KR100382050B1 - Catalyst for Removing Dioxin and Nitrogen Oxides in Flue Gas and Method for Treating Combustion Exhaust Gases Using the Same - Google Patents

Abstract

The present invention relates to a catalyst for removing dioxins and nitrogen oxides contained in combustion flue gas and a method for treating combustion flue gas using the same. Based on TiO ₂ weight, anatase crystal structure versus rutile crystal structure Is added to an auxiliary carrier component selected from the group consisting of SiO ₂ , ZrO ₂ , bentonite, beta zeolite, and mixtures thereof in TiO ₂ present at a ratio of 9: 1 to 7: 3, and rhodium and vanadium are added to the physically mixed carrier. It is characterized in that it is prepared by supporting the rhodium and vanadium on each of the TiO ₂ carrier and auxiliary carrier components and physically mixed thereafter, followed by reduction-reoxidation treatment at a temperature in the range of 100 to 400 ° C. The catalyst of the present invention has superior dioxin and nitrogen oxide removal ability and endothelial toxicity to sulfur, compared with the conventionally commercially available catalyst, and in particular, the low temperature activity is significantly improved. Accordingly, in the incineration process and the like, it is not necessary to install a heat exchanger and a heater required when using a conventional high temperature active catalyst, and has an advantage of preventing dioxin reforming.

Description

Catalytic for removing Dioxin and Nitrogen Oxides in Flue Gas and Method for Treating Combustion Exhaust Gases Using the Same}

The present invention relates to a catalyst for treating flue gas generated during incineration of flue gas and waste in an industrial process and a method of treating flue gas using the same. More specifically, the present invention exhibits an improved removal efficiency for dioxins and nitrogen oxides contained in combustion flue gas at a relatively low temperature, and has excellent endothelial toxicity against sulfur oxides, which are catalyst poisons. It relates to the treatment method of.

Incineration is the most effective method in terms of volume reduction and energy recovery. In particular, overcrowded areas such as Korea are the preferred method due to the lack of landfills. However, the recent need to protect the air environment has been the key to the removal of dioxin generated during the combustion of flue gas and waste. At the present time, the domestic technology development is not completed, as well as the operation of the previously incinerated waste incinerator, it is difficult to build a new incinerator, especially the core technology is dependent on foreign countries. Accordingly, intensive research is being conducted on the treatment of combustion flue gas and the development of catalysts which are essentially required.

Conventionally known methods for removing dioxins contained in flue gases include post-treatment methods, the most preferred method of which passes through an oxidation catalyst layer after adsorbing and controlling dust and heavy metals in flue gas using activated carbon. It is a situation that most dioxins rely on the adsorption removal using an adsorbent because of the problem of performance of the catalyst layer. In addition, the method has a problem that the process of regeneration or disposal of activated carbon adsorbed dioxin is technically difficult and excessive cost.

Therefore, researches for improving the oxidation treatment efficiency of dioxins using a catalyst as a method of generating less secondary waste have been intensively studied. Looking at the patent for the method and the use of the oxidation catalyst studied so far as follows.

U. S. Patent No. 5,292, 704, assigned to Allied-Signal, discloses an organohalogen component and an organic compound using a catalyst having at least one metal selected from the group consisting of V, W, Sn, Pt, Pd and Rh on a TiO ₂ carrier. Disclosed is a method of controlling.

U.S. Patent No. 5,409,681, assigned to Babcock-Hitachi Kabushiki Kaisha of Japan, is a precious metal selected from the group consisting of Pt, Pd, and Ru as the main catalyst based on the previously known V- (Mo and / or W) / TiO ₂ catalyst As a co-catalyst, the two components supported on alumina, silica or zeolite are physically mixed and used as a catalyst for simultaneous control of dioxins and carbon monoxide, and can be used for controlling nitrogen oxides by supplying ammonia to the exhaust gas. It is starting.

U.S. Pat.No. 5,430,230, assigned to Nippon Shokubai, discloses a carrier of the catalyst Ti-Si, Ti-Zr or Ti-Si- in order to reinforce the oxidation power for carbon monoxide in addition to the oxidation power for dioxins in the conventionally known VW / TiO ₂ catalyst. At least one selected from the group consisting of V, Mo, Sn, Ce, and W in place of Zr, and at least from the group consisting of Pd, Pt, Au, Rh, Ru, Cu, Fe, Mn, and Cr on the outer surface; It is disclosed that the addition of one imparts an oxidizing power to carbon monoxide.

Meanwhile, U.S. Patent No. 5,387,734 to Hagenmaier of Germany uses Zn, Ni, Cr, Cu, Fe, Al, Pt, Rh or their metal oxides to form polyvalent halogenated compounds. It is disclosed that it can be processed.

U.S. Patent No. 5,635,438, assigned to The Geon, discloses chlorohydrocarbons, using a catalyst in which chromium is supported on alumina, activated alumina, zeolite, silica-alumina, molybdenum-alumina or silica-magnesia-alumina. It describes the ability to decompose chloro-carbons, hydrocarbons, etc.

U.S. Patent No. 5,643,545, assigned to Engelhard, can effectively lower the reaction temperature depending on the characteristics of each carrier when using a method of supporting precious metals and metal oxides on strong and weakly acidic carriers when treating a mixture of halogenated hydrocarbons and hydrocarbons. It is disclosed. In addition, US Patent No. 5,653,949 to Engelhard Corporation discloses a mixture of carbon monoxide, halogenated hydrocarbons, hydrocarbons, and the like using a catalyst prepared by selecting at least one selected from the group consisting of metals and precious metals selected from the group consisting of Mn, Ce, and Co in ZrO ₂ . Disclosed is a method for removing.

