KR20120096171A

KR20120096171A - Low temperature oxidation catalyst for removal of toxic gases and preparation method thereof

Info

Publication number: KR20120096171A
Application number: KR1020110015422A
Authority: KR
Inventors: 송길홍; 이재수; 차경순
Original assignee: 주식회사 제너럴시스템
Priority date: 2011-02-22
Filing date: 2011-02-22
Publication date: 2012-08-30

Abstract

The present invention relates to a catalyst for low temperature oxidation for removing harmful gases, more specifically 1 selected from the group consisting of copper (Cu), manganese (Mn), nickel (Ni), chromium (Cr), potassium (K). Species or more transition metal precursors; And a novel catalyst containing at least one active noble metal ion selected from the group consisting of platinum (Pt), palladium (Pd) and rhodium (Rd), wherein the catalyst is a low temperature oxidation reaction, as well as sulfur dioxide, formaldehyde and acet. It can effectively remove toxic and harmful gases such as aldehydes and ammonia, and can be used as a material in various fields from indoor air purification to pollution-generating industrial sites.

Description

Low temperature oxidation catalyst for removal of toxic gases and preparation method

The present invention relates to a catalyst for low temperature oxidation for removing harmful gases, more specifically 1 selected from the group consisting of copper (Cu), manganese (Mn), nickel (Ni), chromium (Cr), potassium (K). Species or more transition metal precursors; And a novel catalyst containing at least one active noble metal ion selected from the group consisting of platinum (Pt), palladium (Pd) and rhodium (Rd), wherein the catalyst is a low temperature oxidation reaction, as well as sulfur dioxide, formaldehyde and acet. The present invention relates to a catalyst for low temperature oxidation to remove toxic harmful gases that can be used in various fields from indoor air purification to pollution-generating industrial sites by enabling effective removal of toxic and harmful gases such as aldehydes and ammonia.

The combustion exhaust gases emitted from various combustion apparatuses such as boilers, gas turbines, diesel engines, and gas engines generally contain volatile organic compounds derived from CO, NOx, SOx, and unburned fuel.

There are many ways to selectively remove certain harmful gases, but the most common method is to use sorbents and catalysts.

Activated carbon, zeolites, and the like are commonly used as adsorbents. However, these adsorbents have a limit in adsorption capacity, and thus have a disadvantage in that the adsorbent deteriorates or disappears after a certain time and is not easy to reuse. In addition, there is a disadvantage in that the adsorption treatment of various harmful gases due to the characteristics of activated carbon.

In addition, in the case of using a catalyst, there are advantages in that various active metals are introduced into the carrier to be treated at a relatively high temperature and can be recycled and recycled several times. However, there is a problem that core technology development is not easy.

As expensive precious metals are used as active metals to purify harmful gases, research on technologies that minimize the use of these precious metals or use transition metals as co-catalysts for precious metals is an important issue. There is a problem that technology development is not easy.

In particular, expensive noble metals are generally used as active metals for the purification of toxic gases that are harmful to the human body. Therefore, due to cost competitiveness, the use of such precious metals is minimized, or transition metals as co-catalysts as noble metals are used. Research is being actively conducted.

As an oxidation catalyst at low temperature similar to the present invention, hop calite composed of a mixture of manganese oxide, copper oxide, tin oxide, and the like is relatively economical, but one or two, that is, one that does not remove various harmful gases, Efficacy is excellent by the ability to remove cows, but this also has the drawback that the efficacy decreases in the presence of more than 10% moisture.

In addition, the catalyst composed of nano-sized (5 nm) gold particles supported on the metal oxide is excellent in the ability to oxidize CO at room temperature, but requires a high level of technology to uniformly disperse the metal particles uniformly to nano-sized.

As such, the noble metal catalyst is not yet economical, and in particular, it is easily inactivated by water or sulfur oxides, and thus the function of the catalyst is lost, so much research is required for practical use.

Accordingly, the present inventors have endeavored to develop a novel catalyst that is low in production cost and long-term in efficacy even when water coexists and easily disperses active metal ions evenly and removes a large number of toxic gases even at low temperatures. Transition metal precursors of copper (Cu), manganese (Mn) and potassium (K); And it was confirmed that the catalyst containing the active noble metal ions of platinum (Pt) and palladium (Pd) can effectively remove various toxic gases as well as carbon monoxide at low temperature at the same time and completed the present invention.

