CN111203213A - High-efficiency preferential oxidation catalyst and preparation method thereof - Google Patents
High-efficiency preferential oxidation catalyst and preparation method thereof Download PDFInfo
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Abstract
A high-efficiency preferential oxidation catalyst and a preparation method thereof. The invention provides a CO-PROX catalyst under the condition of hydrogen-rich atmosphere and a preparation method thereof, wherein a catalyst carrier is a through-hole type alumina pore array obtained by calibrating a corrosion anodic oxide film and a displacement reaction, a shielding layer is not arranged in the alumina pore array, the pore structure of the array is complete and uniform, a Ru active component is impregnated on the surface of the alumina pore array to obtain a Ru/Al2O3 catalyst, and the low-temperature catalytic activity of the catalyst is superior to that of a same-grade alumina catalyst.
Description
Technical Field
The invention relates to a through-hole type alumina catalyst carrier and a preparation method thereof, belonging to the fields of electrochemistry and catalysts, in particular to the fields of a supported catalyst and a preparation method thereof. The catalysis is particularly related to the CO-PROX reaction under hydrogen-rich conditions.
Technical Field
The anodic oxidation of aluminum or an aluminum alloy refers to a process in which aluminum or an aluminum alloy is immersed in a suitable electrolyte as an anode and subjected to an electrical treatment to form an oxide film (Al2O layer) on the surface of the aluminum or the aluminum alloy. The existence of the oxide film can improve the corrosion resistance of the aluminum alloy, and meanwhile, by means of the special structure of the oxide film and the post treatment process, for example, the anodic oxide film can be matched with surface painting and other further treatments, so that the base body can achieve a better protection effect in a harsher environment, or aluminum and aluminum alloy workpieces are decorated by dyeing, and the film layer has decoration and other protective properties. Common anodizing processes include sulfuric acid anodizing, chromic acid anodizing, and the like.
From the thermodynamic conditions of chemical reactions, aluminum can generate a stable oxide film layer over a considerable pH range (pH = 4.45-8.38). However, from the mechanism of electrochemical reaction, the formation of the anodic oxide film is actually a result of the combined action of the two processes of film growth and film dissolution.
(1) And (3) growing the film:
cathode, hydrogen evolution reaction 2H++2e→H2
Anodic oxidation reaction of H2O-2e→O+2H+
Oxygen generated in the anode reaction can form oxygen molecules to be separated out in a gaseous state, and an aluminum oxide film layer can be formed on the surface of the anode:
2Al+3O→Al2O3+Q。
the reaction is exothermic, Q =1669J/mol, the anodic oxidation process is fast, a thin, non-porous, compact, strong-adhesion and high-insulation oxide film can be generated by electrifying for a few seconds, the film grows continuously, the thickness increases continuously, the resistance increases, and the reaction speed of the generated film is reduced continuously until the reaction stops.
(2) And (4) dissolving the film. It is the dissolution of the film that allows the film to grow continuously. During the reaction, both the aluminum and the resulting alumina film layer may dissolve in the acidic electrolyte solution.
2Al+6H+→2Al3++3H2
Al2O3+6H+→2Al3++3H2O
The dissolution reaction causes a large number of small pores to be formed on the surface of the aluminum. The dissolving process of the membrane is carried out synchronously with the generating process of the membrane, because the nascent membrane layer is not uniform, the thin part of the membrane layer is easy to dissolve to generate small holes, electrolyte solution can pass through the small holes to enter the membrane, an oxidation membrane is continuously generated on an aluminum substrate and is continuously dissolved at the same time, the small holes (pinholes) of the oxidation membrane are finally formed to form a conical structure from the outside to the inside, and the dissolving of the membrane is related to factors such as the property of the electrolyte, the structure of a reaction product, current, voltage, the temperature of the solution, the electrifying time and the like.
The porous honeycomb structure of the aluminum and aluminum alloy anode oxide film has the film layer with micropores vertical to the surface, and the parameters of the size, the pore diameter, the wall thickness, the barrier layer thickness and the like of the structural units can be controlled by electrolyte components and process parameters, namely the aluminum anode oxide film has two main types, namely a barrier type anode oxide film and a porous type anode oxide film, the barrier type anode oxide film is a compact nonporous thin anode oxide film close to the metal surface, is called a barrier film for short, the thickness of the barrier film is generally very thin depending on the applied anode oxidation voltage and is not more than 0.1 mu m and is mainly used for manufacturing an electrolytic capacitor, the barrier type anode oxide film is also called a barrier layer anode oxide film, and simply, the porous anode oxide film comprises a barrier layer and a porous layer, the barrier layer and the porous layer are obviously different in terms of specific structure and composition, wherein the barrier layer is a compact nonporous amorphous oxide, usually gamma-Al 2O3, and the porous layer is composed of amorphous alumina, and the main component of which is α -AlOOH alumina exists.
