Fe-B-based catalyst and preparation and application thereof
By preparing Fe-B based catalysts, the problems of high energy consumption and high cost in the process of converting hydrogen chloride to chlorine have been solved, realizing an efficient, economical and environmentally friendly hydrogen chloride-hydrogenation reaction to produce chlorine. The catalyst remains stable under harsh conditions.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-19
- Publication Date
- 2026-04-07
AI Technical Summary
In existing technologies, the methods for converting hydrogen chloride into chlorine have problems such as high energy consumption, high cost, and significant environmental impact. In particular, traditional catalysts such as RuO2/TiO2 have high costs due to precious metals and sintering issues. Furthermore, there are no reports on the application of metastable Fe-B-based catalysts in the production of chlorine from hydrogen chloride.
A Fe-B-based catalyst was prepared by reacting a boron-alkali mixed solution with an iron salt solution under a protective atmosphere. The precipitate was then washed, dried, and calcined at a specific temperature to obtain a highly active and stable catalyst for the reaction of chlorination to chlorine.
It improves the efficiency of converting hydrogen chloride to chlorine, reduces production costs, and minimizes environmental impact. The catalyst remains stable under harsh conditions and is suitable for large-scale industrial applications.
Abstract
Description
Technical Field
[0001] This invention belongs to the field of catalytic oxidation of hydrogen chloride to produce chlorine, specifically relating to an Fe-B based catalyst, its preparation method, and its application in the catalytic oxidation of hydrogen chloride to produce chlorine. Technical Background
[0002] Chlorine (Cl2), an indispensable raw material in the chemical industry, is widely used in the production of many products such as polyvinyl chloride (PVC), isocyanates, and resins, resulting in huge market demand. However, in chlorine-containing industries, the low utilization rate of chlorine atoms leads to the generation of large amounts of hydrogen chloride (HCl) as a byproduct, causing not only resource waste but also serious environmental problems. Therefore, developing efficient methods to convert HCl into high-value-added products such as chlorine is of great significance for achieving green and sustainable development in chlorine-containing industries. Traditionally, the methods for converting HCl into Cl2 mainly include electrolysis and catalytic oxidation. Although electrolysis can achieve high conversion rates, it consumes a great deal of energy, requiring approximately 1600–1700 kWh of electricity per ton of Cl2, increasing CO2 emissions. In contrast, catalytic oxidation based on the Deacon process has attracted widespread attention due to its lower energy requirements and better economic benefits.
[0003] Since its initial proposal in 1868, the Deacon process has undergone continuous improvement and development. Early catalysts used CuCl2 / pumice, but the easy loss of copper limited its practical application. Subsequent research attempted to improve catalyst performance using other metals or by adding promoters, such as Cr-based and Ce-based catalysts. In particular, the RuO2 / TiO2 catalyst, due to its excellent activity and long service life of up to two years, has become the only commercially available catalyst for the oxidation of HCl to Cl2. However, ruthenium, as a precious metal, is expensive and presents sintering problems.
[0004] In recent years, metal borides have been extensively studied due to their unique physicochemical properties and are considered one of the key functional components for designing high-performance heterogeneous catalysts. Metastable Fe-B-based catalysts, with their special crystal structure and composition, exhibit unique catalytic properties different from conventional catalysts. These novel catalysts can not only improve reaction efficiency but also significantly reduce production costs and environmental impact. However, there are currently no research reports on the application of metastable Fe-B-based catalysts in the production of chlorine from hydrogen chlorination.
[0005] In view of the above, the present invention aims to provide a novel Fe-B based catalyst and its preparation method, and to explore its potential advantages in the production of chlorine by hydroxyl chloride, in order to provide a new solution to the existing technical problems. Summary of the Invention
[0006] The present invention aims to provide an Fe-B based catalyst, its preparation method, and its application in the reaction of chlorination and hydrogenation to produce chlorine. The catalyst has high activity, high selectivity, and excellent stability, thereby significantly improving the efficiency of HCl to Cl2 conversion and reducing cost and environmental impact.
[0007] To achieve the above-mentioned objectives, the technical solution of the present invention is as follows:
[0008] In a first aspect, the present invention provides an Fe-B based catalyst, which is prepared by a method comprising the following steps: under a protective atmosphere, a boron-alkali mixed solution is added to an iron salt solution with a concentration of 0.1-0.3 mol / L in an ice-water bath and stirred thoroughly; the precipitate generated is separated, washed, and dried under a protective atmosphere; and finally, the catalyst is calcined at 500-600℃ for 3-6 h under a protective atmosphere to obtain the Fe-B based catalyst; wherein the boron-alkali mixed solution is prepared from a boron source reducing agent, a strong base, and water, wherein the concentration of the boron source reducing agent is 1.6-2 mol / L, and the molar ratio of the ions contained is B3-:OH- = 10:1; the ratio of the amount of the boron-alkali mixed solution to the iron salt solution is 3-4 based on the molar ratio of boron and iron contained therein.
