CN112103519B

CN112103519B - Porous nickel-loaded perovskite catalyst

Info

Publication number: CN112103519B
Application number: CN202011113770.9A
Authority: CN
Inventors: 左海珍
Original assignee: Zhejiang Zhiyuan Environmental Technology Co ltd
Current assignee: Zhejiang Zhiyuan Environmental Technology Co ltd
Priority date: 2020-10-17
Filing date: 2020-10-17
Publication date: 2022-06-24
Anticipated expiration: 2040-10-17
Also published as: CN112103519A

Abstract

The invention provides a porous nickel-loaded perovskite catalyst which is an integral three-dimensional porous structure catalyst, has excellent mechanical strength, high heat transfer performance and low local hot spots, and effectively improves the solid-phase mass transfer process and the catalytic effect.

Description

Porous nickel-loaded perovskite catalyst

Technical Field

The invention relates to a porous nickel-loaded perovskite catalyst, belongs to the field of electrochemical dealloying and fuel cell catalysis, and particularly relates to the field of gas-solid phase catalysis.

Technical Field

Firstly, reactants of the fuel cell are hydrogen and an anode, and hydrogen energy is used as a high-efficiency, clean and renewable secondary energy source, so that the application of the hydrogen energy enters various fields of social life, and the demand of the hydrogen energy is increasing in recent years. At present, the main technical fields of hydrogen production include hydrogen production by fossil fuels (methanol, ethanol and natural gas), biological hydrogen production, hydrogen production by water electrolysis and the like. The main approach of the fuel cell hydrogen production technology is to reform or partially oxidize hydrocarbons (methanol, ethanol, natural gas, etc.), and then perform a water gas shift reaction. The obtained reformed gas contains 45 to 75 percent of H₂、15%～25% CO₂0.5 to 2 percent of CO and a small amount of H₂O and N₂. The electrode material of the fuel cell is Pt, and the existence of CO in the hydrogen-rich gas can not only poison the Pt electrode, but also be easily adsorbed on the surface of the catalyst to inhibit the catalytic oxidation of the fuel, so that the content of CO in the hydrogen-rich gas is required to be controlled below 100 ppm, and the CO-PROX reaction is adopted.

At present, catalyst carriers suitable for CO-PROX under hydrogen-rich conditions are mainly (A) powders: such as TiO₂、Fe₂O₃、Co₃O₄、NiO、MnOx、SnO₂、CeO₂Non-metal powder catalyst, which has the following disadvantages (1) that the loading and unloading are troublesome in the practical industrial application process; (2) is not easy to form and the mechanical strength can not meet the requirement; (3) mass and heat transfer are greatly hindered, and the treatment efficiency is reduced; (4) the pressure drop difference between the front and the back of the catalyst bed is large, and the energy consumption is increased; (B) integral block carrier: such as Roberts G W, Chin P, X L Sun, et al, Preferential oxidation of carbon monooxide with Pt/Fe monolithic catalysts, interactions between external transport and the reverse water-gas-shift reaction, Applied Catalysis B, Environmental, 2003, 46(3): 601-611 and Ahluwallia R K, Zhang Q Z, Chmielewski D J, et Al, Performance of CO prediction oxidation reactor with non-metallic catalyst coated on ceramic monolithic for on-board fuel processing applications, Catalysis Today, 2005, 99(3-4): 271-283 published straight channel cordierite, next Zhou S L, Yuan Z S, Wang S D, Selective CO oxidation with reactive catalyst reforming over monolithic Pt group catalysts, PEMFC applications, International Journal of Hydrogen Energy, 2006, 31(7): 924 prepared monolithic Pt/3O reaction on Al2O carrier₂Ratio of/CO, concentration of CO, H₂O and CO₂And the influence of space velocity on the activity, selectivity and stability of the integral catalyst; roberts G W, Chin P, X L Sun, et al, Preferential oxidation of carbon monoxide with Pt/Fe monolithic catalysts, interaction between the external transport and the reverse water-gate-shift reaction, Applied Catalysis B: Environmental, 2003, 46(3): 601-611 and Neri G, Rizzo G, Coriliano F, et al, A novel Pt/zeolite-based catalytic reaction for selective CO oxidation a H2-rich, Catalysis Today, 2009, 147S 210-S214, multi-channel catalysts with several hundred structures, which can significantly reduce the differential pressure of gases passing through the micro-scale reactor, in addition, gradient CO-reactive P, gradient CO-reactive, CuO-reactive, Ca-CO-reactive, CuO-M-S24, a CuO/CeO2 coated ceramic monolithic catalyst is prepared in 224-231 of Chemical Engineering Journal, and when the loading amount of Cu is 7%, the monolithic catalyst shows better activity and selectivity, but the performance of the catalyst is seriously influenced by the presence of CO2 and H2O.

