KR100909989B1 - Diesel catalysts for removing nitrogen oxides from diesel or lean burn engines - Google Patents

Abstract

The present invention relates to a combined catalyst for removing nitrogen oxides (NOx) using only CO in exhaust gas as a reducing agent without additional reducing agent in diesel or lean-burn engine exhaust gas composition conditions. The present invention relates to a DeNOx complex catalyst in which a conventional DeNOx catalyst and a Water Gas Shift Reaction (WGSR) catalyst are mixed.

DeNOx, water gas, transition reaction

Description

DEGNOW combined catalyst applied to passive DeNOx in diesel or Lean-burn exhaust gas}

The present invention relates to a complex catalyst for removing nitrogen oxides (NOx) by using only CO in the exhaust gas as a reducing agent in a diesel or lean-burn engine exhaust gas composition without additional reducing agent input. Specifically, DeNOx The present invention relates to a DeNOx complex catalyst in which a conventional DeNOx catalyst and a Water Gas Shift Reaction (WGSR) catalyst are mixed.

As diesel vehicles are driven by the energy economy and the EU's fuel economy regulations (≤140 g / km in 2009, Korea), the penetration rate of diesel-powered vehicles is gradually increasing not only in Korea but also in Europe. The trend is increasing. Diesel engines operated under excess oxygen conditions have high fuel efficiency, long durability and high fuel economy of about 30-40% compared to gasoline engines. In addition, emissions of carbon dioxide (CO2), carbon dioxide (CO), total hydrocarbons (THC), and evaporated hydrocarbons, which are mainly emitted from gasoline engines, are relatively low in diesel engines, and CO2, which is a major factor of global warming, which causes meteorological changes, in particular, It is positively evaluated from the environmental point of view that the emission of carbon dioxide is about 30% lower. Meanwhile, gasoline engines have been developed through a number of studies on exhaust gas removal technologies such as NO and CO. In addition, the developed three-way catalyst system has been practically used to reduce harmful gases caused by gasoline vehicles. On the other hand, the limitation of pretreatment technologies, such as optimization of combustion chamber shape, fuel supply system, and exhaust gas recirculation (EGR), is emerging as diesel engines are tightened due to tightening emission regulations of diesel vehicles. In addition, diesel engines are far behind gasoline engines, and particulate matters such as nitrogen oxides (NOx) and soot (PM), which are mainly emitted from diesel engines, are recognized as the main culprit of air pollution in large cities. . Nitrogen oxides cause photochemical smog, cause acid rain, and are major factors in ozone generation. Despite these limitations, the use of diesel engines continues to increase, and many developed countries are tightening their emission limits and regulating emissions from diesel engines. In order to overcome these restrictions on NOx, the United States has been operating in large cities with more than 750,000 population since 1980 under the Clean Air Act of 1990, aiming to reduce emissions of diesel engines in operation in the United States. The city bus rebuild / retrofit program has been implemented for city buses since 1995 to reduce emissions, and domestic countermeasures have been taken.

The technology that removes NOx among automobile emissions, which is the leading cause of environmental pollution, can be divided into active DeNOx technology and passive DeNOx technology. Active system technology is being studied for selective Catalytic Reduction (SCR) using urea, ammonia and hydrocarbons as reducing agents. Among these, a promising technique is to convert NOx to N2 selectively using hydrocarbons. Selective catalytic reduction (SCR) is drawing attention. On the other hand, the passive system technology does not use a 4-way catalyst and a reducing agent to remove CO, HC, NOx, and PM at the same time, and removes NOx by using an effective gas included in exhaust gas from a diesel engine. Technology.

HC-SCR is one of the active technologies for NOx removal. Until now, many researchers have used paraffin or olefin-based hydrocarbons as a reducing agent used in selective catalytic reduction, and Cu-ZSM5 is used even in excess oxygen atmosphere. Since it has been reported by Iwamoto et al. That a catalyst can selectively remove NO by a small amount of hydrocarbons, metal ion exchange ZSM5 catalysts are frequently used in hydrocarbon SCRs. In addition, many studies have been conducted on γ-Al2O3, which has been reported to have superior activity in reducing NO2 than NO in hydrocarbon SCR. However, in the case of an active technology in which a reducing agent is added, a separate device for introducing a reducing agent is required, which causes a problem such as a more complicated DeNOx system. In order to solve this problem, a lot of research is being conducted on passive technology that does not supply a separate reducing agent.

