US20140165380A1

US20140165380A1 - Method for fabricating exhaust gas decontamination reactor

Info

Publication number: US20140165380A1
Application number: US14/092,543
Authority: US
Inventors: Shang-Hsiao WONG; Sheng-Shian WU
Original assignee: National Tsing Hua University NTHU
Current assignee: National Tsing Hua University NTHU
Priority date: 2012-12-18
Filing date: 2013-11-27
Publication date: 2014-06-19
Also published as: CN103861453B; TW201424827A; CN103861453A; TWI491436B

Abstract

A method for fabricating an exhaust gas decontamination reactor, which is an exhaust gas decontamination pipe or a exhaust gas decontamination honeycombed structure, comprises steps: respectively coating a cathode layer and an anode layer on an outer wall surface and an inner wall surface of a pipe; and forming an enclosed reducing environment inside an internal channel of the pipe. The method for fabricating an exhaust gas decontamination honeycombed structure comprises steps: respectively coating cathode layers and anode layers on first inner wall surfaces of first passages and second inner wall surfaces of second passages; and forming enclosed reducing environments inside the second passages. Then, the cathode layers function as reaction sites to decontaminate exhaust gas. The present invention needn't arrange a reducing-gas system in the reactor and thus can decrease the volume and fabrication cost thereof.

Description

FIELD OF THE INVENTION

The present invention relates to an electrochemical-catalytic converter, particularly to a method for fabricating an exhaust gas decontamination pipe and an exhaust gas decontamination honeycombed structure.

BACKGROUND OF THE INVENTION

Fresh and clean air is essential for human health. Science and technology has promoted economical development. However, exhaust gas of vehicles and factories, especially motor vehicles and heavy industry factories, seriously pollutes the air.
The emission standard of motor vehicles has been advanced persistently. However, the continuously increasing motor vehicles still bring about more and more serious air pollution. In a motor vehicle, the engine thereof burns fuel and converts chemical energy into mechanical energy. The burning process of fuel generates exhaust gases, including oxynitrides, carbon monoxide (CO), hydrocarbons (HC), and particulate matters, smoke, non-methane hydrocarbons (NMHC), and methane (CH₄), which would form photochemical smog, deplete ozone, enhance the greenhouse effect, cause acid rain, damage the ecological environment and endanger human health.
Carbon monoxide comes from imperfect combustion. The capability of carbon monoxide to combine with hemoglobin to form carboxyhemoglobin (COHb) is 300 times higher than the capability of oxygen to combine with hemoglobin to form oxyhemoglobin (HbO₂). Therefore, too high a concentration of carbon monoxide would degrade the capability of hemoglobin to transport oxygen. Oxynitrides are generated by the combination of nitrogen and oxygen and mainly in form of nitrogen monoxide (NO) and nitrogen dioxide (NO₂). Oxynitrides are also likely to combine with hemoglobin and would impair the breathing and circulating functions. Hydrocarbons can irritate the respiratory system even at a lower concentration and will affect the central nervous system at higher concentration.
Therefore, many nations, including EU, USA, Japan and Taiwan, have regulated stricter emission standards for oxynitrides (NO_x), carbon monoxide (CO) and hydrocarbons (HCs), such as (BINS of USA and EURO 6 of EU), which not only regulate the emission of harmful exhaust gases but also encourage the manufacturers to develop, fabricate or use the newest pollution control technologies and apparatuses.
In the conventional exhaust gas emission control technology of oxygen-enriched combustion, none single device or converter can perform conversion of oxynitrides (NO_x), carbon monoxide (CO) and hydrocarbons (HCs) simultaneously. Most of the catalytic converters of automobiles powered by oxygen-enriched combustion can only catalytically convert carbon monoxide (CO) and hydrocarbons (HCs). Oxynitrides (NO_x) must be converted by another apparatus or system. For example, a catalytic oxidizing converter is installed in the exhaust pipe of a diesel engine vehicle to catalytically convert carbon monoxide (CO) and hydrocarbons (HCs), and an EGR (Exhaust Gas Recirculation) system or a cylinder water-spray apparatus is used to eliminate oxynitrides (NO_x). There is also a newer technology using an SCR (Selective Catalytic Reduction) system to reduce oxynitrides (NO_x).
In the SCR system, ammonia (NH₃) gas or an aqueous urea (CO(NH₂)₂) solution is used as a reactant. The aqueous urea solution is sprayed into the exhaust pipe via nozzles and decomposed into ammonia gas. Then, the ammonia gas reacts with oxynitrides (NO_x) to generate products—nitrogen and water. However, ammonia gas is poisonous, hard to store and likely to leak. Further, incomplete reaction of ammonia will cause secondary pollution. Furthermore, the SCR system is bulky and has to cooperate with precision sensors.
A U.S. Pat. No. 5,401,372 disclosed an “Electrochemical Catalytic Reduction Cell for the Reduction of NO_xin an O₂-Containing Exhaust Emission”, which is dedicated to removing oxynitrides, wherein an electrocatalytic reducing reaction and a vanadium pentaoxide (V₂O₅) catalyst convert oxynitrides into nitrogen. However, the prior-art device must be operated in an encapsulated chamber and needs an electric source to power an electrochemical cell. Therefore, the prior-art device consumes more power but cannot eliminate other harmful gases simultaneously.
A U.S. patent application Ser. No. 13/037,693 disclosed an “Electrochemical-Catalytic Converter for Exhaust Emission Control”, which can eliminate oxynitrides (NO_x), carbon monoxide (CO), hydrocarbons (HC), and particulate matters (PM) in exhaust gas, and which comprises a battery module, wherein oxynitrides are electrocatalytically decomposed into nitrogen and oxygen, and wherein carbon monoxide, hydrocarbons, and particulate matters are converted into water and carbon dioxide by an oxidizing catalyst. Therefore, the prior art can eliminates multiple harmful gases simultaneously.
However, the abovementioned “Electrochemical-Catalytic Converter” needs a reducing-gas system to generate electromotive force, which increases the fabrication cost. Further, the unit for heating the circulating reducing gas will expand and contract, which is likely to damage the structure of the anode. Besides, the
“Electrochemical-Catalytic Converter” is hard to fabricate into a compact structure for vehicle application. Therefore, the prior art still has room to improve.