As described above, in the anodic oxide film material, from bottom to top, the aluminum substrate-shielding layer-porous layer are sequentially used as a catalyst carrier because the pore diameter of the porous layer is controllable and the array is uniform, and the aluminum substrate and the shielding layer are usually removed by various technical means to obtain the porous alumina material, the main method is as follows:
(a) the chemical method comprises the following steps: directly adopting CuCl2-HCl solution or SnCl4And replacing and removing the aluminum material at the bottom of the anodic oxide film, then soaking the anodic aluminum oxide in a phosphoric acid solution, dissolving and removing the shielding layer, and obviously corroding and dissolving part of the anodic oxide porous layer.
(b) A step-by-step pressurization method: the principle is that the thickness of the anode oxidized shielding layer is in direct proportion to the voltage, the thickness of the shielding layer is reduced in the process of reducing the voltage, and the shielding layer is considered to be removed when the voltage is reduced to 0V, but the nano-pore structure of the anode oxidized shielding layer is necessarily damaged in the process of reducing the voltage because the voltage is closely related to the pore size and the uniformity of the pore structure, and although the shielding layer is removed.
(c) Back pressure ofThe method comprises the following steps: the main principle is that after the anode oxidation is finished, a reverse voltage H is provided in the electrolyte+Migration to the bottom of the hole, local high concentration of H+The ions accelerate the dissolution of the barrier layer alumina, and once the barrier layer is dissolved through, H + ions are reduced on the metal cathode to form H2The resulting gas pressure causes the porous film to peel off the aluminum substrate. Although the theory is simple, the actual operation process is extremely difficult to control.
(d) A complete oxidation method: the over-oxidation method is to extend the electrolysis time to completely anodize the aluminum sheet from one side to penetrate through to the lower layer metal to directly obtain the self-supporting through hole film, and the method has the obvious defect that the one-side oxidation is needed, otherwise, the array structure cannot be obtained.
Regarding the CO-PROX reaction under the hydrogen-rich condition, 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 the water gas shift reaction. The obtained reformed gas comprises 45-75% of H2, 15-25% of CO2, 0.5-2% of CO and small amounts of H2O and N2. Since the fuel cell electrode material is Pt and the presence of CO in the hydrogen-rich gas not only poisons the Pt electrode but also easily adsorbs to the surface of the catalyst to inhibit the catalytic oxidation of the fuel, the CO content in the hydrogen-rich gas must be controlled to 100 ppm or less. The most preferred method for controlling the CO content is the CO-PROX reaction, and the method is simple, clean and high in efficiency.
Disclosure of Invention
Based on the problems in the prior art, the invention provides a high-efficiency preferential oxidation catalyst and a preparation method thereof, wherein a catalyst carrier is a through-hole type alumina pore array obtained by calibrating a corrosion anodic oxide film and a displacement reaction, the alumina pore array is not provided with a shielding layer, the pore structure of the array is complete and uniform, a Ru active component is impregnated on the surface of the alumina pore array to obtain a Ru/Al2O3 catalyst, and the catalyst has high catalytic activity at low temperature and is very suitable for the catalytic reaction of preferential oxidation of CO, and the preparation method specifically comprises the following steps:
a preparation method of a high-performance preferential oxidation catalyst comprises the following processing steps:
(1) selecting an aluminum alloy as an aluminum base material, wherein the aluminum base material is preferably a 5-series aluminum alloy, and the thickness of the aluminum alloy is less than 0.5 cm;
(2) pretreating an aluminum substrate;
(3) carrying out anodic oxidation treatment on the treated aluminum substrate to form an oxide film on the surface;
(4) adsorbing a protective film on the surface of the porous layer of the anodic oxide film, wherein the protective film is not adsorbed on the shielding layer;
(5) removing the shielding layer at the bottom of the anodic oxide film to expose the aluminum substrate;
(6) removing the aluminum substrate to obtain an Al2O3 carrier containing only the porous layer of the anodic oxide film;
(7) and (4) taking the Al2O3 obtained in the step (6) as a carrier, taking a ruthenium chloride aqueous solution as a precursor, and performing room-temperature impregnation, freezing, vacuum condensation and drying by adopting an isometric impregnation method to obtain the Ru/Al2O3 catalyst.
Further, in the step (2), the pretreatment comprises the steps of alkalinity, hot water washing, alkaline washing, hot water washing, cold water washing, acid washing and water washing.
