Copper-based catalyst for hydrogen production by methanol steam reforming and method for preparing the same

Abstract

The application relates to the technical field of catalyst preparation, and discloses a copper-based catalyst for hydrogen production by methanol steam reforming and a preparation method thereof, which is prepared by adopting a precipitation method-ball milling method with multiple precursors of copper, zinc, aluminum, titanium and lanthanum as raw materials, specifically, metal salts including copper and zinc are dissolved to obtain A liquid; an alkali solution is prepared to obtain B liquid; in a solvent system, an aluminum precursor and a lanthanum salt are heated and dried to obtain a modified alumina carrier; A liquid and B liquid are blended and reacted, and after the reaction, the modified alumina carrier is added and aged to obtain a precursor; and the precursor and a titanium source are ball milled and then calcined to obtain the catalyst. The copper-based catalyst obtained by the application has excellent methanol low-temperature conversion activity, hydrogen yield and high-temperature resistance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of catalyst preparation, in particular to a copper-based catalyst for hydrogen production by methanol steam reforming and a preparation method thereof. BACKGROUND

[0002] With the large-scale development and use of fossil fuels, global environmental degradation and resource shortage problems are increasingly prominent. Hydrogen energy is attracting global attention because of its cleanliness, low carbon, and no pollution. However, unlike fossil fuels, hydrogen cannot be directly obtained or mined from nature, so it is crucial to choose a suitable hydrogen carrier and hydrogen production process.

[0003] Methanol is the simplest alcohol, has a high H:C ratio, no carbon-carbon bond connection, and has lower hydrogen production temperature than other hydrocarbons, is liquid at room temperature, is easy to store and transport, and is biodegradable. Therefore, methanol is considered an ideal hydrogen carrier and is the first choice for hydrogen-rich fuels. Methanol steam reforming for hydrogen production has the advantages of low hydrogen production cost, mild reaction conditions, few product components, and easy separation, making it the most promising hydrogen supply route.

[0004] Copper-based catalysts have good low-temperature activity, low price, and can produce H2 and CO2 with high selectivity under suitable conditions, making them an extremely important type of catalyst in the field of methanol steam reforming for hydrogen production. However, the melting point of copper is relatively low, resulting in a very low Tammann temperature of 0.5Tm and a very low Schottky temperature of 0.3Tm, which makes copper grains more likely to aggregate and grow than other metal particles, leading to deactivation. Therefore, how to further improve the low-temperature activity or high-temperature stability of copper-based catalysts is the key to improving the comprehensive performance and market competitiveness of copper-based catalysts. SUMMARY

[0005] The technical problem solved by the present application is:

[0006] To solve the problem of performance degradation caused by easy aggregation and growth of copper grains in the prior art.

[0007] The technical solution adopted by the present application is:

[0008] In view of the above technical problems, the present application aims to provide a copper-based catalyst for hydrogen production by methanol steam reforming and a preparation method thereof.

[0009] The specific content is as follows:

[0010] First, the present application provides a preparation method of a copper-based catalyst for hydrogen production by methanol steam reforming, comprising the following steps:

[0011] The metal salt is dissolved to obtain A liquid, the metal salt includes copper and zinc; an alkali solution is prepared to obtain B liquid; in a solvent system, an aluminum precursor and a lanthanum salt are dried by heating to obtain a modified alumina carrier;

[0012] The A liquid and the B liquid are blended and reacted, after the reaction, the modified alumina carrier is added, and after aging, a precursor is obtained; the precursor and a titanium source are ball milled and then calcined to obtain a catalyst.

[0013] Secondly, the application provides a copper-based catalyst obtained by the preparation method.

[0014] The application achieves the following beneficial effects:

[0015] (1) The copper-based catalyst provided by the application introduces titanium elements into the copper-based catalyst, utilizes the electronic effect of the doping elements, promotes the shift of electrons in titanium to copper elements, enhances the reducibility and oxidation resistance of copper ions, and exhibits better methanol low-temperature conversion activity and hydrogen yield.

[0016] (2) The copper-based catalyst provided by the application uses a dispersant-assisted ball milling method to weaken the interaction force of the material itself, enhances the lubricating dispersibility of the material, significantly improves the dispersion degree and specific surface area of the active component copper element, and further improves the low-temperature catalytic activity of the catalyst.