SUMMARY OF THE INVENTION

The primary objective of the present invention is solve the problem that the conventional electrochemical-catalytic converter requires an additional reducing-gas system for generating electromotive force, which makes the fabrication cost increase, the structure likely to damage, and the volume hard to decrease.
To achieve the abovementioned objective, the present invention proposes a method for fabricating an exhaust gas decontamination reactor, which is an exhaust gas decontamination pipe or an exhaust gas decontamination honeycombed structure.
The method for fabricating an exhaust gas decontamination pipe comprises the following steps:
providing a pipe made of a solid-state oxide and including an internal channel, an inner wall surface surrounding the internal channel, and an outer wall surface far away from the inner wall surface;
coating a green cathode layer, which contains a cathode material, on the outer wall surface, and undertaking a first sintering process to convert the green cathode layer into a cathode layer on the outer wall surface;
coating a green anode layer, which contains an anode material, on the inner wall surface, and undertaking a second sintering process to convert the green anode layer into an anode layer on the inner wall surface; and
providing a reducing environment for the internal channel and enclosing the pipe to form a sealed reducing environment, whereby is completed an exhaust gas decontamination pipe with the surface of the cathode layer being a reaction site for exhaust gas decontamination.
The method for fabricating a honeycombed structure comprises the following steps:
providing a honeycombed structure made of a solid-state oxide and including a plurality of tubes and a plurality of separation walls between the tubes;
defining in the tubes a plurality of first passages allowing exhaust gas to pass and a plurality of unsealed second passages, wherein the second passages surround the first passages;
coating green cathode layers, which contain a cathode material, on first inner wall surfaces of the first passages, and undertaking a first sintering process to convert the green cathode layers into cathode layers on the first inner wall surfaces;
coating green anode layers; which contain an anode material, on second inner wall surfaces of the second passages, and undertaking a second sintering process to convert the green anode layers into anode layers on the second inner wall surfaces, whereby the separation walls are between the anode layers and the cathode layers; and
providing reducing environments for the second passages, and enclosing the second passages to form sealed reducing environments, whereby is completed an exhaust gas decontamination honeycombed structure with the cathode layers on the first inner wall surfaces of the first passages being reaction sites for exhaust gas decontamination.
The exhaust gas decontamination pipe and exhaust gas decontamination honeycombed structure fabricated according to the present invention have the following advantages:
1. The exhaust gas decontamination reactor fabricated according to the present invention can merely use the cathode layers to decontaminate exhaust gas without using any additional reducing-gas system. Therefore, the method of the present invention is able to reduce the fabrication cost, and the exhaust gas decontamination reactor fabricated by the present invention is less likely to be damaged.
2. The present invention needn't arrange a reducing-gas system in the exhaust gas decontamination reactor and thus can obviously decrease the volume of the exhaust gas decontamination reactor. Therefore, the exhaust gas decontamination reactor fabricated according to the present invention can be arranged inside the exhaust pipe of a vehicle engine to decontaminate the harmful matters generated by oxygen-enriched combustion and reduce the air pollution.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1D are diagrams schematically showing the process of fabricating an exhaust gas decontamination pipe according to a first embodiment of the present invention; and