In the patent aspect, CN201911161146 discloses a monolithic catalyst for preferential oxidation of CO under a hydrogen-rich condition and a preparation method thereof, wherein although the alloy catalyst carrier has good mechanical properties, the process of reversely preparing the alloy carrier at that time is complicated, the cost is high, and the monolithic catalyst is only suitable for laboratory conditions, and has a barrier to industrial application; CN201510066860 discloses aPreparation and application of CuCo alloy catalyst loaded by LaFeO3 with high specific surface area. The catalyst takes LaFeO3 with high specific surface area as a carrier and La2O3 as an auxiliary agent, and Cu1-xCox alloy is loaded on the carrier. The preparation process comprises the following steps: preparing LaFe1-yCuyO3 with high specific surface area by using mesoporous SiO2 as a hard template agent; soaking a cobalt nitrate solution on a LaFe1-yCuyO3 carrier, and drying and roasting to obtain a catalyst precursor; the precursor is reduced to obtain the CuCo alloy catalyst which is loaded by LaFeO3 and takes lanthanum oxide as an auxiliary agent, and the patent has the following problems: (1) the preparation method of the silicon oxide is to prepare the silicon oxide by a template method, so that the silicon oxide has poor mechanical strength, is usually in a powder state and is difficult to be used as a block-shaped carrier; (2) the citric acid one-step complex method can expand in the reaction process, reactants immersed in the mesoporous silica can obviously break up the silica carrier, and the specific surface area of the silica prepared by the patent template method is as high as 500 m²Per g to obtain LaFeO₃The specific surface area of the catalyst carrier is only 120 m²The key reason for/g.

Based on the above-mentioned foreign documents and patent status, the prior art has been found to have the following problems: (1) the massive monolithic catalyst carrier is mainly concentrated on natural porous materials, and the purification or pretreatment process of the natural materials is complicated; (2) the integral catalyst prepared by the existing reverse template method needs multiple reverse electroplating, has complex working procedures and is difficult to industrially apply; (3) the perovskite catalyst is obtained in powder form, and the application of the perovskite monolithic catalyst in a laboratory or industry is not seen so far.

To deal with the above technical problems, the following technical knowledge needs to be grasped:

(1) the porous metal is a porous material with a large number of directional or random holes dispersed therein, and the diameter of the holes is between about 2um and 25 mm. The porous metal material not only retains the conductivity, ductility, weldability and the like of the metal material, but also has the excellent characteristics of small specific gravity, large specific surface area, high specific strength, energy absorption, shock absorption, noise reduction, electromagnetic shielding, low heat conductivity and the like, and the conventional hierarchical porous material mainly comprises a micropore-mesopore material, a micropore-macropore material, a macropore-mesopore material, a micropore-mesopore-macropore material and a mesopore-mesopore material containing two or more different pore diameters. The main preparation methods comprise a template method, a hydrothermal method, a foaming method, a sol-gel method, a molten salt method and the like, and because the method usually relates to a chemical synthesis method in the synthesis process, the preparation steps are multiple, and the process is complex, the synthesis cost of the existing hierarchical pore material is high, the pore structure control difficulty is large, the process stability is poor, and the large-scale production is difficult. The dealloying method utilizes the potential difference of electrodes of different metal elements in the multi-element alloy to carry out free corrosion in electrolyte solutions such as acid and alkali or promote corrosion to remove relatively active components in the electrolyte solutions by applying voltage, and relatively inert components are reserved to form a bicontinuous open porous structure. The method is simple, convenient and feasible, is easy to repeat, is suitable for preparing the nano porous material on a large scale, and can realize the control of the pore diameter/pore wall size distribution of the porous material by controlling the processes of corrosion, subsequent heat treatment and the like.

