Electrified diesel engine post-treatment catalytic oxidation system and application thereof

Abstract

The invention discloses an electrified diesel engine post-treatment catalytic oxidation system and application thereof, a hollow insulating cylinder with openings at two ends is provided, a conductive catalyst, foam alloy support sheets and an electrode are arranged in the insulating cylinder, the conductive catalyst is filled between the two foam alloy support sheets, and each foam alloy support sheet is connected with the electrode. The electrification process of the reaction system is used for driving the catalytic oxidation reaction, low-temperature efficient oxidation of the diesel engine tail gas can be achieved without additionally heating a catalyst or reaction gas, energy consumption is greatly reduced, system composition and catalyst preparation are simple, and cost is low. And the efficient elimination and conversion of pollutants can be met under the conditions of cold start and low-speed and low-load operation of the engine, and wide application prospects are achieved.

Description

Technical Field

[0001] The invention relates to a highly efficient electrified diesel engine post-treatment catalytic oxidation system and application thereof, belonging to the technical field of catalytic purification of atmospheric pollutants. Background Art

[0002] Diesel engines are widely used in motor vehicles, engineering machinery and other fields due to their good power, economy and durability. However, their exhaust emissions of hydrocarbons (HC), carbon monoxide (CO), nitrogen oxides (NO x ) and particulate matter (PM) cause atmospheric pollution and seriously threaten human health. Governments of various countries have successively introduced emission regulations to limit the emissions of diesel engines. As emission standards become increasingly stringent, new challenges are constantly being raised for diesel engine exhaust catalytic purification technology (including diesel oxidation catalysts, selective catalytic reduction, diesel particulate filters, etc.). In the after-treatment system, the diesel oxidation catalyst (DOC) can not only eliminate CO and HC at the same time, but also oxidize NO to NO2, which is beneficial to increase the NO of the downstream selective catalytic reduction system. x Purification efficiency, therefore, plays a key role in diesel engine exhaust purification. However, during the cold start and warm-up period of the engine, the DOC will not work due to the low exhaust temperature, and more than 80% of CO and HC are emitted during this stage.

[0003] In order to improve the performance of DOC, strategies such as changing the combustion mode, post-injection of fuel or adding an electrically heated catalyst (EHC) are usually used to increase the exhaust temperature. Among them, EHC can directly transfer heat energy from the vehicle battery or on-board generator to the after-treatment system when needed. In the current context of diesel engine hybridization and electrification, EHC is expected to become one of the mainstream technologies that meet emission standards. However, EHC usually requires kilowatt-level power input during the heating process, and it lasts for tens of seconds to reach the target temperature, which consumes a lot of energy and has a slow response speed. In addition, the current mainstream DOC catalysts mainly use precious metals (such as Pt, Pd, etc.) as active components, with poor low-temperature performance and high production costs. Therefore, it is urgent to develop a new and efficient diesel engine after-treatment catalytic oxidation system that meets the increasingly stringent emission regulations while complying with the current national low-carbon, energy-saving and sustainable development trends. Summary of the invention

[0004] In view of the shortcomings of the prior art, the present invention provides an electrified diesel engine after-treatment catalytic oxidation system, which can utilize the electrification process of the reaction system itself to drive the catalytic oxidation reaction. It does not require additional heating of the catalyst or reaction gas, and can achieve low-temperature and efficient oxidation of diesel engine exhaust, greatly reducing energy consumption. The system structure and catalyst preparation are simple, and can meet the needs of efficient elimination and conversion of pollutants under cold start and low-speed and low-load operation conditions of the engine.

[0005] The specific technical solutions of the present invention are as follows:

[0006] An electrified diesel engine aftertreatment catalytic oxidation system comprises: a hollow insulating cylinder with openings at both ends, wherein a conductive catalyst, a foam alloy support sheet and an electrode are arranged in the insulating cylinder, wherein the conductive catalyst is filled between two foam alloy support sheets, and each foam alloy support sheet is connected to the electrode.