U. S. Patent No. 5,759, 504, assigned to Hitachi, discloses a process for decomposing organohalogen components using a catalyst comprising at least one of W and S, P, Mo and V in TiO ₂ .

Bayer's U.S. Patent No. 5,723,404 has similar characteristics of the catalyst even when prepared at pH 3-4 instead of the conventional pH 10 method for preparing TiO ₂ , V, and W catalysts for removing nitrogen oxides. It is disclosed that it can be maintained.

N.E. US Patent No. 5,783,515 to Chemcat discloses silica-barley having at least one metal component selected from the group consisting of Pt, Pd and Ir and a metal component selected from the group consisting of Au, Ag, Cu, Fe, Sb, Se, Te and Ta. Disclosed is a method of supporting an oxidic catalyst of dioxins by supporting a silica-boria-alumina composite oxide or a zeolite support.

Hitachi's U.S. Patent No. 6,077,482 improves the specific surface area by wrapping TiO ₂ with porous tungsten oxide in order to prevent the TiO ₂ from converting to TiOF ₂ due to the fluorine component contained in the combustion flue gas, thereby reducing the activity of the catalyst. Disclosed is a method for decomposing the organohalogen component using the catalyst.

US Patent No. 6,027,697 to Ebara discloses vanadium oxides in TiO ₂ carriers; Tungsten oxide; And a method of controlling dioxins and nitrogen oxides using a catalyst composed of an oxide of at least one component selected from the group consisting of yttrium, boron and lead.

Most of the above-mentioned prior arts include TiO ₂ or TiO ₂ -SiO ₂ , TiO ₂ -ZrO ₂ -SiO ₂ , and the like, which are modified in their acidity, and the active metals include V, W, Mo, Sn, Ce, Fe, Composite oxides composed of a combination of Mn, Cr and precious metals are used as catalysts. As described above, most of the dioxins and nitrogen oxide removal catalysts use TiO ₂ as a carrier. This is because the movement of electrons in TiO ₂ is remarkably superior to that of Al ₂ O ₃ or zeolite, and thus it can give a desirable effect not only in support of catalyst but also in reaction at low temperature (JC Vedrine (GB-2 ), "Industirial features", Catal. Today , 56 , 333-334 (2000); EM Serwicka (PL-1), "Surface area and porosity, X-ray diffraction and chmical analyses", Catal. Today ", 56 , 335-346 (2000); JM Herrmann (F-4) and J. Disdier (F-4), "Electrical properties of V ₂ O ₅ -WO ₃ / TiO ₂ EUROCAT catalysts evidence for redox process in selective catalytic reduction (SCR ) deNOx reaction ", Catal. Today , 56 , 389-401 (2000)). However, the removal of nitrogen oxides and dioxins requires the redox properties of metals and appropriate acid points. As an example, the aforementioned U.S. Patent No. 5,643,545 has the effect of halogenated hydrocarbons when using an acidic carrier. It is easy to oxidize because of the adsorption, and it shows that only hydrocarbons and carbon monoxide can be effectively treated without being affected by halogenated hydrocarbons (250 ~ 350 ℃). In particular, the halogenated hydrocarbons can be effectively controlled, especially the acidity of the carrier can be obtained when the acid is mixed with TiO ₂ , SiO ₂ , ZrO ₂ and sulfides to super acidity (T. Lopez et. Al., "Effect of sulfation methods on TiO ₂ -SiO ₂ sol-gel catalyst acidity ", Appl. Catal. A: Gen., 197 , 107-117 (2000)), and they show very good performance above 300 ° C (Yin-yan Huang et. Al., "A novel way to prepare silica supported sulfated titania", Appl. Catal A: Gen. , 171 , 65-73 (1998). However, in the method of removing dioxin and nitrogen oxide, there is a need to proceed at a low temperature as possible. For this reason, it is economically desirable to reduce the amount of energy required to heat the combustion flue gas, and from above a certain temperature (205 ° C), the substances decomposed by the catalyst may be recombined in the presence of each metal (Cu, Fe, etc.) oxide. (Vogg, H. et. Al., "Recent Findings on the formation and Decomposition of PDCC / PCDF in Municipal Solid Waste Incineration", Waste Management Research , 5 , 285 (1987)). Therefore, there is an urgent need to develop a catalyst capable of obtaining activity at or below 200 ° C.

Oxidation activity at low temperatures has been reported to require not only acidity but also electron transport speed and redox capacity (Jean-Marie Herrmann (F-4) and Jean Disdier (F-4), "Electrical properties of V ₂ O ₅ -WO ₃ / TiO ₂ EUROCAT catalysts evidence for redox process in selective catalytic reduction (SCR) deNOx reaction ", Catal. Today , 56 , 389-401 (2000)). TiO ₂ having semiconductor properties as a carrier of currently known catalysts is a widely used material because of its excellent performance in electron transfer. Therefore, acidity can be enhanced when a material such as SiO ₂ having low electrical conductivity is added to the TiO ₂ lattice, while a decrease in the electron transfer rate is a necessary result.