[0009] Preferably, the iron salt is selected from one of ferric nitrate, ferric chloride, ferric sulfate, and ferrous sulfate.
[0010] Preferably, the boron source reducing agent is selected from sodium borohydride or potassium borohydride.
[0011] Preferably, the strong alkali is selected from sodium hydroxide and potassium hydroxide.
[0012] Preferably, the concentration of the iron salt solution is 0.1-0.2 mol / L, and most preferably 0.2 mol / L.
[0013] Preferably, the concentration of the boron source reducing agent in the boron-alkali mixed solution is 2 mol / L.
[0014] Preferably, the boron-iron molar ratio is 4.
[0015] Preferably, the protective atmosphere is nitrogen or argon.
[0016] Preferably, the calcination temperature is 600℃.
[0017] Preferably, the calcination time is 4-5 hours.
[0018] Secondly, the present invention provides a method for preparing the Fe-B based catalyst described in the first aspect, comprising the following steps: under a protective atmosphere, adding a boron-alkali mixed solution to an iron salt solution with a concentration of 0.1-0.3 mol / L in an ice-water bath and stirring thoroughly; separating, washing, and drying the generated precipitate under a protective atmosphere; and finally calcining at 500-600℃ for 3-6 h under a protective atmosphere to obtain the Fe-B based catalyst; wherein the boron-alkali mixed solution is prepared from a boron source reducing agent, a strong base, and water, wherein the concentration of the boron source reducing agent is 1.6-2 mol / L, and the molar ratio of the ions contained is B3-:OH- = 10:1; the ratio of the amount of the boron-alkali mixed solution to the iron salt solution is 3-4 based on the molar ratio of boron and iron contained therein.
[0019] Preferably, the iron salt is selected from one of ferric nitrate, ferric chloride, ferric sulfate, and ferrous sulfate.
[0020] Preferably, the boron source reducing agent is selected from sodium borohydride or potassium borohydride.
[0021] Preferably, the strong alkali is selected from sodium hydroxide and potassium hydroxide.
[0022] Preferably, the concentration of the iron salt solution is 0.1-0.2 mol / L, and most preferably 0.2 mol / L.
[0023] Preferably, the concentration of the boron source reducing agent in the boron-alkali mixed solution is 2 mol / L.
[0024] Preferably, the boron-iron molar ratio is 4.
[0025] Preferably, the protective atmosphere is nitrogen or argon.
[0026] Preferably, the stirring reaction time is 25-40 min, more preferably 30-35 min.
[0027] Preferably, the precipitate is washed 3-5 times with deionized water and ethanol, respectively.
[0028] Preferably, the drying temperature is 40-90℃, more preferably 50-80℃, even more preferably 60-70℃, and most preferably 60℃.
[0029] Preferably, the calcination temperature is 600℃.
[0030] Preferably, the calcination time is 4-5 hours.
[0031] Thirdly, the present invention provides the application of the Fe-B based catalyst described in the first aspect in the production of chlorine gas by chlorination and hydrogenation.
[0032] Preferably, the reaction conditions for producing chlorine by hydroxyl chloride are: reaction temperature 400–450℃, reaction pressure 0.1 MPa, molar ratio of raw gas n(HCl) / n(O2) = 3–1 / 2, and hydrogen chloride gas space velocity 1–150 h⁻¹. -1 .
[0033] In one implementation, the application is carried out as follows:
[0034] The Fe-B based catalyst was placed in a fixed-bed reactor, the gas flow rate was adjusted and the temperature was increased, and then hydrogen chloride and oxygen were introduced into the fixed-bed reactor through flow meters to control their flow rates and react to generate chlorine gas.
[0035] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0036] 1. Iron and boron have relatively low costs. Compared with precious metal catalysts (such as ruthenium-based catalysts), Fe-B-based catalysts have significant economic advantages and are suitable for large-scale industrial applications.
[0037] 2. Due to its high hardness, good corrosion resistance and mechanical strength, Fe-B alloy can remain stable under harsh working conditions, thus extending the service life of the catalyst.
[0038] 3. By controlling the preparation method, the present invention makes the Fe-B based catalyst particularly suitable for the oxidation of HCl to Cl2, exhibiting high catalytic activity and stability.
[0039] In summary, the Fe-B based catalyst and its preparation method described in this invention provide a novel technical route for achieving efficient, economical, and environmentally friendly HCl oxidation to Cl2. Detailed Implementation
[0040] The present invention will be illustrated below with specific examples. It should be noted that the embodiments are only for further illustration of the present invention and should not be construed as limiting the scope of protection of the present invention, which is not limited thereto in any way. Those skilled in the art can make some non-essential improvements and adjustments based on the above-described invention.
[0041] Unless otherwise specified in the embodiments of this invention, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained through conventional technical means or commercially available.