[0007] Furthermore, the insulating cylinder is preferably circular in cross section and is made of insulating material. The insulating cylinder is embedded in the exhaust pipe of the diesel engine, and the foam alloy support sheets are placed at both ends of the insulating cylinder to ensure that the foam alloy support sheets and the conductive catalyst do not contact the exhaust pipe to avoid short circuit.

[0008] Further, the conductive catalyst itself has conductivity, and its main component is a conductive composite, which is filled in an insulating cylinder, or the conductive composite is first coated on a conductive carrier, and then the conductive carrier is filled in the insulating cylinder. The conductive composite can be made into a granular shape by a commonly used industrial granulation method, and then filled in the insulating cylinder. The diameter of the particles is generally 1-2mm. The filling amount of the conductive catalyst in the insulating cylinder can be selected according to actual conditions, but it is necessary to ensure that the electrode and the foam alloy support sheet are located in the insulating cylinder to avoid short circuit.

[0009] Furthermore, the conductive composite is a conductive powder loaded with active components, wherein the conductive powder has conductivity and is a carrier, and the active component has a catalytic effect. The conductive powder material is at least one of antimony tin oxide (ATO), indium tin oxide (ITO), titanium carbide (TiC), and titanium nitride (TiN). The active ingredient is at least one of cerium oxide, manganese oxide, copper oxide, iron oxide, and cobalt oxide. The mass fraction of the active ingredient in the conductive composite is 1-20wt.%.

[0010] Furthermore, the active components can be loaded onto the conductive powder by a loading method commonly used in the prior art, such as an excess impregnation method, an equal volume impregnation method, and the like.

[0011] In a specific embodiment of the present invention, a method for achieving active component loading by an excessive impregnation method is provided, and the specific operation includes: adding conductive powder to the precursor solution of the active component, stirring and mixing until the water evaporates to dryness, then drying in an oven, and calcining at 450-550° C. in a muffle furnace to obtain a conductive powder loaded with the active component. The precursor of the active component can be a water-soluble salt thereof, such as cerium nitrate, iron nitrate, manganese nitrate, copper nitrate, and cobalt nitrate.

[0012] Furthermore, the conductive carrier is honeycomb-shaped and has conductivity. The conductive composite is coated on the conductive carrier, and the honeycomb structure can increase the contact area between the catalyst and the gas, thereby improving the catalytic effect. The conductive carrier can be any commercially available honeycomb-shaped conductive carrier, such as at least one of a commercial iron-chromium-aluminum metal honeycomb carrier, a commercial metal foam carrier, a commercial Si-SiC composite honeycomb carrier, and the like.

[0013] Further, the coating amount of the conductive composite on the conductive carrier is 50-200 g / L. G / L means the number of grams of the conductive composite per liter of the conductive carrier.

[0014] Furthermore, the electrified diesel engine post-treatment catalytic oxidation system may also be provided with a temperature measuring element for detecting the temperature of the conductive catalyst. The temperature measuring element may be a temperature sensor, which is mounted on the insulating cylinder, preferably on the cylinder wall in the middle of the insulating cylinder, and extends into the interior of the insulating cylinder.

[0015] The present invention also provides a method for treating exhaust gas from a diesel engine. The method uses the above-mentioned electrified diesel engine after-treatment catalytic oxidation system of the present invention to treat the exhaust gas from the diesel engine.

[0016] Furthermore, the electrified diesel engine after-treatment catalytic oxidation system is embedded in the exhaust pipe of the diesel engine. When the exhaust gas enters the exhaust pipe, low-power direct current is applied to the electrode to energize the conductive catalyst and catalytically oxidize the exhaust gas.

[0017] Furthermore, the power of the direct current is 1-20W, for example, 1W, 2W, 3W, 4W, 5W, 6W, 7W, 8W, 9W, 10W, 11W, 12W, 13W, 14W, 15W, 16W, 17W, 18W, 19W, and 20W.