On the other hand, many studies on the reducing properties of each material show that Rh has an amazing ability to adsorb oxygen even at -30 ° C (Chin-Pei Hwang et. Al., "Rhodium-oxide species formed on progressive oxidation of rhodium clusters dispersed on alumina ", Catal. Today , 51 , 93-101 (1999); JN Coupe et. al.," A comparative study of SiO ₂ supported Rh-Sn catalysts prepared by different methods in the hydrogenation of citral ", Appl Catal. A: Gen. , 199 , 45-51 (2000)). In addition, in the case of Pt in the precious metals, it is possible to promote the reduction of Ce at 200 ℃ when mixed with Ce (C. Serre et. Al., "Reactivity of Pt / Al ₂ O ₃ and Pt-CeO ₂ / Al ₂ O ₃ Catalysts for the Oxidation of Carbon Monoxide by Oxygen ", J. Catal. , 141 , 1-8 (1993), Pd can be reduced from 120 ° C when dispersed on an alumina surface (FB Noronha et. Al. , "Promoting effect of Nb ₂ O ₅ addition to Pd / Al ₂ O ₃ catalysts on propane oxidation", Catal. Today , 57 , 275-282 (2000)), Ru is reduced at 100 ° C when supported on TiO ₂ . (K. Hadjivanov et. Al., "FTIR Study of CO Interaction with Ru / TiO ₂ Catalyst", J. Catal. , 176, 415-425 (1998)). In addition, Rh showed the best performance in reducing properties at low temperatures, and the combination of Ag-V, Pd-Mn, Au-Mn as other metal oxides also had excellent redox function at low temperatures. JJ Spivey and JB Butt, Literature Review: Deactivation of Catalysts in the Oxidation of Volatile Organic Compounds " Catal. Today , 11 , 465-500 (1992); Jong Soo Park et. Al.," High catalytic activity of PdO _x / MnO ₂ for CO oxidation and importance of oxidation state of Mn ", Topics in Catalysis, 10, 127-131 (2000); Steven D. Gardner et. al., "Comparison of the performance Characteristics of Pt / SnOx and Au / MnOx Catalysts for Low-Temperaure CO Oxidation", J. of Catal ., 129 , 114-120 (1991)). it has been evaluated to be unsuitable hagieneun the concentration of SO ₂ applied to the midrange furnace up to average 50 ppm. In addition, even in the case of a metal having excellent redox performance at low temperature, it shows a significant difference in the performance according to the preparation method of the catalyst, because the reduction temperature is absolutely affected by the chlorine component included in the catalyst manufacturing process.

On the other hand, the process of processing the flue-gas discharged from an incineration process using the dioxin removal catalyst is known. As illustrated in FIG. 1, in the process of treating combustion flue gas using a conventional high temperature active catalyst, there is a need to pass a gas discharged from the catalyst tower through a heat exchanger. However, due to this heating process, dioxin may be resynthesized, and thus requires a separate heat exchanger and a heater to be economically disadvantageous.

On the other hand, the present inventors focused on the development of a highly active dioxin control catalyst when securing the electrical conductivity and the redox performance of the metal while giving an appropriate weak acid point on the carrier in order to overcome the limitation of the prior art. As a result of the research, in order to combine the electronic properties of TiO ₂ and the acid point properties of SiO ₂ , ZrO ₂ , silica-alumina, zeolite and the like, a physically mixed carrier was used and the metal redox at low temperature was used. A catalyst for removing dioxins and nitrogen oxides having high activity in a low temperature region through appropriate post-treatment after carrying out Rh and V having excellent performance, or physically mixing them after supporting Rh and V on the respective carriers. The new combustion flue gas treatment process was developed.

Accordingly, an object of the present invention is to provide a catalyst capable of removing dioxin and nitrogen oxide contained in combustion flue gas at low temperature with high efficiency.

Another object of the present invention is to provide a process capable of efficiently and economically treating combustion flue gas discharged from an incineration process using the catalyst.

In order to achieve the above object, one aspect of the dioxin and nitrogen oxide removal catalyst contained in the combustion flue gas of the present invention is based on the TiO ₂ weight, the anatase crystal structure versus rutile crystal structure is 9: 1-7: the TiO ₂ present in a proportion of 3 SiO _2, ZrO _2, bentonite, zeolite beta and auxiliary carrier selected from the group consisting of mixtures of these components 0.5 to 30 0.001 to 5 rhodium on a carrier are mixed physically by the addition of% by weight % And vanadium 0.1 to 20% by weight is supported, characterized in that the reduction-reoxidation treatment in the temperature range of 100 to 400 ℃ after the supporting step.

Another aspect of the dioxin and nitrogen oxide removal catalyst contained in the combustion flue gas of the present invention for achieving the above object is TiO _{2 having} an anatase crystal structure and a rutile crystal structure in a ratio of 9: 1 to 7: 3. Rhodium and vanadium are respectively supported on the carrier and auxiliary carrier components selected from the group consisting of SiO ₂ , ZrO ₂ , bentonite, beta zeolite, and mixtures thereof based on the weight of the TiO ₂ , and then physically mixed with each other. It is characterized in that the reduction-reoxidation treatment in the temperature range, the content of the auxiliary carrier component based on the TiO ₂ weight is 0.5 to 30% by weight, the total content of the rhodium and vanadium is 0.001 to 5% by weight and 0.1 It is -20 weight%.

In order to achieve the other object, the low temperature treatment method of the combustion flue gas discharged during the incineration process using the catalyst of the present invention is to remove the water in order to prevent dioxin regeneration and to remove sulfur oxides, chlorides and dust contained in the flue flue gas primarily. Cooling the temperature of the combustion exhaust gas discharged through the incinerator to 180 to 200 ° C; Additional removal of sulfur oxides, chlorides and dust in a spray dryer reactor (SDR) and / or bag filter; And treating the combustion flue gas in the presence of the catalyst installed in the catalyst tower, and is not subjected to the waste heat recovery step.

1 is a process chart showing a process of treating combustion flue gas discharged during incineration using a conventional catalyst showing dioxin removal activity at a high temperature.

Figure 2 is a process diagram showing one embodiment of a process for treating the combustion exhaust gas discharged in the incineration process using the catalyst according to the present invention.