[0017] (3) The copper-based catalyst provided by the application enhances the interaction between the active component copper and the carrier by introducing titanium, inhibits the migration and fusion of copper grains at high temperature, and makes the catalyst have better high-temperature resistance.

[0018] (4) The copper-based catalyst provided by the application slowly hydrolyzes the titanium source in the dispersant during the ball milling process, the hydrolysis product of titanium is highly dispersed in the auxiliary ball milling process, the interaction between the active component copper and the carrier is enhanced, the migration and fusion of copper grains at high temperature are inhibited, and the catalyst has better high-temperature resistance. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical scheme and advantages of the embodiments of the application more clear, the technical scheme in the embodiments of the application will be clearly and completely described below. If the specific conditions are not specified in the embodiments, the conventional conditions or the conditions recommended by the manufacturer are used. If the reagents or instruments used are not specified by the manufacturer, they are all conventional products that can be purchased on the market.

[0020] TECHNICAL SCHEME

[0021] Firstly, the application provides a preparation method of a methanol steam reforming hydrogen copper-based catalyst, which comprises the following steps:

[0022] The metal salt is dissolved to obtain A liquid, the metal salt includes copper and zinc; an alkali solution is configured to obtain B liquid; in a solvent system, an aluminum precursor and a lanthanum salt are heated and dried to obtain a modified alumina carrier;

[0023] The A liquid and the B liquid are blended and reacted, after the reaction is completed, the modified alumina carrier is added, and after aging, a precursor is obtained; the precursor and a titanium source are calcined to obtain a catalyst.

[0024] In the present application, the salt types of the metal salt include at least one of nitrate, sulfate and acetate.

[0025] In the present application, the solutes of the alkali solution include at least one of sodium hydroxide, sodium carbonate, sodium bicarbonate and ammonium carbonate.

[0026] In the present application, the aluminum precursor includes at least one of aluminum nitrate, pseudo-boehmite and alumina.

[0027] In the present application, the salt types of the lanthanum salt include at least one of nitrate, sulfate and acetate.

[0028] In the present application, the titanium source includes at least one of titanium tetrachloride, titanyl sulfate, titanium sulfate, titanium dioxide and tetrabutyl titanate. The addition form of the titanium dioxide can be titanium dioxide powder, titanium dioxide colloid or both.

[0029] In the present application, the preparation method includes at least one of features (1-1) to (1-4):

[0030] (1-1) In the A liquid, the total concentration of metal ions is 0.8-1.5 mol / L, preferably 1 mol / L.

[0031] (1-2) In the B liquid, the solute concentration is 0.8-2 mol / L, preferably 1 mol / L.

[0032] (1-3) The heating and drying condition is 180-220 DEG C; preferably 200 DEG C.

[0033] (1-4) The mass percentage of the aluminum precursor and the lanthanum salt is 90-99.9%:0.1-10%.

[0034] In the present application, the preparation method includes at least one of features (2-1) to (2-5):

[0035] (2-1) The reaction end point pH value of the A liquid and the B liquid is 4.5-12, preferably 6.5-8.5, and further preferably 7.

[0036] (2-2) The aging parameters: the time is 1-5 h, and the temperature is 30-90 DEG C; preferably 2-4 h, 60-80 DEG C.

[0037] (2-3) The precursor is subjected to filtration, washing and drying; drying parameters: temperature 80~120℃, time 1~5h;

[0038] (2-4) The precursor and titanium source are ball-milled and then calcined;

[0039] (2-5) Calcination parameters: temperature is 300-600℃, time is 3-5h; preferably 400℃, 4h.

[0040] In this invention, the method includes ball milling of the precursor and titanium source followed by calcination; the ball milling includes any one of features (3-1) to (3-2):

[0041] (3-1) The ball milling is a dry ball milling, and the titanium source is selected from at least one of titanium dioxide powder, titanium dioxide colloid, and titanium sulfate.

[0042] (3-2) The ball milling is a wet ball milling process. The titanium source is selected from at least one of titanium oxysulfate, titanium tetrachloride, and tetrabutyl titanate. The parameters for wet ball milling are: ball milling time 0.5 to 4 h; the dispersing-hydrolysis agent used for wet ball milling includes at least one of water, anhydrous ethanol, glycerol, isopropanol, and n-butanol; the amount of dispersant used is 0 to 50 mL / 100 g precursor.