[0018] The present invention has the following beneficial effects:

[0019] 1. The electrified diesel engine after-treatment catalytic oxidation system of the present invention has a simple structure and adopts a conductive catalyst. When the exhaust gas of the diesel engine enters the exhaust pipe, low-power direct current (less than or equal to 20 watts) is applied to the positive and negative electrodes of the system to energize the conductive catalyst. When the current flows through the catalyst, the interface resistance between the conductive catalyst particles or between the active component and the conductive carrier will produce a local Joule heating effect under the action of the external current. The current in the electrification process and the generated Joule heating effect work together. The current and temperature flowing through the conductive catalyst can be adjusted by controlling the input electric power. Low-temperature and efficient oxidation of diesel engine exhaust can be achieved without additional heating of the catalyst or the reaction gas, so that the entire reaction system can be used to treat hydrocarbons (HCs), carbon monoxide (CO), and nitrogen oxides (NOx) in the exhaust gas. xThe catalytic oxidation efficiency of pollutants such as ) is significantly improved.

[0020] 2. The input power required by the electrified diesel engine aftertreatment catalytic oxidation system of the present invention is much lower than the kilowatt-level input power required by the existing DOC front-end EHC device, and the thermal efficiency is greatly improved, and instant and rapid heating and reaction can be achieved. The present invention greatly reduces the energy consumption of the diesel engine aftertreatment system, and the system structure and catalyst preparation are simple, which can meet the requirements of efficient elimination and conversion of pollutants under cold start and low speed and low load operation conditions of the engine. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required to be used in the embodiments or the technical solutions in the prior art are briefly introduced below.

[0022] Figure 1 A schematic structural diagram of the electrified diesel engine aftertreatment catalytic oxidation system provided by the present invention.

[0023] Figure 2 Graph showing the change in HCs, CO and NO conversion rates, power and temperature over time in Example 2 of the present invention.

[0024] Figure 3 It is a curve diagram of the conversion rate of C3H6, CO, and NO as the temperature changes in the programmed power increase method in Example 2 of the present invention and the traditional programmed temperature increase heating method in the comparative example.

[0025] In the figure, 1. foam alloy support sheet, 2. conductive catalyst, 3. insulating cylinder, 4. exhaust pipe, 5. temperature measuring element, 6. stainless steel rod, 7. electrode sheet, 8. air inlet, 9. air outlet, 10. sealing ring. DETAILED DESCRIPTION

[0026] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0027] Unless otherwise specified, the raw materials in the examples of the present invention were purchased from commercial sources.

[0028] Example 1

[0029] like Figure 1As shown, the present invention provides a high-efficiency electrified diesel engine post-treatment catalytic oxidation system, including a foam alloy support sheet 1, an insulating cylinder 3, a temperature measuring element 5, a conductive catalyst 2 and an electrode sheet 7. Among them, the insulating cylinder has a hollow structure and has openings at both ends, and its cross-section is circular. The conductive catalyst, the foam alloy support sheet and the electrode sheet are located in the insulating cylinder, and the two foam alloy support sheets are located at the two ends of the insulating cylinder for tightly clamping the conductive catalyst. A number of conductive catalysts are filled between the foam alloy support sheets, and the centers of the two foam alloy support sheets are respectively connected to the electrode sheets. The electrode sheets are respectively connected to the positive and negative poles of the DC power supply.

[0030] Furthermore, a temperature measuring element is installed on the insulating cylinder to detect the temperature of the conductive catalyst. The temperature measuring element can be a temperature sensor, such as a thermocouple, which is installed on the insulating cylinder, preferably on the cylinder wall in the middle of the insulating cylinder, and extends into the interior of the insulating cylinder.

[0031] Further, the conductive catalyst itself has conductivity, and its main component is a conductive composite, which is filled in an insulating cylinder, or the conductive composite is first coated on a conductive carrier, and then the conductive carrier is filled in the insulating cylinder. The conductive composite can be made into a granular shape by a commonly used industrial granulation method, and then filled in the insulating cylinder. The size of the particles is generally 1-2mm. The filling amount of the conductive catalyst in the insulating cylinder is not fixed and can be selected according to actual conditions, but it is necessary to ensure that the electrode and the foam alloy support sheet are located in the insulating cylinder to avoid short circuit.