Further, in the step (3), the solution used for anodic oxidation is a mixed solution of oxalic acid, phosphoric acid and sulfosalicylic acid, the concentration of oxalic acid is 0.25-0.3M, the concentration of phosphoric acid is 0.2-0.4M, the concentration of sulfosalicylic acid is 0.05-0.15M, the voltage in the anodic oxidation process is 20-30V, the temperature is 30 ℃ and the current density is 2-3A/dm2 for 20-30 min.
Further, the solution adopted in the step (4) is a mixed solution of gamma-chloropropyltrimethylsilane and anhydrous toluene, the concentration of the gamma-chloropropyltrimethylsilane is 10-20 wt%, the dosage of the gamma-chloropropyltrimethylsilane is 3-5% of the weight of the anodized aluminum material, and the step (4) is assisted by vacuum pumping treatment, and the vacuum degree is 90-100 Pa.
Further, the solution adopted for removing the shielding layer in the step (5) is a mixed solution of NaOH, NaF and ethanol, wherein the ratio of NaOH: NaF: the mass ratio of the ethanol is (2-5) to (1-2) to 7.
Further, the solution used for removing the aluminum substrate in the step (6) is copper chloride-hydrochloric acid aqueous solution, the concentration of hydrochloric acid is 7-10wt.%, and the concentration of copper chloride is 0.1-0.15M.
Furthermore, the pore channel structure of the alumina carrier obtained in the step (6) is through type.
Further, the loading amount of ruthenium metal in ruthenium chloride on the surface of the Al2O3 carrier in the step (7) is 0.1-5 wt.%.
Further, in the step (7), the freezing temperature is lower than zero, the freezing time is longer than 12 hours, the temperature of vacuum condensation drying is lower than-35 ℃, and the vacuum degree is 10-15 Pa.
A high performance preferential oxidation catalyst having good low temperature catalytic activity with 100% CO conversion and 50% selectivity at a temperature range of 90-130 ℃.
The following detailed explanation is made with respect to the reagents, concentrations, and principles used in the above-described preparation method:
(1) the selection of the base material is not particularly limited, but a 5-series aluminum alloy is preferable because of the superiority of the anodic oxidation treatment, the aluminum alloy is a magnesium-aluminum alloy, the anodic oxidation is easy, and the subsequent replacement treatment is easy.
(2) Regarding the pretreatment: firstly, pretreatment is an essential treatment means, if grease on the surface of the aluminum alloy is not removed, the bonding force between an oxide film and a base material is seriously influenced, and if the alkali acid does not remove the oxide film, the subsequent anodic oxidation cannot be carried out, specifically:
(a) alkaline degreasing: the invention adopts alkaline solution for degreasing, which can saponify the vegetable oil and the animal oil on the surface of the substrate to generate soap dissolved in water, and then the soap is removed, and the reaction is as follows:
(C17H35COO)3C3H5+3NaOH→3C17H35COONa+C3H5(OH)3
the deoiling liquid is a mixed aqueous solution of 20-25 g/L sodium carbonate and 2-3g/L sodium phosphate, the temperature is 65-70 ℃, the soaking time is 5-6min, the alkali of sodium carbonate is weaker than that of sodium hydroxide, the deoiling liquid has certain saponification capacity, the pH value of the solution is buffered, the corrosivity to metal and the irritation to skin are lower than those of sodium hydroxide, the price is low, the deoiling liquid is often used as main salt in aluminum alloy degreasing liquid, the sodium phosphate is alkalescent, has certain saponification capacity and the buffering effect on the pH value, can complex metal ions in water, enables the water quality to be soft, and is an emulsifier, high in solubility and good in washability. The alkaline degreasing comprises primary washing and secondary washing, for example, the primary washing can be washed by hot water at 60-70 ℃, so that pollutants remained on the surface of the workpiece after degreasing can be effectively removed.
(b) Alkali washing: after the degreasing process, the aluminum alloy workpiece cannot be subjected to conversion film treatment, the surface of the aluminum alloy workpiece generally has defects of a natural oxide film, processing stripes and the like, and the aluminum alloy workpiece needs to be subjected to corrosion treatment to remove the natural oxide film and activate the surface. The alkaline corrosion is the most common corrosion process, the main component is NaOH solution, the alkaline solution is 20-30g/LNaOH and 3-5g/L sodium citrate aqueous solution, the temperature is 10-20 ℃, the soaking time is 15-20min, wherein a natural alumina film and sodium hydroxide react to form sodium metaaluminate, the corrosion speed of the aluminum is in direct proportion to the total content of the sodium hydroxide in the solution, and the corrosion speed is increased along with the increase of the temperature. The sodium citrate is mainly used as a complexing agent, so that aluminum ions can be effectively masked, and the generation of hydrogen production aluminum oxide precipitates is avoided.