The main object of the present invention is to provide a low temperature oxidation catalyst for removing harmful gases that can more efficiently remove toxic harmful gases such as carbon monoxide, acetaldehyde, ammonia at low temperatures.

Another object of the present invention to provide a method for producing a low-temperature oxidation catalyst for removing the harmful gas.

The present invention, at least one transition metal precursor selected from the group consisting of copper (Cu), manganese (Mn), nickel (Ni), chromium (Cr), potassium (K); And at least one active precious metal ion selected from the group consisting of platinum (Pt), palladium (Pd), and rhodium (Rd). The catalyst is 20? Since it can be oxidized at low temperature of 80 ℃, it effectively removes harmful gases at room temperature.

In particular, it is preferable that the active noble metal contains platinum (Pt) and palladium (Pd) ions and the transition metal precursor contains copper (Cu), manganese (Mn) and potassium (K) ions.

At this time, the mass fraction is 2.35601% to 2.37516% for palladium ions, 0.04757% to 0.04848% for platinum ions, 13.35278% to 13.46967% for copper ions, 81.22348% to 81.37473% for manganese ions, and potassium ions Silver is preferably contained in 2.86506% to 2.889%.

That is, it is most preferable that the palladium ions and the platinum ions are contained in a molar ratio of 47: 1, and the copper ions, manganese ions and potassium ions are contained in a mass ratio of 268: 1626: 1.

In addition, the palladium ions and the platinum ions may be derived from precursor compounds in the form of nitrates, halides, acetates, ammonium salts, ammonium complexes, and hydroxides, among which the palladium ions are derived from precursor compounds in the form of nitrates, Platinum ions are preferably derived from precursor compounds in the form of ammonium salts.

In addition, the copper and manganese ions may be derived from nitrates, and potassium ions may be derived from precursor compounds in the form of acetates.

The harmful gas to be removed by the catalyst of the present invention includes, but is not limited to, carbon monoxide, sulfur dioxide, acetaldehyde, formaldehyde, volatile organic compounds, ammonia, and the like.

On the other hand, the catalyst of the present invention is more preferably prepared by the coprecipitation method, and thus, provides a method for producing a catalyst for low temperature oxidation for removing the harmful gas comprising the following steps.

(a) applying an acid chloride _{(? H 2 PtC l6 6H 2} O) and palladium nitrate solution was added a solution of sodium carbonate and a nitrate solution of Mn, Cu of (Pd (NO ₃₎ ₂₎ co-precipitation;

(b) separating the precipitate by centrifugation;

(c) ionizing and drying; And

(d) firing

Particularly, in the step (a), platinum (Pt) and palladium (Pd) are used as active noble metals, and all copper (Cu), manganese (Mn) and potassium (K) are contained as transition metal precursors, and pH8 is It is preferable to carry out while maintaining.

In step (b) and (c), the water may be separated by a centrifugal separator, firstly dried at about 150 ° C., then dissolved in distilled water, and further dried at about 200 ° C. after the ionization process once more. . And finally performs a firing process of step (e) at about 200 ℃ ~ 400 ℃. Most preferably, it is made at about 400 ℃.

As described above, the present invention utilizes a novel catalyst containing palladium ions, platinum ions, copper ions, manganese ions, and potassium ion salts in an optimal composition ratio to efficiently treat various toxic gases at low temperatures without a separate heating device. As it can be removed, it can be used as a material in various fields from indoor air purification to pollution-producing industrial sites.

1 is a diagram showing the process and equipment for producing a catalyst of the present invention.
In the case of the prohmaldehyde in FIG.
3 shows the case of toluene,
4 shows the case of carbon monoxide,
5 shows the case of nitrogen dioxide,
Figure 6 is a graph confirming the harmful gas removal capacity of the catalyst of the present invention for the case of ammonia.
Figure 7 is a graph comparing the characteristics when the catalyst of the present invention prepared by the impregnation method and co-precipitation method.
8 is a graph comparing temperature characteristics and conversion rates of the catalyst of the present invention with a catalyst having a different composition.

Hereinafter, the present invention will be described in detail.

The present invention relates to a new catalyst for oxidation that can be removed at low temperatures by an easy method of toxic harmful gases such as carbon monoxide, sulfur dioxide, acetaldehyde and ammonia.

The catalyst of the present invention comprises at least one transition metal precursor selected from the group consisting of copper (Cu), manganese (Mn), nickel (Ni), chromium (Cr), potassium (K); And a catalyst containing at least one active precious metal ion selected from the group consisting of platinum (Pt), palladium (Pd), and rhodium (Rd), in particular, the active precious metal containing platinum (Pt) and palladium (Pd) ions. And it is preferable to contain together copper (Cu), manganese (Mn), and potassium (K) ion as a transition metal precursor.