[0032] Further, the conductive composite is a conductive powder loaded with active components, wherein the conductive powder has conductivity and is a carrier, and the active component has a catalytic effect. The conductive powder material is at least one of antimony tin oxide (ATO), indium tin oxide (ITO), titanium carbide (TiC), and titanium nitride (TiN). The active ingredient is at least one of cerium oxide, manganese oxide, copper oxide, iron oxide, and cobalt oxide. The mass fraction of the active ingredient in the conductive composite is 1-20wt.%, such as 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%.

[0033] Furthermore, the active components can be loaded onto the conductive powder by a loading method commonly used in the prior art, such as an excess impregnation method, an equal volume impregnation method, and the like.

[0034] Furthermore, the conductive carrier is honeycomb-shaped and has conductivity. The conductive composite is coated on the conductive carrier, and the honeycomb structure can increase the contact area between the catalyst and the gas, thereby improving the catalytic effect. The conductive carrier can be any commercially available honeycomb-shaped conductive carrier, such as at least one of a commercial iron-chromium-aluminum metal honeycomb carrier, a commercial metal foam carrier, a commercial Si-SiC composite honeycomb carrier, and the like.

[0035] Further, the conductive composite is coated on the conductive carrier, the conductive composite is mixed with water to form a slurry, and then the slurry is coated on the conductive carrier. In order to improve the coating effect of the conductive composite, a binder such as silica sol and pseudo-boehmite can be added to the slurry. The coating can be carried out manually or mechanically, and can be carried out by spraying, dipping, brushing, etc. The coating amount of the conductive composite on the conductive carrier is 50-200g / L, for example, 50g / L, 100g / L, 150g / L, 200g / L. G / L means the grams of the conductive composite on each liter of the conductive carrier.

[0036] Furthermore, the insulating cylinder is made of insulating material, such as a ceramic insulating cylinder.

[0037] Furthermore, the foam alloy support sheet is in direct contact with the conductive catalyst. The foam alloy support sheet can transmit current to the conductive catalyst and also fix the catalyst, and its own continuous pores can ensure that the exhaust gas flows through the catalyst. The material of the foam alloy can be a metal or alloy material with conductive function. The shape and size of the foam alloy support sheet match the cross-section of the insulating cylinder to prevent the conductive catalyst from being displaced under the action of the exhaust gas. For example, the foam alloy support sheet can be a copper filter sheet or a copper filter column.

[0038] Furthermore, the electrode is a common conductive metal material, and the electrode is connected to a DC power supply to energize the conductive catalyst. The electrode is divided into a positive electrode and a negative electrode, and the positive electrode and the negative electrode are made of the same material, and there is no special requirement for the size of the electrode.

[0039] Furthermore, the insulating cylinder is embedded in the exhaust pipe of the diesel engine, and the electrodes are connected to the positive and negative electrodes of the DC power supply through the stainless steel rod 6, and the stainless steel rod and the exhaust pipe are sealed by a sealing ring. The exhaust gas of the diesel engine enters from the air inlet 8 and flows out from the air outlet 9. When the exhaust gas enters the exhaust pipe, low-power DC is applied to the positive and negative electrodes to energize the conductive catalyst; the current and the Joule heat effect generated when it flows through the conductive catalyst are used, and the current and temperature flowing through the conductive catalyst are adjusted by controlling the input electric power, so as to achieve efficient catalytic oxidation of hydrocarbons (HCs), carbon monoxide (CO), and nitrogen oxides (NO x ) and other pollutants.

[0040] Furthermore, the low-power direct current is 1-20W, for example, 1W, 2W, 3W, 4W, 5W, 6W, 7W, 8W, 9W, 10W, 11W, 12W, 13W, 14W, 15W, 16W, 17W, 18W, 19W, and 20W.