Disclosure of Invention

In view of the defects of the prior art, the invention provides a porous nickel-loaded perovskite catalyst aiming at the defects of the traditional powder catalyst or porous block catalyst. The method has simple process and low cost, the strength and catalytic activity of the obtained porous metal bulk catalyst are suitable for industrial popularization, the pore diameter of the porous nickel is distributed between 5 and 30 mu m, and the specific surface area is 30 to 60m²Per g, porosity 50-70%, the perovskite is LaCo_0.7Cu_0.3O₃The perovskite is uniformly loaded on the inner surfaces of the pore channels of the porous nickel, and the specific surface area of the catalyst is 20-50m²The compressive strength of the catalyst is 2-4 MPa.

The porous nickel supported perovskite catalyst is a non-powdered catalyst and comprises the following steps:

(1) preparing a Ni-Al alloy block:

(a) uniformly mixing 30-40wt.% of 1-5 μm nickel powder and 60-70wt.% of 5-10 μm aluminum powder;

(b)300-400 Mpa;

(c) sintering at high temperature in inert atmosphere or reducing atmosphere, wherein the sintering temperature is 1300-1400 DEG C^oC, high temperature lasting for 1-3h, natural cooling,

the pressure maintaining time for press forming is 5-10 min; the inert atmosphere is N₂The reducing atmosphere is H₂(ii) a Temperature programming rate of the high temperature sintering 10^oC/min。

This step should be noted:

the proportion and the size of the nickel and the aluminum powder directly influence the pore size distribution, the specific surface area and the porosity of porous nickel obtained subsequently, and the range of the invention is defined as follows: 30-40wt.%1-5 μm nickel powder, 60-70wt.%5-10 μm aluminum powder, preferably 33-38wt.% 2-3 μm nickel powder, 62-68wt.%,7-8 μm aluminum powder, most preferably 35wt.% 2-3 μm nickel powder, 65wt.%,7-8 μm aluminum powder.

The three-dimensional porous catalyst has certain compressibility and deformability, the volume and the size of the three-dimensional porous catalyst are larger than or equal to the size of the reactor, the exceeding range is not higher than 10 percent and cannot be lower than the size or the volume of the reactor, otherwise, the reactor has poor tightness, and reaction gas cannot effectively contact the catalyst.

Thirdly, the impurity degree and the stability of the alloy are determined by the sintering atmosphere, if oxygen is mixed, the state of the Ni-Al alloy is obviously influenced, and the influence of oxides on the state of the alloy is also obviously influenced.

And fourthly, the sintering temperature mainly influences the specific form of the alloy.

(2) Preliminary dealloying by chemical lye corrosion: the corrosive liquid used for preliminary dealloying by chemical alkaline corrosion is 1-2M NaOH aqueous solution, the corrosion time is 12-24h, and the temperature is 30-35^oAnd C, removing bubbles by ultrasonic assistance in the corrosion process, and washing with deionized water for multiple times after corrosion.

The primary de-alloying is mainly based on electroless corrosion, mainly based on the following considerations:

firstly, preliminary dealloying is electroless corrosion, namely, the electroless corrosion is completely eliminated, the electroless corrosion is mainly used for taking the electrified corrosion as an anode, and the Ni-Al alloy is used in the invention, wherein Al does not have corrosion reaction, but forms alumina due to anodic oxidation, or forms an oxide film on the Ni-Al alloy, thus not only a corrosion pore channel can not be formed, but also a protective film can be formed.

Secondly, the corrosive liquid of the electroless corrosion for preliminary alloy removal is sodium hydroxide, Al is known to be an amphoteric compound, both acid and alkali can carry out corrosion reaction, and the problem of selective corrosion is considered by only selecting the sodium hydroxide, so that only the Al in the sodium hydroxide is corroded without corroding Ni, and the corrosion is very important for the formation of the uniformity of the three-dimensional pore channel.

In the corrosion process, the reaction of aluminum and sodium hydroxide can generate hydrogen which can not be captured by naked eyes, and the ultrasonic wave of the hydrogen can obstruct the contact of the sodium hydroxide and the aluminum, so that the ultrasonic assistance must be added in the electroless corrosion process, and the diffusion and the separation of small bubbles are facilitated.

Fourthly, the concentration, the time and the temperature in the electroless corrosion process are obtained through orthogonal experiments, and the porous nickel aluminum material carrier is preliminarily obtained for optimizing the range.

(3) Deep dealloying by electrochemical acid corrosion: taking the nickel material obtained in the step (2) as an anode, taking a Pt sheet as a cathode and taking 0.6-0.7M HNO₃The corrosion voltage is 0.3-0.5V, the corrosion time is 2-3h, and the electrochemical corrosion temperature is normal temperature.

