay, etc. One or more of them may be selected, and the metal catalyst component is added thereto and the metal antibacterial component is added thereto, mixed for a predetermined time, and then processed into a predetermined form. The binder includes at least one of sodium silicate, methyl cellulose, PVA (polivinylalcohol), silica sol, titania sol, and the like.

In the present invention, in order to increase the activity of the catalyst, the catalyst was prepared by synthesizing the metal oxide catalyst as a multicomponent compound by coprecipitation and impregnation. For example, TiO ₂ -MnO ₂ , MnO ₂ -CuO, TiO ₂ -CuO, form a two-component system compounds such as CuO-Fe ₂ O _2, or _{TiO 2 -MnO 2 -CuO, MnO 2} -CuO-Fe 2 O TiO ₂ the addition of three-component compound such as ₂ -SiO ₂ -MnO ₂ Multicomponent compounds such as -CuO were prepared by coprecipitation, and multi-component metal oxide catalysts were prepared by impregnating metal chloride, metal nitrate, metal sulfate, or metal acetate solution to contain other metal oxides.

In addition, the average particle size of activated carbon and sepiolite added to enhance the adsorption power of the gas component is about 10 μm, which is impregnated with an aqueous metal salt solution, followed by drying and heat treatment to form an inorganic powder with a catalyst. Mixed with. Then, when molding to a certain shape, kneading well by adding a binder, and then forming a shape, ie, pellet (ball type), ball type (honey type), honeycomb type (honeycomb type) and heat treatment appropriately Low temperature active catalysts were prepared. Subsequently, Ag, Cu, Zn, etc., which are antimicrobial metals, were impregnated or mixed with a molding catalyst to impart antimicrobial ability.

In more detail, first, the coprecipitation method is alkali in a mixed aqueous solution of two or more chloride, sulfate, nitrate or acetate among Mn, Cu, Cr, V, Fe, Ti, Si, Ni, Co, Ce, and Ag. The aqueous solution is mixed and co-precipitated to produce a precipitate. The catalyst powder is then prepared by washing, drying and calcining steps. Here, the washing is using distilled water at room temperature, the drying was heated in the air for 6 to 24 hours in the range of 100 to 200 degrees Celsius. Subsequently, the metal oxide was prepared by heating at 500 to 700 ° C. for 1 to 24 hours in air using an electric furnace. In addition, the impregnation method was used to attach a metal oxide component to the metal oxide powder prepared as described above, or to attach a noble metal or an antimicrobial metal component to an adsorbent or a refractory.

In addition, the activated carbon powder used in the present invention is made by carbonization of palm charcoal as a carbonaceous raw material. The specific surface area of the activated carbon powder is 1200 m 2 / g or more, and when a catalyst substance is attached to the surface, a certain concentration of aqueous metal salt solution (metal impregnated with salt solution), dried at 100 ° C., heat treated at 200 ° C., and then ground to a fine powder of 1 to 10 μm.

Sepiolite is impregnated with a metal salt solution of a certain concentration using a cation exchange capacity of 18 to 45meq / 100g, specific surface area of 200 to 700㎡ / g, dried at 100 ° C and heat treated at 500 ° C Ground to 1 to 10μm fine powder.

(Example 1)

550 grams of titanium tetrachloride (TiCl ₄ ) was slowly added dropwise to 10 liters of distilled or ion-exchanged water with ice-cooling stirring, and mixed with copper nitrate {Cu (NO ₃ ) ₂ · 3H ₂ O (0.25 mol / l)} 2 liters 2 liters of manganese nitrate {Mn (NO ₃ ) .6H ₂ O (0.25 mol / l)} and 3 liters of zirconium oxychloride {ZrOCl ₂ 8H ₂ O (0.25 mol / l)} are mixed and stirred for about 1 hour. . Ammonia water (NH ₄ OH, 0.5 mol / l) was slowly added dropwise to the mixed solution, followed by stirring to form a precipitate, which was continued until pH 7 was reached. Then stop stirring and hold for about 24 hours. Subsequently, the precipitate is filtered, washed sufficiently with distilled water, and dried for 10 hours in a drying oven at 90 to 100 ° C. It is then calcined at 600 ° C. for 2 hours to form a coprecipitation compound of TiO ₂ -CuO-MnO ₂ -ZrO ₂ composition. It is made into a powder of 20 microns or less using a ball mill. Subsequently, it was impregnated for 5 minutes in an aqueous solution of palladium nitrate {Pd (NO ₃ ) ₂ } having a palladium concentration of 1.6 gPd / l, followed by drying for 6 hours at 120 ° C., and then firing at 450 ° C. for 6 hours (powder A).