(c) Acid washing: the surface of an aluminum alloy workpiece subjected to alkaline degreasing and alkaline corrosion is generally provided with a layer of black ash. In order to obtain a bright metal surface, it is necessary to perform a brightening treatment with an acidic solution. Even pure aluminum workpieces and alkaline liquid on the surface are difficult to completely clean by water and need to be neutralized by acid solution, and the acid washing ash removing solution is mixed aqueous solution of 50-70g/L HNO3 and 4-8g/L NaF, and is at normal temperature for 2-3 min.
(d) Washing with water: any aluminum workpiece treated by the chemical solution should be immediately washed with water after being removed from the treatment solution, and the faster the aluminum workpiece is, the better the aluminum workpiece is. Since the workpiece is exposed to air away from the treatment liquid and the surface is in a non-uniform state, it is necessary to immediately wash away the chemical agent with water to terminate the chemical reaction. And simultaneously prevents the chemical agent from being brought into the next processing liquid to pollute the next chemical processing groove.
(3) Regarding anodic oxidation: the thickness of the barrier layer depends on the voltage of the anodic oxidation, the size of the pores and pore bodies of the porous layer is related to the composition, concentration and operating conditions of the electrolyte, the invention uses oxalic acid as main acid, and is compounded with phosphoric acid and sulfosalicylic acid, wherein the oxalic acid has smaller dissolving capacity to aluminum than sulfuric acid, so that a film layer which is more stable than the sulfuric acid anodic oxidation is easily obtained, such as the anodic oxidation film of the application with the thickness of 0.5-1 μm; when phosphoric acid is generally used for anodic oxidation, the porosity of the anodic oxide film can be effectively improved, the pore diameter is larger, for example, the pore number of the anodic oxide film is 80-150/mu m2, the addition of sulfosalicylic acid organic acid can effectively reduce the use amount of oxalic acid and phosphoric acid, and the reduction of the thickness of the shielding layer of the anodic oxide film is slightly promoted.
Voltage: in the oxalic acid oxidation process, the voltage should be increased slowly, for example, the voltage is increased too fast, which causes current concentration at the uneven part where the oxide film is newly formed, so that serious electrical breakdown occurs at the part, which causes corrosion of the metal aluminum, the voltage is preferably 20-30V, the number of pores of the anodic oxide film is obviously reduced along with the increase of the voltage, and the pores of the anodic oxide film are larger along with the increase of the voltage, so that the porosity is reduced.
Current density: the current density is proportional to the alumina formation rate, and the higher the current density, the faster the alumina formation rate. However, the rate of formation of the oxide film is not completely proportional to the current density. The rate of formation of the oxide film is equal to the rate of formation of alumina minus the rate of dissolution of alumina in the electrolyte, which is a chemical process independent of the electrolytic current density and depends on the concentration of the electrolyte and the local temperature of the solution. The higher the concentration of the electrolyte, the higher the local temperature of the solution, and the faster the dissolution rate of alumina. Therefore, under the same electrolyte concentration and temperature conditions, the dissolution rate of alumina is not changed. The current density is increased, the oxide film formation rate is increased, and the oxide film porosity is decreased.
Temperature: the temperature is increased, the film layer is reduced, if the pH value of the electrolyte is increased at higher temperature, the thickness of the film can be increased, and the optimal temperature is 25-40 ℃, preferably 30 DEG CoC。
(4) Regarding the adsorption protection film and the selective removal of the barrier layer, the anodic oxide film generally comprises a barrier layer and a nano-array porous layer at the bottom of the pore channel of the anodic oxide film, wherein the main component of the barrier layer is γ -Al2O3, i.e., anhydrous, with few hydroxyl groups, and the porous layer is generally α -AlOOH alumina, rich in crystalline water and hydroxyl groups, γ -chloropropyltrimethylsilane is introduced by vacuum-pumping inside the anodic oxide film based on the above-mentioned difference between the barrier layer and the porous layer, and 75 deg.CoAnd C, reacting the gamma-chloropropyltrimethylsilane with hydroxyl to form a tripodal silicon-oxygen bond with strong binding force, wherein the reaction formula is as follows:
and the surface of the anode oxide film porous layer is effectively coated, because the bottom of the shielding layer has no or only few hydroxyl groups, the gamma-chloropropyltrimethylsilane is not pasted and adsorbed on the surface of the shielding layer, so that the gamma-chloropropyltrimethylsilane is accurately coated, in addition, a vacuumizing means is assisted in the process of positioning and marking the protective film, so that the gamma-chloropropyltrimethylsilane effectively overcomes the capillary effect of the anode oxide film nanotube, in addition, the nanopore of the anode oxide film is open at one end, the aluminum base at one end is sealed, and the gamma-chloropropyltrimethylsilane can enter the nanopore more conveniently by vacuumizing, which is an indispensable auxiliary means in the invention.