The catalyst can be oxidized at low temperatures and, unlike the conventional use of carbon monoxide removal, is very efficient in removing not only the carbon monoxide but also various toxic harmful gases.

The present invention relates to a catalyst for removing harmful gases including volatile organic compounds such as carbon monoxide, formaldehyde, BTEX (Benzene, Toluene, Ethylbenzene, Xylenes).

Harmful gases

The catalyst of the present invention and the method of using the same can be applied to harmful gases emitted from various conventional industrial apparatuses or facilities (hereinafter referred to as sources). Specifically, combustion exhaust gases of boilers, gas turbines, diesel engines, gas engines, heating furnaces, and other industrial processes are listed. The components contained in the combustion exhaust gas vary depending on the above source, and also on environmental conditions such as emission standards.

Specifically, examples of gas components that may adversely affect the environment include CO, for example, nitrogen oxides (NOx), sulfur oxides (SOx), and the like.

In the case of combustion exhaust gas, volatile organic compounds (VOCs), which are components derived from fuel but not combusted, are contained, and adverse effects on the environment are problematic.

VOC compound refers to a substance that causes photochemical smog by generating photochemical oxidizing substances such as ozone and pan (PAN: peroxyacetyl nitrate) when it coexists with nitrogen oxide in the air to produce photochemical reactions through sunlight. It is an air pollutant and a carcinogenic toxic chemical and a precursor to photochemical oxides. It is also a source of global warming and can cause odors. In particular, 31 substances and products including benzene, acetylene and gasoline are regulated. From solvents used in many industries to organic gases emitted from chemical and pharmaceutical factories or plastic drying processes, hydrocarbons commonly used in everyday life such as low boiling liquid fuel, paraffin, olefins, aromatic compounds, etc. do.

The catalyst of the present invention is also effective for the treatment of the exhaust gas containing the carbon monoxide, the above-described nitrogen oxides (NOx) and volatile organic compounds. For example, it is effective for removing carbon monoxide, formaldehyde, acetaldehyde, toluene, ammonia and the like.

The catalyst for removing the noxious gas of the present invention and the method using the same are effective even for low concentration of noxious gas, and specifically, even if the concentration of noxious gas is 1000 ppm or less, it is effective. For example, aldehydes such as acetaldehyde (CH3CHO) are at a concentration of about 500 ppm or less, ammonia (NH3), hydrogen sulfide (H2S), methyl mercaptan (CH3SH) and the like at a concentration of about 200 ppm or less, and Others such as benzene (C ₆ H ₆ ), xylene (C ₆ H ₄ (CH ₃ ) ₂ ) and toluene (C6H5CH3) can be processed at concentrations up to about 1000 ppm.

catalyst

In the catalyst for low temperature oxidation for the removal of harmful gases of the present invention, the catalyst is characterized by consisting of a mixed oxide containing a specific transition metal precursor and a specific active noble metal ion.

Certain transition metal precursors and active noble metal ion-containing catalysts of the present invention may be used alone or supported on a carrier, and have a constant activity even when they contain water (vapor). In addition, when the content of water is completely removed or lowered, it is possible to effectively remove various industrial harmful gases because of its excellent regeneration and high stability to restore the original activity.

(Catalyst Component A)

In the catalyst for low temperature oxidation for removing the noxious gas of the present invention, a catalyst component consisting of a noble metal element is used as the catalyst component A. Specifically as the noble metal element, for example, at least one of the group consisting of Pt, Pd, Ph, Rd, Ir, and Au can be used, and preferably 1 of platinum (Pt), palladium (Pd), and rhodium (Rd). The species or more is most preferably used together with platinum (Pt) and palladium (Pd).

The catalyst component A may be a metal composed of the noble metal element, or may be a compound (oxide, etc.).

As a feedstock for the catalyst component A, a material used for producing a conventional catalyst can be used. Specifically, they may be nitrates, halides, acetates, ammonium salts, cancer complexes, hydroxides and the like. That is, the palladium ions and the platinum ions may be derived from precursor compounds in the form of nitrates, halides, acetates, ammonium salts, am complexes and hydroxides, among which the palladium ions are derived from precursor compounds in the form of nitrates, Platinum ions are preferably derived from precursor compounds in the form of ammonium salts.