[0043] Second, the present invention provides a copper-based catalyst obtained by the aforementioned preparation method.

[0044] Furthermore, the components of the copper-based catalyst, by weight percentage, include 20-60% copper oxide, 10-30% zinc oxide, 5-30% aluminum oxide, 0.1-20% titanium dioxide, and 0.1-2% lanthanum oxide.

[0045] <Example>

[0046] g is the unit of mass (gram); mL is the unit of volume (milliliters); mm is the unit of length (millimeters); ℃ is the unit of temperature (degrees Celsius); mol / L is the unit of concentration (mol / L); mL / min is the liquid feed rate (milliliters / minute); h -1 It is a unit of liquid volume hourly space velocity.

[0047] Example 1

[0048] (1) Dissolve 36.23g of copper nitrate trihydrate and 14.58g of zinc nitrate hexahydrate in 199ml of H2O to prepare a 1mol / L mixed metal salt solution A;

[0049] (2) Dissolve 21.09g of anhydrous sodium carbonate in 199ml of H2O to prepare a 1mol / L alkaline solution B;

[0050] (3) 0.58 g of lanthanum nitrate was dissolved in 18 ml of H2O to form a salt solution, and then 4.13 g of pseudo-boehmite was added and stirred to mix, and a modified alumina carrier was obtained by drying at 200°C for 2 h;

[0051] (4) Under a certain stirring speed, the mixed solution A was neutralized with the alkali solution B at a certain speed, so that the pH value of the end point solution was 7. After the addition was completed, the modified alumina carrier was added to the above-mentioned precipitate, and aging was performed for 3 h, and the temperature of the whole precipitation process was controlled to be 70°C;

[0052] (5) The precipitate was suction filtered, washed, and dried at 100°C for 5 h;

[0053] (6) The catalyst precursor obtained in step (5) was ball milled with 1.0 g of TiO2 powder for 2 h;

[0054] (7) The dried precipitate precursor was calcined in a muffle furnace at 400°C for 4 h to obtain a copper-based catalyst.

[0055] Example 2

[0056] (1) 36.23 g of copper nitrate trihydrate and 14.58 g of zinc nitrate hexahydrate were dissolved in 199 ml of H2O to prepare a 1 mol / L mixed metal salt solution A;

[0057] (2) 21.09 g of anhydrous sodium carbonate was dissolved in 199 ml of H2O to prepare a 1 mol / L alkali solution B;

[0058] (3) 0.58 g of lanthanum nitrate was dissolved in 18 ml of H2O to form a salt solution, and then 4.13 g of pseudo-boehmite was added and stirred to mix, and a modified alumina carrier was obtained by drying at 200°C for 2 h;

[0059] (4) Under a certain stirring speed, the mixed solution A was neutralized with the alkali solution B at a certain speed, so that the pH value of the end point solution was 7. After the addition was completed, the modified alumina carrier was added to the above-mentioned precipitate, and aging was performed for 3 h, and the temperature of the whole precipitation process was controlled to be 70°C;

[0060] (5) The precipitate was suction filtered, washed, and dried at 100°C for 5 h;

[0061] (6) The catalyst precursor obtained in step (5) was ball milled with 1 g of TiO2 powder and 10 ml of deionized water for 2 h, and dried at 100°C for 5 h;

[0062] (7) The dried precipitate precursor was calcined in a muffle furnace at 400°C for 4 h to obtain a copper-based catalyst.

[0063] Example 3

[0064] (1) 36.23 g of copper nitrate trihydrate, 14.58 g of zinc nitrate hexahydrate were dissolved in 199 ml of H2O to prepare a 1 mol / L mixed metal salt solution A;

[0065] (2) 21.09 g of anhydrous sodium carbonate was dissolved in 199 ml of H2O to prepare a 1 mol / L base solution B;

[0066] (3) 0.58 g of lanthanum nitrate was dissolved in 18 ml of H2O to form a salt solution, and then 4.13 g of pseudo-boehmite was added and stirred and mixed, and a modified alumina carrier was obtained by drying at 200°C for 2 hours;

[0067] (4) Under a certain stirring speed, the mixed solution A was neutralized with the base solution B at a certain speed, so that the pH value of the end point solution was 7, after the addition was completed, the modified alumina carrier was added to the above precipitate, and the aging was 3 hours, and the temperature of the whole precipitation process was controlled at 70°C;

[0068] (5) The precipitate was filtered, washed, and dried at 100°C for 5 hours;

[0069] (6) The catalyst precursor obtained in step (5) was ball milled with 1 g of TiO2 powder and 10 ml of anhydrous ethanol for 2 hours, and dried at 100°C for 5 hours;

[0070] (7) The dried precipitate precursor was calcined in a muffle furnace at 400°C for 4 hours to prepare a copper-based catalyst.

