CN105244523B - A kind of SOFC with anti-carbon function - Google Patents

Abstract

The invention provides a solid oxide fuel cell with an anti-carbon deposition function, which belongs to a solid oxide fuel cell based on a nickel anode, including an anode, an electrolyte, a cathode, and a quartz gas guide tube, and is characterized in that an independent catalyst layer is arranged on the anode side . The catalyst layer is composed of a substrate and a catalyst; the substrate material is an oxide material with high hardness; the catalyst is a material with high oxidation catalytic activity for hydrocarbon fuels. The invention not only solves the problem of cell swelling and cracking caused by the thermal expansion mismatch between the catalyst and the anode material, but also effectively suppresses carbon deposition on the anode, and greatly improves the stability and reliability of the solid oxide fuel cell.

Description

A solid oxide fuel cell with anti-carbon deposition function

technical field

The invention relates to a chemical power source, in particular to a nickel anode-based solid oxide fuel cell, and more particularly to a solid oxide fuel cell with anti-carbon deposition function.

Background technique

Solid oxide fuel cell (SOFC) has the advantages of high energy conversion efficiency, wide range of fuel application, and no pollution, making it a new generation of fuel cells that can be used in stationary power stations, auxiliary power supplies for vehicles, and small mobile power supplies. Nickel-based ceramic composite anodes are still the most commonly used anode materials so far due to their high electrochemical activity, high electronic conductivity, good stability, and low cost, which show stable performance when hydrogen is used as fuel. However, due to technical limitations in hydrogen production, storage, and transportation, hydrogen-fueled SOFCs are unlikely to be widely used in the next few years. Since SOFC is a high-temperature power generation device (500-1000 degrees), the current carbon-based fuels can in principle generate hydrogen and CO that can be used for power generation under SOFC working conditions, such as natural gas, coalbed methane, shale gas, biological Biogas, gasoline, liquefied petroleum gas, etc., so these substances can be used as SOFC fuel. However, under the high-temperature working conditions of SOFC, hydrocarbon fuels will inevitably be cracked to form carbon deposits deposited on the Ni anode. On the one hand, the active sites on the Ni surface are blocked, and the catalytic performance decreases. The thermal expansion performance does not match, and with the increase of carbon deposits, the battery cracks. At present, many research groups are actively improving SOFC nickel anodes with anti-carbon deposition properties. One of the methods is to cover the surface of the anode with a catalyst coating that promotes the reforming of hydrocarbon fuels so that the hydrocarbon fuels are first catalytically reformed into CO and hydrogen before reaching the Ni anode for electrochemical reactions, and then hydrogen and CO are released at the anode. The electrochemical oxidation reaction occurs in the three-phase interface region to generate electricity. However, the thermal expansion properties of most catalyst materials and anode materials are not consistent. If the catalyst coating is directly covered on the surface of the battery anode by spraying or printing, the thermal expansion properties of the materials often do not match during the heating process of the battery. The battery will burst when the temperature rises (Figure 2a). Therefore, the amount of catalyst used in the current catalyst layer prepared by spraying or printing must be very small, but the insufficient amount of catalyst will cause the problem of insufficient fuel reforming. In addition, the direct coverage of the catalyst on the surface of the anode also blocks a part of the anode pores and increases the gas diffusion resistance.

Contents of the invention

The object of the present invention is to provide a stable solid oxide fuel cell that can be used for hydrocarbon fuels and has an anti-carbon deposition function to solve the problem that the existing solid oxide fuel cell based on nickel anodes is easy to generate carbon deposits when it is applied to hydrocarbon fuels. Oxide fuel cells.

The invention provides a solid oxide fuel cell based on a nickel anode, which includes a cathode, an electrolyte, an anode, and a quartz air duct, and is characterized in that an independent catalyst layer is arranged on the anode side.