Then, the shielding layer is corroded by using a corrosive liquid, wherein the corrosive liquid is an alkaline corrosive liquid but not an acidic corrosive liquid, protons used in the acidic corrosive liquid are easy to dissociate silicon-oxygen bonds adsorbed on the surface of the porous layer, so that the gamma-chloropropyltrimethylsilane is desorbed from the surface of the porous layer and finally loses the function of the protective layer, the alkaline sodium hydroxide does not influence the gamma-chloropropyltrimethylsilane, and meanwhile, the alkaline sodium hydroxide can be effectively contacted with the shielding layer to generate NaOH + Al contact, so that NaOH + Al contact is generated, and the shielding layer is protected against corrosion2O3→NaAlO2+H2O, and further, a reaction for effectively removing alumina is realized, and in addition, the above-mentioned corrosion reaction can occur at normal temperature without heating.
In addition, the corrosive liquid of the inventionConsists of NaOH, NaF and ethanol, does not contain any water, and is mainly because Al + NaOH + H is very easy to occur under the condition of the existence of water2O—NaAlO2+3H2Cause the loss of substrate, when there is not moisture in the corrosion process (the water that produces in the corrosion shielding layer process is less, can ignore), it is difficult only to take place the reaction of Al and NaOH, in addition, this corrosion process, the supplementary nitrogen protection that has, the corruption of alkali and substrate can not or hardly take place more, simple easy location is corroded, and the damage of substrate does not take place, in addition, NaF is the penetrant, be favorable to the corrosion reaction of sodium hydroxide and compact sclausura shielding layer.
(5) For removing aluminum substrates, a simple chemical displacement reaction CuCl is used2+ al (mg) → AlCl3(MgCl2) + Cu, the aluminum material participating in the displacement reaction and the alumina not participating in the reaction during the whole process, and finally removing the substrate, it is worth noting that hydrochloric acid is added to the copper chloride mainly to prevent the copper chloride from hydrolyzing to form copper hydroxide precipitate, which affects the displacement reaction effect, so hydrochloric acid is added to reduce the hydrolysis reaction, but the addition amount of hydrochloric acid cannot be too high, otherwise the anodic oxide film will react with hydrochloric acid, which affects the performance of the catalyst carrier.
In addition, it is noted that the anode substrate of the present application does not need to be anodized on a single side, but anodized on both sides, and after the anodic oxidation is finished, copper chloride can react with the aluminum material positioned in the middle through the pore channels of the shielding layer, so as to finally obtain the through-hole alumina substrate.
(6) As for the active component, the catalytic activity of the Ru metal is used, the Ru metal known in the prior art has better CO-PROX low-temperature catalytic activity, the noble metal is expensive, the loading amount of the noble metal is controlled to be 0.1-5wt.%, and the preferable cost performance is the most excellent in 3wt.%, and the condensation drying is adopted, so that the integrity of the array structure of the porous alumina can be kept to the maximum extent due to the condensation drying, and the collapse of the pore array caused by the evaporation of water in the common drying is avoided.
The scheme of the invention has the following beneficial effects:
(1) the shielding layer at the bottom of the anodic oxide film pore channel can be effectively corroded through the selective adsorption reaction of gamma-chloropropyltrimethylsilane on the porous layer and the shielding layer and the subsequent alkaline corrosion reaction.
(2) Can be anodized on both sides without a single-sided alumina substrate.
(3) The aluminum oxide pore array obtained by removing the aluminum base through the replacement reaction has complete and uniform pore structure.
(4) The whole preparation process is simple to operate, convenient to implement and high in repetition rate.
(5) The catalyst carrier pore array has complete structure and large specific surface area, and is favorable for mass transfer of gas and loading of active components.
(6) The catalyst has 100 percent of CO conversion rate and 50 percent of selectivity in the temperature range of 80-130 ℃. .
Detailed Description
The preferential oxidation feed gas of CO consists of 1vol.% CO, 1vol.% O2, 50vol.% H2 and 48vol.% N2 as equilibrium gas, water and CO2 are respectively removed from tail gas through silica gel and caustic soda asbestos, a 5A molecular sieve chromatographic column is adopted, hydrogen is taken as carrier gas, the flow rate of the carrier gas is 30 mL.min < -1 >, and a thermal conductivity cell (TCD) is adopted to detect O2, N2 and CO; the methane converter is used for amplifying a CO signal, detecting hydrogen Flame (FID), analyzing the amplified CO signal and CH4, and the detection accuracy of the CO can reach 1 ppm.
Example 1
A preparation method of a high-efficiency preferential oxidation catalyst comprises the following processing steps:
(1) 5 series aluminum alloy with the thickness less than 0.5cm is selected as a base material.