FIGS. 2A-2D are diagrams schematically showing the process of fabricating an exhaust gas decontamination honeycombed structure according to a second embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The technical contents of the present invention are described in detail in cooperation with drawings below.
The present invention provides a method for fabricating an exhaust gas decontamination reactor, which is an exhaust gas decontamination pipe or an exhaust gas decontamination honeycombed structure. Below, a first embodiment and a second embodiment are respectively used to demonstrate a method for fabricating an exhaust gas decontamination pipe and a method for fabricating an exhaust gas decontamination honeycombed structure.
Refer to FIGS. 1A-1D diagrams schematically showing the process of fabricating an exhaust gas decontamination pipe according to a first embodiment of the present invention. The method for fabricating an exhaust gas decontamination pipe comprises Steps 1-4.
In Step 1, provide a pipe 10 made of a solid-state oxide, as shown in FIG. 1A. The solid-state oxide is a fluoride metal oxide or a perovskite metal oxide, such as a fluorite YSZ (yttria-stabilized zirconia), a stabilized zirconia, a fluorite GDC (gadolinia-doped ceria), a dopedceria, a perovskite LSGM (strontium/magnesium-doped lanthanum gallate), or a doped lanthanum gallate. In the first embodiment, the pipe 10 is made of zirconia. The pipe 10 includes an internal channel 11, a first opening 14, a second opening 15, an inner wall surface 12, and an outer wall surface 13. The internal channel 11 is between the first opening 114 and the second opening 15 and interconnects the first opening 14 and the second opening 15. The inner wall surface 12 surrounds the internal channel 11. The outer wall surface 13 is far away from the inner wall surface 12.
In Step 2, coat a green cathode layer, which contains a cathode material, on the outer wall surface 13, and undertake a first sintering process to form a cathode layer 20 on the outer wall surface 13, as shown in FIG. 1B. The cathode material is selected from a group consisting of perovskite metal oxides, fluorite metal oxides, metal-containing perovskite metal oxides, and metal-containing fluorite metal oxides. In one embodiment, the cathode layer is made of a perovskite lanthanum strontium cobalt copper oxide, a lanthanum strontium manganese copper oxide, a combination of a lanthanum strontium cobalt copper oxide and a gadolinia-doped ceria; a combination of a lanthanum strontium manganese copper oxide and a gadolinia-doped ceria, a silver-containing lanthanum strontium cobalt copper oxide, a silver-containing lanthanum strontium manganese copper oxide, a combination of a silver-containing lanthanum strontium cobalt copper oxide and a gadolinia-doped ceria, or a combination of a silver-containing lanthanum strontium manganese copper oxide and a gadolinia-doped ceria. The first sintering process is to degrease the cathode material and sinter the cathode material to form the cathode layer 20. The procedures and cycles of heating and cooling are dependent on the selected cathode material.
In the first embodiment, the green cathode layer is exemplified by one containing a combination of a lanthanum strontium manganese copper oxide and a gadolinia-doped ceria. Firstly, enclose the first opening 14 and the second opening 15 with adhesive tapes. Next, coat a fluorite gadolinia-doped ceria on the outer wall surface 12 with a dipping method. Next, take off the adhesive tapes, and dry the pipe 10 in an oven at a temperature of 50° C. for 6 hours. Next, heat the pipe 10 at a temperature rising speed of 5° C./min to a temperature of 600° C., and soak the pipe 10 at 600° C. for 2 hours. The following heating processes and cooling processes will be undertaken at the speed of 5° C./min also. Next, heat the pipe 10 to a temperature of 900° C., and soak the pipe 10 at 900° C. for 2 hours. Next, heat the pipe 10 to a temperature of 1200° C., and soak the pipe 10 at 1200° C. for 4 hours. Next, cool the pipe 10 at the same speed through the same lengths of soaking time to an ambient temperature. Next, enclose the first opening 14 and the second opening 15 with adhesive tapes again. Next, coat a lanthanum strontium manganese copper oxide on the outer wall surface 12 with a dipping method. Next, take off the adhesive tapes, and dry the pipe 10 in an oven at a temperature of 50° C. for 6 hours. Next, heat the pipe 10 at a temperature rising speed of 5° C./min to a temperature of 300° C., and soak the pipe 10 at 300° C. for 2 hours. Next, heat the pipe 10 to a temperature of 600° C., and soak the pipe 10 at 600° C. for 2 hours. Next, heat the pipe 10 to a temperature of 900° C., and soak the pipe 10 at 900° C. for 4 hours. Next, cool the pipe 10 at the same speed through the same lengths of soaking time to an ambient temperature. Then is formed the cathode layer 20.