[0042] Example 1
[0043] 1) Weigh 1.01 g of ferric nitrate nonahydrate, dissolve it in 12.5 ml of deionized water and mix well to obtain a 0.2 mol / L ferric nitrate solution.
[0044] 2) Under the conditions of ice-water bath and nitrogen atmosphere, weigh 0.04g of sodium hydroxide and dissolve it in 5ml of water. After mixing evenly, weigh 0.38g of sodium borohydride and dissolve it in the solution to obtain a sodium borohydride mixed solution with a concentration of 2mol / L.
[0045] 3) Add the mixed solution obtained in step 2) to the solution in step 1) in the ice water bath at a rate of 1 ml / min using a peristaltic pump, and stir vigorously for 30 minutes under a nitrogen atmosphere to obtain a black precipitate.
[0046] 4) Under a nitrogen atmosphere, wash the precipitate obtained in step 3) three times each with deionized water and ethanol, and then dry it in a vacuum oven at 60°C for 6 hours.
[0047] 5) Calcine the dried product obtained in step 4) at 600°C for 5 hours under an argon atmosphere.
[0048] 6) Load 0.5g of the calcined catalyst from step 5) into a micro fixed-bed reactor, and then introduce a mixture of hydrogen chloride and oxygen in a molar ratio of n(HCl):n(O2) = 1:1.4. The reaction temperature is 450℃, the reaction pressure is 0.1MPa, and the mass hourly space velocity of hydrogen chloride is 50h⁻¹. -1 The reaction products were absorbed with excess 0.2 mol / L potassium iodide solution. The chlorine gas generated was determined by iodometry, and the unreacted hydrogen chloride was obtained by acid-base titration. The conversion rate of hydrogen chloride was calculated from these results. After 30 hours of reaction, the conversion rate of hydrogen chloride was 93%, and after 500 hours, the conversion rate was 92%, showing no significant decrease.
[0049] Comparative Example 1 (Reducing the concentration of sodium borohydride mixed solution)
[0050] 1) Weigh 1.01 g of ferric nitrate nonahydrate, dissolve it in 12.5 ml of deionized water and mix well to obtain a 0.2 mol / L ferric nitrate solution.
[0051] 2) Under the conditions of ice-water bath and nitrogen atmosphere, weigh 0.04g of sodium hydroxide and dissolve it in 10ml of water. After mixing evenly, weigh 0.38g of sodium borohydride and dissolve it in the solution to obtain a sodium borohydride mixed solution with a concentration of 1mol / L.
[0052] 3) The mixed solution obtained in step 2) is added to the solution in step 1) in the ice water bath at a rate of 1 ml / min using a peristaltic pump, and stirred vigorously for 30 min under a nitrogen atmosphere to obtain a black precipitate.
[0053] 4) Under a nitrogen atmosphere, wash the precipitate obtained in step 3) three times each with deionized water and ethanol, and then dry it in a vacuum oven at 60°C for 6 hours.
[0054] 5) Calcine the dried product obtained in step 4) at 600°C for 5 hours under an argon atmosphere.
[0055] 6) Load 0.5g of the calcined catalyst from step 5) into a micro fixed-bed reactor, and then introduce a mixture of hydrogen chloride and oxygen in a molar ratio of n(HCl):n(O2) = 1:1.4. The reaction temperature is 450℃, the reaction pressure is 0.1MPa, and the mass hourly space velocity of hydrogen chloride is 50h⁻¹. -1 The reaction products were absorbed with excess 0.2 mol / L potassium iodide solution. The chlorine gas produced was determined by iodometry, and the unreacted hydrogen chloride was obtained by acid-base titration. The conversion rate of hydrogen chloride was calculated from these results. After 30 hours of reaction, the conversion rate of hydrogen chloride was 70%, and after 500 hours, it was 65%.
[0056] Comparative Example 2 (reducing the proportion of ferroboron)
[0057] 1) Weigh 2.02g of ferric nitrate nonahydrate, dissolve it in 12.5ml of deionized water and mix well to obtain a 0.4mol / L ferric nitrate solution.
[0058] 2) Under the conditions of ice-water bath and nitrogen atmosphere, weigh 0.04g of sodium hydroxide and dissolve it in 5ml of water. After mixing evenly, weigh 0.38g of sodium borohydride and dissolve it in the solution to obtain a sodium borohydride mixed solution with a concentration of 2mol / L.
[0059] 3) The mixed solution obtained in step 2) is added to the solution in step 1) in the ice water bath at a rate of 1 ml / min using a peristaltic pump, and stirred vigorously for 30 min under a nitrogen atmosphere to obtain a black precipitate.
[0060] 4) Under a nitrogen atmosphere, wash the precipitate obtained in step 3) three times each with deionized water and ethanol, and then dry it in a vacuum oven at 60°C for 6 hours.
[0061] 5) Calcine the dried product obtained in step 4) at 600°C for 5 hours under an argon atmosphere.