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

As a support for the dioxin and nitrogen oxide removal catalyst of the present invention, a mixed carrier obtained by physically mixing TiO ₂ with an auxiliary carrier component selected from the group consisting of SiO ₂ , ZrO ₂ , beta zeolite, silica-alumina, bentonite, and mixtures thereof use. In the present invention, the mixed carrier not only serves as a simple support of the active metal, but also plays a role in the formation of acid sites and the function of the transfer medium of electrons. The content of the secondary component carrier to be mixed with TiO ₂ is 0.5 to 30% by weight as TiO _2, is a problem that when the content of the component is less than 0.5% by weight, the weak acid of the carrier, thereby lowering the adsorption of halogenated hydrocarbons, If it exceeds 30% by weight, the low temperature activity may be reduced due to excessive acidity. Preferably, 3 to 20% by weight of the auxiliary carrier component is used in combination with TiO ₂ .

Meanwhile, in the present invention, TiO _{2, which} is a main component of the mixed carrier, may be used as a commercial product or may be directly manufactured, but it is preferable to use one having a specific crystal structure. In particular, when the TiO ₂ (for example, P-25 of Daegu) having a weight ratio of anatase structure to rutile structure is 9: 1 to 7: 3, It is possible to improve the oxidation activity for dioxin at low temperature. Since TiO ₂ shows a lot of difference in crystal structure according to the manufacturing method, commercially selected products having the above crystal structure are selected. In addition, TiO ₂ usable in the present invention is distinguished according to the operating temperature range of the catalyst (L. Lietti et. Al., "Reactivity of V ₂ O ₅ -WO ₃ / TiO ₂ catalysts in the selective catalytic reduction of nitric oxide by ammonia ", Catalysis Today, 29, 143-148 (1996)). It is preferable to use a TiO ₂ based carrier which increases the acidity and specific surface area of the catalyst at a high temperature reaction of 260 ° C. or higher, whereas the low temperature oxidation reaction at around 200 ° C. shows the above-described crystal structure, which has a high transfer rate and semiconductor performance. It is advantageous to use the form having.

In the catalyst of the present invention, the active metal consists of a mixture of rhodium and vanadium, wherein the content of rhodium is 0.001 to 5% by weight based on the weight of TiO ₂ . At this time, if the content of rhodium is less than 0.001% by weight, the redox performance at low temperature is lowered, and if it exceeds 5% by weight, it is not preferable because the cost increases compared to the increase in efficiency. In addition, the content of vanadium is 0.1 to 20% by weight based on the weight of TiO ₂ , the content of vanadium is less than 0.1% by weight of the activity of the catalyst is too low, if it exceeds 20% by weight of the catalyst as well as the increase in the production cost of the catalyst Activity is rather reduced.

Optionally, the present invention supports the active metal components of rhodium and vanadium on the above-described TiO ₂ carrier, and separately from the group consisting of SiO ₂ , ZrO ₂ , bentonite, beta zeolite and mixtures thereof based on the TiO ₂ weight. Rhodium and vanadium may be supported on 0.5-30 wt% of the selected auxiliary carrier component, followed by physical mixing. Even in this case, the total contents of rhodium and vanadium are 0.001 to 5% by weight and 0.1 to 20% by weight, respectively, based on the weight of TiO ₂ .

On the other hand, in order to prevent the activity of the catalyst is reduced by the moisture and SO ₂ contained in the combustion exhaust gas, 0.1 to 20% by weight of tungsten (W) and / or molybdenum (Mo) may be further loaded on the basis of the TiO ₂ weight. . Therefore, in the combustion flue gas treatment process in which the content of SO ₂ supplied to the catalyst bed, such as a large incinerator, is maintained at 10 ppm or less, it is preferable to prepare the catalyst so that the content of W or Mo is less than 3% by weight, whereas in a system including a high concentration of SO ₂ or more is preferable to maintain at least 5% by weight. That is, the content of tungsten and molybdenum can be supported in an appropriate amount depending on the concentration of SO ₂ contained in the flue gas treated. In particular, when the content of W and / or Mo is excessive, not only the oxidation power of the catalyst may be reduced, but also the problem of raising the catalyst production cost may be caused.

In addition, the catalyst prepared in the present invention is subjected to a post-treatment step of reoxidation after reducing (removing) the chlorine component included in the catalyst manufacturing process using hydrogen. This post-treatment step reduces the supported catalyst for 1 to 5 hours at a temperature of 100 to 400 ° C. under hydrogen or a reducing atmosphere, and then reoxidizes it to a temperature of 100 to 400 ° C. for 1 to 5 hours under an air atmosphere. It is the process of making. In the case where the reduction-reoxidation step is not performed, the redox temperature of the catalyst is increased due to the chlorine component remaining in the catalyst, thereby reducing the low temperature activity. As described above, it is possible to lower the oxidation-reduction temperature through such post-treatment, and in particular, it has the advantage of significantly improving the low temperature conversion rate of dioxins in the combustion flue gas.

On the other hand, the catalyst of the present invention may be used by being coated on a support such as a monolith, a metal plate, a ceramic filter or a bag filter by pulverizing into fine particles having a diameter of 10 μm or less according to the process or use applied. . In addition, the mixed carrier may be used after the extrusion process in the form of a single body or particles to support the active metal, or to prepare a catalyst in the form of a powder, and then extruded in the form of a particle or a single body. Such techniques may be practiced according to methods known in the art.