(2) The method comprises the following steps of pretreating an aluminum substrate, wherein the pretreatment process comprises the steps of alkalinity, hot water washing, alkaline washing, hot water washing, cold water washing, acid washing and water washing.
(3) And carrying out anodic oxidation treatment on the treated aluminum substrate to form an oxide film on the surface, wherein the solution used for anodic oxidation is a mixed solution of oxalic acid, phosphoric acid and sulfosalicylic acid, the concentration of the oxalic acid is 0.25M, the concentration of the phosphoric acid is 0.2M, the concentration of the sulfosalicylic acid is 0.05M, the voltage in the anodic oxidation process is 20V, the temperature is 30 ℃ and the current density is 2A/dm2 for 20 min.
(4) And (3) adsorbing a protective film on the surface of the porous layer of the anodic oxide film, wherein the protective film is not adsorbed on the shielding layer, the solution adopted in the step (4) is a mixed solution of gamma-chloropropyltrimethylsilane and anhydrous toluene, the concentration of the gamma-chloropropyltrimethylsilane is 10wt.%, the dosage of the gamma-chloropropyltrimethylsilane is 3% of the weight of the anodized aluminum material, and the vacuum degree is 90-100Pa in the process of the step (4) in an auxiliary manner.
(5) Removing the shielding layer at the bottom of the anodic oxide film to expose the aluminum substrate; the solution adopted for removing the shielding layer in the step (5) is a mixed solution of NaOH, NaF and ethanol, wherein the ratio of NaOH: NaF: the mass ratio of the ethanol is (2) to (1) to 7, and the whole process is under the protection of nitrogen.
(6) And (3) after the sample is subjected to vacuum freeze drying treatment, soaking the sample in a copper chloride-hydrochloric acid aqueous solution, wherein the concentration of hydrochloric acid is 7wt.%, the concentration of copper chloride is 0.1M, the soaking time is more than 24h, and the soaking temperature is 25 ℃.
(7) And washing with deionized water for multiple times.
(8) Preparing ruthenium chloride aqueous solution, and impregnating the active component by an isometric impregnation method.
(7) The mixture was frozen overnight in a refrigerator and placed in a vacuum freeze-drying oven to obtain a through-hole alumina catalyst support of 1wt.% Ru/Al2O 3.
Example 2
A preparation method of a high-efficiency preferential oxidation catalyst comprises the following processing steps:
(1) selecting 5 series aluminum alloy less than 0.5cm as a base material;
(2) the method comprises the following steps of pretreating an aluminum substrate, wherein the pretreatment process comprises the steps of alkalinity, hot water washing, alkaline washing, hot water washing, cold water washing, acid washing and water washing.
(3) And carrying out anodic oxidation treatment on the treated aluminum substrate to form an oxide film on the surface, wherein the solution used for anodic oxidation is a mixed solution of oxalic acid, phosphoric acid and sulfosalicylic acid, the concentration of the oxalic acid is 0.275M, the concentration of the phosphoric acid is 0.3M, the concentration of the sulfosalicylic acid is 0.1M, the voltage in the anodic oxidation process is 25V, the temperature is 30 ℃ and the current density is 2.5A/dm2 for 25 min.
(4) And (3) adsorbing a protective film on the surface of the porous layer of the anodic oxide film, wherein the protective film is not adsorbed on the shielding layer, the solution adopted in the step (4) is a mixed solution of gamma-chloropropyltrimethylsilane and anhydrous toluene, the concentration of the gamma-chloropropyltrimethylsilane is 15 wt%, the dosage of the gamma-chloropropyltrimethylsilane is 4% of the weight of the anodized aluminum material, and the vacuum degree is 90-100Pa in the process of the step (4) in an auxiliary manner.
(5) Removing the shielding layer at the bottom of the anodic oxide film to expose the aluminum substrate; the solution adopted for removing the shielding layer in the step (5) is a mixed solution of NaOH, NaF and ethanol, wherein the ratio of NaOH: NaF: the mass ratio of the ethanol is (3.5): 1.5):7, and the whole process is under the protection of nitrogen.
(6) After the sample is subjected to vacuum freeze drying treatment, the sample is placed in a copper chloride-hydrochloric acid aqueous solution for soaking, wherein the concentration of hydrochloric acid is 8.5wt.%, the concentration of copper chloride is 0.15M, the soaking time is more than 24h, and the soaking temperature is 28 oC.
(7) And washing with deionized water for multiple times.
(8) Preparing ruthenium chloride aqueous solution, and impregnating the active component by an isometric impregnation method.
(7) The mixture was frozen overnight in a refrigerator and placed in a vacuum freeze-drying oven to obtain a through-hole alumina catalyst support of 3wt.% Ru/Al2O 3.