In Step 3, coat a green anode layer, which contains an anode material, on the inner wall surface 12, and undertake a second sintering process to form an anode layer 30 on the inner wall surface 12, as shown in FIG. 1C. The anode material is selected from a group consisting of fluorite metal oxides, perovskite metal oxides, metal-containing fluorite metal oxides, and metal-containing perovskite metal oxides. For example, the anode material is a nickel-containing yttria-stabilized zirconia (Ni—YSZ cermet).
In the first embodiment, the green anode layer is exemplified by one containing Ni—YSZ cermet. Firstly, pour a slurry made of the anode material into the pipe 10 along the inner wall surface 12, and let the residual slurry slip away spontaneously, and then air-dry the slurry. Next, undertake a second sintering process. Beforehand, dry the pipe 10 in an oven at a temperature of 50° C. for 6 hours. Then, undertake heat treatments at a temperate rising speed of 5° C./min. Heat the pipe 10 to a temperature of 300° C., and soak the pipe 10 at 300° C. for 2 hours. Next, heat the pipe 10 to a temperature of 600° C., and soak the pipe 10 at 600° C. for 2 hours. Next, heat the pipe 10 to a temperature of 900° C., and soak the pipe 10 at 900° C. for 4 hours. Next, cool the pipe 10 at the same speed through the same lengths of soaking time to an ambient temperature. The objective of the second sintering process is the same as that of the first sintering process and will not repeat herein. As a combination of nickel oxide and the Ni—YSZ cermet is used as the anode material, the second sintering process is different from the first sintering process in that nickel oxide needs to be reduced into nickel metal. Therefore, the green anode layer together with the pipe 10 is placed in a quartz tube for a reducing heat treatment. The quartz tube is filled with hydrogen, heated at a temperature-rising speed of 5° C./min to a temperature of 400° C., and soaked at the temperature of 400° C. for 8 hours to reduce the combination of nickel oxide and the Ni—YSZ cermet into nickel metal and the Ni—YSZ cermet. Thereby is completed the anode layer 30.
In Step 4, provide a reducing environment 111 for the internal channel 11, and seal the pipe 10 to enclose the reducing environment 111 and complete the exhaust gas decontamination pipe, as shown in FIG. 1D. In the first embodiment, a reducing agent 112 is filled into the internal channel 11 to form the reducing environment 111. The reducing agent 112 may be a solid-state reducing agent (such as graphite powder or carbon black), a liquid reducing agent (such as aqueous ammonia solution), or a gaseous reducing agent (such as methane or hydrogen). The reducing agent 112 is enclosed inside the internal channel 11 by sealing elements 113 to form the reducing environment 111. In one embodiment, the sealing elements 113 are made of a heat-resistant ceramic putty having a thermal expansion coefficient near that of the pipe 10. The sealing element 113 normally contains aluminum oxides and silicon oxides. Thus is completed the exhaust gas decontamination pipe. The surface of the cathode layer 20 is exposed to the external, functioning as the reaction site for decontaminating an exhaust gas 40. The reducing environment 111 facilitates the anode layer 30 and the cathode layer 20 to generate an electromotive force therebetween to enable the cathode layer 20 to undertake a catalytic decomposition reaction of oxynitrides of the exhaust gas 40. Alternatively, the internal channel 11 is not filled with the reducing agent 112 but directly sealed by the sealing elements 113, and the air pressure inside the internal 11 is lowered to below 1 atm, e.g. a vacuum state, whereby is also formed the reducing environment 111.
Refer to FIGS. 2A-2D diagrams schematically showing the process of fabricating an exhaust gas decontamination honeycombed structure according to a second embodiment of the present invention. The method for fabricating an exhaust gas decontamination honeycombed structure comprises Steps A-E.
In Step A, provide a honeycombed structure 50 made of a solid-state oxide. The honeycombed structure 50 includes a plurality of tubes 51 and a plurality of separation walls 52 between each two tubes 51, as shown in FIG. 2A. The tubes 51 are separated by the separation walls 52 and arranged together. In the first embodiment, the tubes 51 have square sections. However, the present invention does not constrain that the sections of the tubes 51 must be square. In the present invention, the tubes 51 may have circular or hexagonal sections, which are closely arranged to form a compact structure.