In addition, if the catalyst component A is used by being supported on a carrier, a means common to a conventional noble metal supported metal oxide catalyst can be employed. In the treatment step in which the catalyst component A is supported on the carrier, it is carried out in a high concentration near the outer surface of the carrier. That is, it can be localized in the carrier on the outer surface and / or near the outer surface. In the case of removing harmful gases such as carbon monoxide by contacting the catalyst with the exhaust gas at a high space velocity (SV), it is thought that most of the fine action by the catalyst occurs in the surface layer portion of the catalyst. In such a case, the catalyst component A is unevenly supported and supported on the surface of the catalyst contacted with the noxious gas, thereby improving the treatment efficiency of the noxious gas by the catalyst.

Although the amount of catalyst component A varies depending on the combination of materials, the conditions of the supporting process, and the like, the palladium ions are generally 2.35601% to 2.37516%, and the platinum ions are 0.04757% to 0.04848% based on the total mass of the catalyst. It is characterized by. In particular, it is preferable that palladium ion and platinum ion are contained in the mass ratio of 47: 1. If the loading amount of the catalyst component A is too small, the catalytic activity becomes low. Even if the supporting amount of the catalyst component A is too large, the efficiency of the improvement of the activity cannot be expected, which only impairs the economical efficiency, and also results in a disadvantage that the conversion of SO2 to SO3 is also high.

The catalyst component A is usually supported on the carrier in the form of particles. The particle diameter of the catalyst component A is preferably 30 nm or less, more preferably 20 nm or less. The smaller the particle size of the catalyst component A and the more highly dispersed, the higher the activity.

( Catalyst Component B )

In the catalyst for low temperature oxidation for removing the noxious gas of the present invention, a catalyst component consisting of a transition metal precursor is used as the catalyst component B.

The term “precursor” refers to any compound, complex, and the like, upon calcination or use that the initial phase decomposes or otherwise converts into a catalytically active form. Examples include, but are not limited to, chlorides, hydroxides, amines, hydrates, and mixed compounds or complexes.

As the transition metal element, for example, one or more metals selected from the group consisting of copper (Cu), manganese (Mn), nickel (Ni), chromium (Cr), and potassium (K) can be used, and the compound (Acid compounds) and the like. Preferably, copper (Cu), manganese (Mn) and potassium (K) ions are used together as a transition metal precursor. It is known that the type of anion moiety associated with the transition metal compound does not significantly affect the performance of the catalyst. Examples include hydroxides, carbonates, bicarbonates, nitrites, nitrites, formates, acetates, acetates, oxalates, citrates and lactates. (lactate), oxides (oxides), and the like, halogens (halides), sulfate (sulfate) and the like are examples.

The catalyst component B can improve the treatment performance of various volatile organic compounds and can effectively reduce the amount of the catalyst component A used. At the same time, since the catalyst component B coexists in the catalyst, stable treatment efficiency can be maintained for a long time even when the amount of the catalyst component A supported is small.

Even when the catalyst component B is supported and used, the catalyst component B is not particularly limited, and can be supported by a method used for producing a conventional catalyst. The catalyst component B has a mass fraction of 13.35278% to 13.46967%, manganese ions 81.22348% to 81.37473%, and potassium ions 2.86506% to 2.889%, based on the total mass of the catalyst. Most preferably, copper ions, manganese ions, and potassium ions are contained in a mass ratio of 268: 1626: 58.

If the supported amount of the catalyst component B is too small, the above-described effects peculiar to the catalyst component B cannot be obtained, and even if the supported amount exceeding the above range is increased, the effect on the activity improvement is difficult to be expected, and on the other hand, the activity is lowered.

As such, the present invention relates to a catalyst containing palladium (Pd) ions, platinum (Pt) ions, copper (Cu) ions, manganese (Mn) ions, and potassium (K) ions, and most preferably, It may be contained in the mole fraction or mass fraction range, such as.

Mole fraction

pt: 0.0136% ~ 0.01366%

pd: 1.24014% ~ 1.25034%

Mn: 82.72013% to 82.86334%

Cu: 11.77697% ~ 11.88162%

K: 4.10386% ~ 4.13815%

Mass fraction

pt: 0.04757% to 0.04848% (0.04)

pd: 2.35601% ~ 2.37516% (2.37)

Mn: 81.22348% ~ 81.37473% (81.30)

Cu: 13.35278% ~ 13.46967% (13.41)

K: 2.86506% ~ 2.889% (2.88)

In this ratio, the catalyst of the present invention is low in production cost, continuous in efficacy and easily disperses the active metal ions evenly, and can effectively remove a large number of harmful gases at low temperature (room temperature) at the same time.