[0041] The high-efficiency electrified diesel engine after-treatment catalytic oxidation systems used in the following embodiments are all high-efficiency electrified diesel engine after-treatment catalytic oxidation systems of the structure of this embodiment, and the high-efficiency electrified diesel engine after-treatment catalytic oxidation system will not be specifically described in the following embodiments.

[0042] Example 2

[0043] The exhaust gas was treated using the electrified diesel engine post-treatment catalytic oxidation system of Example 1, wherein the conductive catalyst used was: ATO as a conductive powder, manganese oxide as an active component, and the mass fraction of manganese oxide in the conductive composite was 7wt%. The preparation method of the conductive catalyst was:

[0044] Add 150ml of deionized water to a beaker, add 6.18ml of 50wt% Mn(NO3)2 solution, stir at room temperature for 1h, then slowly add 30g of ATO powder to the above solution, continue stirring at room temperature for 1h to ensure that manganese nitrate is completely impregnated on the ATO surface, transfer the beaker to an 80℃ water bath and stir dry, transfer the beaker to a 105℃ oven to dry overnight. Calcinate in a 500℃ muffle furnace for 3h to obtain an ATO conductive composite with a manganese oxide loading of 7wt%. Subsequently, the conductive composite with a particle size of 1-2mm is obtained by tabletting and sieving.

[0045] 500 ml of conductive catalyst is measured by a volume tube and placed in the insulating cylinder 3. The two ends of the conductive catalyst are tightly clamped by two foam alloy support sheets 1. The electrode sheets 7 at both ends of the foam alloy support sheets are connected to the positive and negative electrodes of the DC power supply through stainless steel rods 6. The stainless steel rods 6 and the exhaust pipe are sealed by an insulating sealing ring. The K-type thermocouple 5 on the middle wall of the insulating cylinder 3 is used to monitor the temperature of the conductive catalyst. The diesel engine exhaust gas introduced roughly contains 600 ppm C3H6, 2000 ppm CO, 500 ppm NO and other gases. The volume air velocity is controlled to be about 25000 h -1The power applied by the DC power supply was programmed from 0W to 10W at 0.1W / min, and the gas after the reaction entered the gas analyzer for component analysis. The results showed that when the power was 2.6W and the temperature was 121°C, the conversion rate of C3H6 was 100%; when the power was 3W and the temperature was 143°C, the conversion rates of C3H6 and CO were 100%; when the power was 3.3W and the temperature was 157°C, the conversion rates of C3H6 and CO were 100%, and the highest NO conversion rate was 56%. This shows that the system of the present invention achieves efficient catalytic oxidation at low temperatures.

[0046] Example 3

[0047] The exhaust gas was treated using the electrified diesel engine post-treatment catalytic oxidation system of Example 1, wherein the conductive catalyst used was: ITO as a conductive powder, iron oxide as an active component, and the mass fraction of iron oxide in the conductive composite was 2wt%. The preparation method of the conductive catalyst was:

[0048] Add 150ml of deionized water to the beaker, add 3.084g of Fe(NO3)3·9H2O, stir at room temperature for 1h, ensure that the ferric nitrate nine hydrate is fully dissolved, slowly add 30g of ITO powder to the above solution, continue stirring at room temperature for 1h, ensure that the ferric nitrate nine hydrate is completely impregnated on the ITO surface, transfer the beaker to an 80℃ water bath and stir dry, transfer the beaker to a 105℃ oven to dry overnight. Roast in a 500℃ muffle furnace for 3h to obtain an ITO conductive composite with an iron oxide loading of 2wt%. Subsequently, the conductive composite with a particle size of 1-2mm is obtained by tabletting and sieving.

