KR20130036529A - Exhaust gas cleaning system for desel engine - Google Patents

Exhaust gas cleaning system for desel engine Download PDF

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Publication number
KR20130036529A
KR20130036529A KR1020110100665A KR20110100665A KR20130036529A KR 20130036529 A KR20130036529 A KR 20130036529A KR 1020110100665 A KR1020110100665 A KR 1020110100665A KR 20110100665 A KR20110100665 A KR 20110100665A KR 20130036529 A KR20130036529 A KR 20130036529A
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South Korea
Prior art keywords
photocatalyst
exhaust gas
titanium oxide
exhaust
photocatalytic reaction
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KR1020110100665A
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Korean (ko)
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이종식
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네오원 (주)
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
    • F01N3/18—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control
    • F01N3/20—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control specially adapted for catalytic conversion ; Methods of operation or control of catalytic converters
    • F01N3/2086—Activating the catalyst by light, photo-catalysts
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
    • F01N3/24—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by constructional aspects of converting apparatus
    • F01N3/28—Construction of catalytic reactors
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N13/00—Exhaust or silencing apparatus characterised by constructional features ; Exhaust or silencing apparatus, or parts thereof, having pertinent characteristics not provided for in, or of interest apart from, groups F01N1/00 - F01N5/00, F01N9/00, F01N11/00
    • F01N13/008—Mounting or arrangement of exhaust sensors in or on exhaust apparatus
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N13/00—Exhaust or silencing apparatus characterised by constructional features ; Exhaust or silencing apparatus, or parts thereof, having pertinent characteristics not provided for in, or of interest apart from, groups F01N1/00 - F01N5/00, F01N9/00, F01N11/00
    • F01N13/009—Exhaust or silencing apparatus characterised by constructional features ; Exhaust or silencing apparatus, or parts thereof, having pertinent characteristics not provided for in, or of interest apart from, groups F01N1/00 - F01N5/00, F01N9/00, F01N11/00 having two or more separate purifying devices arranged in series
    • F01N13/0097—Exhaust or silencing apparatus characterised by constructional features ; Exhaust or silencing apparatus, or parts thereof, having pertinent characteristics not provided for in, or of interest apart from, groups F01N1/00 - F01N5/00, F01N9/00, F01N11/00 having two or more separate purifying devices arranged in series the purifying devices are arranged in a single housing
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2370/00—Selection of materials for exhaust purification
    • F01N2370/02—Selection of materials for exhaust purification used in catalytic reactors
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2570/00—Exhaust treating apparatus eliminating, absorbing or adsorbing specific elements or compounds
    • F01N2570/10—Carbon or carbon oxides
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2570/00—Exhaust treating apparatus eliminating, absorbing or adsorbing specific elements or compounds
    • F01N2570/12—Hydrocarbons
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2570/00—Exhaust treating apparatus eliminating, absorbing or adsorbing specific elements or compounds
    • F01N2570/14—Nitrogen oxides

Abstract

An exhaust purification system for a diesel engine of the present invention, comprising: an exhaust pipe through which exhaust gas of a diesel engine is discharged; A purification module connected to the exhaust pipe and configured to purify the exhaust gas by a photocatalyst; A power supply unit supplying power to the purification module; A detection sensor provided inside the exhaust pipe and detecting a concentration of a hazardous substance contained in the exhaust gas; And a control unit for controlling the power supply intensity of the power supply unit according to the detection result of the sensor, wherein the photocatalyst is a first type of titanium oxide, which is an antimicrobial titanium oxide nanoparticle using a hydrothermal synthesis method, and a microwave low temperature plasma method. Photocatalyst material comprising titanium oxide of surface type 2, ceramic material comprising alumina having alpha-alumina (α-Al2O3) or particles of 0.2cc / g or more and having an area of more than 20 m2 / g, and A monolithic photocatalyst comprising a cocatalyst comprising a zeolite, wherein the titanium oxide of the first type is at least 35 wt% in the monolithic photocatalyst, and the titanium oxide of the second type is 20 wt% in the monolithic photocatalyst Included above, the alpha-alumina (α-Al2O3) is at least 7 wt% of the monolithic photocatalyst, the particles are 0.2cc / g or more, having an area of more than 20 m 2 / g Alumina is characterized in that comprises at least 7 wt% of said monolithic photocatalyst.

Description

EXHAUST GAS CLEANING SYSTEM FOR DESEL ENGINE}

The present invention relates to an exhaust purification system, and more particularly, to an exhaust purification system of a diesel engine for purifying exhaust gas of a diesel engine using a photocatalyst.