Attention is paid to:

the electrochemical corrosion is positioned after the electroless corrosion, and the steps can not be randomly reversed.

The electrochemical corrosion liquid is acid liquid, which can be sulfuric acid, nitric acid, phosphoric acid and oxalic acid, and the nitric acid is preferably selected in consideration of corrosion effect and corrosion rate, in addition, the acid liquid is adopted for corrosion in the electrochemical corrosion process, so that the preparation steps of the catalyst carrier can be reduced, namely, the preliminary corrosion and the deep corrosion directly do not need any cleaning and drying treatment, and certainly, if the preliminary corrosion nickel-aluminum material can be cleaned and air-dried by water and repeated for multiple times, the subsequent deep corrosion has the best porous structure, but for convenience of operation, the acid liquid can be selected to directly neutralize the alkali corrosion liquid to remove the adhesive film on the surface of the nickel-aluminum alloy.

And thirdly, the electrochemical corrosion is preferred because the aluminum can be removed by the electroless corrosion but can not be completely removed, at least within 12-24h of the invention, the aluminum can not be effectively removed by the electroless corrosion, and the existence of the aluminum can obviously reduce the porosity of a three-dimensional pore channel structure, so that the residual aluminum can be effectively removed by the subsequent electrochemical corrosion, and further, mesopores are effectively formed, the generation of the mesopores is favorable for improving the specific surface area of the porous nickel, and the pore size distribution of the obtained porous nickel is 5-30 μm, the specific surface area is 30-60m2/g, and the porosity is 50-70%.

The concentration and the voltage of the corrosive acid liquid are lower, the time is shorter, and the consideration of preventing the anodic oxidation of the aluminum is based on the premise of effective corrosion.

(4) Oxidation and activation: the oxidation activation is carried out for 5-10min under the condition of 40wt.% oxygen-air.

The porous material obtained at the moment is a porous nickel material and is used as a carrier of a subsequent catalyst, the carrier of the catalyst has certain binding force with an active component directly, and if the active component cannot be effectively loaded, the loss of catalytic activity can be caused.

(5) Preparing a copper-cobalt perovskite precursor solution: lanthanum nitrate, cobalt nitrate and copper nitrate are sequentially mixed in a mixed solution of citric acid and ethylene glycol, wherein the molar ratio of La to Co to Cu to citric acid to ethylene glycol is =1:0.7:0.3:2.5:0.53, a proper perovskite bimetallic catalyst can be selected in the prior art, and LaCo is selected in the invention_0.7Cu_0.3O₃Is an active component.

(6) Preparation of LaCo by dipping-high temperature roasting_0.7Cu_0.3O₃Porous nickel catalyst: soaking the nickel material obtained in the step (4) in the cobalt-gallium perovskite precursor solution obtained in the step (5) for a certain timeSoaking at normal temperature for 12-24 hr, stirring in 80 deg.C water bath for 8 hr, and heating at 3 deg.C^oC/min is increased to 150min, the temperature is kept for 12h, and then 2^oC/min is increased to 550^oC, preserving the heat for 5-7h, naturally cooling along with a muffle furnace, and LaCo_0.7Cu_0.3O3 porous nickel, the LaCo_0.7Cu_0.3O3/porous nickel catalyst was passed through 3-5vol.% H before use₂/N₂Reducing for 3-5 h.

The scheme of the invention has the following beneficial effects:

(1) the three-dimensional porous nickel material is obtained through electroless primary dealloying and charged deep dealloying treatment, wherein macropores are favorable for gas mass transfer, mesopores are favorable for surface area improvement and loading of active components, the pore diameter of porous nickel is distributed at 5-30 mu m, and the specific surface area is 30-60m²G, porosity 50-70%.

(2) The catalyst carrier is metal, has high heat conductivity, and the metal characteristics determine that the catalyst carrier can effectively avoid the hot spot problem of a catalyst bed layer, avoid inactivation, is favorable for the stability of the catalyst, has high mechanical strength, and meets the basic requirements of a massive catalyst carrier.

(3) The shape and appearance of the catalyst carrier are obtained through alloying treatment, the shape and structure of the catalyst carrier are adjustable, the applicability is strong, the mechanical performance of the carrier is high, and the compressive strength of the catalyst is 2-4 Mpa.

(4) The activation treatment is favorable for improving the bonding strength of the active component of the catalyst and the carrier, the catalyst has excellent stability, the perovskite is uniformly loaded on the inner surface of the pore channel of the porous nickel, and the specific surface area of the catalyst is 20-50m²/g。

(5) Catalyst at 120-^oCan completely purify CO in the range of C.