The inventors of the exhaust gas analysis of the Euro IV diesel engine performed in the New European Driving Cycle (NEDC) mode showed that the ratio of UHC (Unburned Hydrocarbon) concentration to NOx concentration was 5.5, and the ratio of CO concentration to NOx concentration was average. It was found that 16 (Fig. 1). Through this, the possibility of passive DeNOx using self CO in exhaust gas as a reducing agent of NOx was confirmed.

The basic idea of the present invention is the passive DeNOx reaction by decomposing hydrogen through the reaction of CO and water contained in the exhaust gas under passive conditions without a separate hydrogen supply through a complex catalyst system in which a conventional DeNOx catalyst is mixed with a water gas shift reaction catalyst. It is to improve the performance of DeNOx by utilizing the hydrogen hydrogen with CO as a reducing agent of. Accordingly, an object of the present invention is to provide a DeNOx complex catalyst that can efficiently remove NOx contained in the exhaust gas in the excess oxygen atmosphere without additional injection of a reducing agent.

In order to achieve the above object, the present invention is a DeNOx complex in which a water gas shift reaction (WGSR) catalyst is further mixed in a DeNOx catalyst for removing NOx contained in a diesel or lean-burn engine exhaust gas. It is to propose a catalyst.

Non-limiting features of the invention are as follows.

In the DeNox complex catalyst according to the present invention, the DeNOx catalyst is Pd / TiO2 / Al2O3, and the WGSR catalyst is a complex catalyst of metal and metal oxide. At this time, the metal of the WGSR catalyst is one or two or more components selected from the group consisting of Cu, Au, Ru, Rh, Pd, Pt and Ce, the metal oxide of the WGSR catalyst from the group consisting of ZnO, Fe2O3, Al2O3 and CeO2 It is characterized by one or more components selected.

In addition, the DeNOx composite catalyst according to the present invention is characterized in that the mixing ratio of the DeNOx catalyst and the WGSR catalyst is 1: 0.1 to 10 by weight ratio, and the content of Pd in the DeNOx catalyst Pd / TiO2 / Al2O3 is based on the total weight of the DeNOx catalyst. 0.5% to 5% by weight, the content of TiO2 of the WGSR catalyst is characterized in that 5 to 50% by weight relative to the weight of TiO2 / Al2O3.

The DeNOx composite catalyst according to the present invention is effective for NOx removal by promoting the catalytic reduction reaction of NOx contained in exhaust gas composition by using only CO as a reducing agent without introducing a separate reducing agent under engine exhaust gas composition conditions operating in excess oxygen conditions. Provide effect.

Hereinafter, the present invention will be described with specific examples. The DeNOx complex catalyst according to the present invention is a DeNOx catalyst and a WGSR catalyst mixture, and unless otherwise stated, the DeNOx catalyst should be understood as one catalyst included in the DeNOx complex catalyst.

First, an example of preparing a DeNOx catalyst which is one catalyst of a DeNOx complex catalyst will be described. Next, an example of preparing a WGSR catalyst, which is another catalyst of the DeNOx complex catalyst, will be described, and an example of preparing a DeNOx complex catalyst as a mixture thereof will be described.

Example

1. Example of DeNOx Catalyst Preparation

1) Preparation of TiO2 / Al2O3 Support

The TiO 2 / Al 2 O 3 carrier was prepared by mixing titania sol and γ-Al 2 O 3 powder (Sasol, Disperal P3). Titanium tetraisopropoxide (Sigma-Aldrich, 97%) and a certain proportion of isopropanol (isopropanol, Sigma-Aldrich, 99%), acetylacetone (acetylacetone, Sigma-Aldrich, 99%) The mixture was stirred for 15 minutes at room temperature, γ-Al2O3 powder was added thereto, and hydrochloric acid (Sigma-Aldrich, 37%) and water were added slowly and reacted at 80 ° C. for 16 hours while stirring. After filtering only the material except the solvent and dried at 110 ℃ for 12 hours. After calcination for 3 hours at 550 ℃ in air conditions to prepare a 10 wt% TiO2 / Al2O3 carrier.