Exhaust gases from diesel engines include mixtures of air pollutants consisting of carbon monoxide (CO), unburned hydrocarbons (HC), nitrogen oxides (NOx), and particulate matter containing SOFs (Soluble Organic Fractions). Exhaust gas allowances for diesel engines are usually mandated by law, and their allowances are often determined by engine management, engine design, and post-treatment of exhaust gases.

In a conventional diesel engine, HC and CO are purged within a predetermined range by a platinum oxidation catalyst (DOC) based on platinum (Pt), and NOx emission is controlled by an exhaust gas recirculation (EGR) system of a diesel engine. Particulate matter (PM) is collected in a diesel particulate filter (DPF) and its discharge is controlled within a predetermined range. However, the above technique is made by attaching an additional device such as a heater or burner to burn the particulate matter collected in the soot filter at a high temperature, or coating and oxidizing the catalyst inside the soot filter to regenerate the soot filter. Its practicality fell greatly.

As a conventional technology, Johnson Matthey oxidizes NO in exhaust gas to NO 2 with excellent oxidation reactivity and uses the oxidized NO 2 as an oxidant at the front of the soot filter. Has been proposed to regenerate the particulate filter collected by oxidizing particulate matter. This technique is disclosed in EP-A-0341832 and US4902487 and is widely known under the trade name CRTTM.

However, the above technique uses ultra low sulfur (Pt), which is highly toxic by sulfur present in diesel exhaust, as an oxidation catalyst for oxidizing NO to NO 2. Therefore, ultra low sulfur oil (ULSD) must be used as a fuel. In addition, since only about 3 to 8% of NOx is reduced in the exhaust gas, there is still a need for an additional technique for reducing nitrogen oxides.

In response, Johnson Matthey developed the SCRTTM system as a four-way post-treatment system using SCR (Selective Catalytic Reduction) catalysts for soot filtration. The system is known to reduce HC and CO and reduce particulate matter and nitrogen oxides by approximately 75-90%. However, this system requires more than 13.6 times the volume of the aftertreatment of the exhaust gas, which is currently being tested in large diesel engines, but its practicality is known to be poor, and sulfur poisoning problems still exist. It was.

Meanwhile, Japan's Toyota Motor Co., Ltd. DPNR (Diesel Particulate NOx Reduction) that reduces particulate matter and nitrogen oxide simultaneously by coating NOx adsorption catalyst on a general particulate filter (DPF) and placing a platinum oxidation catalyst on the particulate filter. The system has been developed, and such a conventional DPNR system is disclosed in Japanese Patent Laid-Open No. 6-159037.

In the conventional DPNR technology, in the lean combustion condition (a) of a diesel engine, O 2 and NO react with each other in the vicinity of Pt, which is an oxidation catalyst, and active oxygen O * and NO 2 are generated, and NO 2 is absorbed in the adsorption catalyst. It will exist in the form of a salt. In addition, PM (particulate matter) is oxidized by O * generated at this time and O 2 in the exhaust gas, and the oxidized PM is further reacted with O 2 in the exhaust gas and oxidized to CO 2 .

In addition, in the rich combustion condition (b) of a diesel engine, NO x adsorbed in the form of a salt to the adsorption catalyst is released into NO and O * by high temperature exhaust and instantaneous rich exhaust conditions. Reacts with HC and CO through oxidation of Pt to CO 2 , H 2 O, and N 2 . In addition, PM can be oxidized to CO 2 by reacting with O * from the adsorption catalyst even in rich oxygen-rich combustion conditions.

However, the following technical limitations still exist in Toyota Motor's DPNR system, which adopts the continuous regeneration method. First, since platinum is used as an oxidation catalyst, performance degradation caused by poisoning by sulfur present in a large amount in diesel exhaust cannot be prevented.

Second, since only the rich combustion conditions must be provided periodically to purify the adsorbed nitrogen oxides, it inhibits the high fuel efficiency, which is the biggest advantage of the diesel engine. In addition, additional fuel injectors must be installed on top of the DPNR system to provide periodic enriched combustion conditions, resulting in increased costs or post injection from the engine's combustion injectors, which can impair stable operation. There is this.

In addition, since the NOx adsorption amount of the adsorption catalyst is limited under the lean combustion conditions of the diesel engine, the diesel engine needs to be operated under the theoretical air-fuel ratio or rich combustion conditions with low oxygen periodically. This implies that the technique is inadequate for diesel passenger car engines that operate primarily in lean combustion zones and do not experience periodic high load conditions.

In addition, the prior art requires a high activation temperature and therefore high energy in order to have the oxidation power of Pt oxidizing catalyst, there is a problem that does not have any purification function for the exhaust gas until the activation temperature is reached. .