[0062] 6) Load 0.5g of the calcined catalyst from step 5) into a micro fixed-bed reactor, and then introduce a mixture of hydrogen chloride and oxygen in a molar ratio of n(HCl):n(O2) = 1:1.4. The reaction temperature is 450℃, the reaction pressure is 0.1MPa, and the mass hourly space velocity of hydrogen chloride is 50h⁻¹. -1 The reaction products were absorbed with excess 0.2 mol / L potassium iodide solution. The chlorine gas produced was determined by iodometric titration, while unreacted hydrogen chloride was obtained by acid-base titration. The conversion rate of hydrogen chloride was calculated from these results. After 30 hours of reaction, the conversion rate of hydrogen chloride was 75%, and after 500 hours, it was 71%.
[0063] Through Example 1 and Comparative Examples 1 and 2, it can be seen that a low sodium borohydride solution concentration and a boron-iron molar ratio may lead to incomplete reduction and failure to generate effective active substances.
[0064] Example 2
[0065] 1) Weigh 0.41g of ferric chloride, dissolve it in 12.5ml of deionized water and mix well to obtain a 0.2mol / L ferric chloride solution.
[0066] 2) Under the conditions of ice-water bath and nitrogen atmosphere, weigh 0.04g of sodium hydroxide and dissolve it in 5ml of water. After mixing evenly, weigh 0.38g of sodium borohydride and dissolve it in the solution to obtain a sodium borohydride mixed solution with a concentration of 2mol / L.
[0067] 3) Add the mixed solution obtained in step 2) to the solution in step 1) in the ice water bath at a rate of 1 ml / min using a peristaltic pump, and stir vigorously for 30 minutes under a nitrogen atmosphere to obtain a black precipitate.
[0068] 4) Under a nitrogen atmosphere, wash the precipitate obtained in step 3) three times each with deionized water and ethanol, and then dry it in a vacuum oven at 60°C for 6 hours.
[0069] 5) Calcine the dried product obtained in step 4) at 600°C for 5 hours under an argon atmosphere.
[0070] 6) Load 0.5g of the calcined catalyst from step 5) into a micro fixed-bed reactor, and then introduce a mixture of hydrogen chloride and oxygen in a molar ratio of n(HCl):n(O2) = 1:1.4. The reaction temperature is 450℃, the reaction pressure is 0.1MPa, and the mass hourly space velocity of hydrogen chloride is 50h⁻¹. -1 The reaction products were absorbed with excess 0.2 mol / L potassium iodide solution. The chlorine gas generated was determined by iodometry, and the unreacted hydrogen chloride was obtained by acid-base titration. The conversion rate of hydrogen chloride was calculated from these results. After 30 hours of reaction, the conversion rate of hydrogen chloride was 93%, and after 500 hours, the conversion rate was 91%, showing no significant decrease.
[0071] Comparative Example 3 (changing the order of addition)
[0072] 1) Weigh 0.41g of ferric chloride, dissolve it in 12.5ml of deionized water and mix well to obtain a 0.2mol / L ferric chloride solution.
[0073] 2) Under the conditions of ice-water bath and nitrogen atmosphere, weigh 0.04g of sodium hydroxide and dissolve it in 5ml of water. After mixing evenly, weigh 0.38g of sodium borohydride and dissolve it in the solution to obtain a sodium borohydride mixed solution with a concentration of 2mol / L.
[0074] 3) Add the solution obtained in step 1) to the solution mixture in step 2) in the ice water bath at a rate of 1 ml / min using a peristaltic pump, and stir vigorously for 30 minutes under a nitrogen atmosphere to obtain a black precipitate.
[0075] 4) Under a nitrogen atmosphere, wash the precipitate obtained in step 3) three times each with deionized water and ethanol, and then dry it in a vacuum oven at 60°C for 6 hours.
[0076] 5) Calcine the dried product obtained in step 4) at 600°C for 5 hours under an argon atmosphere.
[0077] 6) Load 0.5g of the calcined catalyst from step 5) into a micro fixed-bed reactor, and then introduce a mixture of hydrogen chloride and oxygen in a molar ratio of n(HCl):n(O2) = 1:1.4. The reaction temperature is 450℃, the reaction pressure is 0.1MPa, and the mass hourly space velocity of hydrogen chloride is 50h⁻¹. -1 The reaction products were absorbed with excess 0.2 mol / L potassium iodide solution. The chlorine gas generated was determined by iodometry, and the unreacted hydrogen chloride was obtained by acid-base titration. The conversion rate of hydrogen chloride was calculated from these results. After 30 hours of reaction, the conversion rate of hydrogen chloride was 82%, and after 500 hours, the conversion rate was 80%, showing no significant decrease.
[0078] Comparative Example 4 (changing the order of addition)
[0079] 1) Weigh 0.41g of ferric chloride, dissolve it in 12.5ml of deionized water and mix well to obtain a 0.2mol / L ferric chloride solution.