Meanwhile, 300 grams of activated carbon powder (more than 20μm) and 300 grams of sepiolite (less than 20μm) made by carbonization of palm charcoal with carbonaceous material were mixed in V-mixer for 3 hours, followed by Mn (NO ₃₎ while 6H ₂ O (0.25mol / l) aqueous solution of copper nitrate and _{{Cu (NO 3) 2 ·} 3H 2 O (0.25 mol / l)} slowly stirring the mixture solution was added to continue the stirring for 30 minutes. After stopping the stirring, the mixture was left for 5 hours, filtered and then washed with distilled water, dried at 90 ° C. for 5 hours, and heat-treated at 250 ° C. for 3 hours. After cooling to room temperature, it is ground to 1 to 10 탆 (powder B).

Powder A and powder B are mixed for 3 hours using a V-mixer, and water, silica sol and methyl cellulose are added in an appropriate amount and kneaded sufficiently so that they can be completely mixed using a kneader. Subsequently, the catalyst is formed in a honeycomb form with a cell size of 200 mm / in and a size of 70 mm X 70 mm X 30 mm. And dried at 100 ° C for 3 hours and calcined at 350 ° C for 5 hours to complete the catalyst.

(Example 2)

Powder A and Example B of Example 1 were prepared in the same manner and mixed with the powder produced by the following process. 5.9 g of silver nitrate (AgNO ₃ ) and 10.0 g of copper nitrate {Cu (NO ₃ ) ₂ · 3H ₂ O} were dissolved in 1000 ml of distilled water, and slowly stirred, 500 g of zeolite powder (Na-zeolite) was slowly added thereto. Mix. Then slowly stir for about 3 hours and leave to stand in air for 10 hours. Then, the powder is filtered, washed with distilled water, dried in a drying furnace at 100 degrees and pulverized, and then heat treated at 500 degrees in an electric furnace for 2 hours. After cooling to room temperature, the particles are ground to a particle size of 1 to 10 μm. (Powder C)

500 grams of Powder A, 500 grams of Powder B and 500 grams of Powder C of Example 1 were mixed in a V-mixer for 3 hours, and then water, silica sol, and methyl cellulose were added to the mixture, and the mixture was thoroughly mixed using kneader. Knead enough to make. Subsequently, the catalyst is formed in a honeycomb form with a cell size of 200 mm / in and a size of 70 mm X 70 mm X 30 mm. And dried at 100 ° C for 3 hours and calcined at 350 ° C for 5 hours to complete the catalyst.

(Example 3)

Add 500 grams, 500 grams, 400 grams and 500 grams of Powder A, B of Example 1 and Powder C of Example 2, respectively, in a V-mixer and mix for 3 hours, followed by adding water, silica sol, and methyl cellulose. Add an appropriate amount and knead sufficiently to mix thoroughly using kneader. Subsequently, the catalyst is formed in a honeycomb form with a cell size of 200 mm / in and a size of 70 mm X 70 mm X 30 mm. And dried at 100 ° C for 3 hours and calcined at 350 ° C for 5 hours, followed by dissolving 5.0 g of silver nitrate (AgNO ₃ ) and 10.0 g of copper nitrate {Cu (NO ₃ ) ₂ .3H ₂ O} in 1000 ml of distilled water. The honeycomb was soaked for 5 minutes, taken out, and the excess aqueous solution was removed using a pneumatic nozzle and dried at 100 ° C. for 2 hours. Then, the same process was repeated three times in silver nitrate and copper nitrate aqueous solution, followed by immersion and drying, followed by heat treatment at 500 ° C. for 3 hours to complete a predetermined catalyst.