In Step B, define in the tubes 51 a plurality of first passages 511 allowing an exhaust gas 80 (shown in FIG. 2D) to pass and a plurality of second passages 513 to be sealed later. Each first passage 511 is adjacent to several second passages 513. In the second embodiment, the first passages 511 and the second passages 513 are alternately arranged to make each first passage 511 surrounded by four second passages 513. However, the present invention is not limited by the second embodiment.
In Step C, coat a green cathode layer containing a cathode material on a first inner wall surface 512 of each first passage 511, and undertake a first sintering process to convert the green cathode layer into a cathode layer 60 on the first inner wall surface 512, as shown in FIG. 2B. In comparison with Step 2 of the first embodiment, Step C of the second embodiment is characterized in that the second passages 513 are sealed with silicone pads before the green cathode layers are coated on the first inner wall surfaces 512. The method to coat the green cathode layer and the first sintering process are the same as those in Step 2 and will not repeat herein. Thereby is obtained the cathode layer 60 in Step C.
In Step D, coat a green anode layer containing an anode material on a second inner wall surface 514 of the second passage 513, and undertake a second sintering process to convert the green anode layer into an anode layer 70 on the second inner wall surface 514, as shown in FIG. 2C. Thus, the separation walls 52 are between the anode layers 70 and the cathode layers 60. In comparison with Step 3 of the first embodiment, Step D of the second embodiment is characterized in that the silicone pads sealing the second passages 513 are removed, and that the first passages 511 are sealed with silicone pads before the anode material is coated on the second inner wall surface 514 with a dipping method. Then, take off the silicone pads from the first passages 511, and undertake the same second sintering process and reducing process as that used in Step 3 to convert the green anode layer into the anode layer 70 on the second inner wall surface 514.
In Step E, provide reducing environments 515 for the second passages 513, and seal the second passages 513 to enclose the reducing environments 515 and complete the exhaust gas decontamination honeycombed structure. The reducing agents 516, the sealing elements 517 and the method to form the reducing environments 515 are similar to those used in Step 4. However, Step E is different from Step 4 in that the reducing environments 515 are formed in the second passages 513, and that the exhaust gas 80 flows through the first passages 511, and that the separation walls 512 are formed between the first passages 511 and the second passages 513. Thus, the reducing environment 515, the anode layer 70, the separation wall 52 and the cathode layer 60 are sequentially formed from the second passage 513 to the first passage 511. Then, the surfaces of the cathode layers 60 function as reaction sites to undertake a catalytic decomposition reaction of oxynitrides and decontaminate the exhaust gas 80.
In conclusion, the exhaust gas decontamination pipe and honeycombed structure fabricated according to the present invention can merely use the cathode layers to decontaminate exhaust gas without using any additional reducing-gas system. Therefore, the method of the present invention is able to reduce the fabrication cost, and the exhaust gas decontamination reactor fabricated by the present invention is less likely to be damaged. As the present invention needn't arrange a reducing-gas system in the exhaust gas decontamination reactor, the present invention can obviously decrease the volume of the exhaust gas decontamination reactor. Therefore, the exhaust gas decontamination reactor fabricated according to the present invention can be arranged inside the exhaust pipe of a vehicle engine to decontaminate the harmful matters generated by oxygen-enriched combustion and reduce the air pollution.
The present invention possesses utility, novelty and non-obviousness and meets the condition for a patent. Thus, the Inventors file the application for a patent. It is appreciated if the patent is approved fast.
The embodiments described are only to exemplify the present invention but not to limit the scope of the present invention. Any equivalent modification or variation according to the spirit of the present invention is to be also included within the scope of the present invention.