[0071] Example 4

[0072] (1) 27.33 g of copper nitrate trihydrate, 10.97 g of zinc nitrate hexahydrate were dissolved in 150 ml of H2O to prepare a 1 mol / L mixed metal salt solution A;

[0073] (2) 25.20 g of sodium bicarbonate was dissolved in 300 ml of H2O to prepare a 1 mol / L base solution B;

[0074] (3) 0.45 g of lanthanum nitrate was dissolved in 14 ml of H2O to form a salt solution, and then 3.09 g of pseudo-boehmite was added and stirred and mixed, and a modified alumina carrier was obtained by drying at 200°C for 2 hours;

[0075] (4) Under a certain stirring speed, the mixed solution A was neutralized with the base solution B at a certain speed, so that the pH value of the end point solution was 7, after the addition was completed, the modified alumina carrier was added to the above precipitate, and the aging was 3 hours, and the temperature of the whole precipitation process was controlled at 70°C;

[0076] (5) The precipitate was filtered, washed, and dried at 100°C for 5 hours;

[0077] (6) The catalyst precursor obtained in step (5) is ball-milled with 3.19 g of tetrabutyl titanate for 2 h;

[0078] (7) The dried precipitated precursor is calcined in a muffle furnace at 400°C for 4 h to obtain a copper-based catalyst.

[0079] Comparative Example

[0080] (1) 36.23 g of copper nitrate trihydrate and 14.58 g of zinc nitrate hexahydrate are dissolved in 199 ml of H2O to prepare a 1 mol / L mixed metal salt solution A;

[0081] (2) 21.09 g of anhydrous sodium carbonate is dissolved in 199 ml of H2O to prepare a 1 mol / L alkali solution B;

[0082] (3) 0.58 g of lanthanum nitrate is dissolved in 18 ml of H2O to form a salt solution, and then 4.13 g of pseudoboehmite is added and stirred to mix, and a modified alumina carrier is obtained by drying at 200°C;

[0083] (4) Under a certain stirring speed, the mixed solution A is neutralized with the alkali solution B at a certain speed, so that the pH value of the solution at the end point of the dropwise addition is 7. After the dropwise addition is completed, the modified alumina carrier is added to the above-mentioned precipitate, and the aging is performed for 3 h, and the temperature of the entire precipitation process is controlled to be maintained at 70°C;

[0084] (5) The precipitate is suction filtered, washed, and dried at 100°C for 5 h;

[0085] (6) The dried precipitated precursor is calcined in a muffle furnace at 400°C for 4 h to obtain a copper-based catalyst.

[0086] Test Example

[0087] The catalyst activity evaluation is performed on a fixed bed reactor. A certain amount of graphite (1-3 wt%) is added to the calcined catalyst powder, and the tablet granulation is performed to 16-24 mesh, which is loaded into a reaction tube with an inner diameter of 15 mm. Before the reaction, the catalyst is reduced and activated with diluted H2. The raw material methanol aqueous solution (water-methanol molar ratio is 1.2) is pumped at 0.3 mL / min, which is gasified by a gasification furnace and then enters the reaction tube for reaction. The reaction temperature is 200-240°C, and the reaction product is analyzed by gas chromatography after condensation.

[0088] Heat resistance stability test: the catalyst is heat treated at 723 K for 10 h under the reaction conditions, and then reduced to 493 K. The heat resistance stability is evaluated by comparing the activities before and after the heat treatment.

[0089] Table 1 shows the activity evaluation results of the catalysts prepared in Examples 1-4 and the comparative example at a temperature of 220°C, a water-methanol molar ratio of 1.2, and a liquid hourly space velocity of 2.4 h -1 -1 .

[0090] Table 1

[0091]

[0092] From the comparison of the test results of the examples and the comparative examples in Table 1, it can be seen that the introduction of titanium into the copper-based catalyst and the solvent-assisted ball milling method have obvious effects on improving the low-temperature activity and heat resistance of the catalyst.