In addition, the conventional technique is that the HC and CO are rapidly oxidized by the high temperature activated Pt oxidation catalyst under the rich combustion conditions in which the regeneration of the NO x adsorption catalyst may occur, so that the reduction of NO x may be prevented. To prevent this, the prior art takes a post-injection method that injects more fuel in consideration of the amount of HC and CO under rich combustion conditions, which leads to waste of diesel fuel.

SUMMARY OF THE INVENTION An object of the present invention is to provide an exhaust purification system of a diesel engine having a structure particularly suitable for a diesel passenger car engine which operates mainly in a lean combustion region and does not generate periodic high load conditions due to its combustion characteristics.

Another object of the present invention is to provide an exhaust purification system of a diesel engine that can reduce fuel consumption by solving the problems of the prior art, which is further injected separately for the composition of the reducing atmosphere of NO x .

In addition, another object of the present invention, to solve the problems of the prior art using a catalyst activated under a high exhaust temperature, it is possible to purify the harmful substances such as HC, CO, PM, NO x at a relatively low temperature, Since the time required for the activation of the catalyst is not substantially required, it is to provide an exhaust purification system of a diesel engine with higher purification efficiency of exhaust gas.

Another object of the present invention is to use the components such as HC, CO, C or NO2 in the exhaust gas as the oxidizing agent or reducing agent used in the step-by-step oxidation or reduction, to increase the purification efficiency of the exhaust gas through the control of the components and exhaust It is to provide an exhaust purification system of a diesel engine that can reduce the energy consumption required for gas purification.

The above objects and various advantages of the present invention will become more apparent from the preferred embodiments of the present invention by those skilled in the art.

The object of the present invention can be achieved by an exhaust purification system of a diesel engine. An exhaust purification system for a diesel engine of the present invention includes: an exhaust pipe through which exhaust gas of the diesel engine is discharged; A purification module connected to the exhaust pipe and configured to purify the exhaust gas by a photocatalyst; A power supply unit supplying power to the purification module; A detection sensor provided inside the exhaust pipe and detecting a concentration of a hazardous substance contained in the exhaust gas; And a control unit for controlling the power supply intensity of the power supply unit according to the detection result of the sensor, wherein the photocatalyst is a first type of titanium oxide, which is an antimicrobial titanium oxide nanoparticle using a hydrothermal synthesis method, and a microwave low temperature plasma method. Photocatalyst material comprising titanium oxide of surface type 2, ceramic material comprising alumina having alpha-alumina (α-Al2O3) or particles of 0.2cc / g or more and having an area of more than 20 m2 / g, and A monolithic photocatalyst comprising a cocatalyst comprising a zeolite, wherein the titanium oxide of the first type is at least 35 wt% in the monolithic photocatalyst, and the titanium oxide of the second type is 20 wt% in the monolithic photocatalyst Included above, the alpha-alumina (α-Al2O3) is at least 7 wt% of the monolithic photocatalyst, the particles are 0.2cc / g or more, having an area of more than 20 m 2 / g Alumina is characterized in that comprises at least 7 wt% of said monolithic photocatalyst.

According to one embodiment, the purification module, the first photocatalytic reaction unit for oxidizing the HC, CO, NO or particulate matter in the exhaust gas; A second photocatalytic reaction part for collecting particulate matter in exhaust gas through the first photocatalytic reaction part in a soot filtration filter and oxidizing the collected particulate matter to regenerate the soot filtration filter; The photocatalyst and the adsorbent may include a third photocatalytic reaction unit for adsorbing NO x in the exhaust gas passing through the second reactor by the adsorbent and removing the NO x through a reduction reaction.

According to one embodiment, the first photocatalytic reaction unit, the second photocatalytic reaction unit and the third photocatalytic reaction unit, respectively, the purification frame; It includes a porous filter coupled to the purification frame, the photocatalyst is formed is coated on the surface of the porous filter.

The present invention can easily control the photocatalytic reaction and easily adsorb NOx to the adsorbent without additional supply of fuel or reducing agent under various combustion conditions of a diesel engine, and easily remove the adsorbed NOx to remove and remove NOx. There is less need for periodic high load conditions, which has the effect that can be very advantageously used in diesel passenger car engines.

In addition, the present invention has the effect of significantly reducing the fuel consumption by solving the problems of the prior art that was further injected separately fuel for the composition of the reducing atmosphere of NOx.