(Example 4)

550 grams of titanium tetrachloride (TiCl4) was slowly added dropwise to 10 liters of distilled or ion-exchanged water with ice-cooling stirring, mixed with 2 liters of copper nitrate {Cu (NO ₃ ) ₂ · 3H ₂ O (0.25 mol / l)} 2 liters of {Mn (NO ₃ ) .6H ₂ O (0.25 mol / l)} is added, and it fully mixes. Then 3 liters of zirconium oxychloride {ZrOCl ₂ 8H ₂ O (0.25 mol / l)} is mixed and stirred for about 1 hour. Ammonia water (NH ₄ OH, 0.5 mol / l) was slowly added dropwise to the mixed solution, followed by stirring to form a precipitate, which was continued until pH 7 was reached. Then stop stirring and hold for about 24 hours. Subsequently, the precipitate is filtered, washed sufficiently with distilled water, and dried for 10 hours in a drying oven at 90 to 100 ° C. Here, 200 grams of sepiolite (20 μm or less), 200 grams of zeolite powder (20 μm or less) and 200 g of activated carbon powder with a specific surface area of 1200 m 2 / g or more are mixed in a V-mixer for 3 hours. (Powdered)

In a separate vessel, 8.5 grams of manganese nitrate {Mn (NO ₃ ) 6H ₂ O}, 3.0 grams of silver nitrate (AgNO ₃ ) and 1.5 grams of palladium nitrate {Pd (NO ₃ ) ₂ } were dissolved in 1500 ml of distilled water. Put it. (Aqueous solution)

Methyl cellulose, silica sol and alumina sol are added to the 'powder value' and 'aqueous solution value' together with distilled water and thoroughly kneaded in a kneader for at least 1 hour to form a slurry. Dip the alumina honeycomb with the size of 70mm x 70mm x 30mm at 200cell / in, remove it, remove excess coating liquid by using a high pressure nozzle, dry it at 100 ° C for 3 hours, and then fire at 500 ° C for 5 hours. To produce honeycomb type catalyst.

(Example 5)

The catalyst of Example 1 was manufactured in a honeycomb form having a width of 70 mm, a length of 70 mm, a thickness of 30 mm, and 200 cpsi, and a reactor was fabricated using an acrylic plate having a width of 300 mm, a length of 500 mm, and a height of 300 mm. An initial concentration of 115 ppm, 66.4 ppm methyl mercaptan (CH ₃ SH) and 186 ppm hydrogen sulfide (H ₂ S) was placed at the center of the oxidation catalyst, and the concentration of the gas was changed over time. The results of measurements at 2 hour intervals using Japan) are shown in Figures 1, 2, and 3, respectively.

The present invention is a semi-permanent adsorption and oxidation catalyst material that can be used semi-permanently by forming a transition metal oxide, a noble metal component, an inorganic adsorbent component into a complex compound, which gives oxidative decomposition of ethylene gas, removal of odor gas and antibacterial ability. This can significantly reduce the odor gas, ethylene gas, and bacteria generated during cold storage of fruits and vegetables such as vegetables and fruits, distribution to refrigerated vehicles, and storage at room temperature. The economic benefit effect is very large.

Claims (7)

Adsorption agent of the catalyst material which consists of two or more components as a compound or a mixture among transition metal oxides, such as Mn, Cu, Cr, V, Fe, Ti, Si, Ni, Co, Zr, Ce, and the gas which consists of porous inorganic materials A transition metal oxide catalyst for ethylene gas oxidative decomposition, which contains noble metal components such as Pd and Pt and antibacterial components such as Ag, Zn and Cu, which can improve gas decomposition activity. In claim 1, the transition metal oxide may be prepared by copricipitation, sol-gel, and impregnation, and includes a Ti component and is made of a compound or a mixture of two or more metal components. Characterized in that. The adsorbent of the gas of claim 1 is an adsorbent of ethylene gas or a catalyst material carrier, and includes at least one of sepiolite, TiO ₂ , zeolite, activated carbon, and activated clay. Ethylene Gas Adsorption Oxidative Decomposition Catalyst The antimicrobial metal component of claim 1 includes Ag, Zn, Cu, which is included in the ethylene gas adsorption or catalyst component in the form of ions, metals, hydroxides or oxides. A binder may be added when each component of claim 1 is mixed and manufactured in a specific shape, and as a binder, sodium silicate, methyl cellulose, CMC, PVA (polivinylalcohol), silica sol, titania at least one of sol and alumina sol. Mixing the components of claim 1 and the components of claim 5 and adding an appropriate amount of distilled water or ion-exchanged water and kneading sufficiently to prepare a coating slurry. Preparation of ethylene gas adsorption oxidative decomposition catalyst of a certain shape using the components of claim 1, claim 6, and artificially through the gas to be treated containing an appropriate amount of ethylene and the like to facilitate the adsorption oxidation reaction smoothly Characterized by the manufacture of a tool or device and its mounting or inclusion therein.