[0093] The preferred embodiments of the present application have been described above with the purpose of only limiting the present application, and the present application can have various modifications and changes for those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing a copper-based catalyst for hydrogen production by methanol steam reforming, characterized by, The method comprises the following steps: The metal salt is dissolved to obtain A liquid, and the metal salt comprises copper, zinc; An alkali solution is prepared to obtain B liquid; In a solvent system, the aluminum precursor and the lanthanum salt are heated and dried to obtain a modified alumina carrier; The A liquid and the B liquid are blended and reacted, and after the reaction is completed, the modified alumina carrier is added and aged to obtain a precursor; The precursor and a titanium source are ball milled and then calcined to obtain a catalyst.

2. The method for preparing the copper-based catalyst for methanol steam reforming to hydrogen according to claim 1, characterized in that, The salt type of the metal salt comprises at least one of nitrate, sulfate and acetate; and / or the solute of the alkali solution comprises at least one of sodium hydroxide, sodium carbonate, sodium bicarbonate and ammonium carbonate.

3. The method for preparing the copper-based catalyst for methanol steam reforming to hydrogen according to claim 1, characterized in that, The aluminum precursor comprises at least one of aluminum nitrate, pseudo-boehmite and alumina.

4. The method for preparing the copper-based catalyst for methanol steam reforming to hydrogen according to claim 1, characterized in that, The salt type of the lanthanum salt comprises at least one of nitrate, sulfate and acetate.

5. The method for preparing the copper-based catalyst for methanol steam reforming to hydrogen according to claim 1, characterized in that, The titanium source comprises at least one of titanium tetrachloride, titanyl sulfate, titanium sulfate, titanium dioxide powder, titanium dioxide colloid and tetrabutyl titanate.

6. The method of claim 1 to 5, wherein the copper-based catalyst for hydrogen production by methanol steam reforming is prepared by the steps of: The method comprises at least one of features (1-1) to (1-4): (1-1) In the A liquid, the total concentration of metal ions is 0.8-1.5 mol / L; (1-2) In the B liquid, the concentration of the solute is 0.8-2 mol / L; (1-3) The heating and drying condition is 180-220 DEG C; (1-4) The mass percentage of the aluminum precursor and the lanthanum salt is 90-99.9%:0.1-10%.

7. The method for preparing the copper-based catalyst for methanol steam reforming to hydrogen according to any one of claims 1 to 5, characterized in that, The method comprises at least one of features (2-1) to (2-5): (2-1) The reaction end point pH value of the A liquid and the B liquid is 4.5-12; (2-2) The aging parameters: the time is 1-5 h, and the temperature is 30-90 DEG C; (2-3) The precursor is subjected to filtration, washing and drying treatment; wherein the drying parameters: the temperature is 80-120 DEG C, and the time is 1-5 h; (2-4) The precursor and the titanium source are ball milled and then calcined; (2-5) The calcination parameters: the temperature is 300-600 DEG C, and the time is 3-5 h.

8. The method for preparing the copper-based catalyst for methanol steam reforming to hydrogen according to claim 7, characterized in that, The method comprises ball milling the precursor and the titanium source; the ball milling comprises any one of features (3-1) to (3-2): (3-1) The ball milling is dry ball milling, and the titanium source is selected from at least one of titanium dioxide powder, titanium dioxide colloid and titanium sulfate; (3-2) The ball milling is wet ball milling, and the titanium source is selected from at least one of titanyl sulfate, titanium tetrachloride and tetrabutyl titanate; the wet ball milling parameters are that the ball milling time is 0.5-4 h; the wet ball milling uses a dispersion-hydrolysis agent comprising at least one of water, anhydrous ethanol, glycerol, isopropyl alcohol and n-butanol; and the amount of the dispersion-hydrolysis agent is 0-50 mL / 100 g of the precursor.

9. A copper-based catalyst prepared by the method according to any one of claims 1 to 8.

10. The copper-based catalyst of claim 9, wherein the copper-based catalyst is a copper-based catalyst as defined in any one of claims 1 to 8. The components comprise, by weight percentage, 20-60% of copper oxide, 10-30% of zinc oxide, 5-30% of aluminum oxide, 0.1-20% of titanium dioxide and 0.1-2% of lanthanum oxide.

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