In addition, the present invention can solve the problems of the prior art that the catalyst is activated under the high exhaust temperature used to purify the exhaust gas to purify the harmful substances such as HC, CO, PM, NOx at a relatively low temperature, and However, since the time required for the activation of the catalyst is not substantially required, the purification efficiency of the exhaust gas is very excellent.

In addition, the present invention is an oxidizing agent or reducing agent used in the oxidation or reduction step by step HC, CO, C or NO 2 in the exhaust gas By using such components, the control of the components to increase the efficiency of exhaust gas purification and has the effect of reducing the energy consumption required for exhaust gas purification.

In addition, since the present invention uses TiO 2 having excellent endothelial toxicity against sulfur components as a photocatalyst, it is possible to prevent degradation of the durability of the system due to sulfur components and to enable the use of diesel fuel containing a large amount of sulfur components as compared to the conventional art.

1 is a schematic diagram schematically showing the configuration of a diesel engine exhaust purification system of the present invention;
Figure 2 is a perspective view showing the configuration of the photocatalytic reaction unit of the diesel engine exhaust purification system of the present invention,
3 is an exemplary view showing a state of use of the photocatalytic reaction unit of the diesel engine exhaust purification system of the present invention;
Figure 4 and a graph measuring the amount of cumulative hydrocarbon over time when using the diesel engine exhaust purification system of the present invention,
Figure 5 is a graph measuring the amount of cumulative hydrocarbons over time when using the diesel engine exhaust purification system of the present invention.

In order to fully understand the present invention, preferred embodiments of the present invention will be described with reference to the accompanying drawings. The embodiments of the present invention may be modified into various forms, and the scope of the present invention should not be construed as being limited to the embodiments described in detail below. The present embodiments are provided to enable those skilled in the art to more fully understand the present invention. Therefore, the shapes and the like of the elements in the drawings can be exaggeratedly expressed to emphasize a clearer description. It should be noted that in the drawings, the same members are denoted by the same reference numerals. Detailed descriptions of well-known functions and constructions which may be unnecessarily obscured by the gist of the present invention are omitted.

1 is a schematic diagram schematically showing a configuration of an exhaust purification system 1 of a diesel engine according to the present invention.

As shown, the exhaust purification system 1 of the diesel engine according to the present invention includes an exhaust pipe 100 through which exhaust gas of the diesel engine A is discharged, and a purification module connected to the exhaust pipe 100 to purify the exhaust gas. 200, the power supply unit 400 for supplying power to the photocatalytic reaction units 220, 230, 240 and the low temperature plasma units 250, 260, 270 of the purification module 200, and a sensor for detecting the concentration of harmful substances contained in the exhaust gas ( 300 and the differential pressure sensor 500 for measuring the difference in pressure between the exhaust pipe 100 before and after the purification module 200, and the power supply unit based on the values measured by the sensor 300 and the differential pressure sensor 500. It includes a control unit 600 for adjusting the power supply degree of 400.

The exhaust pipe 100 is connected to the rear end of the diesel engine to guide the exhaust gas generated by the combustion of the diesel engine to the purification module 200. The exhaust pipe 100 is connected before and after the purification module 200 so that the purified exhaust gas is discharged to the outside.

The purification module 200 purifies the exhaust gas supplied through the exhaust pipe 100. Purification module 200 according to the present invention is provided with a plurality of photocatalytic reaction units 220, 230, 240 for purifying the harmful substances contained in the exhaust gas by using a photocatalyst. The plurality of photocatalytic reaction parts 220, 230, and 240 may be provided with HC, CO, PM, NO x in exhaust gas. Purify the back sequentially.

Each of the photocatalytic reaction units 220, 230, and 240 each includes a photocatalyst that reacts with the low temperature plasma from the low temperature plasma units 250, 2260, and 270 to cause a photocatalytic action. At this time, the action of the photocatalyst is varied by the intensity of the low temperature plasma, and the low temperature plasma units 250, 260, 270 are controlled by the controller 600 according to the oxygen concentration (or the dilution concentration) in the exhaust gas.

FIG. 2 is a perspective view illustrating a configuration of the first photocatalytic reaction unit 220, and FIG. 3 is an enlarged perspective view illustrating an enlarged view of the first porous filter 223 of the first photocatalytic reaction unit 220 of FIG. 2.

As shown, the first photocatalytic reaction unit 220 includes a first photocatalyst frame 221 coupled to the tubular module body 210 and a first porous filter 223 coupled to the first photocatalyst frame 221. And a photocatalyst 223a coated on the surface of the first porous filter 223, an electrode terminal 225 coupled to the first photocatalyst frame 221, and a section coupled before and after the first photocatalyst frame 221. The body 227 is included.