Drawings

FIG. 1 is an SEM-Mapping diagram of a porous nickel material obtained after primary dealloying-deep dealloying.

Fig. 2 SEM images of porous nickel material obtained after preliminary dealloying-deep dealloying.

FIG. 3 catalyst LaCo_0.7Cu_0.3O₃SEM image of porous nickel.

FIG. 4 catalyst LaCo_0.7Cu_0.3O₃SEM magnified view of porous nickel.

Detailed Description

Example 1

A porous nickel supported perovskite catalyst, which is a non-powdered catalyst, comprising the steps of:

(1) preparing a Ni-Al alloy block:

(a) uniformly mixing 30wt.% of 2-3 μm nickel powder and 70wt.% of 7-8 μm aluminum powder;

(b) pressing and molding under 300 Mpa;

(c) sintering at high temperature 1300 deg.C in inert atmosphere^oC, high temperature lasting for 1h, natural cooling,

the pressure maintaining time of the compression molding is 5 min; the inert atmosphere is N₂(ii) a Temperature programming rate of the high temperature sintering 10^oC/min。

(2) Preliminary dealloying by chemical lye corrosion: the corrosive liquid used for preliminary dealloying by the corrosion of the chemical alkali liquor is 1M NaOH aqueous solution, the corrosion time is 12h, and the temperature is 30^oAnd C, removing bubbles by ultrasonic assistance in the corrosion process, and washing with deionized water for multiple times after corrosion.

(3) Deep dealloying by electrochemical acid corrosion: taking the nickel material obtained in the step (2) as an anode, taking a Pt sheet as a cathode and taking 0.6M HNO₃The corrosion voltage is 0.3V, the corrosion time is 2h, and the electrochemical corrosion temperature is normal temperature.

(4) Oxidation and activation: the oxidation activation is oxidation under 40wt.% oxygen-air condition for 5 min.

(5) Preparing a copper-cobalt perovskite precursor solution: lanthanum nitrate, cobalt nitrate and copper nitrate are sequentially mixed in a mixed solution of citric acid and glycol, wherein the molar ratio of La to Co to Cu to citric acid to glycol is =1:0.7:0.3:2.5: 0.53.

(6) Preparation of LaCo by dipping-high temperature roasting_0.7Cu_0.3O₃Porous nickel catalyst: soaking in waterSoaking the nickel material obtained in the step (4) in the cobalt-gallium perovskite precursor solution obtained in the step (5) for 12-24h at normal temperature, continuously stirring in a 80 ℃ water bath for 8h, and performing high-temperature roasting at a programmed temperature of 3 DEG C^oRaising C/min to 150min, keeping the temperature for 12h, and then 2^oC/min is increased to 550^oC, preserving the heat for 5 hours, and naturally cooling along with a muffle furnace to obtain LaCo_0.7Cu_0.3O3/porous nickel catalyst.

Example 2

(1) preparing a Ni-Al alloy block:

(a) uniformly mixing 35wt.% of 2-3 μm nickel powder and 65wt.% of 7-8 μm aluminum powder;

(b) pressing and molding under 350 MPa;

(c) sintering at high temperature in reducing atmosphere at 1350 deg.C^oC, high temperature lasting for 2 hours, natural cooling,

the pressure maintaining time for press forming is 7.5 min; the reducing atmosphere is H₂(ii) a Temperature programming rate of the high temperature sintering 10^oC/min。

(2) Preliminary dealloying by chemical lye corrosion: the corrosive liquid used for primary dealloying by the corrosion of the chemical alkali liquor is 1.5M NaOH aqueous solution, the corrosion time is 20h, and the temperature is 33^oAnd C, removing bubbles by ultrasonic assistance in the corrosion process, and washing with deionized water for multiple times after corrosion.

(3) Deep dealloying by electrochemical acid corrosion: taking the nickel material obtained in the step (2) as an anode, taking a Pt sheet as a cathode and taking 0.65M HNO₃The corrosion voltage is 0.4V, the corrosion time is 2.5h, and the electrochemical corrosion temperature is normal temperature.

(4) Oxidation and activation: the oxidation activation is oxidation under 40wt.% oxygen-air condition for 8 min.