The method of treating the combustion flue gas using the catalyst is mainly different in process conditions depending on the components to be treated, but the space velocity (GHSV (STP)) of the combustion flue gas in the temperature range of 100 ~ 500 ℃ 1000 ^~ 80000hr- It is preferable to keep it at ¹ and to treat it. In particular, the process conditions suitable for dioxin removal are preferably a space velocity of 1000 to 20000 hr ⁻¹ at a reaction temperature of 160 to 260 ° C., and when the nitrogen oxides are removed by a selective catalytic reduction method, the equivalent ratio of nitrogen oxides to 0.3 to It is preferable to supply three times and to process on 120-400 degreeC and the space velocity conditions of 1500-80000 ^hr <^-1> . In addition, the space velocity of 80-500 degreeC and 1500-80000hr <^-1> is preferable at the time of the removal of carbon monoxide contained in combustion flue gas.

By using the catalyst having excellent low temperature activity of the present invention it is possible to more efficiently configure the combustion flue gas treatment process discharged during incineration.

Figure 2 is a process diagram showing one embodiment of a process for treating the combustion exhaust gas discharged in the incineration process using the catalyst according to the present invention.

In this figure, the temperature of the incinerator is typically maintained at about 1000 ° C. or higher so that hot gases are discharged therefrom. Therefore, such hot gas is generally provided as a heat source of a cogeneration plant such as a steam production boiler in terms of recycling waste heat. Through the above process, the temperature of the combustion flue gas is lowered to about 500 to 600 ° C. and is transferred to the quenching apparatus. In the quenching apparatus, water is injected to lower the temperature of the combustion flue gas to 180 to 200 ° C, and in the process, it is possible to prevent the remodeling of dioxins and to rinse sulfur oxides such as sulfur dioxide, chlorides, dusts, and the like. After the quenching process, the catalyst of the present invention is installed in the dioxins and nitrogen oxide control catalyst tower (about 200 ℃). However, in order to further remove acidic gas (sulfur oxide, chlorine-containing gas), dust, etc. remaining in the exhaust gas, a spray dryer reactor (SDR) and / or a bag filter may be further roughened. In SDR, it is aimed to control acid gases such as sulfur oxides and HCl by injection of alkali lime (Ca (OH) ₂ ) or magnesium hydroxide (Mg (OH) ₂ ). In addition, by simultaneously spraying activated carbon with an alkali slurry, it can be configured to be able to adsorb and remove heavy metals. At this time, in the case of the incineration system (generating a dioxin concentration of 60 ng / m ³ or more) of a specific waste having a high content of dioxin precursor, when the catalyst of the present invention is coated on the bag filter, the concentration of dioxin in the exhaust gas is effectively reduced. This is more effective when the system is configured in a half-load format. That is, since the active temperature of the catalyst is lowered to 200 ° C. or lower by using the catalyst of the present invention as described above, the catalyst can be secured as a commercial product by coating the catalyst on a low-cost bag filter having a heat resistance temperature of 200 ° C. or lower. will be. In addition, in the case of medium and small incinerators having an incineration size of 5 tons / day, when the catalyst tower is separately installed, a large initial investment and construction area are increased, so it is difficult to configure all systems such as a large incinerator having an incineration size of 50 tons / day. have. Therefore, even if only the bag filter coated with the catalyst for low temperature of the present invention can be installed, the current regulation value of 0.5 ng / m ³ or less can be sufficiently satisfied.

As can be seen from the above process, unnecessary steps, such as not requiring the installation of a heat exchanger and a heater, which have been required when using a conventional high temperature active catalyst, can be omitted, thereby improving energy efficiency and improving process economy. Therefore, in the present invention, rather than simply the meaning of the high activity catalyst itself, it is meaningful that this allows the development of a new flue gas treatment process.

The present invention can be more clearly understood by the following examples, which are only intended to illustrate the present invention and are not intended to limit the scope of the invention.

Example 1

Titanium dioxide (P-25 from Daegu) and silica gel (Aldrich Catal. No. 21,441-8) were used as a support of the active metal. 95% by weight of titanium dioxide and 5% by weight of silica gel were mixed and uniformly remixed for 2 hours or more using mortar.

0.22 g of vanadium precursor ammonium metavanadate (Aldrich Catal. No. 20,555-9) in a solution of 0.34 g of oxalic acid in 20 g of distilled water and RhCl ₃ .3H ₂ O (Lot No. 808062 from KOJIMA) 0.26 g was sequentially added and dissolved in a water bath at 50 to 60 ° C., followed by cooling to room temperature. 5 g of the mixture of TiO ₂ and SiO ₂ were added to the solution, stirred at room temperature for 20 minutes, and most of the water was removed from a vacuum rotary evaporator, and dried in a drier at 105 ° C. for 24 hours. Then, by firing in an air atmosphere at 400 ℃ to convert each metal into the form of an oxide while removing the organics. After the completion of the calcination, the catalyst was ground to a particle diameter of 40 to 80 mesh and reduced for 2 hours under a hydrogen atmosphere of 250 ° C. to remove chlorine contained in the precursor of the metal, and then calcined for 1 hour in an air atmosphere of 300 ° C. to prepare a catalyst. . As a result of the component analysis, the catalyst was Rh [2] -V [2] / (TiO ₂ [95] -SiO ₂ [5]).

The 1,2-DCB oxidation power of the catalyst prepared as described above was measured in a quartz tube fixed bed reactor having an inner diameter of 4 mm. At this time, the test conditions were 1,2-DCB 314 ppmv, oxygen 10%, moisture 1.2%, GHSV 10,000hr ^-1 was maintained. 0.134 g of catalyst was charged to the reactor and the reactant was fed under the above experimental conditions while heating the temperature of the catalyst bed to 200 ° C. After 3 hours from the time when the temperature of the reactor reached steady state, the concentration of 1,2-DCB flowing out of the reactor was measured and the reduction ratio was calculated by calculating the conversion rate ((1-supply concentration / emission concentration) × 100). Decided. As an analysis device, Hewlett-Packard's HP-6890 gas chromatography equipped with an HP-1 column and ECD was used. As a result, 78% conversion was obtained as shown in Table 1 below.