Example 3
A preparation method of a high-efficiency preferential oxidation catalyst comprises the following processing steps:
(1) selecting 5 series aluminum alloy less than 0.5cm as a base material;
(2) the method comprises the following steps of pretreating an aluminum substrate, wherein the pretreatment process comprises the steps of alkalinity, hot water washing, alkaline washing, hot water washing, cold water washing, acid washing and water washing.
(3) And carrying out anodic oxidation treatment on the treated aluminum substrate to form an oxide film on the surface, wherein the solution used for anodic oxidation is a mixed solution of oxalic acid, phosphoric acid and sulfosalicylic acid, the concentration of the oxalic acid is 0.3M, the concentration of the phosphoric acid is 0.4M, the concentration of the sulfosalicylic acid is 0.15M, the voltage in the anodic oxidation process is 30V, the temperature is 30 ℃ and the current density is 3A/dm2 for 30 min.
(4) And (3) adsorbing a protective film on the surface of the porous layer of the anodic oxide film, wherein the protective film is not adsorbed on the shielding layer, the solution adopted in the step (4) is a mixed solution of gamma-chloropropyltrimethylsilane and anhydrous toluene, the concentration of the gamma-chloropropyltrimethylsilane is 20 wt%, the dosage of the gamma-chloropropyltrimethylsilane is 5% of the weight of the anodized aluminum material, and the vacuum degree is 90-100Pa in the process of the step (4) in an auxiliary manner.
(5) Removing the shielding layer at the bottom of the anodic oxide film to expose the aluminum substrate; the solution adopted for removing the shielding layer in the step (5) is a mixed solution of NaOH, NaF and ethanol, wherein the ratio of NaOH: NaF: the mass ratio of the ethanol is 5: 2:7, and the whole process is under the protection of nitrogen.
(6) And (3) after the sample is subjected to vacuum freeze drying treatment, soaking the sample in a copper chloride-hydrochloric acid aqueous solution, wherein the concentration of hydrochloric acid is 10wt.%, the concentration of copper chloride is 0.15M, the soaking time is more than 24h, and the soaking temperature is 30 ℃.
(7) And washing with deionized water for multiple times.
(8) Preparing ruthenium chloride aqueous solution, and impregnating the active component by an isometric impregnation method.
(7) The mixture was frozen overnight in a refrigerator and placed in a vacuum freeze-drying oven to obtain a through-hole alumina catalyst support of 5wt.% Ru/Al2O 3.
As shown in the table, in the actual use process, the 3wt.% Ru/Al2O3 has the most excellent catalytic activity, and conforms to the actual working temperature range of the proton exchange membrane fuel cell, and the hydrogen selectivity is high, and the methanation degree is low.
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 (10)
1. A preparation method of a high-efficiency preferential oxidation catalyst is characterized by comprising the following processing steps:
(1) selecting an aluminum alloy as an aluminum base material, wherein the aluminum base material is preferably a 5-series aluminum alloy, and the thickness of the aluminum alloy is less than 0.5 cm;
(2) pretreating an aluminum substrate;
(3) carrying out anodic oxidation treatment on the treated aluminum substrate to form an oxide film on the surface;
(4) adsorbing a protective film on the surface of the porous layer of the anodic oxide film, wherein the protective film is not adsorbed on the shielding layer;
(5) removing the shielding layer at the bottom of the anodic oxide film to expose the aluminum substrate;
(6) removing the aluminum substrate to obtain an Al2O3 carrier containing only the porous layer of the anodic oxide film;
(7) and (4) taking the Al2O3 obtained in the step (6) as a carrier, taking a ruthenium chloride aqueous solution as a precursor, and performing room-temperature impregnation, freezing, vacuum condensation and drying by adopting an isometric impregnation method to obtain the Ru/Al2O3 catalyst.
2. The method for preparing a high-performance preferential oxidation catalyst according to claim 1, wherein in the step (2), the pretreatment comprises the steps of alkalinity-hot water washing-alkaline washing-hot water washing-cold water washing-acid washing-water washing.
3. The method according to claim 1, wherein in the step (3), the solution used in the anodic oxidation is a mixture of oxalic acid, phosphoric acid and sulfosalicylic acid, the concentration of oxalic acid is 0.25-0.3M, the concentration of phosphoric acid is 0.2-0.4M, the concentration of sulfosalicylic acid is 0.05-0.15M, the voltage of the anodic oxidation process is 20-30V, the temperature is 30 ℃ and the current density is 2-3A/dm2 for 20-30 min.