[0080] 2) Under the conditions of ice-water bath and nitrogen atmosphere, weigh 0.04g of sodium hydroxide and dissolve it in 5ml of water. After mixing evenly, weigh 0.38g of sodium borohydride and dissolve it in the solution to obtain a sodium borohydride mixed solution with a concentration of 2mol / L.
[0081] 3) The solution obtained in step 1) and the mixture obtained in step 2) were added to beakers in an ice-water bath at a rate of 2.5 ml / min and 1 ml / min respectively using peristaltic pumps, and then stirred vigorously for 30 minutes under a nitrogen atmosphere to obtain a black precipitate.
[0082] 4) Under a nitrogen atmosphere, wash the precipitate obtained in step 3) three times each with deionized water and ethanol, and then dry it in a vacuum oven at 60°C for 6 hours.
[0083] 5) Calcine the dried product obtained in step 4) at 600°C for 5 hours under an argon atmosphere.
[0084] 6) Load 0.5g of the calcined catalyst from step 5) into a micro fixed-bed reactor, and then introduce a mixture of hydrogen chloride and oxygen in a molar ratio of n(HCl):n(O2) = 1:1.4. The reaction temperature is 450℃, the reaction pressure is 0.1MPa, and the mass hourly space velocity of hydrogen chloride is 50h⁻¹. -1 The reaction products were absorbed with excess 0.2 mol / L potassium iodide solution. The chlorine gas generated was determined by iodometry, and the unreacted hydrogen chloride was obtained by acid-base titration. The conversion rate of hydrogen chloride was calculated from these results. After 30 hours of reaction, the conversion rate of hydrogen chloride was 80%, and after 500 hours, the conversion rate was 79%, showing no significant decrease.
[0085] Through Example 2 and Comparative Examples 3 and 4, it can be seen that the order of addition can greatly affect the final activity of the product.
[0086] Example 3
[0087] 1) Weigh 1.01 g of ferric nitrate nonahydrate, dissolve it in 12.5 ml of deionized water and mix well to obtain a 0.2 mol / L ferric nitrate solution.
[0088] 2) Under the conditions of ice-water bath and nitrogen atmosphere, weigh 0.056g of potassium hydroxide and dissolve it in 5ml of water. After mixing evenly, weigh 0.54g of potassium borohydride and dissolve it in the solution to obtain a potassium borohydride mixed solution with a concentration of 2mol / L.
[0089] 3) Add the mixed solution obtained in step 2) to the solution in step 1) in the ice water bath at a rate of 1 ml / min using a peristaltic pump, and stir vigorously for 30 minutes under a nitrogen atmosphere to obtain a black precipitate.
[0090] 4) Under a nitrogen atmosphere, wash the precipitate obtained in step 3) three times each with deionized water and ethanol, and then dry it in a vacuum oven at 60°C for 6 hours.
[0091] 5) Calcine the dried product obtained in step 4) at 600°C for 5 hours under an argon atmosphere.
[0092] 6) Load 0.5g of the calcined catalyst from step 5) into a micro fixed-bed reactor, and then introduce a mixture of hydrogen chloride and oxygen in a molar ratio of n(HCl):n(O2) = 1:1.4. The reaction temperature is 450℃, the reaction pressure is 0.1MPa, and the mass hourly space velocity of hydrogen chloride is 50h⁻¹. -1 The reaction products were absorbed with excess 0.2 mol / L potassium iodide solution. The chlorine gas generated was determined by iodometry, and the unreacted hydrogen chloride was obtained by acid-base titration. The conversion rate of hydrogen chloride was calculated from these results. After 30 hours of reaction, the conversion rate of hydrogen chloride was 93%, and after 500 hours, the conversion rate was 91%, showing no significant decrease.
[0093] Comparative Example 5 (without protective atmosphere)
[0094] 1) Weigh 1.01 g of ferric nitrate nonahydrate, dissolve it in 12.5 ml of deionized water and mix well to obtain a 0.2 mol / L ferric nitrate solution.
[0095] 2) Under the conditions of ice-water bath and nitrogen atmosphere, weigh 0.056g of potassium hydroxide and dissolve it in 5ml of water. After mixing evenly, weigh 0.54g of potassium borohydride and dissolve it in the solution to obtain a potassium borohydride mixed solution with a concentration of 2mol / L.
[0096] 3) Add the mixed solution obtained in step 2) to the solution in step 1) in the ice water bath at a rate of 1 ml / min using a peristaltic pump, and stir vigorously for 30 minutes to obtain a black precipitate.
[0097] 4) Wash the precipitate obtained in step 3) three times each with deionized water and ethanol, and then dry it in a vacuum oven at 60°C for 6 hours.
[0098] 5) Calcine the dried product obtained in step 4) at 600°C for 5 hours under an argon atmosphere.