(5) Preparing a copper-cobalt perovskite precursor solution: lanthanum nitrate, cobalt nitrate and copper nitrate are sequentially mixed in a mixed solution of citric acid and ethylene glycol, wherein the molar ratio of La to Co to Cu to citric acid to ethylene glycol is =1:0.7:0.3:2.5: 0.53.

(6) Preparation of LaCo by dipping-high temperature roasting_0.7Cu_0.3O₃Porous nickel catalyst: soaking the nickel material obtained in the step (4) in the copper-cobalt perovskite precursor solution obtained in the step (5) for 20h at normal temperature, and then soaking at 80 DEG C^oC, continuously stirring for 8 hours in a water bath, and carrying out a programmed heating process of 3 in the high-temperature roasting process^oRaising C/min to 150min, keeping the temperature for 12h, and then 2^oC/min is increased to 550^oC, preserving the heat for 6 hours, and naturally cooling along with a muffle furnace to obtain LaCo_0.7Cu_0.3O3/porous nickel catalyst, named S.

Example 3

(1) preparing a Ni-Al alloy block:

(a) uniformly mixing 40wt.% of 2-3 μm nickel powder and 60wt.% of 7-8 μm aluminum powder;

(b) pressing and molding under 400 Mpa;

(c) sintering at high temperature of 1400 deg.C in inert atmosphere^oC, high temperature lasting for 3 hours, natural cooling,

the pressure maintaining time for press forming is 10 min; the inert atmosphere is N₂(ii) a Temperature programming rate of the high temperature sintering 10^oC/min。

(2) Preliminary dealloying by chemical lye corrosion: the corrosive liquid used for primary dealloying by the corrosion of the chemical alkali liquor is 2M NaOH aqueous solution, the corrosion time is 24h, and the temperature is 35^oAnd C, removing bubbles by ultrasonic assistance in the corrosion process, and washing with deionized water for multiple times after corrosion.

(3) Deep dealloying by electrochemical acid corrosion: taking the nickel material obtained in the step (2) as an anode, taking a Pt sheet as a cathode and taking 0.7M HNO₃The corrosion voltage is 0.5V, the corrosion time is 3h, and the electrochemical corrosion temperature is normal temperature.

(4) Oxidation and activation: the oxidation activation is oxidation for 10min under 40wt.% oxygen-air condition.

(6) Preparation of LaCo by dipping-high temperature roasting_0.7Cu_0.3O₃Porous nickel catalyst: soaking the nickel material obtained in the step (4) in the copper-cobalt perovskite precursor solution obtained in the step (5) for 24 hours at normal temperature, and then soaking at 80 DEG C^oC, continuously stirring for 8 hours in a water bath, and carrying out a programmed heating process of 3 in the high-temperature roasting process^oRaising C/min to 150min, keeping the temperature for 12h, and then 2^oC/min is increased to 550^oC, preserving the heat for 7 hours, and naturally cooling along with a muffle furnace to obtain LaCo_0.7Cu_0.3O3/porous nickel catalyst.

Comparative example 1

(1) preparing a Ni-Al alloy block:

(b) pressing and molding under 350 MPa;

the pressure maintaining time for the compression molding is 7.5 min; the reducing atmosphere is H₂(ii) a Temperature programming rate of the high temperature sintering 10^oC/min。

(2) Dealloying by electrochemical acid etching: taking the nickel-aluminum alloy material as an anode, taking a Pt sheet as a cathode and taking 0.65M HNO₃The electrolyte is used, the corrosion voltage is 0.4V, the corrosion time is 2.5h, and the electrochemical corrosion temperature is normal temperature.

(3) Dealloying by chemical lye corrosion: the corrosive solution used for dealloying by the corrosion of the chemical alkali liquor is 1.5M NaOH aqueous solution, the corrosion time is 20h, and the temperature is 33^oAnd C, removing bubbles by ultrasonic assistance in the corrosion process, and washing with deionized water for multiple times after corrosion.

(6) Preparation of LaCo by dipping-high temperature roasting_0.7Cu_0.3O₃Porous nickel catalyst: soaking the nickel material obtained in the step (4) in the copper-cobalt perovskite precursor solution obtained in the step (5) for 20h at normal temperature, and then soaking at 80 DEG C^oC, continuously stirring for 8 hours in a water bath, and carrying out a programmed heating process of 3 in the high-temperature roasting process^oRaising C/min to 150min, keeping the temperature for 12h, and then 2^oC/min is increased to 550^oC, preserving the heat for 6 hours, and naturally cooling along with a muffle furnace to obtain LaCo_0.7Cu_0.3O3/porous nickel catalyst, named D-1.