The first porous filter 223 is formed by passing through a plurality of channels 223b which are microchannels in a direction in which harmful pollutants enter. The cross-sectional shape of the first porous filter 223 is formed similarly to the cross-sectional shape of the flow path. That is, the cross-sectional shape of the first porous filter 223 is provided in a circular shape as shown, or is formed in a polygon including a quadrangle.

In addition, in the first porous filter 223, a plurality of channels 223b having a hexagonal shape, a pentagonal shape, a circular shape, a square shape, and the like in a cross-section in the flow direction of the exhaust gas are formed to have a predetermined length in the longitudinal direction so that the exhaust gas can flow. Here, the first porous filter 223 of the present invention is provided with a channel 223b in a rectangular shape, but may be provided in a honeycomb (hexagonal) shape to be strong in impact and to widen a gas collection area.

Meanwhile, the photocatalyst 223a is coated on the surface of the first porous filter 223. The photocatalyst 223a reacts with the low temperature plasma generated by the first low temperature plasma unit 250 to act as a photocatalyst. This allows HC, CO, PM, NO x in the exhaust gas. The back is purified sequentially.

The photocatalyst 223a used in the purification module 200 of the present invention is a ceramic comprising a photocatalyst material including titanium oxide of type 1 and titanium oxide of type 2, alumina of type 1 and alumina of type 2 Material, and a promoter comprising a zeolite. At this time, the titanium oxide of the first type is preferably 35 wt% or more in the photocatalyst 223a, and the titanium oxide of the second type is contained 20 wt% or more in the photocatalyst 223a. Titanium oxide is excellent in durability when used in mixing the first type and the second type, and relatively excellent in purification performance when combined in the above-described weight ratio.

In addition, the alumina of the first type is preferably contained 7 wt% or more in the photocatalyst 223a, and the alumina of the second type is contained 7 wt% or more in the photocatalyst. Alumina is used to provide sufficient opportunities for the catalyst and exhaust gas to come into contact, to connect the photocatalytic materials with each other, and to provide mechanical strength after sintering. At this time, the above-mentioned efficacy is most excellent when mixed in the above-described weight ratio.

Titanium oxide of type 1 and titanium oxide of type 2 include TiO (molecular weight: 63.866, CAS registration number: 12137-20-1), TiO 2 (molecular weight: 79.866, CAS registration number: 13463-67-7), TiO 2 (molecular weight: 79.866, CAS registration number: 1317-80-2), TiO 2 (molecular weight: 79.866, CAS registration number: 1317-70-0), TiO 2 (molecular weight: 79.866, Cas registration number: 1309-63 At least one of -3) may be used. At this time, it is preferable that titanium oxide of a 1st type and titanium oxide of a 2nd type use a different titanium oxide.

Meanwhile, at least one of TiOA and TiOB may be used as the titanium oxide of the first type and the titanium oxide of the second type. At this time, it is preferable that titanium oxide of a 1st type and titanium oxide of a 2nd type use a different titanium oxide.

TiOA may be used as an antimicrobial titanium oxide nanoparticles using a hydrothermal synthesis method. TiOA can be generated by the following procedure.

Distilled water was added to Ti (SO 4 ) 2 (Kanto Co., 24%) used as a starting material to prepare 0.1M Ti (SO 4 ) 2 aqueous solution, and then ammonium hydroxide (NH 4 OH, Junsei Co., 28%) was added. Slowly dropwise, adjust the pH of the precipitated Ti (OH) 4 to 6-9, and stir for about 30 minutes to allow sufficient reaction. The obtained precipitate was repeatedly washed several times in a centrifugal separator to sufficiently remove impurities, and the washed precipitate was diluted with distilled water to 0.1M aqueous solution and then completely dispersed through stirring and sonication.

The 0.1 M Ti (OH) 4 aqueous solution obtained above was hydrothermally treated at 150 ° C. under saturated steam pressure conditions for 3 hours using an autoclave apparatus to prepare a final titanium oxide solution, and sodium hydroxide (NaOH) Titanium oxide (Anatase) is formed at 557.6 ℃ using.

TiOB is titanium oxide which is surface treated by microwave low temperature plasma method to deposit carbon on the surface. When titanium oxide is used for the photocatalyst 223a according to the present invention, plasma discharge may be performed at a low pressure (2V to 24V), and thus ozone is hardly generated, and energy consumption is reduced by low voltage plasma discharge. have.

The alumina of type 1 and the alumina of type 2 may be at least one of alpha-alumina (α-Al 2 O 3) or alumina having particles having a high porosity of 0.2cc / g or more and an area of more than 20 m 2 / g. It is preferable that alumina of type 1 and alumina of type 2 use different aluminas.