2) Preparation of Pd Supported DeNOx Catalyst (Pd / Al2O3 and Pd / TiO2 / Al2O3)

Pd / Al2O3 and Pd / TiO2 / Al2O3 catalysts were prepared by supporting Pd on the γ-Al2O3 powder and the TiO2 / Al2O3 founder carrier prepared in 1), respectively. Pd precursor was used as palladium chloride (Sigma-Aldrich, 99.9 +%), and the initial wet impregnation method was applied to the TiO2 / Al2O3 carrier prepared from γ-Al2O3 and 1) with an aqueous solution of palladium chloride precursor. After repeating the process of supporting and drying to meet a constant mass ratio and calcined for 4 hours at air conditions, 550 ℃ to prepare a 2.0 wt% Pd / Al 2 O 3 and 2.0 wt% Pd / TiO 2 / Al 2 O 3 catalyst, respectively.

2. Preparation Example of Water Gas Transfer Reaction (WGSR) Catalyst (Au / Ru / Fe2O3)

Au / Ru / Fe2O3 catalyst, which is a Water-Gas Shift Reaction (WGSR) catalyst, was prepared using a deposition-precipitation method. A predetermined amount of iron nitrate nonahydrate (Sigma-Aldrich, 98 +%) aqueous solution is precipitated with ammonium hydroxide (ammonium hydroxide, Sigma-Aldrich, Reagent grade) until it reaches pH 8.6 at room temperature to form a gel. It was. Gold chloride (Aldrich, 99.99 +%) and ruthenium chloride hydrate (Aldrich) were added to the formed gel and placed at room temperature for 6 hours with vigorous stirring. The gel was filtered through a filter and washed with distilled water. After drying for 12 hours at 120 ℃ and calcined for 3 hours at 400 ℃ in air, to prepare a 3, 3 wt% Au / Ru / Fe 2 O 3 catalyst.

3. Example of DeNOx Complex Catalyst Preparation

As the WGSR catalyst, Cu / ZnO / Al2O3 (ICI), a commercially available LTS (Low Temperature Shift) catalyst, and Au / Ru / Fe2O3 prepared in 2 were used, and the ratio of Pd / TiO2 / Al2O3 and WGSR catalyst prepared in 1 was used. Were mixed to be 1: 0.5, 1: 1, 1: 1.5, respectively, to prepare a DeNOx complex catalyst.

On the other hand, unlike the method used as a single mixed catalyst, it was implemented in a two-stage catalyst layer method in which the WGSR catalyst is located at the front end and the DeNOx catalyst is located at the rear end.

The NOx conversion (to N2) of the DeNOx complex catalyst was tested by the following apparatus.

DeNOx Reaction Experimental Example

1. Experiment apparatus

Gases used are NO, CO, O2, CO2, H2, N2 (balance), He (balance), H2O. The reaction gases were supplied to the reactor stably at a constant flow rate through a pressure regulator and a mass flow controller (MFC). H 2 O was injected using a syringe pump, and heated to 100 ° C. using a heating band from the portion where H 2 O was injected to the upper inlet of the reactor. The reaction gas proceeded in two compositions: lean NOx conditions (500 ppm NOx) and conditions for N2 measurement (2000 ppm NOx). The reactor used a commonly used continuous fixed bed reactor, and supported the catalyst with quartz wool inside the reactor. The reactor internal temperature was measured by placing a thermocouple in the center of the catalyst bed and controlling the reaction temperature using a heater and thermostat. A cold trap was installed at the rear of the reactor to condense moisture, and a NOx analyzer (Thermo Environmental Instruments, Model 42h) and a gas chromatograph (Gas Chromatograph, Younglin, 600D) were installed to enable online analysis. Quantitative analysis of changes in NOx (NO + NO2), N2, and CO was performed. The analytical column of Gas Chromatograph (GC) used a packed column filled with Washed Molecular Sieve 5A 80/100 (Alltech) material and a TCD (Thermal Conductivity detector) as a detector.