[0099] 6) Load 0.5g of the calcined catalyst from step 5) into a micro fixed-bed reactor, and then introduce a mixture of hydrogen chloride and oxygen in a molar ratio of n(HCl):n(O2) = 1:1.4. The reaction temperature is 450℃, the reaction pressure is 0.1MPa, and the mass hourly space velocity of hydrogen chloride is 50h⁻¹. -1 The reaction products were absorbed with excess 0.2 mol / L potassium iodide solution. The generated chlorine gas was determined by iodometry, and unreacted hydrogen chloride was obtained by acid-base titration. The conversion rate of hydrogen chloride was calculated from these results. After 30 hours of reaction, the conversion rate of hydrogen chloride was 60%, and after 500 hours, it was 55%.
[0100] Examples 3 and 5 demonstrate that the protective atmosphere plays a crucial role in the catalyst preparation process. Without a protective atmosphere, the sample will oxidize, causing the active components to become ineffective.
[0101] Example 4
[0102] 1) Weigh 0.5g of ferric sulfate, dissolve it in 12.5ml of deionized water and mix well to obtain a 0.1mol / L ferric sulfate solution.
[0103] 2) Under the conditions of ice-water bath and nitrogen atmosphere, weigh 0.04g of sodium hydroxide and dissolve it in 5ml of water. After mixing evenly, weigh 0.38g of sodium borohydride and dissolve it in the solution to obtain a sodium borohydride mixed solution with a concentration of 2mol / L.
[0104] 3) Add the mixed solution obtained in step 2) to the solution in step 1) in the ice water bath at a rate of 1 ml / min using a peristaltic pump, and stir vigorously for 30 minutes under a nitrogen atmosphere to obtain a black precipitate.
[0105] 4) Under a nitrogen atmosphere, wash the precipitate obtained in step 3) three times each with deionized water and ethanol, and then dry it in a vacuum oven at 60°C for 6 hours.
[0106] 5) Calcine the dried product obtained in step 4) at 600°C for 5 hours under an argon atmosphere.
[0107] 6) Load 0.5g of the calcined catalyst from step 5) into a micro fixed-bed reactor, and then introduce a mixture of hydrogen chloride and oxygen in a molar ratio of n(HCl):n(O2) = 1:1.4. The reaction temperature is 450℃, the reaction pressure is 0.1MPa, and the mass hourly space velocity of hydrogen chloride is 50h⁻¹. -1 The reaction products were absorbed with excess 0.2 mol / L potassium iodide solution. The chlorine gas generated was determined by iodometry, and the unreacted hydrogen chloride was obtained by acid-base titration. The conversion rate of hydrogen chloride was calculated from these results. After 30 hours of reaction, the conversion rate of hydrogen chloride was 91%, and after 500 hours, the conversion rate was 90%, showing no significant decrease.
[0108] Comparative Example 6 (Calming temperature varied)
[0109] 1) Weigh 0.5g of ferric sulfate, dissolve it in 12.5ml of deionized water and mix well to obtain a 0.1mol / L ferric sulfate solution.
[0110] 2) Under the conditions of ice-water bath and nitrogen atmosphere, weigh 0.04g of sodium hydroxide and dissolve it in 5ml of water. After mixing evenly, weigh 0.38g of sodium borohydride and dissolve it in the solution to obtain a sodium borohydride mixed solution with a concentration of 2mol / L.
[0111] 3) Add the mixed solution obtained in step 2) to the solution in step 1) in the ice water bath at a rate of 1 ml / min using a peristaltic pump, and stir vigorously for 30 minutes under a nitrogen atmosphere to obtain a black precipitate.
[0112] 4) Under a nitrogen atmosphere, wash the precipitate obtained in step 3) three times each with deionized water and ethanol, and then dry it in a vacuum oven at 60°C for 6 hours.
[0113] 5) Calcine the dried product obtained in step 4) at 300°C for 5 hours under an argon atmosphere.
[0114] 6) Load 0.5g of the calcined catalyst from step 5) into a micro fixed-bed reactor, and then introduce a mixture of hydrogen chloride and oxygen in a molar ratio of n(HCl):n(O2) = 1:1.4. The reaction temperature is 450℃, the reaction pressure is 0.1MPa, and the mass hourly space velocity of hydrogen chloride is 50h⁻¹. -1 The reaction products were absorbed with excess 0.2 mol / L potassium iodide solution. The chlorine gas produced was determined by iodometry, and the unreacted hydrogen chloride was obtained by acid-base titration. The conversion rate of hydrogen chloride was calculated from these results. After 30 hours of reaction, the conversion rate of hydrogen chloride was 60%, and after 500 hours, it was 36%.
[0115] Comparative Example 7 (Calming temperature varied)
[0116] 1) Weigh 0.5g of ferric sulfate, dissolve it in 12.5ml of deionized water and mix well to obtain a 0.1mol / L ferric sulfate solution.