Comparative example 2

A porous nickel supported perovskite catalyst, which catalyst is a non-powder catalyst, comprising the steps of preparing:

(1) preparing a Ni-Al alloy block:

(b) pressing and molding under 350 Mpa;

(3) Deep dealloying by electrochemical acid corrosion: obtained in step (2)Nickel material as anode, Pt sheet as cathode, 0.65M HNO₃The corrosion voltage is 0.4V, the corrosion time is 2.5h, and the electrochemical corrosion temperature is normal temperature.

(4) Preparing a copper-cobalt perovskite precursor solution: lanthanum nitrate, cobalt nitrate and copper nitrate are sequentially mixed in a mixed solution of citric acid and ethylene glycol, wherein the molar ratio of La to Co to Cu to citric acid to ethylene glycol is =1:0.7:0.3:2.5: 0.53.

(5) Preparation of LaCo by dipping-high temperature roasting_0.7Cu_0.3O₃Porous nickel catalyst: soaking the nickel material obtained in the step (3) in the copper-cobalt perovskite precursor solution obtained in the step (4) for 20h at normal temperature, and then soaking at 80 DEG C^oC, continuously stirring for 8 hours in a water bath, and carrying out a programmed heating process of 3 in the high-temperature roasting process^oC/min is increased to 150min, the temperature is kept for 12h, and then 2^oC/min is increased to 550^oC, preserving the heat for 6 hours, and naturally cooling along with a muffle furnace to obtain LaCo_0.7Cu_0.3O3/porous nickel catalyst, named D-2.

Comparative example 3

A foam-supported perovskite catalyst comprising the steps of preparing:

(1) commercially available nickel foam was purchased and subjected to a cleaning degreasing treatment.

(2) Oxidation and activation: the oxidation activation is oxidation under 40wt.% oxygen-air condition for 8 min.

(3) Preparing a copper-cobalt perovskite precursor solution: lanthanum nitrate, cobalt nitrate and copper nitrate are sequentially mixed in a mixed solution of citric acid and glycol, wherein the molar ratio of La to Co to Cu to citric acid to glycol is =1:0.7:0.3:2.5: 0.53.

(4) Preparation of LaCo by dipping-high temperature roasting_0.7Cu_0.3O₃Porous nickel catalyst: soaking the nickel material obtained in the step (2) in the copper-cobalt perovskite precursor solution obtained in the step (3) for 20h at normal temperature, and then soaking at 80 DEG C^oC, continuously stirring for 8 hours in a water bath, and carrying out a programmed heating process of 3 in the high-temperature roasting process^oRaising C/min to 150min, keeping the temperature for 12h, and then 2^oC/min is increased to 550^oC, heat preservation 6h, naturally cooling along with a muffle furnace to obtain LaCo_0.7Cu_0.3O3/foam catalyst, named D-3.

As shown in the attached drawing 1, an SEM-Mapping graph of the porous nickel material is obtained after the preliminary dealloying and the deep dealloying, which is a distribution graph of the elements of Ni, Co, and Cu from top to bottom, that is, the lanthanum-cobalt-copper perovskite can be uniformly distributed on the surface of the Ni metal, and the nickel is in a porous structure.

Referring to fig. 2, SEM images of the porous nickel material obtained after the preliminary dealloying-deep dealloying can visually see the three-dimensional porous channels obtained by dealloying.

As shown in fig. 3 and fig. 4, it can be visually seen that the perovskite active component is attached to the surface of the pore channel.

Carrying out a preferential oxidation test of carbon monoxide in the hydrogen-rich gas under the following test conditions: the total flow rate of the test gas was 30ml/min, and the composition of the feed gas was 1 vol.% CO and 1 vol.% O₂、50 vol.% H₂And N₂Balancing qi.

TABLE 1

As shown in Table 1, LaCo of example 2 of the present invention_0.7Cu_0.3The O3/porous nickel catalyst (S) has excellent catalytic activity, and the catalyst is 120-130-^oThe CO can be completely purified in the range of C, the concentration of the CO in the tail gas is lower than 1ppm, in comparison, the dealloying sequence is changed, for example, the D-1 catalyst has more obvious influence on the catalytic performance and poorer catalytic efficiency, in comparison, in the treatment process, the influence of the deletion of the activation step on the catalytic activity of the catalyst is not obvious, and the catalyst is prepared at the temperature of 120-^oThe catalyst can almost completely purify CO in the range of C, and the catalytic activity of the catalyst is extremely poor for D-4 catalysis, so that the catalyst is not considered.