4. The method for preparing a high-performance preferential oxidation catalyst according to claim 1, wherein the solution adopted in the step (4) is a mixed solution of gamma-chloropropyltrimethylsilane and anhydrous toluene, the concentration of the gamma-chloropropyltrimethylsilane is 10-20 wt%, and the dosage of the gamma-chloropropyltrimethylsilane is 3-5% of the weight of the anodized aluminum material, and the step (4) is assisted by vacuumizing, and the vacuum degree is 90-100 Pa.
5. The method according to claim 1, wherein the solution used for removing the shielding layer in step (5) is a mixture of NaOH, NaF, and ethanol, wherein the ratio of NaOH: NaF: the mass ratio of the ethanol is (2-5) to (1-2) to 7.
6. The method of claim 1, wherein the aluminum substrate is removed in step (6) using an aqueous solution of cupric chloride-hydrochloric acid having a hydrochloric acid concentration of 7-10wt.% and a cupric chloride concentration of 0.1-0.15M.
7. The method according to claim 1, wherein the pore structure of the alumina carrier obtained in step (6) is through-type.
8. The method for preparing a high performance preferential oxidation catalyst according to claim 1, wherein the loading amount of ruthenium metal in ruthenium chloride on the surface of Al2O3 carrier in step (7) is 0.1-5 wt.%.
9. The method for preparing a high efficiency preferential oxidation catalyst as claimed in claim 1, wherein the freezing temperature in step (7) is lower than zero, the freezing time is more than 12h, the temperature for vacuum condensation drying is less than-35 ℃, and the vacuum degree is 10-15 Pa.
10. A high-performance preferential oxidation catalyst obtained by the process for preparing a high-performance preferential oxidation catalyst according to any one of claims 1 to 9, said catalyst having good low-temperature catalytic activity with a CO conversion of 100% and a selectivity of 50% at a temperature ranging from 90 to 130 ℃.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112169845A (en) * | 2020-11-08 | 2021-01-05 | 赵伟 | Preparation method of composite carbon catalytic material |
| CN115032245A (en) * | 2022-05-23 | 2022-09-09 | 飞思仪表（深圳）有限公司 | Manufacturing method of aluminum oxide interdigital humidity sensor and interdigital humidity sensor |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20140202868A1 (en) * | 2013-01-23 | 2014-07-24 | Asian Institute Of Technology | System and method of anodized aluminum oxide nano-porous membrane preparation |
| CN104233430A (en) * | 2014-07-29 | 2014-12-24 | 中国科学院西安光学精密机械研究所 | Preparation method of nanopore array anodic aluminum oxide film and alumina microchannel plate |
| CN104233428A (en) * | 2014-09-26 | 2014-12-24 | 湖南大学 | Method for improving alkaline resistance of anode oxide film on surface of aluminum or aluminum alloy material |
| CN107502936A (en) * | 2017-08-04 | 2017-12-22 | 西北工业大学 | A kind of method for obtaining large aperture doubled via AAO films |
-
2020
- 2020-03-21 CN CN202010204528.6A patent/CN111203213B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20140202868A1 (en) * | 2013-01-23 | 2014-07-24 | Asian Institute Of Technology | System and method of anodized aluminum oxide nano-porous membrane preparation |
| CN104233430A (en) * | 2014-07-29 | 2014-12-24 | 中国科学院西安光学精密机械研究所 | Preparation method of nanopore array anodic aluminum oxide film and alumina microchannel plate |
| CN104233428A (en) * | 2014-09-26 | 2014-12-24 | 湖南大学 | Method for improving alkaline resistance of anode oxide film on surface of aluminum or aluminum alloy material |
| CN107502936A (en) * | 2017-08-04 | 2017-12-22 | 西北工业大学 | A kind of method for obtaining large aperture doubled via AAO films |
Non-Patent Citations (2)
| Title |
|---|
| E. ADROVER等: "Study of Cu-Zn and Au/TiO2 Catalysts on Anodized Aluminum Monoliths for Hydrogen Generation and Purification", 《INTERNATIONAL JOURNAL OF CHEMICAL REACTOR ENGINEERING》 * |
| 王东辉等: "《纳米金催化剂及其应用》", 31 October 2006, 国防工业出版社 * |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112169845A (en) * | 2020-11-08 | 2021-01-05 | 赵伟 | Preparation method of composite carbon catalytic material |
| CN112169845B (en) * | 2020-11-08 | 2023-12-26 | 赵伟 | Preparation method of catalytic material |
| CN115032245A (en) * | 2022-05-23 | 2022-09-09 | 飞思仪表（深圳）有限公司 | Manufacturing method of aluminum oxide interdigital humidity sensor and interdigital humidity sensor |
| CN115032245B (en) * | 2022-05-23 | 2024-04-30 | 飞思仪表（深圳）有限公司 | Manufacturing method of aluminum oxide interdigital humidity sensor and interdigital humidity sensor |
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