The catalyst layer is prepared by a method comprising the following steps: (1) uniformly mixing the base material with a small amount of pore-forming agent, and molding it into a thin sheet with a tablet press; (2) uniformly mixing the catalyst with a small amount of pore-forming agent, laying Sprinkle on the surface of the sheet made in step (1), co-press to form, demould, and bake in a muffle furnace.

The base material is an oxide material with high hardness such as Al ₂ O ₃ , zirconium dioxide, and silicon dioxide.

The pore formers are high-temperature combustibles such as organic matter and carbon materials.

The catalyst is a material with high oxidation catalytic activity for hydrocarbon fuels, including perovskite materials that can generate oxygen holes, such as Sr ₂ MoFeO _6-δ , La _0.6 Sr _0.4 Co _0.9 Fe _0.1 O _3-δ etc.; also includes materials containing transition metals such as nickel, copper, iron, cobalt, molybdenum, cerium and their oxides, such as NiO/BaO/CeO ₂ /Al ₂ O ₃ , NiO/BaO/CeO ₂ .

A kind of preparation method of solid oxide fuel cell based on nickel anode provided by the present invention comprises the following steps:

1) Mix the high-hardness oxide material with a small amount of pore-forming agent evenly, and mold it into a thin sheet with a tablet press;

2) mixing the catalyst with a small amount of pore-forming agent evenly, spreading it on the surface of the sheet made in step 1), co-pressing, demolding, and roasting in a muffle furnace to obtain a catalyst layer composed of a substrate and a catalyst;

3) Place the catalyst layer prepared above on the upper end of the quartz gas guide tube, with the catalyst facing the fuel side, and fix it with silver paste;

4) Bond silver wires to the cathode and anode of the battery respectively, and place them on the catalyst layer according to the anode side towards the catalyst layer, and seal the battery and the catalyst layer together on the quartz tube with high-temperature conductive silver paste.

The NiO/BaO/CeO ₂ /Al ₂ O ₃ catalyst provided by the present invention is prepared by a method comprising the following steps: weighing according to the mass fraction of Ni:BaO:CeO ₂ :Al ₂ O ₃ is 13:2:42.5:42.5 Nickel nitrate, barium nitrate, cerium nitrate, and aluminum nitrate are dissolved in deionized water and added to glycine. The molar ratio (G/M ⁿ⁺ ) of glycine to metal ions is 3:1. Place it on an electric furnace and heat and stir. After the water is evaporated to dryness, it will spontaneously ignite to obtain a primary powder. Put it in an oven and dry it at 240°C for 8 hours. After cooling, it was calcined at 850°C for 2h in a muffle furnace with a heating rate of 5°C min ^-1 .

The NiO/BaO/ _CeO2 catalyst provided by the present invention is prepared by the method comprising the following steps: by Ni:BaO: _CeO2 mass fraction is 13:2:85 and takes nickel nitrate, barium nitrate, cerium nitrate respectively, uses Glycine was added after the ionized water was dissolved, and the molar ratio of glycine to total metal ions (G/M ⁿ⁺ ) was 3:1. Place it on an electric furnace to heat and stir, and after the water is evaporated to dryness, it will spontaneously ignite to obtain a primary powder, and then put it in an oven for 8 hours at 240°C. After cooling, it was calcined at 850°C for 2h in a muffle furnace with a heating rate of 5°C min ^-1 .

Compared with the prior art, the present invention has the following beneficial effects: firstly, there is no substantial close contact between the catalyst layer and the anode layer, independent of the anode layer, and the mismatch of the thermal expansion properties of the catalyst and anode materials will not occur. The resulting battery cracks (Figure 2a), and more importantly, the battery discharge performance is good. Secondly, the fuel gas first passes through the catalyst layer for catalytic reforming reaction to generate CO and hydrogen, and then these two gases pass through the catalyst substrate to reach the anode of the battery for electrochemical reaction to generate electricity. After being blocked by the catalyst layer, the concentration of hydrocarbon fuel on the surface of the Ni anode is greatly reduced, reducing the deposition of cracked carbon on the anode; third, because the catalyst layer and the battery do not affect each other, the amount of catalyst can be increased to improve the catalytic conversion of fuel efficiency. Although the embodiment uses wet methane as fuel, considering that different hydrocarbon fuels have corresponding reforming catalysts, the battery prepared according to the method of the present invention can be applied to any hydrocarbon fuel. Therefore, the invention not only solves the problem of battery swelling and cracking caused by the thermal expansion of the catalyst, but also effectively suppresses carbon deposition on the anode, so that the performance of the battery is stable.