In another aspect, the present invention relates to a method for preparing a catalyst for low temperature oxidation for removing the noxious gas.

The specific noble metal catalyst and the transition metal oxide catalyst may be mixed with an appropriate binder and aqueous solution of a metal precursor to prepare a catalyst having excellent catalytic activity at room temperature through a drying process, an ionization process, a drying process, and a calcination process. At this time, a catalyst is prepared by the deposition precipitation method.

Hereinafter, a low temperature oxidation catalyst production process for removing harmful gases of the present invention will be described as an example.

First, the copper, manganese, and potassium compounds of each catalyst component B are dissolved in distilled water in a desired mass ratio, mixed with a solution of a noble metal (catalyst component A: platinum, palladium) prepared first, stirred for 30 minutes, and then the aqueous solution of the metal precursor and NH Stir and adjust to pH 8 while adding ₄ OH or Na ₂ CO ₃ aqueous solution.

The completely mixed reactant is separated and dehydrated from the surface of the active metal particles and the metal precursor mixed with a vacuum rotary centrifuge (Ionization process). After drying at about 150 ° C., distilled water is added to an appropriate amount of the dried active metal and the metal precursor. After stirring, the water is separated and separated from the re-mixed metal precursor and the active metal by a centrifuge (Ionization process). Then, after drying for 6 hours at about 200 ℃ 400 ℃ 8hr N ₂ Firing in an atmosphere prepares the catalyst of the present invention.

A carrier may also be used.

The treatment method of supporting the catalyst component A or the catalyst component B on the carrier is not particularly limited, but an impregnation method or a coprecipitation method can be used, for example. Preferably, coprecipitation can be used. The supporting order is not particularly limited either. After supporting the catalyst component A, the catalyst component B may be supported, and before the catalyst component A is supported, the catalyst component B may be supported, and the catalyst component A and the catalyst component B may be simultaneously supported. It is preferable to simultaneously support component A and catalyst component B.

In one embodiment of the impregnation method, in the present invention, platinum chloride and palladium nitrate are dissolved in distilled water with a salt containing platinum palladium, which is a precious metal, and the solution is warmed while being uniformly deposited by adding a predetermined amount of metal oxide (manganese, copper, etc.). After drying, it may be prepared by sintering and sintering at 200 ° C and 400 ° C in an electric furnace. In addition, in one embodiment of the coprecipitation method, in the present invention, sodium carbonate in a solution of chloroplatinic acid (H2PtCl6-6H2O) and palladium nitrate (Pd (NO3) 2) and nitrate solutions such as Mn and Cu, which are metal oxide carriers. Coprecipitation was added by adding a solution of, and the precipitate was separated by centrifugation, washed with water, dried and calcined in an electric furnace at 200 ° C. and 400 ° C. for 8 hours to prepare a catalyst. Using this coprecipitation method, finer platinum and palladium particles can be supported on the metal oxide carrier than the impregnation method.

Accordingly, in one embodiment, the present invention provides a method for preparing a catalyst for low temperature oxidation for removing the noxious gas, comprising the following steps:

(a) coprecipitation by adding a solution of sodium carbonate to a solution of chloroplatinic acid (H2PtCl6? 6H2O) and palladium nitrate (Pd (NO3) 2) and a nitrate solution of Mn and Cu;

(b) separating the precipitate by centrifugation;

(c) ionizing and drying; And

(d) firing

In particular, in step (a), it is preferable to use platinum (Pt) and palladium (Pd) as active noble metals, and to include all of copper (Cu), manganese (Mn) and potassium (K) as transition metal precursors. It is preferable to carry out while maintaining pH8.

Steps (b) and (c) may separate the water by a centrifugal separator, and after first drying at about 150 ° C., dissolves in distilled water again, passes through an ionization step once more, and then secondarily dried at about 200 ° C. And finally performs a firing process of step (e) at about 200 ℃ ~ 400 ℃. Most preferably, it is made at 400 ℃.

As such, the active metal ions contained in the catalyst for low temperature oxidation prepared according to the present invention may remove various toxic gases while causing an oxidation / reduction reaction.