[0049] 500 ml of conductive catalyst is measured with a volume tube and placed in the insulating cylinder 3, and the two ends are tightly clamped by two foam alloy support sheets 1. The electrode sheets 7 at both ends of the foam alloy support sheets are connected to the positive and negative electrodes of the DC power supply through stainless steel rods 6. The stainless steel rods 6 and the exhaust pipe are sealed by an insulating sealing ring. The K-type thermocouple 5 on the middle wall of the insulating cylinder 3 is used to monitor the temperature of the conductive catalyst. The diesel engine exhaust gas introduced roughly contains 600 ppm C3H6, 2000 ppm CO, 500 ppm NO and other gases, and the volume air velocity is controlled to be about 25000 h -1 The power applied by the DC power supply was programmed from 0 W to 10 W at a rate of 0.1 W / min. The gas after the reaction entered the gas analyzer for component analysis. The results showed that when the power was 2.9 W and the temperature was 170 ° C, the C3H6 conversion rate was 100%; when the power was 4 W and the temperature was 221 ° C, the C3H6 and CO conversion rates were 100%; when the power was 4.8 W and the temperature was 255 ° C, the C3H6 and CO conversion rates were 100%, and the NO conversion rate was as high as 30%.

[0050] Example 4

[0051] The exhaust gas was treated using the electrified diesel engine post-treatment catalytic oxidation system of Example 1, wherein the conductive catalyst used was: Si-SiC as a conductive carrier, ATO-loaded active component manganese oxide as a conductive composite, and the coating amount was 100 g / L. The preparation method of the conductive catalyst is:

[0052] 1. According to the method of Example 2, an ATO-supported active component manganese oxide is prepared, and then the ATO-supported active component manganese oxide, silica sol and water are mixed to obtain a conductive composite slurry;

[0053] 2. Coat the conductive composite onto the conductive carrier. The specific steps are as follows: weigh the mass of a blank Si-SiC conductive carrier and record it as m0; then immerse the Si-SiC conductive carrier in the conductive composite slurry and pull it up repeatedly; blow away the residual liquid in the pores after pulling and coating with flowing air, and wipe the residual liquid in the outer wall with filter paper; place the coated catalyst in a 70°C oven for drying for 6 hours and then move it to a 105°C oven for drying for 6 hours. After drying, weigh the mass and record it as m; continue to repeat the coating steps, and calculate the difference in each weighing until the coating amount is 100g / L.

[0054] A conductive catalyst of Φ12cm×13cm is selected and placed in an insulating cylinder 3, with its two ends tightly clamped by two foam alloy support sheets 1. The electrode sheets 7 at both ends of the foam alloy support sheets are connected to the positive and negative electrodes of the DC power supply through stainless steel rods 6. The stainless steel rods 6 and the exhaust pipe are sealed by an insulating sealing ring. The K-type thermocouple 5 on the middle wall of the insulating cylinder 3 is used to monitor the temperature of the conductive catalyst. The diesel engine exhaust gas introduced roughly contains 600ppm C3H6, 2000ppm CO, 500ppm NO and other gases, and the volume air velocity is controlled to be about 25000h -1 The power applied by the DC power supply was programmed from 0 W to 10 W at a rate of 0.1 W / min. The gas after the reaction entered the gas analyzer for component analysis. The results showed that when the power was 2.8 W and the temperature was 180°C, the conversion rate of C3H6 was 100%; when the power was 3.9 W and the temperature was 230°C, the conversion rates of C3H6 and CO were 100%; when the power was 4.9 W and the temperature was 260°C, the conversion rates of C3H6 and CO were 100%, and the highest NO conversion rate was 42%.

[0055] Example 5

[0056] The exhaust gas was treated using the electrified diesel engine post-treatment catalytic oxidation system of Example 1, wherein the conductive catalyst used was: TiN as a conductive powder, cerium oxide as an active component, and the mass fraction of cerium oxide in the conductive composite was 5wt%. The preparation method of the conductive catalyst was:

[0057] Add 150ml of deionized water to a beaker, add 3.825g of Ce(NO3)3·6H2O, stir at room temperature for 1h, ensure that the hexahydrated cerium nitrate is fully dissolved, slowly add 30g of TiN powder to the above solution, continue stirring at room temperature for 1h, ensure that the hexahydrated cerium nitrate is completely impregnated on the TiN surface, transfer the beaker to an 80℃ water bath and stir dry, transfer the beaker to a 105℃ oven to dry overnight. Calcinate in a 500℃ muffle furnace for 3h to obtain a TiN conductive composite with a cerium oxide loading of 5wt%. Subsequently, the conductive composite with a particle size of 1-2mm is obtained by tabletting and sieving.