Description of drawings

Fig. 1 is the structure schematic diagram of described solid oxide fuel cell

Figure 2(a) shows the battery swelling and cracking caused by the mismatch of thermal expansion performance during the process of spraying the catalyst on the surface of the battery anode with an art spray gun

Fig. 2 (b) is the cell morphology after 40 hours of wet methane constant current discharge test with solid oxide fuel cell of the present invention

Figure 3 is the discharge performance life test of a blank solid oxide fuel cell without a catalyst layer under the same conditions

Fig. 4 is the discharge performance life test of the solid oxide fuel cell prepared in embodiment 1

Fig. 5 is the discharge performance life test of the solid oxide fuel cell prepared in embodiment 2

Fig. 6 is the discharge performance life test of the solid oxide fuel cell prepared in embodiment 3

Fig. 7 is the discharge performance life test of the solid oxide fuel cell prepared in embodiment 4

Fig. 8 is the discharge performance life test of the solid oxide fuel cell prepared in embodiment 5

Fig. 9 is the discharge performance life test of the solid oxide fuel cell prepared in Example 6

Detailed ways

The present invention will be described in detail below in conjunction with specific examples. The following examples will help those skilled in the art to further understand the present invention, but do not limit the protection scope of the present invention.

In the following examples, YSZ refers to 8% yttrium-stabilized zirconia, and LSM refers to La _0.8 Sr _0.2 MnO _3-δ . The pore former PVB refers to polyvinyl butyral.

Example 1

The classic NiO-YSZ/YSZ/LSM-YSZ is used as a single cell, Al ₂ O ₃ is used as the substrate of the catalyst layer, and the NiO/BaO/CeO ₂ mixture synthesized in a certain proportion is used as the catalyst:

(1) Catalyst powder preparation: Weigh nickel nitrate, barium nitrate, cerium nitrate respectively according to Ni:BaO:CeO ₂ mass fraction is 13:2:85, add glycine after dissolving with deionized water, glycine and total metal ion The molar ratio (G/M ⁿ⁺ ) was 3:1. Place it on an electric furnace to heat and stir, and after the water is evaporated to dryness, it will spontaneously ignite to obtain a primary powder, and then put it in an oven for 8 hours at 240°C. After cooling, it was calcined at 850°C for 2h in a muffle furnace with a heating rate of 5°C min ^-1 .

(2) Catalyst layer preparation: Weigh 0.3g of Al ₂ O ₃ and PVB mixed uniform powder with a mass ratio of 9:1, press the catalyst layer base with a tablet die at 144MPa, and then mix 0.03g with 10% PVB catalyst powder is uniformly dispersed on the surface of the substrate, co-pressed at 240MPa, demolded, and calcined at 900°C for 4 hours to obtain a catalyst layer composed of the substrate and the catalyst.

(3) The catalyst layer prepared above is placed on the upper end of the quartz gas guide tube, and the catalyst is fixed with silver paste towards the fuel side;

(4) Bond silver wires to the cathode and anode of the NiO-YSZ/YSZ/LSM-YSZ battery respectively, and place the anode side toward the catalyst layer above the catalyst layer, and seal the battery and the catalyst layer together with high-temperature conductive silver paste on the quartz tube.