The most basic mechanism shown in the literature for low temperature oxidation catalysts is the redox mechanism first proposed by Rogers et al. In this reaction, the CO gas in the processing gas is oxidized by the catalytic oxygen, and the reduced oxide then takes oxygen. If the surface oxygen of the catalyst is Os and the empty site is V

CO + O _S → CO ₂ + V

V + 1 / 2O ₂ → CO _S

. In addition to this basic mechanism, it is also proceeded by the intermediate carbonate (Carbonate) as follows.

_S + 2O → CO + CO _3S V

CO _3S → CO ₂ + O _S

Here, the reversibility of the last reaction is obtained by adsorption of carbon dioxide to the surface of the catalyst by carbon dioxide, which has been verified by studying the exchange of oxygen between carbon dioxide and the oxide surface.

The mechanism of the catalyst of the present invention is as follows.

(One) CO + Pd (NO ₃ ) ₂ + H ₂ O → CO ₂ + Pd (O) + 2HNO ₃

(2) Pd (O) + 2Cu (NO ₃ ) ₂ → Pd (NO ₃ ) ₂ + Cu ⁺

(3) 2Cu ⁺ + 2H ⁺ + 1 / 2O ₂ → 2Cu ⁺² + H ₂ O

(4) Pd (NO ₃ ) ₂ + Cu ⁺⁺ → Cu (NO ₃ ) ₂ + Pd (O)

(CO + 1 / 2O ₂ → CO ₂ )

In the above scheme, Pd (NO ₃ ) ₂ is reduced to Pd (O) by carbon dioxide and CO is oxidized to carbon dioxide. In addition, Cu + is oxidized by oxygen and hydrogen ions to survive as Cu ++.

As a result, in the above reaction scheme, the precious metals (Pd) and Cu ++ are accompanied by redox reactions, and are regenerated and recycled, respectively, to appropriate amounts of precious metals (platinum, palladium), Cu (NO ₃ ) ₂ , Mn (NO ₃ ) ₂ , and K _2. CO ₃ is a mechanism to involve oxidation and reduction with each other. And, Mn or K serves as an enhancer of the reaction.

Using the catalyst prepared in the present invention as described above to remove various toxic gases by oxidation / reduction reaction. In general, benzene, toluene and acetaldehyde, which are gas components with CmHn composition, are oxidized to form carbon dioxide and water, and ammonia is adsorbed on active metal to form nitrogen and water by redox reaction. In the case of hydrogen sulfide having a sulfur component (S), methyl mercaptan and the like, sulfate is formed as a product and removed.

The catalyst for removing a noxious gas of the present invention is an integrally formed body comprising only the catalyst composition carrying a catalyst component.

The catalyst is usually used by being accommodated in a catalytic reactor composed of metal or the like. The catalyst reactor is provided with an inlet and an outlet of the exhaust gas, and is provided with a structure such that the exhaust gas can efficiently contact the catalyst contained therein.

As described above, the present invention is a catalyst capable of simultaneously removing gases such as carbon monoxide, sulfur dioxide, acetaldehyde and ammonia, which are toxic and economically, even at low temperatures without a separate heating device.

That is, in the past, at the low temperature, the harmful exhaust gas reducing catalyst portion is excellent in removing any harmful gas (specific harmful gas) with a mixture of tin oxide, manganese oxide, copper oxide, etc. Has the drawback that the efficacy is reduced. In addition, the noble metal catalyst supported on the metal oxide has excellent activity for purifying characteristic gas harmful to the human body, but requires a reaction temperature of at least 180 or higher, and it is economically and practical to easily inactivate poisonous substances such as sulfur components and lose the function of the catalyst. There were a lot of problems.

In contrast, the present invention is low in production cost, long-lasting and easy to disperse the active metal ions evenly and can remove toxic gases even at low temperature (room temperature), which can remove various toxic gases as well as one harmful gas at the same time. It is a low-temperature oxidation catalyst that is economically and practically excellent and can be used as a catalyst for improving indoor air quality.

Example

Hereinafter, the present invention will be described in more detail with reference to Examples. These examples are only for illustrating the present invention, and it will be apparent to those skilled in the art that the scope of the present invention is not to be construed as being limited by these examples.

Example 1 Preparation of Catalyst for Low Temperature Oxidation

Pd (NO ₃ ) 0.0087 mole, Pt (NH ₃ ) ₄ (OH) ₂ solution 0.0965 x 10 ^-3 mole, Mn (NO ₃ ) ₂ ˜3H ₂ O 0.58 mole, Cu (NO ₃ ) _{2 to} 3 H ₂ O 0.083 mole, K ₂ CO ₃ 0.029 mole was dissolved in order to prepare a mixed aqueous solution. At this time, pH 8 was maintained.