[0058] 500 ml of conductive catalyst is measured with a volume tube and placed in the insulating cylinder 3, and the two ends are tightly clamped by two foam alloy support sheets 1. The electrode sheets 7 at both ends of the foam alloy support sheets are connected to the positive and negative electrodes of the DC power supply through stainless steel rods 6. The stainless steel rods 6 and the exhaust pipe are sealed by an insulating sealing ring. The K-type thermocouple 5 on the middle wall of the insulating cylinder 3 is used to monitor the temperature of the conductive catalyst. The diesel engine exhaust gas introduced roughly contains 600 ppm C3H6, 2000 ppm CO, 500 ppm NO and other gases, and the volume air velocity is controlled to be about 25000 h -1 The power applied by the DC power supply was programmed from 0 W to 10 W at a rate of 0.1 W / min. The gas after the reaction entered the gas analyzer for component analysis. The results showed that when the power was 2.5 W and the temperature was 175 ° C, the C3H6 conversion rate was 100%; when the power was 3.8 W and the temperature was 240 ° C, the C3H6 and CO conversion rates were 100%; when the power was 4.8 W and the temperature was 255 ° C, the C3H6 and CO conversion rates were 100%, and the NO conversion rate was as high as 31%.

[0059] Example 6

[0060] The exhaust gas was treated using the electrified diesel engine post-treatment catalytic oxidation system of Example 1, wherein the conductive catalyst used was: TiC as a conductive powder, copper oxide as an active component, and the mass fraction of copper oxide in the conductive composite was 5wt%. The preparation method of the conductive catalyst was:

[0061] Add 150ml of deionized water to a beaker, add 4.581g of Cu(NO3)2·3H2O, stir at room temperature for 1h, ensure that copper nitrate trihydrate is fully dissolved, slowly add 30g of TiC powder to the above solution, continue stirring at room temperature for 1h, ensure that copper nitrate trihydrate is completely impregnated on the TiC surface, transfer the beaker to an 80℃ water bath and stir dry, transfer the beaker to a 105℃ oven to dry overnight. Roast in a 500℃ muffle furnace for 3h to obtain a TiC conductive composite with a copper oxide loading of 5wt%. Subsequently, the conductive composite with a particle size of 1-2mm is obtained by tabletting and sieving.

[0062] 500 ml of conductive catalyst is measured with a volume tube and placed in the insulating cylinder 3, and the two ends are tightly clamped by two foam alloy support sheets 1. The electrode sheets 7 at both ends of the foam alloy support sheets are connected to the positive and negative electrodes of the DC power supply through stainless steel rods 6. The stainless steel rods 6 and the exhaust pipe are sealed by an insulating sealing ring. The K-type thermocouple 5 on the middle wall of the insulating cylinder 3 is used to monitor the temperature of the conductive catalyst. The diesel engine exhaust gas introduced roughly contains 600 ppm C3H6, 2000 ppm CO, 500 ppm NO and other gases, and the volume air velocity is controlled to be about 25000 h -1 The power applied by the DC power supply was programmed from 0 W to 10 W at a rate of 0.1 W / min. The gas after the reaction entered the gas analyzer for component analysis. The results showed that when the power was 3 W and the temperature was 170 ° C, the C3H6 conversion rate was 100%; when the power was 4.5 W and the temperature was 230 ° C, the C3H6 and CO conversion rates were 100%; when the power was 6 W and the temperature was 270 ° C, the C3H6 and CO conversion rates were 100%, and the NO conversion rate was as high as 28%.