2. Experimental conditions and methods

0.5 g of the test catalyst was fixed with quartz wool inside the reactor, and the catalyst inside the reactor was reduced at 350 ° C. with 10% H 2 / N 2 for 1 hour before the reaction. Before setting the engine simulation gas condition for the DeNOx reaction, it was confirmed that the engine exhaust gas of a small diesel vehicle that meets the Euro-IV standard produces less than 200 ppm of NOx and 0.04-0.8% of CO. In the small diesel engine exhaust gas based on Euro-IV, it was found that CO, which can be used as a reducing agent of NOx, was found to be 16 times the average of NOx. Catalytic reaction was carried out while descending by 25 ℃ in the temperature range from 300 ℃ to 100 ℃, the gas passing through the catalyst bed of the reactor and the exhaust gas analyzed NOx (NO + NO 2), N 2, CO through the NOx analyzer and GC I did it. In the WGSR + DeNOx experiment, the WGSR catalyst was a commercially available low temperature shift (LTS) catalyst, Cu / ZnO / Al2O3 (ICI), and Au / Ru / Fe2O3 prepared above. The ratio of Pd / TiO2 / Al2O3 and WGSR catalyst The mixing was performed in a manner of using a single catalyst layer by mixing 1: 0.5, 1: 1, and 1: 1.5, and a two-stage catalyst layer in which the WGSR catalyst was placed at the front end and the DeNOx catalyst was placed at the rear end.

Hereinafter, the conversion result of the DeNOx catalyst will be described, and the results of the DeNOx complex catalyst experiment according to the present invention will be summarized.

1.Evaluation of NOx to N2 of DeNOx Catalyst (Pd / TiO2 / Al2O3 Catalyst)

In order to evaluate the effect of using only CO as a reducing agent of NOx, the results of a DeNOx reaction experiment supplying 32000 ppm of CO, which is 16 times the NOx concentration, are shown in FIG. 2. The catalyst was used 2 wt% Pd / TiO2 / Al2O3 and the reaction experiment was carried out for the condition of no water and with water. At the reaction temperature of 225 ℃, N2 was not measured at all temperature ranges. Through this, it can be seen that the conversion reaction of NOx-> N2 does not proceed only through the DeNOx catalyst under the condition of reducing CO / NOx = 16 alone CO.

2. DeNOx performance evaluation of DeNOx complex catalyst (Cu / ZnO / Al2O3 + Pd / TiO2 / Al2O3)

WGSR + DeNOx reaction experiments using Cu / ZnO / Al2O3, a typical commercially available LTS (Low Temperature Shift) catalyst, as the WGSR catalyst and 2 wt% Pd / TiO2 / Al2O3 as the DeNOx catalyst were carried out. The combination method of Cu / ZnO / Al2O3 and 2 wt% Pd / TiO2 / Al2O3 is used as a single catalyst layer by mixing the two catalysts, placing Cu / ZnO / Al2O3 at the front end and 2 wt% Pd / TiO2 at the rear end. It has been applied in two forms of the two-stage catalyst bed method for placing / Al2O3. Reaction experiments when Cu / ZnO / Al2O3 was mixed with the WGSR catalyst and used as a single catalyst layer method are shown in FIGS. 3, 4, and 5, and when Cu / ZnO / Al2O3 was used as the two-stage catalyst layer method. The results are shown in FIG. In the case of the single catalyst layer method, the mixing ratio of Cu / ZnO / Al2O3 and 2 wt% Pd / TiO2 / Al2O3 is 0.5: 1, 1: 1, 1.5: 1 by mass ratio, and Cu / ZnO / in case of the two-stage catalyst layer method. The ratio of Al 2 O 3 and 2 wt% Pd / TiO 2 / Al 2 O 3 was 1: 1 by mass ratio.

As shown in Figs. 3, 4 and 5, the composite catalyst of Cu / ZnO / Al2O3 and 2 wt% Pd / TiO2 / Al2O3 exhibited a characteristic of having a specific active temperature region similar to the result of using Pd / TiO2 / Al2O3 alone. As the ratio of Cu / ZnO / Al2O3 increased, it was confirmed that the active temperature range moved to low temperature. It was confirmed that the conversion of NOx-> N2 occurred in this active temperature range, although the H2 was produced by the WGSR catalyst Cu / ZnO / Al2O3 to generate O2, but the generated H2 was used as a reducing agent for the DeNOx reaction. Means used. Compared with the results of using Pd / TiO2 / Al2O3 alone, the introduction of Cu / ZnO / Al2O3 tended to decrease the total NOx conversion rate because the concentration of CO coexisting in the reactants was reduced while H2 was produced. It is expected.