First photocatalytic reaction unit 220 The second photocatalytic reaction unit 230 and the third photocatalytic reaction unit 240 have the same structure, but play a different role. The first photocatalytic reaction unit 220 generates a photocatalytic reaction by the photocatalyst 223a in response to the low temperature plasma generated by the first low temperature plasma unit 250, and purifies HC, CO, etc. in the exhaust gas by the photocatalytic action. Promotes oxidation

The second photocatalytic reaction unit 230 uses a soot filtration filter (SiC DPF) as a second porous filter (not shown), and a photocatalyst is coated on the surface of the second porous filter (not shown). The soot filtration filter has a porous structure in which the filter wall filters PM (particulate matter), and can capture PM in the exhaust gas. In addition, the photocatalyst coated on the surface of the second porous filter (not shown) promotes the action of oxidizing particulate matter, ie PM, collected in the soot filtration filter in response to the low temperature plasma generated in the second low temperature plasma unit 260. Let's do it.

The third photocatalytic reaction unit 240 is formed by coating an adsorbent (Ads; adsorber) made of potassium (K) and / or barium (Ba) and a photocatalyst on a third porous filter (not shown). At this time, the adsorbent Ads adsorbs NO x , that is, nitrogen oxides for a certain period of time, and the photocatalyst reacts with the low temperature plasma generated in the third low temperature plasma unit 270 to reduce the NO x and thereby reduce the reducing power during regeneration of the adsorbent. It plays a role in controlling.

The sensor 300 is provided inside the exhaust pipe 100 to measure the concentration of harmful gas contained in the exhaust gas. The detection sensor 300 may be provided as an oxygen sensor for measuring the oxygen concentration in the exhaust gas.

The power supply unit 400 supplies power to the electrode terminals 225 and the low temperature plasma units 250, 260, and 270 of the photocatalytic reaction units 220, 230, and 240. The differential pressure sensor 500 measures the differential pressure between the upstream 510 and the downstream 520 of the purification module 200.

The control unit 600 determines whether the diesel engine is a dilute combustion condition or a rich combustion condition according to the oxygen concentration value measured by the oxygen sensor, and supplies power to the low temperature plasma unit 250, 260, 270 according to the determination. By controlling 400, the photocatalytic reactions of the photocatalytic reaction units 220, 230, and 240 are adjusted in whole or individually.

In addition, the controller 600 adjusts the power supply to the low temperature plasma units 250, 260, and 270 in consideration of the differential pressure of the exhaust gas measured by the differential pressure sensor 500.

An exhaust gas purification process of the exhaust purification system 1 of the diesel engine according to the present invention having such a configuration will be described with reference to FIGS. 1 to 3.

When the exhaust gas generated in the diesel engine A is introduced through the exhaust pipe 100, the first low temperature plasma unit 250 irradiates a low temperature plasma on the photocatalyst 223a in the first photocatalytic reaction unit 220. It produces free radicals and free reactors, which oxidize HC, CO, NO, and some of the SOF in the PM. HC and CO are oxidized to CO 2 And purified with water, and the oxidized SOF is also purified with water and CO 2 . In addition, NO, which occupies 90% or more of NOx, is changed to NO 2 and used as an oxidant for oxidation of PM (particulate matter) in the second photocatalytic reaction unit 230 and regeneration of the soot filtration filter.

At this time, the control unit 600 reduces the power applied to the first low-temperature plasma unit 250 in the lean combustion conditions with a large amount of oxygen in the exhaust gas, thereby reducing the oxidation by the photocatalyst 223a, and enriching combustion with a small amount of oxygen. In the condition, it is preferable to increase the oxidation applied by the photocatalyst 223a by increasing the power applied to the first low temperature plasma unit 250.

In addition, the controller 600 appropriately controls the amount of NO 2 used as the oxidant in the second photocatalytic reaction unit 230 according to the concentration of the exhaust gas. In the second photocatalytic reaction unit 230, PMs (particulate matter) that are not removed from the first photocatalytic reaction unit 220 are collected on the second porous filter (not shown). The PM collected in the second porous filter (not shown) is activated with a free reactor generated on NO 2 in the exhaust gas generated in the first photocatalytic reaction unit 220 and the photocatalyst coated on the second photocatalytic reaction unit 230. It is oxidized by oxygen and changes to CO, HC, H 2 , water, NO and the like. Through this oxidation reaction, the second porous filter (not shown) of the second photocatalytic reaction unit 230 may be continuously regenerated.