[0117] 2) Under the conditions of ice-water bath and nitrogen atmosphere, weigh 0.04g of sodium hydroxide and dissolve it in 5ml of water. After mixing evenly, weigh 0.38g of sodium borohydride and dissolve it in the solution to obtain a sodium borohydride mixed solution with a concentration of 2mol / L.
[0118] 3) Add the mixed solution obtained in step 2) to the solution in step 1) in the ice water bath at a rate of 1 ml / min using a peristaltic pump, and stir vigorously for 30 minutes under a nitrogen atmosphere to obtain a black precipitate.
[0119] 4) Under a nitrogen atmosphere, wash the precipitate obtained in step 3) three times each with deionized water and ethanol, and then dry it in a vacuum oven at 60°C for 6 hours.
[0120] 5) Calcine the dried product obtained in step 4) at 800°C for 5 hours under an argon atmosphere.
[0121] 6) Load 0.5g of the calcined catalyst from step 5) into a micro fixed-bed reactor, and then introduce a mixture of hydrogen chloride and oxygen in a molar ratio of n(HCl):n(O2) = 1:1.4. The reaction temperature is 450℃, the reaction pressure is 0.1MPa, and the mass hourly space velocity of hydrogen chloride is 50h⁻¹. -1 The reaction products were absorbed with excess 0.2 mol / L potassium iodide solution. The chlorine gas produced was determined by iodometry, and the unreacted hydrogen chloride was obtained by acid-base titration. The conversion rate of hydrogen chloride was calculated from these results. After 30 hours of reaction, the conversion rate of hydrogen chloride was 67%, and after 500 hours, it was 63%.
[0122] Through Example 4 and Comparative Examples 6 and 7, it can be seen that during the catalyst preparation process, if the calcination temperature is too high, it will lead to high-temperature decomposition of the active phase, and if the calcination temperature is too low, it will lead to rapid deactivation of the catalyst.
[0123] Example 5
[0124] 1) Weigh 1.01 g of ferric nitrate nonahydrate, dissolve it in 12.5 ml of deionized water and mix well to obtain a 0.2 mol / L ferric nitrate solution.
[0125] 2) Under the conditions of ice-water bath and nitrogen atmosphere, weigh 0.04g of sodium hydroxide and dissolve it in 5ml of water. After mixing evenly, weigh 0.38g of sodium borohydride and dissolve it in the solution to obtain a sodium borohydride mixed solution with a concentration of 2mol / L.
[0126] 3) Add the mixed solution obtained in step 2) to the solution in step 1) in the ice water bath at a rate of 1 ml / min using a peristaltic pump, and stir vigorously for 30 minutes under a nitrogen atmosphere to obtain a black precipitate.
[0127] 4) Under a nitrogen atmosphere, wash the precipitate obtained in step 3) three times each with deionized water and ethanol, and then dry it in a vacuum oven at 60°C for 6 hours.
[0128] 5) The dried catalyst product obtained in step 4) is calcined at 500°C for 5 hours under an argon atmosphere.
[0129] 6) Load 0.5g of the calcined catalyst from step 5) into a micro fixed-bed reactor, and then introduce a mixture of hydrogen chloride and oxygen in a molar ratio of n(HCl):n(O2) = 1:1.4. The reaction temperature is 450℃, the reaction pressure is 0.1MPa, and the mass hourly space velocity of hydrogen chloride is 50h⁻¹. -1 The reaction products were absorbed with excess 0.2 mol / L potassium iodide solution. The chlorine gas generated was determined by iodometry, and the unreacted hydrogen chloride was obtained by acid-base titration. The conversion rate of hydrogen chloride was calculated from these results. After 30 hours of reaction, the conversion rate of hydrogen chloride was 91%, and after 500 hours, it was 92%, showing no significant decrease.
[0130] Comparative Example 8 (without calcination)
[0131] 1) Weigh 1.01 g of ferric nitrate nonahydrate, dissolve it in 12.5 ml of deionized water and mix well to obtain a 0.2 mol / L ferric nitrate solution.
[0132] 2) Under the conditions of ice-water bath and nitrogen atmosphere, weigh 0.04g of sodium hydroxide and dissolve it in 5ml of water. After mixing evenly, weigh 0.38g of sodium borohydride and dissolve it in the solution to obtain a sodium borohydride mixed solution with a concentration of 2mol / L.
[0133] 3) Add the mixed solution obtained in step 2) to the solution in step 1) in the ice water bath at a rate of 1 ml / min using a peristaltic pump, and stir vigorously for 30 minutes under a nitrogen atmosphere to obtain a black precipitate.
[0134] 4) Under a nitrogen atmosphere, wash the precipitate obtained in step 3) three times each with deionized water and ethanol, and then dry it in a vacuum oven at 60°C for 6 hours.