TABLE 2

Due to S andd-2 was similarly catalytically active and its stability was investigated under test conditions at 130 deg.C^oC, reaction atmosphere: 1% CO, 1% O₂, 50 vol.% H₂And N₂Balance gas, as shown in table 2: for the S catalyst, extremely high catalytic activity can be maintained, CO can be completely purified within 60h, the stability of the catalytic activity is reduced to some extent along with the increase of time, the reduction speed is slow, namely the stability of the S catalyst is good, in contrast, the catalytic stability of D-2 is poor, and the time for completely purifying CO is 5h, which is caused by the lack of an activation step, so that the bonding force between an active component and a carrier is not strong, and the perovskite is peeled off from the surface of the catalyst carrier to lose the catalytic activity.

Although the present invention has been described above by way of examples of preferred embodiments, the present invention is not limited to the specific embodiments, and can be modified as appropriate within the scope of the present invention.

Claims

1. A porous nickel-supported perovskite catalyst which is a CO preferential oxidation catalyst in a non-powder state, and is characterized in that the pore size distribution of the porous nickel is 5-30 mu m, and the specific surface area is 30-60m²Per g, porosity 50-70%, the perovskite is LaCo_0.7Cu_0.3O₃The perovskite is uniformly loaded on the inner surfaces of the pore channels of the porous nickel, and the specific surface area of the catalyst is 20-50m²The catalyst has the compressive strength of 2-4MPa, and is prepared by the following steps:

(1) preparing a Ni-Al alloy body;

(2) preliminary dealloying by chemical lye corrosion;

(3) deep dealloying by electrochemical acid corrosion;

(4) oxidation activation;

(5) preparing a copper-cobalt perovskite precursor solution: lanthanum nitrate, cobalt nitrate and copper nitrate are sequentially mixed in a mixed solution of citric acid and glycol, wherein the molar ratio of La to Co to Cu to citric acid to glycol: 1:0.7:0.3:2.5: 0.53;

(6) impregnation-high temperature calcinationPreparation of LaCo_0.7Cu_0.3O₃Soaking the nickel material obtained in the step (4) in the cobalt-gallium perovskite precursor liquid obtained in the step (5) for 12-24h at normal temperature, continuously stirring for 8h in a water bath kettle at 80 ℃, wherein the programmed heating process of the high-temperature roasting process is that the temperature is increased to 150 ℃ at the rate of 3 ℃/min, the temperature is kept for 12h, then the temperature is increased to 550 ℃ at the rate of 2 ℃/min, the temperature is kept for 5-7h, and the catalyst is naturally cooled along with a muffle furnace.

2. A porous nickel-supported perovskite catalyst as claimed in claim 1, wherein the Ni-Al alloy body prepared in step (1) is prepared by the following process: (a) uniformly mixing 30-40wt.% of 1-5 mu m nickel powder and 60-70wt.% of 5-10 mu m aluminum powder physically, (b) press forming at 400Mpa of 300-; the inert atmosphere is N₂The reducing atmosphere is H₂。

3. The porous nickel-supported perovskite catalyst according to claim 1, wherein the etching solution used for preliminary dealloying in step (2) by chemical alkaline etching is 1-2M NaOH aqueous solution, the etching time is 12-24h, the temperature is 30-35 ℃, bubbles are removed by ultrasonic assistance in the etching process, and deionized water is washed for many times after etching.

4. The porous nickel-supported perovskite catalyst of claim 1, wherein in the step (3) of deep dealloying by electrochemical acid etching, the nickel material obtained in the step (2) is used as an anode, the Pt sheet is used as a cathode, and 0.6-0.7M HNO is used as an anode₃The corrosion voltage is 0.3-0.5V, the corrosion time is 2-3h, and the electrochemical corrosion temperature is normal temperature.

5. A porous nickel-supported perovskite catalyst as claimed in claim 1, wherein the step (4) of oxidative activation is oxidation under 40wt.% oxygen-air conditions for 5-10 min.

6. The porous nickel-supported perovskite catalyst of claim 1, wherein the LaCo is_0.7Cu_0.3O₃Porous nickel catalyst was passed through 3-5vol.% H before use₂/N₂Reducing for 3-5 h.