On the other hand, as shown in Figure 6, compared to the case of the single catalyst layer system, the reaction temperature range of the entire reaction temperature in the case of the two-stage catalyst layer system of Cu / ZnO / Al 2 O 3 and 2 wt% Pd / TiO 2 / Al 2 O 3 (mass ratio = 1: 1) The total NOx conversion was decreased at, and the NOx-> N2 conversion was also decreased, and it was confirmed that the conversion of NOx-> N2 was performed only at the temperature of 200 ° C., which showed the highest total NOx conversion. It is expected that this is because CO was consumed by Cu / ZnO / Al 2 O 3, and the generated H 2 was not used as a reducing agent of the DeNO x reaction while reacting with most O 2. As a result, in the WGSR + DeNOx complex catalyst combining Cu / ZnO / Al2O3 and 2 wt% Pd / TiO2 / Al2O3, the single catalyst layer method combining the two catalysts has a higher DeNOx performance than the two-stage catalyst layer method in which the two catalysts are separated and disposed. It was confirmed to show.

In addition, a WGSR + DeNOx reaction experiment using 3, 3 wt% Au / Ru / Fe2O3 prepared in 2 as the WGSR catalyst and 2 wt% Pd / TiO2 / Al2O3 as the DeNOx catalyst was performed. The combination method of 3, 3 wt% Au / Ru / Fe2O3 and 2 wt% Pd / TiO2 / Al2O3 uses a mixture of two catalysts as a single catalyst layer and places 3, 3 wt% Au / Ru / Fe2O3 at the front end. It was applied in two forms of a two-stage catalyst layer method in which 2 wt% Pd / TiO 2 / Al 2 O 3 was placed at the rear end. The reaction test results when 3, 3 wt% Au / Ru / Fe2O3 were mixed with the WGSR catalyst and used as a single catalyst layer method are shown in FIGS. 7, 8, and 9, and 3, 3 wt% Au / Ru / Fe2O3 was 2 However, the reaction test results when used in the catalyst layer method is shown in FIG. In the case of the single catalyst layer method, the mixing ratio of 3, 3 wt% Au / Ru / Fe2O3 and 2 wt% Pd / TiO2 / Al2O3 is 0.5: 1, 1: 1, 1.5: 1 by mass ratio. The ratio of 3, 3 wt% Au / Ru / Fe2O3 to 2 wt% Pd / TiO2 / Al2O3 was 1: 1 in mass ratio.

7, 8, and 9, compared with the results of using Pd / TiO2 / Al2O3 alone, the high temperature region when using a mixed catalyst of 3, 3 wt% Au / Ru / Fe2O3 and 2 wt% Pd / TiO2 / Al2O3 ( It was confirmed that the total NOx conversion at 250 ° C to 300 ° C was improved to form a relatively wide range of active temperature ranges of 200 ° C to 300 ° C. In this active temperature range, high levels of NOx-> N2 conversion were also shown, which was produced by the WGSR catalyst 3, 3 wt% Au / Ru / Fe2O3, despite the relatively high temperature conditions with the presence of O2. H2 was effectively used as a reducing agent in the DeNOx reaction.

As shown in FIG. 10, the two-stage catalyst layer method of 3, 3 wt% Au / Ru / Fe2O3 and 2 wt% Pd / TiO2 / Al2O3 (mass ratio = 1: 1) compared to the case of the single catalyst bed method The total NOx conversion was decreased in the reaction temperature range, and the total NOx conversion was particularly decreased in the high temperature range of 250 ° C to 300 ° C. The overall NOx-> N2 conversion was also reduced, which also means that the concentration of CO was reduced by WGSR and that the effective utilization of H2 produced was not achieved. Through this, the WGSR + DeNOx system, which combines 3, 3 wt% Au / Ru / Fe2O3 and 2 wt% Pd / TiO2 / Al2O3, is also a two-stage catalyst layer in which two catalysts are separated and disposed as in the case of combining Cu / ZnO / Al2O3. It was found that the single catalyst bed method of mixing the two catalysts showed higher DeNOx performance than the method. However, when comparing the same amount of catalyst, 3, 3 wt% Au / Ru / Fe2O3 + 2 wt% Pd / TiO2 / Al2O3 composite catalysts are better than Cu / ZnO / Al2O3 + 2 wt% Pd / TiO2 / Al2O3 composite catalysts. It was confirmed to exhibit DeNOx performance.

The following conclusions can be drawn about the catalytic reduction of NOx using only its own CO as a reducing agent in the engine exhaust gas composition operating in the actual excess oxygen conditions without the introduction of a separate reducing agent.