[0063] Comparative Example

[0064] According to the system settings of Example 2, the exhaust gas treatment is carried out. The exhaust gas composition of the diesel engine and the volume space velocity of the reaction do not change. The only difference is that the catalyst is not connected to the DC power supply, and the catalyst is directly heated by an external electric furnace. The occurrence of catalytic oxidation is driven by thermal heating, and the influence of different driving modes on the catalytic oxidation activity is explored. The heating rate of the external heat source is the same as the heating rate caused by the Joule heating effect on the conductive catalyst caused by the DC power supply power rate. The gas after the reaction enters the gas analyzer for component analysis. The results show that when the temperature is 250°C, the C3H6 conversion rate is 100%; when the temperature is 282°C, the C3H6 and CO conversion rates are 100%; when the temperature is 331°C, the C3H6 and CO conversion rates are 100%, and the NO conversion rate is up to 69%. Figure 3 The conversion rates of C3H6, CO and NO in Example 2 and Comparative Example 2 vary with temperature.

[0065] From the above, it can be seen that the electrification method is far superior to traditional thermal catalysis in conversion rate and energy consumption.

[0066] The applicant declares that the above are only several embodiments of the present invention and do not limit the present invention in any form. Any technician familiar with the profession who makes easy changes or substitutions using the above technical contents without departing from the scope of the technical solution of the present invention is equivalent to an equivalent implementation case and falls within the protection scope and disclosure scope of the present invention.

Claims

1. An electrified diesel engine aftertreatment catalytic oxidation system, characterized in that: include: The insulating cylinder is hollow and has openings at both ends. A conductive catalyst, a foam alloy support sheet and electrodes are arranged in the insulating cylinder. The conductive catalyst is filled between two foam alloy support sheets, and each foam alloy support sheet is connected to the electrode.

2. The electrified diesel engine aftertreatment catalytic oxidation system according to claim 1, characterized in that: The conductive catalyst is a conductive composite, or a conductive support coated with a conductive composite.

3. The electrified diesel engine aftertreatment catalytic oxidation system according to claim 2, characterized in that: The conductive composite is a conductive powder loaded with active components; Preferably, the conductive powder is at least one of antimony tin oxide, indium tin oxide, titanium carbide, and titanium nitride; Preferably, the active ingredient is at least one of cerium oxide, manganese oxide, copper oxide, iron oxide, and cobalt oxide; Preferably, the mass fraction of the active ingredient in the conductive composite is 1-20 wt.%.

4. The electrified diesel engine aftertreatment catalytic oxidation system according to claim 2 or 3, characterized in that: The conductive carrier is at least one of an iron-chromium-aluminum metal honeycomb carrier, a metal foam carrier, and a Si-SiC composite material honeycomb carrier; preferably, the coating amount of the conductive composite on the conductive carrier is 50-200 g / L.

5. The electrified diesel engine aftertreatment catalytic oxidation system according to claim 1, 2 or 3, characterized in that: A temperature measuring element is also provided and is mounted on the insulating cylinder.

6. The electrified diesel engine aftertreatment catalytic oxidation system according to claim 1, 2 or 3, characterized in that: The conductive catalyst is in contact with the foam alloy support sheet.

7. The electrified diesel engine aftertreatment catalytic oxidation system according to claim 1, 2 or 3, characterized in that: The shape and size of the foam alloy supporting sheet match the cross section of the insulating cylinder.

8. The electrified diesel engine aftertreatment catalytic oxidation system according to claim 1, 2 or 3, characterized in that: The electrodes are connected to a DC power supply.

9. A method for treating diesel engine exhaust, characterized in that: The exhaust gas of a diesel engine is treated by using the electrified diesel engine after-treatment catalytic oxidation system according to any one of claims 1 to 8.

10. The processing method according to claim 9, characterized in that: The electrified diesel engine after-treatment catalytic oxidation system is embedded in the exhaust pipe of the diesel engine. When the exhaust gas enters the exhaust pipe, low-power direct current is applied to the electrode to energize the conductive catalyst and perform catalytic oxidation treatment on the exhaust gas. Preferably, the power of the direct current is 1-20W.

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