On the other hand, since the TiO 2 photocatalyst activated by low temperature plasma is used as a catalyst for regeneration of the second porous filter (not shown), it is possible to continuously regenerate the second porous filter (not shown) even under a low exhaust temperature. Since the activation of the photocatalyst can be performed quickly by irradiation of the second low temperature plasma unit, the time required for regeneration of the second porous filter (not shown) can be greatly shortened.

At this time, the controller 600 adjusts the power supply amount to the second low temperature plasma unit 260 according to the concentration of harmful substances (HC, CO, PM) of the exhaust gas. In particular, it is preferable to partially oxidize SOF in PM into carbon monoxide (CO) and short carbon ring hydrocarbon (HC), rather than completely oxidizing carbon dioxide and water, and the carbon monoxide and hydrocarbons are converted into NOx in the third photocatalytic reaction unit 240. It can be used as a reducing agent.

In the third photocatalytic reaction unit 240, NOx in the exhaust gas passing through the first and second photocatalytic reaction units 220 and 230 is adsorbed to the adsorbent Ads so that the third porous filter of the third photocatalytic reaction unit 240 is not shown. ) And NOx adsorbed to the adsorbent (Ads) through a photocatalytic reduction reaction using HC, CO or C in the exhaust gas as a reducing agent is reduced, and the adsorbent (Ads) can be regenerated through this reduction reaction.

At this time, the control unit 600 may control the power supply to the third low-temperature plasma unit 270 to adjust the reducing power for NOx, which is a reduction reaction of NOx even by oxygen-rich lean burning conditions This can be done without effect, eliminating the need for a separate reducing agent supply for the reduction of NOx. In addition, the controller 200 may prevent the nitrogen in the exhaust gas from being oxidized to further generate nitrogen oxide by appropriately controlling the third low temperature plasma unit 270.

On the other hand, Figure 4 is a graph measuring and displaying the hydrocarbon removal capacity of the photocatalyst used in the purification module 200 of the present invention.

Experimental Example  One

In order to measure the hydrocarbon removal ability of the photocatalyst, the MCC (Manifold Catalyst Converter, 120K Engine Bench Aged Converter) and the photocatalyst converter (PPH) of the present invention are installed together, and after the hydrocarbon is released at a constant rate, The amount of total hydrocarbon accumulated over time was measured.

Comparative example  One

Only the Manifold Catalyst Converter (MCC) and 120K Engine Bench Aged Converter (MCC) were installed, and the hydrocarbons were released at a constant rate, and the amount of total hydrocarbons accumulated over time was measured.

As shown in FIG. 4, in Experimental Example 1, the photocatalyst reacts from about 40 seconds, and as the hydrocarbon is decomposed, the cumulative rate of hydrocarbons released at a constant rate decreases. In addition, in the case of Experimental Example 1, it can be seen that the amount of accumulated total hydrocarbons (THC) is smaller than that of Comparative Example 1. Therefore, it can be seen that the contaminant removal efficiency of the photocatalyst of the present invention is high.

On the other hand, Figure 5 is a graph measuring the amount of accumulated nitrogen oxides (NO x ) over time.

Experimental Example  2 photocatalyst of  Nitrogen oxides NOx ) Removal capability measurement

After installing the MCC (Manifold Catalyst Converter, 120K Engine Bench Aged Converter) and the photocatalyst converter (PPH) of the present invention together, releasing nitrogen oxides (NOx) at a constant rate, accumulated over time The amount of total NOx was measured.

Comparative example  2

Only a Manifold Catalyst Converter (MCC) and a 120K Engine Bench Aged Converter (MCC) were installed, and the nitrogen oxides (NOx) were released at a constant rate, and then the total amount of NOx accumulated over time was measured.

Experimental results As shown in FIG. 5, in Experimental Example 2, it can be seen that as the nitrogen oxides (NOx) are decomposed, the cumulative rate of nitrogen oxides (NOx) released at a constant rate decreases. In addition, in the case of Experimental Example 2 it can be seen that the amount of accumulated nitrogen oxides (NOx) is less than that of Comparative Example 2. Therefore, it can be seen that the contaminant removal efficiency of the photocatalyst of the present invention is high.

As described above, when the exhaust purification system of the diesel engine of the present invention is used for exhaust purification of a diesel engine, the first photocatalytic reaction unit may purify unburned hydrocarbons and carbon monoxide generated at a low exhaust temperature at low load regardless of the exhaust temperature. Can be. In addition, the second photocatalytic reaction unit captures PM generated mainly in the acceleration section of the diesel engine on the second porous filter, which is a soot filtration filter, while applying a high voltage to the second low temperature plasma unit, and promoting photocatalytic reaction. The collected PMs are continuously oxidized, whereby the second porous filter can be continuously regenerated.