Example 2

The oxidation power of 1,2-DCB was measured using the same catalytic catalyst as in Example 1, except that 50 ppm of SO ₂ was further added to the reaction. The conversion rate of 1,2-DCB was 40%.

Example 3

A catalyst was prepared in the same manner as in Example 1 except that SiO ₂ was replaced with beta zeolite, and the activity thereof was measured. The prepared catalyst was represented by Rh [2] -V [2] / (TiO ₂ [95] -beta Zeolite [5]). The conversion rate of 1,2-DCB was 75%.

Example 4

A catalyst was prepared in the same manner as in Example 1 except that SiO ₂ was replaced with ZrO ₂ (manufactured by Yakuri), and the activity was measured. The prepared catalyst was represented by Rh [2] -V [2] / (TiO ₂ [95] -ZrO ₂ [5]). The conversion rate of 1,2-DCB was 76%.

Example 5

A catalyst was prepared in the same manner as in Example 1 except that SiO ₂ was replaced with bentonite (Aldrich Cat. No 23,523-4) and the activity was measured. The prepared catalyst was represented by Rh [2] -V [2] / (TiO ₂ [95] -Bento [5]). As a result, the 1,2-DCB conversion was 72%.

Example 6

A catalyst was prepared in the same manner as in Example 1, except that tungsten was added as an active metal of the catalyst and simultaneously supported with rhodium and vanadium. The prepared catalyst was represented by Rh [2] -V [2] -W [1] / (TiO ₂ [95] -SiO ₂ [5]). Experimental results showed that the conversion of 1,2-DCB was 74%.

Example 7

In order to evaluate the effect of SO ₂ on the catalyst of Example 6, the experiment was carried out in the same manner as in Example 6 except that the concentration of SO ₂ in the reactant was 50 ppm. As a result, the conversion rate of 1,2-DCB was 74%, from which it was confirmed that the endothelial toxicity to SO ₂ can be secured by the addition of tungsten.

Example 8

Oxidation of chlorophenol was carried out using the catalyst prepared in Example 6. The concentration of the reactant supplied was 500 ppm and the other experimental conditions were kept the same. As a result, the conversion of chlorophenol was 99% or more.

Example 9

Oxidation of chlorobenzene was carried out using the catalyst prepared in Example 6. The concentration of the reactant supplied was 500 ppm, and the other experimental conditions were kept the same. As a result, the conversion rate of chlorobenzene was 95% or more.

Example 10

The catalyst was prepared in the same manner as in Example 1 except that vanadium was first supported and calcined, followed by rhodium supported, dried and calcined in order for the active metal to be supported. The catalyst prepared as above was represented by Rh [2] / V [2] / (TiO ₂ [95] -SiO ₂ [5]). As a result of the measurement, the conversion rate of 1,2-DCB was 79%, and considering that the result was similar to that of Example 1, it was evaluated that there was no influence by the supporting method of the active metal.

Example 11

A catalyst was prepared in the same manner as in Example 1, except that the concentration of Rh was 0.5 wt%, the concentration of V was 2.0 wt%, and the concentration of W was maintained at 1.0 wt%. The catalyst prepared as above was represented by Rh [0.5] -V [2] -W [1] / TiO ₂ -D. Experimental conditions were 1, 2-DCB 16 ppm, O ₂ 7%, water 2.4%, GHSV (STP) 10000hr ^-1 , and the reaction temperature was carried out to 160 ℃, 180 ℃, 200 ℃, 220 ℃ respectively. Experimental results showed conversion rates of 75% (160 ° C), 83% (180 ° C), 94% (200 ° C), and 99.9% (220 ° C).

Example 12

Nitrogen oxide control power of the catalyst prepared by the same method as in Example 1 was measured. The experiment was conducted under NO _x 470 ppm, ammonia 470 ppm, O ₂ 3%, GHSV (STP) 30,000hr ^-1 conditions. As a result, 80% and 83% nitrogen oxides could be removed at 200 ° C and 220 ° C, respectively. At this time, the emission concentration of NO ₂ and NH ₃ was found to be 1 ppm or less. Therefore, it was confirmed that it can be used as a catalyst for removing nitrogen oxides.

Example 13

Oxidation power of carbon monoxide was measured using a catalyst prepared by the same method as in Example 1. The experiment was carried out using Micromeritic's AutoChem 2910 to adsorb carbon monoxide at 50 ° C and supplying 3% O ₂ / Ar gas while heating the temperature of the catalyst bed to 10 ° C / min. Measured. As a result, the concentration of carbon dioxide began to increase from 80 ℃ and gradually decreased after peaking at 110 ℃. That is, the oxidation reaction of carbon monoxide showed an activity that proceeds below 110 ℃.

Comparative Example 1

A catalyst was prepared in the same manner as in Example 1 except for the reduction and reoxidation using hydrogen. The catalyst prepared as above was Rh [2] -V [2] / (TiO ₂ [95] -SiO ₂ [5])-calc. marked only. The conversion rate of 1,2-DCB using the catalyst was found to be 30%. The result was only 38% of the performance of the catalyst of Example 1, which was subjected to post-treatment of reduction-reoxidation. Therefore, it can be seen that the post-treatment of reduction-reoxidation is a very important process in the preparation of the catalyst.