The mixed aqueous solution thus prepared was separated from the water by using a centrifuge as in the ionization process, dried in a 150 ° C. drying furnace, and then dissolved in 300 ml of distilled water. The mixed aqueous solution was separated from the water using a centrifuge and then dried in a 200 ° C. drying furnace. Thereafter, the mixture was calcined at 400 ° C. to obtain a catalyst for low temperature oxidation (catalyst 3 in Table 1 below).

Comparative example 1: Characteristics according to the catalyst production method

First, the catalyst for low temperature oxidation of this invention was manufactured by the impregnation method.

Platinum chloride and palladium nitrate are dissolved in distilled water with a salt containing platinum palladium. The solution is added to a certain amount of metal oxides (manganese, copper, etc.), dried and heated slightly with uniform deposition. To give a catalyst.

On the other hand, the catalyst for low temperature oxidation of the present invention was prepared by a coprecipitation method. A solution of sodium carbonate (Na ₂ CO ₃ ) was added to a solution of chloroplatinic acid (H2PtCl6-6H2O) and palladium nitrate (Pd (NO3) 2) and nitrate solutions such as metal oxide carriers, Mn and Cu, and coprecipitation was carried out. After separation by centrifugation, the mixture was washed with water, dried and calcined in an electric furnace at 200 ° C. and 400 ° C. for 8 hours to obtain a catalyst.

As described above, catalysts of the metal oxide carrier and the noble metal solution according to the preparation method were prepared by two methods, a coprecipitation method and an impregnation method, and their toluene oxidation capability was compared.

As a result, as can be seen in Figure 7, the catalyst prepared by the coprecipitation method showed a superior oxidation capacity than the case prepared by the impregnation method. This is because the catalyst prepared by the coprecipitation method has a much finer surface area than that of the impregnation method because the size of the precious metal particles is very fine. Therefore, by using this coprecipitation method, finer platinum and palladium particles can be supported on the metal oxide carrier than the impregnation method.

Example 2 ? 5

In the same manner as in Example 1, using the metal precursors Cu, Mn, K in addition to platinum and palladium as the active metal as described below to prepare a low-temperature oxidation catalyst with the composition and content shown in Table 1.

Experimental Example 1: remove harmful gas

How to measure the residual concentration of treatment while operating the test specimen at the rated air flow (surface speed 0.5 m / s, 1.0 m / s) when hazardous gas (toluene, carbon monoxide, nitrogen dioxide, etc.) is reached within the range of 10 to 15 ppm in a sealed chamber. Was used.

Of the catalysts prepared in Table 1, the catalyst 3 was converted to chloroaldehyde (H.CHO), toluene (C ₇ H ₈ ), carbon monoxide (CO), nitrogen dioxide (NO ₂ ), and ammonia.

At this time, the tested temperature and relative humidity are as follows.

Exam conditions Item Temperature Relative Humidity (%) Degassing test 23 ℃ 49

Each harmful gas removal rate is shown in FIG. 2 to FIG. 6 as a change in concentration with time.

In FIG. 2, the case of the prohmaldehyde, the case of toluene in FIG. 3, the case of carbon monoxide in FIG. 4, the case of nitrogen dioxide in FIG. 5, FIG. 6 is the harmful of the catalyst prepared in Example 1 with respect to the case of ammonia. The gas removal ability was confirmed.

As a result, it was found that the concentration of toxic gases such as prohmaldehyde, toluene, carbon monoxide, nitrogen dioxide, ammonia and the like decreased significantly after about 5 to 10 minutes at a low temperature of 23 ° C. In addition, when a catalyst containing platinum, palladium, and metal precursors Cu, Mn, and K ions are present in an appropriate ratio, oxidation / reduction reactions are performed smoothly, and various toxic gases can be efficiently removed. have.

Comparative example 2: Comparison of Characteristics of Catalysts According to Different Component Combinations

The temperature characteristics and the conversion rate were compared with the low temperature oxidation catalyst of the present invention and another catalyst composed of an active noble metal and a metal precursor having a different composition. That is, the Cu / Mn / K / pt / pd catalyst of the present invention, Pd / MnO _{2 made by} other companies And the conversion rate with respect to temperature for Cu / Mn was observed.