Claims

What is claimed is:

1. A method for fabricating an exhaust gas decontamination pipe, comprising steps:

providing a pipe made of a solid-state oxide and including an internal channel, an inner wall surface surrounding the internal channel, and an outer wall surface far away from the inner wall surface;

coating a green cathode layer, which contains a cathode material, on the outer wall surface, and undertaking a first sintering process to convert the green cathode layer into a cathode layer on the outer wall surface;

coating a green anode layer, which contains an anode material, on the inner wall surface, and undertaking a second sintering process to convert the green anode layer into an anode layer on the inner wall surface; and

forming a reducing environment for the internal channel, and sealing the pipe to enclose the reducing environment and obtain an exhaust gas decontamination pipe, wherein a surface of the cathode layer functions as a reaction site for decontaminating an exhaust gas.

2. The method for fabricating an exhaust gas decontamination pipe according to claim 1, wherein forming the reducing environment comprises steps:

filling a reducing agent into the internal channel; and

sealing the pipe via sealing elements to enclose the reducing agent inside the internal channel to form the reducing environment.

3. The method for fabricating an exhaust gas decontamination pipe according to claim 2, wherein the reducing agent is selected form a group consisting of solid-state reducing materials, liquid reducing materials, and gaseous reducing materials.

4. The method for fabricating an exhaust gas decontamination pipe according to claim 1, wherein forming the reducing environment comprises steps:

forming a air pressure lower than 1 atm inside the internal channel; and

sealing the pipe via sealing elements to form the reducing environment inside the internal channel.

5. The method for fabricating an exhaust gas decontamination pipe according to claim 1, wherein the solid-state oxide is selected from a group consisting of fluoride metal oxides, perovskite metal oxides, and combinations thereof.

6. The method for fabricating an exhaust gas decontamination pipe according to claim 1, wherein the cathode material is selected from a group consisting of perovskite metal oxides, fluorite metal oxides, metal-containing perovskite metal oxides, metal-containing fluorite metal oxides, and combinations thereof.

7. The method for fabricating an exhaust gas decontamination pipe according to claim 1, wherein the anode material is selected from a group consisting of fluorite metal oxides, perovskite metal oxides, metal-containing fluorite metal oxides, metal-containing perovskite metal oxides, cermets containing metals and fluorite metal oxides, and combinations thereof.

8. A method for fabricating an exhaust gas decontamination honeycombed structure, comprising steps:

providing a honeycombed structure made of a solid-state oxide and including a plurality of tubes and a plurality of separation walls between the tubes;

defining in the tubes a plurality of first passages allowing a exhaust gas to pass and a plurality of unsealed second passages, wherein the second passages surround the first passages;

coating a green cathode layer containing a cathode material on a first inner wall surface of each first passage, and undertaking a first sintering process to convert the green cathode layer into a cathode layer on the first inner wall surface;

coating a green anode layer containing an anode material on a second inner wall surface of each second passage, and undertaking a second sintering process to convert the green anode layer into an anode layer on the second inner wall surface; and

forming reducing environments for the second passages and sealing the second passages to enclose the reducing environments to obtain an exhaust gas decontamination honeycombed structure, wherein surfaces of the cathode layers facing the first passages function as reaction sites to decontaminate the exhaust gas.

9. The method for fabricating an exhaust gas decontamination honeycombed structure according to claim 8, wherein forming the reducing environment comprises steps:

filling a reducing agent into each second passage; and

sealing the second passage via sealing elements and enclose the reducing agent inside the second passage to form the reducing environments.

10. The method for fabricating an exhaust gas decontamination honeycombed structure according to claim 9, wherein the reducing agent is selected form a group consisting of solid-state reducing materials, liquid reducing materials, and gaseous reducing materials.

11. The method for fabricating an exhaust gas decontamination honeycombed structure according to claim 8, wherein forming the reducing environment comprises steps:

forming a air pressure lower than 1 atm inside each second passage; and

sealing the second passage via sealing elements to form the reducing environments inside the second passage.

12. The method for fabricating an exhaust gas decontamination honeycombed structure according to claim 8, wherein the solid-state oxide is selected from a group consisting of fluoride metal oxides, perovskite metal oxides, and combinations thereof.

13. The method for fabricating an exhaust gas decontamination honeycombed structure according to claim 8, wherein the cathode material is selected from a group consisting of perovskite metal oxides, fluorite metal oxides, metal-containing perovskite metal oxides, metal-containing fluorite metal oxides, and combinations thereof.

14. The method for fabricating an exhaust gas decontamination honeycombed structure according to claim 8, wherein the anode material is selected from a group consisting of fluorite metal oxides, perovskite metal oxides, metal-containing fluorite metal oxides, metal-containing perovskite metal oxides, cermets containing metals and fluorite metal oxides, and combinations thereof.