Using wet methane (97% methane, 3% water vapor) as fuel, the electrochemical performance and battery discharge life were tested according to the conventional solid oxide fuel cell test method. The battery voltage stabilized after 13 hours of steady discharge at a load current of 333mA/ ^cm2 (see Figure 4), the battery surface has no cracks.

Control: The battery with the same catalyst layer prepared by the art spray gun spraying method, the battery bursts before the temperature rises to the required temperature (Figure 2(a)), and cannot be tested.

Example 2

Using NiO-YSZ/YSZ/LSM-YSZ as a single cell, YSZ as a catalyst substrate, and synthesized NiO/BaO/ _CeO2 as a catalyst:

The preparation method is the same as in Example 1, except that Al ₂ O ₃ in Example 1 is replaced by YSZ, and the discharge life of the battery is shown in FIG. 5 .

Example 3

Using NiO-YSZ/YSZ/LSM-YSZ as a single cell, Al ₂ O ₃ as a catalyst substrate, and NiO/BaO/CeO ₂ /Al ₂ O ₃ synthesized in a certain proportion as a catalyst:

(1) Catalyst powder preparation: Weigh nickel nitrate, barium nitrate, cerium nitrate, aluminum nitrate according to the mass fraction of Ni:BaO:CeO ₂ :Al ₂ O ₃ as 13:2:42.5:42.5, and dissolve them in deionized water Glycine is added, and the molar ratio (G/M ⁿ⁺ ) of glycine to metal ions is 3:1. Place it on an electric furnace and heat and stir. After the water is evaporated to dryness, it will spontaneously ignite to obtain a primary powder. Put it in an oven and dry it at 240°C for 8 hours. After cooling, it was calcined at 850°C for 2h in a muffle furnace with a heating rate of 5°C min ^-1 .

(2)-(5) Same as Example 1, the constant current discharge life of the battery is shown in FIG. 6 .

Example 4

Using NiO-YSZ/YSZ/LSM as a single cell, YSZ as a catalyst substrate, and the synthesized NiO/BaO/CeO ₂ /Al ₂ O ₃ as a catalyst:

The preparation method is the same as in Example 3, except that Al ₂ O ₃ in Example 3 is replaced by YSZ, and the constant current discharge life of the battery is shown in FIG. 7 .

Example 5

NiO-YSZ/YSZ/LSM is used as a single cell, Al ₂ O ₃ is used as a catalyst substrate, and the double perovskite material Sr ₂ MoFeO _6-δ synthesized at a certain ratio is used as a catalyst:

(1) Catalyst powder _preparation : take a certain _{amount of Sr(NO 3 ) 2 ,} (NH ₄ ) ₆ Mo ₇ O ₂₄ ·4H ₂ O and Fe(NO ₃ ) ₃ , add deionized water and stir until completely dissolved. Add ammonia solution of ethylenediaminetetraacetic acid (EDTA) to the metal ion solution, and then add a certain amount of citric acid, wherein, EDTA:citric acid:metal ion:NH ₃ ·H ₂ O=1:2:1: 10 (molar ratio). Fine-tuning an appropriate amount of citric acid makes the pH of the precursor solution weakly acidic (pH=6-7). After heating to remove excess moisture, the obtained gel-like precursor was placed in a blast drying oven, and dried at 250° C. for 8 hours to obtain a solid precursor. Finally, put the solid precursor into a muffle furnace and calcinate for 2 hours at 1100 degrees in an air atmosphere to obtain Sr ₂ MoFeO _6-δ powder. The powder is tested by X-ray powder diffraction.

(2) Catalyst layer preparation: Mix alumina powder and PVB powder evenly at a mass ratio of 25:3, weigh 0.3g of the powder and put it into a Φ13mm steel mold, and press the substrate with a pressure of 144MPa through a tablet press powder to obtain the base powder; then mix the Sr ₁ Mo _0.5 Fe _0.5 powder and PVB powder evenly at a mass ratio of 12:5, weigh 0.3g of the catalyst powder, and spread it evenly on the base powder , perform secondary film compression (240MPa) by a tablet press, hold the pressure for 1min, press to form a catalyst/substrate double-layer green body, calcinate at 900°C for 4h, and control the heating rate to 5°Cmin ^-1 to obtain a catalyst layer.