Comparative Example 2

A catalyst was prepared in the same manner as in Example 1 except that only TiO _{2 was} used as the support for the active metal. The catalyst was designated Rh [2] -V [2] / TiO ₂ . Experimental results, the conversion of 1,2-DCB was 62%. The result was confirmed that the mixing effect of SiO ₂ has a significant effect on the dioxin removal to 74% of the performance of the catalyst of Example 1. Moreover, compared with the result of Example 3 which mixed zeolite in a support | carrier, the activity fall of about 30% was shown. Compared with the result of Example 4 in which ZrO ₂ was mixed in the carrier, the activity was also reduced to about 30%. As a result, it was judged that using a carrier in which TiO ₂ was physically mixed with silica, zeolite, or zirconia was more effective in 1,2-DCB oxidation than in the case of using TiO ₂ alone.

Comparative Example 3

The influence of SO ₂ on the catalyst of Comparative Example 2 was evaluated. The reaction conditions were the same as in Comparative Example 2, except that SO _{2 was} 50 ppmv. As a result, the conversion of 1,2-DCB was 30%.

Comparative Example 4

A catalyst was prepared in the same manner as in Example 1, except that only SiO _{2 was} used as the active metal carrier. The catalyst prepared as above was represented by Rh [2] -V [2] / SiO ₂ . As a result of measuring 1,2-DCB conversion, it was 4%, and when SiO ₂ alone was used as a catalyst carrier, dioxin removal efficiency was significantly reduced, and it was proved that proper synergy could be obtained only when used as a physically mixed carrier. It became.

Comparative Example 5

A catalyst was prepared in the same manner as in Example 1 except that only ZrO _{2 was} used as a support for the active metal. The catalyst prepared as above was represented by Rh [2] -V [2] / ZrO ₂ . The conversion rate of 1,2-DCB was 12.8%.

Comparative Example 6

A catalyst was prepared in the same manner as in Example 10, except that the rhodium precursor was replaced with chloroplatinic acid (H ₂ PtCl ₆ .6H ₂ O, Inuisho Precious Metals Co., LTD, Lot No. 90301). The catalyst prepared as described above was expressed as Pt [2] / V [2] / (TiO ₂ [95] -SiO ₂ [5]). As a result, the conversion rate of 1,2-DCB was 38%. Accordingly, it was confirmed that all kinds of metal oxides were used together with vanadium to exhibit no synergistic effect. In particular, Rh [2] / V [2] / (TiO ₂ [95] -SiO ₂ [5]) of Example 10 and Pt [2] / V [2] / (TiO of Comparative Example 6 from the above results. It can be seen that the performance between ₂ [95] -SiO ₂ [5]) is different, demonstrating that Rh function is effective among precious metals in improving the redox performance of the metal at low temperatures.

Comparative Example 7

A catalyst was prepared in the same manner as in Example 1 except that TiO ₂ from Daegu was replaced with TiO ₂ from Yakuri, Japan. The catalyst prepared as described above was represented by Rh [2] -V [2] / TiO ₂ -Y. Experimental results showed that the conversion rate was reduced by more than 50% when TiO ₂ was used when using Daegu products with a conversion rate of 1,2-DCB of 28%. In this regard, it was evaluated that the results were completely different depending on the characteristics of TiO ₂ .

Comparative Example 8

The cod's P-25 with TiO ₂ A catalyst was prepared by the same manner as in Example 11 except that the replacement by ISHIHARA SANGYO KAISHA LTD's ST-01 (Lot. No. 0027 ). The catalyst prepared as described above was represented by Rh [0.5] -V [2] -W [1] / TiO ₂ -ST01. Experimental conditions were maintained in the same manner as in Example 11. As a result, conversion rates of 56% (180 ° C), 80% (200 ° C), and 97% (220 ° C) were obtained.

Comparative Example 9

A catalyst was prepared according to the same method as Example 11 except that TiO ₂ was used ST-31 (Lot. No. 0024) of ISHIHARA SANGYO KAISHA LTD. The catalyst prepared as described above was represented by Rh [0.5] -V [2] -W [1] / TiO ₂ -ST31. Experimental conditions were maintained in the same manner as in Example 11. Experimental results were obtained 0% (180 ℃), 5% (200 ℃), 20% (220 ℃).

Item catalyst SO ₂ concentration 1,2-DCB conversion rate (%) Example 1 Rh [2] -V [2] / (TiO ₂ [95] -SiO ₂ [5]) 0 78 Example 2 Rh [2] -V [2] / (TiO ₂ [95] -SiO ₂ [5]) 50 40 Example 3 Rh [2] -V [2] / (TiO ₂ [95] -beta Zeolite [5]) 0 75 Example 4 Rh [2] -V [2] / (TiO ₂ [95] -ZrO ₂ [5]) 0 76 Example 5 Rh [2] -V [2] / (TiO ₂ [95] -Bento [5]) 0 72 Example 6 Rh [2] -V [2] -W [1] / (TiO ₂ [95] -SiO ₂ [5]) 0 74 Example 7 Rh [2] -V [2] -W [1] / (TiO ₂ [95] -SiO ₂ [5]) 50 74 Example 10 Rh [2] / V [2] / (TiO ₂ [95] -SiO ₂ [5]) 0 78 Example 11 Rh [2] -V [2] / TiO ₂ -D 0 78 (160 ° C) 83 (180 ° C) 94 (200 ℃) 99 (220 ℃) Comparative Example 1 Rh [2] -V [2] / (Ti0 ₂ [95] -SiO ₂ [5])-calc. only 0 30 Comparative Example 2 Rh [2] -V [2] / TiO ₂ 0 62 Comparative Example 3 Rh [2] -V [2] / TiO ₂ 50 30 Comparative Example 4 Rh [2] -V [2] / SiO ₂ 0 4 Comparative Example 5 Rh [2] -V [2] / ZrO ₂ 0 12.8 Comparative Example 6 Pt [2] / V [2] / (TiO ₂ [95] -SiO ₂ [5]) 0 38 Comparative Example 7 Rh [2] -V [2] / TiO ₂ -Y 0 28 Comparative Example 8 Rh [2] -V [2] / TiO ₂ -ST01 0 56 (180 degrees Celsius) 80 (200 ℃) 97 (220 ° C) Comparative Example 9 Rh [2] -V [2] / TiO ₂ -ST31 0 0 (180 ℃) 5 (200 ℃) 20 (220 degrees Celsius)