In addition, the third photocatalytic reaction part adsorbs NOx generated at a high concentration at the beginning of the acceleration section of the diesel engine using an adsorbent (Ads), and then partially oxidizes in the second photocatalytic reaction part to generate HC, C, With CO as a reducing agent, NOx adsorbed on the adsorbents (Ads) can be effectively removed.

In addition, the diesel engine exhaust purification system of the present invention can easily control the generation of HC, C, and CO through power control of the plurality of photocatalytic reaction units, which contributes to the improvement of NOx removal efficiency and energy efficiency.

In addition, TiO 2 used as a photocatalyst in each photocatalytic reaction part is excellent in endothelial toxicity against sulfur components even when sulfur content in fuel is 50PPM or more, thereby preventing deterioration of system performance by sulfur components in diesel fuel. .

Exemplary embodiments of the exhaust gas purifying system of the diesel engine of the present invention described above are merely exemplary, and those skilled in the art to which the present invention pertains can make various modifications and other equivalent embodiments therefrom. You will know well. Therefore, it is to be understood that the present invention is not limited to the above-described embodiments. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims. It is also to be understood that the invention includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.

1: exhaust purification system 100: exhaust pipe
200: purification module 210: module body
220: first photocatalytic reaction unit 221: first photocatalyst frame
223a: photocatalyst 223b: channel
225: electrode terminal 227: insulator
230: second photocatalytic reaction part 240: third photocatalytic reaction part
250: first low temperature plasma unit 260: second low temperature plasma unit
270: third low temperature plasma unit 300: detection sensor
400: power supply 500: differential pressure sensor
600:

Claims (3)

In the exhaust purification system of diesel engine,
An exhaust pipe through which exhaust gas of the diesel engine is discharged;
A purification module connected to the exhaust pipe and configured to purify the exhaust gas by a photocatalyst;
A power supply unit supplying power to the purification module;
A detection sensor provided inside the exhaust pipe and detecting a concentration of a hazardous substance contained in the exhaust gas;
It includes a control unit for controlling the power supply strength of the power supply according to the detection result of the sensor,
The photocatalyst,
A photocatalyst material comprising titanium oxide of type 1, which is an antimicrobial titanium oxide nanoparticle using hydrothermal synthesis, and titanium oxide of type 2, surface-treated by a microwave low temperature plasma method,
A ceramic material comprising alumina having an alpha-alumina (α-Al 2 O 3) or particles of 0.2 cc / g or more and an area of more than 20 m 2 / g, and
A promoter comprising a zeolite,
The titanium oxide of the first type is at least 35 wt% in the photocatalyst, the titanium oxide of the second type is at least 20 wt% in the photocatalyst, and the alpha-alumina (α-Al2O3) is 7 wt% in the photocatalyst As described above, the alumina having an area of 0.2 cc / g or more and an area of more than 20 m 2 / g includes at least 7 wt% of the photocatalyst.
The method of claim 1,
The purification module,
A first photocatalytic reaction unit for oxidizing HC, CO, NO or particulate matter in the exhaust gas;
A second photocatalytic reaction part for collecting particulate matter in exhaust gas through the first photocatalytic reaction part in a soot filtration filter and oxidizing the collected particulate matter to regenerate the soot filtration filter;
Comprises the photocatalyst and the adsorbent, the diesel comprises parts 3 photocatalytic reaction, by the adsorbent and adsorbing the NO x in the exhaust gas passed through the second reactor, the removal of the NO x through reduction Engine exhaust purification system.
The method of claim 2,
The first photocatalytic reaction part, the second photocatalytic reaction part and the third photocatalytic reaction part, respectively,
A photocatalyst frame;
It includes a porous filter coupled to the photocatalyst frame,
The photocatalyst is exhaust purification system of the diesel engine, characterized in that the coating on the surface of the porous filter.
KR1020110100665A 2011-10-04 2011-10-04 Exhaust gas cleaning system for desel engine KR20130036529A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107398144A (en) * 2016-06-08 2017-11-28 黄华丽 A kind of gas discharge collaboration solution absorbs the method and apparatus for removing removing and harmful gas

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107398144A (en) * 2016-06-08 2017-11-28 黄华丽 A kind of gas discharge collaboration solution absorbs the method and apparatus for removing removing and harmful gas
CN107398144B (en) * 2016-06-08 2020-10-09 黄华丽 Method and device for removing harmful gas by gas discharge in cooperation with solution absorption

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