(3)-(5) The preparation method is the same as in Example 1, and the discharge life of the battery is shown in FIG. 8 .

Example 6

Using NiO-YSZ/YSZ/LSM as a single cell, Al ₂ O ₃ as a catalyst substrate, and a perovskite material La _0.6 Sr _0.4 Co _0.9 Fe _0.1 O _3-δ synthesized in a certain proportion as a catalyst:

(1) Catalyst powder preparation: take a certain amount of La(NO ₃ ) ₃ , Sr(NO ₃ ) ₂ , Co(NO ₃ ) according to the stoichiometric ratio of the chemical formula of La _0.6 Sr _0.4 Co _0.9 Fe _0.1 O _{3-δ 3.} and Fe(NO ₃ ) ₃ , add deionized water and stir until completely dissolved. Add ammonia solution of ethylenediaminetetraacetic acid (EDTA) to the metal ion solution, and then add a certain amount of citric acid, wherein, EDTA:citric acid:metal ion:NH ₃ ·H ₂ O=1:2:1: 10 (molar ratio). Fine-tuning an appropriate amount of citric acid makes the pH of the precursor solution weakly acidic (pH=6-7). After heating to remove excess moisture, the obtained gel-like precursor was placed in a blast drying oven, and dried at 250 ^o C for 8 hours to obtain a solid precursor. Finally, put the solid precursor into a muffle furnace and calcinate it in an air atmosphere at 900 degrees for 2 hours to obtain La _0.6 Sr _0.4 Co _0.9 Fe _0.1 O _3-δ powder. The powder is tested by X-ray powder diffraction.

(2)-(5) The preparation method is the same as in Example 1, and the discharge life of the battery is shown in FIG. 9 .

Claims (4)

1. a kind of SOFC based on nickel anode, including negative electrode, electrolyte, anode, quartzy airway tube, it is special Sign is, independent catalyst layer is set in anode-side；

Described catalyst layer is prepared by a method comprising the following steps to obtain：1) base material is mixed with a small amount of pore creating material Uniformly, it is molded flakiness with tablet press machine；2) catalyst is well mixed with a small amount of pore creating material, paving is sprinkled upon thin slice made of step 1) Surface, it is molded altogether, the demoulding, it is placed in Muffle kiln roasting.

A kind of 2. SOFC based on nickel anode as claimed in claim 1, it is characterised in that described base Bottom material is the high oxide material of hardness；

The high oxide material of the hardness is Al₂O₃Or YSZ, the YSZ refer to 8% yttria stabilized zirconia.

3. a kind of SOFC based on nickel anode as claimed in claim 1, it is characterised in that described urges Agent is that can produce the perovskite material of oxygen vacancies, or the material of the oxide containing transition metal oxide and cerium.

4. a kind of preparation method of the SOFC based on nickel anode, it is characterised in that comprise the following steps：

1) oxide material of high rigidity is well mixed with a small amount of pore creating material, flakiness is molded with tablet press machine；

2) catalyst being well mixed with a small amount of pore creating material, paving is sprinkled upon sheet surface made of step 1), molded altogether, the demoulding, Muffle kiln roasting is placed in, obtains the catalyst layer being made up of substrate and catalyst；

3) catalyst layer of above-mentioned preparation is positioned over to the upper end of quartzy airway tube, catalyst is fixed towards fuel-side with silver paste；

4) silver wire is bonded respectively in the negative electrode and anode of battery, and be positioned over the upper of catalyst layer towards catalyst layer by anode-side Battery and catalyst layer, are sealed on quartz ampoule by side together with high-temperature electric conduction silver paste.