1.WGSR + DeNOx reaction experiment using Cu / ZnO / Al2O3 as WGSR catalyst and 2 wt% Pd / TiO2 / Al2O3 as DeNOx catalyst and supplying only CO as reducing agent of NOx. In the case of the method, Pd / TiO2 / Al2O3 alone showed a specific active temperature range similar to the results, and it was confirmed that the conversion reaction of NOx-> N2 proceeded in this active temperature range. In the case of the two-stage catalyst bed method in which the two catalysts are disposed separately, the total NOx conversion was decreased in the entire reaction temperature range compared to the case of the single catalyst bed method, and the conversion rate of NOx-> N2 was also reduced to show the highest total NOx conversion rate. It was confirmed that the conversion of NOx-> N2 only proceeded at ℃.

2. As a result of the WGSR + DeNOx reaction experiment using 3, 3 wt% Au / Ru / Fe2O3 as the WGSR catalyst, 2 wt% Pd / TiO2 / Al2O3 as the DeNOx catalyst, and supplying only CO as the reducing agent of NOx, the two catalysts were mixed. In the case of using a single catalyst layer method, the total NOx conversion in the high temperature range (250 ° C to 300 ° C) is improved compared to the result of using Pd / TiO2 / Al2O3 alone, and thus, a relatively wide range of active temperatures of 200 ° C to 300 ° C It was confirmed that a zone was formed and a high level of NOx-> N2 conversion proceeded in this active temperature zone. In the case of the two-stage catalyst bed system in which the two catalysts are disposed separately, the total NOx conversion was reduced in the entire reaction temperature range compared to the case of the single catalyst bed method. Decreased. The conversion of NOx-> N2 was also reduced, confirming that it was up to 20% at 225 ° C.

3. In the WGSR + DeNOx reaction experiment using a combination of WGSR and DeNOx catalysts, it was found that a single catalyst layer method using a mixture of two catalysts showed better DeNOx performance than a two-stage catalyst layer method in which two catalysts were separated. .

FIG. 1 shows (a) UHC / NOx ratio and (b) CO / NOx ratio in diesel engine exhaust gas based on flow path IV.

FIG. 2 shows NOx conversion with temperature of 2 wt% Pd / TiO2 / Al2O3 DeNOx catalyst (conditions: 2000 ppm NO, 8% O2, 5% CO2, 32000 ppm CO, 10% H2O present, He balance, flow rate = 300 ml min-1, w / f = 0.1 gs ml-1).

3, 4, and 5 show NOx according to the temperature of the DeNOx composite catalyst of the mixed single layer 2 wt% Pd / TiO2 / Al2O3 (0.25g) + Cu / ZnO / Al2O3 (0.125g, 0.25g, 0.375g), respectively. Conversion rate is shown (conditions: 2000 ppm NO, 8% O2, 5% CO2, 32000 ppm CO, 10% H2O, He balance, flow rate = 150 ml min-1, w / f = 0.1 gs ml-1) .

FIG. 6 shows NOx conversion with temperature of catalysts arranged in a line with Cu / ZnO / Al2O3 (0.25g) + 2 wt% Pd / TiO2 / Al2O3 (0.25g) (same conditions as in FIG. 3).

7, 8, and 9, 2 wt% Pd / TiO 2 / Al 2 O 3 (0.25 g) + 3, 3 wt% Au / Ru / Fe 2 O 3 (0.125 g, 0.25 g, 0.375 g) mixed single layer DeNOx complex catalyst, respectively Shows NOx conversion with temperature (conditions: 2000 ppm NO, 8% O2, 5% CO2, 32000 ppm CO, 10% H2O, He balance, flow rate = 150 ml min-1, w / f = 0.1 gs ml-1).

FIG. 10 shows NOx conversion with temperature of catalysts arranged in a line of Cu / ZnO / Al2O3 (0.25g) + 3, 3 wt% Au / Ru / Fe2O3 (0.25g) (same conditions as in FIG. 7).

Claims (5)

DeNOx catalyst for NOx removal in diesel or lean-burn engine exhaust, and water gas transition reaction selected from Cu / ZnO / Al ₂ O ₃ or Au / Ru / Fe ₂ O ₃ WGSR) catalyst, characterized in that the mixed catalyst DeNOx. The DeNOx complex catalyst of claim 1, wherein the DeNOx catalyst is Pd / TiO ₂ / Al ₂ O ₃ . delete The DeNOx complex catalyst according to claim 1 or 2, wherein the mixing ratio of the DeNOx catalyst and the WGSR catalyst is 1: 0.1 to 10 by weight ratio. delete

Images