The catalyst of the present invention has superior dioxin and nitrogen oxide removal ability and endothelial toxicity to sulfur, compared with the conventionally commercially available catalyst, and in particular, the low temperature activity is significantly improved. Accordingly, since it is not necessary to install a heat exchanger and a heater required for the use of a conventional high temperature active catalyst in an incineration process, unnecessary steps can be omitted, thereby improving energy efficiency and improving process economics, as well as achieving combustion. It has the advantage of significantly reducing the risk of dioxin regeneration that may occur during gas treatment.

All simple modifications and variations of the present invention fall within the scope of the present invention, and the specific scope of the present invention will be apparent from the appended claims.

Claims (14)

Group consisting of SiO ₂ , ZrO ₂ , bentonite, beta zeolite and mixtures thereof in TiO ₂ in which the anatase crystal structure to the rutile crystal structure are present in a ratio of 9: 1 to 7: 3, based on the TiO ₂ weight 0.5 to 30% by weight of the auxiliary carrier component selected from 0 to 5% by weight of rhodium and 0.1 to 20% by weight of vanadium are supported on the physically mixed carrier, and reduced at a temperature in the range of 100 to 400 ° C. after the supporting step. A catalyst for the removal of dioxins and nitrogen oxides contained in combustion flue gas, characterized by reoxidation. TiO ₂ carrier having anatase crystal structure to rutile crystal structure in a ratio of 9: 1 to 7: 3, and SiO ₂ , ZrO ₂ , bentonite, beta zeolite, and mixtures thereof based on the TiO ₂ weight Rhodium and vanadium are supported on each of the auxiliary carrier components selected from the group, and physically mixed, followed by reduction-reoxidation in a temperature range of 100 to 400 ° C., for removing dioxins and nitrogen oxides contained in the combustion flue gas. The content of the auxiliary carrier component is 0.5-30 wt% based on the weight of the catalyst, TiO ₂ , and the total content of rhodium and vanadium is 0.001-5 wt% and 0.1-20 wt%, respectively. The catalyst for removing dioxins and nitrogen oxides contained in the combustion flue gas according to claim 1 or 2, wherein W and / or Mo is added in an amount of 0.1 to 20% by weight based on the weight of TiO ₂ . The dioxins contained in the combustion flue gas according to claim 1 or 2, wherein the catalyst is ground to 10 µm or less and coated on a monolith, a metal plate, a ceramic filter or a bag filter. And a catalyst for removing nitrogen oxides. The catalyst for removing dioxins and nitrogen oxides contained in the combustion flue gas according to claim 1, wherein the mixed carrier is supported by the metal component after extruding the mixture into a single or particle form. A catalyst for removing dioxins and nitrogen oxides contained in a combustion flue gas, wherein the powder obtained by pulverizing the catalyst of claim 1 or 2 is extruded into a granular or monolithic form. A process for treating combustion flue gas using a catalyst according to claim ¹ under a temperature range of 80 to 500 ° C. and a space velocity (GHSV (STP)) of 1000 to 80000hr ⁻¹ . The process according to claim 7, wherein dioxins in the flue gas are treated under a temperature range of 130 to 400 ° C. and a space velocity (GHSV (STP)) condition of 1500 to 80000hr ⁻¹ . 8. The process according to claim 7, wherein ammonia is supplied at an equivalence ratio of nitrogen oxides 0.3 to 3 times and the nitrogen oxides in the combustion flue gas are treated under a space velocity condition of 120 to 400 DEG C and 1500 to 80000hr ^-1 . The process according to claim 7, wherein the carbon monoxide in the combustion flue gas is treated under a temperature range of 80 to 500 ° C. and a space velocity (GHSV (STP)) condition of flue gas of 1500 to 80000hr ⁻¹ . Cooling the temperature of the combustion flue gas discharged through the incinerator to 180 to 200 ° C. by spraying water to prevent dioxin regeneration and to primarily remove sulfur oxides, chlorides and dust contained in the flue gas; Additional removal of sulfur oxides, chlorides and dust in a spray dryer reactor (SDR) and / or bag filter; And Treating the combustion flue gas in the presence of the catalyst of claim 1 or 2 installed in a catalyst tower; It includes, and characterized in that not subjected to the waste heat recovery step, low temperature treatment method of the combustion exhaust gas discharged during incineration. 12. The method of claim 11, wherein the catalyst of claim 1 or 2 is coated on the bag filter. Cooling the temperature of the combustion flue gas discharged through the incinerator to 180 to 200 ° C. by spraying water to prevent dioxin regeneration and to primarily remove sulfur oxides, chlorides and dust contained in the flue gas; And Treating the cooled flue gas with a bag filter coated with the catalyst of claim 1; It includes, and characterized in that not subjected to the waste heat recovery step, low temperature treatment method of the combustion exhaust gas discharged during incineration. 15. The method of claim 13, further comprising the step of treating the combustion flue gas in an SDR before treating it with a coated bag filter.