At this time, Pd / MnO ₂ manufactured by another company The main components of the catalyst are Pd and Mn, and the mixing ratio is approximately Pd <0.2 wt%, Mn: 95 wt%, and other Ni> 4 wt%, and the other components Cu / Mn are Cu and Mn. The mixing ratio is composed of Cu: 24 wt%, Mn: 74 wt%, and other Co (cobalt) <2 wt%.

As a result of observing the conversion rate according to the temperature, as can be seen in FIG. 8, the Pd / MnO ₂ and Cu / Mn catalysts have an oxidation capacity initially but then rapidly decrease and stabilize after a certain time, in particular, the conversion rate is 60 It was confirmed to decrease to less than% (temperature 50 ℃) and less than 35% (temperature 20 ℃).

On the contrary, the pt / pd catalyst using the metal oxide carrier of Cu / Mn / K prepared by the coprecipitation method of the present invention has excellent oxidation ability after about 15 to 20 minutes until the initial stabilization time, so that 90 to about 30 minutes before and after The conversion was maintained at more than 95% and showed higher oxidative efficiency at 50 ° C than at 20 ° C.

That is, in the case of using a catalyst containing the components of the present invention in an optimum composition ratio, it can be seen that the oxidation capacity is maintained at a high efficiency, so that the removal of harmful gases is more effective.

Claims

At least one transition metal precursor selected from the group consisting of copper (Cu), manganese (Mn), nickel (Ni), chromium (Cr), and potassium (K); And
A catalyst for low temperature oxidation for the removal of harmful gases containing at least one active precious metal ion selected from the group consisting of platinum (Pt), palladium (Pd) and rhodium (Rd).

The process of claim 1 wherein the active noble metal comprises platinum (Pt) and palladium (Pd) ions and transition metal precursors containing copper (Cu), manganese (Mn) and potassium (K) ions. Low temperature oxidation catalyst.

The method of claim 2, wherein the total catalyst mass
Palladium ion mass fraction is 2.35601% to 2.37516%, and platinum ion is contained 0.04757% to 0.04848% low temperature oxidation catalyst for the removal of harmful gases.

The method of claim 3, wherein
The palladium ions and platinum ions are catalysts for low-temperature oxidation for the removal of harmful gases, characterized in that contained in a mass ratio of 47: 1.

The method of claim 2, wherein, relative to the total catalyst mass,
A catalyst for low temperature oxidation for removing toxic gases, wherein the mass fraction contains 13.35278% to 13.46967% of copper ions, 81.22348% to 81.37473% of manganese ions, and 2.86506% to 2.889% of potassium ions.

The method of claim 5, wherein
Copper ions, manganese ions and potassium ions is a low-temperature oxidation catalyst for the removal of harmful gases, characterized in that contained in a mass ratio of 268: 1626: 58.

The method according to claim 1 or 2, wherein the palladium ions and platinum ions are respectively low temperature oxidation for removal of toxic gases, characterized in that derived from the precursor compounds in the form of nitrates, halides, acetates, ammonium salts, agglomerates, hydroxides Catalyst.

8. The catalyst for cryogenic oxidation for toxic gas removal according to claim 7, wherein the palladium ions are derived from the precursor compound in the form of nitrate, and the platinum ions are derived from the precursor compound in the form of ammonium salt.

The catalyst for cryogenic oxidation for toxic gas removal according to claim 1 or 2, wherein the copper ions and manganese ions are derived from nitrates, and potassium ions are derived from precursor compounds in the form of acetate.

The method of claim 1, wherein the catalyst is 20? A low temperature oxidation catalyst for removing harmful gases, characterized in that the oxidation at a low temperature of 80 ℃.

[Claim 2] The low-temperature oxidation catalyst for removing harmful gases according to claim 1, wherein the harmful gas is at least one gas selected from the group consisting of carbon monoxide, sulfur dioxide, acetaldehyde, formaldehyde, volatile organic compounds, and ammonia. .

The catalyst for cryogenic oxidation for removing toxic gases according to claim 1 or 2, wherein the catalyst is prepared by coprecipitation.

A process for preparing a low temperature oxidation catalyst for removing the noxious gas according to claim 1 or 2 comprising the following steps:
(a) applying an acid chloride _{(? H 2 PtC l6 6H 2} O) and palladium nitrate solution was added a solution of sodium carbonate and a nitrate solution of Mn, Cu of (Pd (NO ₃₎ ₂₎ co-precipitation;
(b) separating the precipitate by centrifugation;
(c) ionizing and drying; And
(d) firing

The method of claim 13, wherein step (e) is performed at 200 ° C to 400 ° C.