[0135] 5) Load 0.5g of the dried catalyst product obtained in step 4) into a micro fixed-bed reactor, and then introduce a mixed gas with a molar ratio of hydrogen chloride to oxygen of n(HCl):n(O2) = 1:1.4. The reaction temperature is 450℃, the reaction pressure is 0.1MPa, and the mass hourly space velocity of hydrogen chloride is 50h⁻¹. -1 The reaction products were absorbed with excess 0.2 mol / L potassium iodide solution. The chlorine gas produced was determined by iodometry, and the unreacted hydrogen chloride was obtained by acid-base titration. The conversion rate of hydrogen chloride was calculated from these results. After 30 hours of reaction, the conversion rate of hydrogen chloride was 93%, and after 500 hours, the conversion rate was 34%.
[0136] Through Example 5 and Comparative Example 8, it can be seen that if calcination is not carried out during the catalyst preparation process, the catalyst will undergo structural changes during the reaction, resulting in a significant decrease in stability.
[0137] Example 6
[0138] 1) Weigh 1.01 g of ferric nitrate nonahydrate, dissolve it in 12.5 ml of deionized water and mix well to obtain a 0.2 mol / L ferric nitrate solution.
[0139] 2) Under the conditions of ice-water bath and nitrogen atmosphere, weigh 0.03g of sodium hydroxide and dissolve it in 3.75ml of water. After mixing evenly, weigh 0.285g of sodium borohydride and dissolve it in the solution to obtain a sodium borohydride mixed solution with a concentration of 2mol / L.
[0140] 3) Add the mixed solution obtained in step 2) to the solution in step 1) in the ice water bath at a rate of 1 ml / min using a peristaltic pump, and stir vigorously for 30 minutes under a nitrogen atmosphere to obtain a black precipitate.
[0141] 4) Under a nitrogen atmosphere, wash the precipitate obtained in step 3) three times each with deionized water and ethanol, and then dry it in a vacuum oven at 60°C for 6 hours.
[0142] 5) The dried catalyst product obtained in step 4) is calcined at 500°C for 5 hours under an argon atmosphere.
[0143] 6) Load 0.5g of the calcined catalyst from step 5) into a micro fixed-bed reactor, and then introduce a mixture of hydrogen chloride and oxygen in a molar ratio of n(HCl):n(O2) = 1:1.4. The reaction temperature is 450℃, the reaction pressure is 0.1MPa, and the mass hourly space velocity of hydrogen chloride is 50h⁻¹. -1 The reaction products were absorbed with excess 0.2 mol / L potassium iodide solution. The chlorine gas generated was determined by iodometry, and the unreacted hydrogen chloride was obtained by acid-base titration. The conversion rate of hydrogen chloride was calculated from these results. After 30 hours of reaction, the conversion rate of hydrogen chloride was 87%, and after 500 hours, the conversion rate was 84%, showing no significant decrease.
Claims
1. A Fe-B based catalyst, characterized in that: The Fe-B based catalyst is prepared by a method comprising the following steps: under a protective atmosphere, a boron-alkali mixed solution is added to an iron salt solution with a concentration of 0.1-0.3 mol / L in an ice-water bath and stirred thoroughly; the precipitate generated is separated, washed, and dried under a protective atmosphere; and finally, the catalyst is calcined at 500-600℃ for 3-6 h under a protective atmosphere to obtain the Fe-B based catalyst. The boron-alkali mixed solution is prepared from a boron source reducing agent, a strong base, and water, wherein the concentration of the boron source reducing agent is 1.6-2 mol / L, and the molar ratio of the ions contained is B3-:OH- = 10:
1. The ratio of the amount of the boron-alkali mixed solution to the iron salt solution is 3-4, based on the molar ratio of boron to iron contained therein.
2. The Fe-B based catalyst as described in claim 1, characterized in that: The iron salt is selected from one of ferric nitrate, ferric chloride, ferric sulfate, and ferrous sulfate; the boron source reducing agent is selected from one of sodium borohydride and potassium borohydride; and the strong base is selected from one of sodium hydroxide and potassium hydroxide.
3. The Fe-B based catalyst as described in claim 1, characterized in that: The concentration of the iron salt solution is 0.1-0.2 mol / L, with 0.2 mol / L being the most preferred.
4. The Fe-B based catalyst as described in claim 1, characterized in that: In the boron-alkali mixed solution, the concentration of the boron source reducing agent is 2 mol / L.
5. The Fe-B based catalyst as described in claim 1, characterized in that: The boron-iron molar ratio is 4.
6. The Fe-B based catalyst according to claim 1, characterized in that: The protective atmosphere is nitrogen or argon.
7. The Fe-B based catalyst according to claim 1, characterized in that: The calcination temperature is 600℃.
8. The Fe-B based catalyst according to claim 1, characterized in that: The calcination time is 4-5 hours.
9. A method for preparing an Fe-B based catalyst as described in any one of claims 1-8, characterized in that: The preparation method includes the following steps: under a protective atmosphere, a boron-alkali mixed solution is added to an iron salt solution with a concentration of 0.1-0.3 mol / L in an ice-water bath and stirred thoroughly. Under a protective atmosphere, the generated precipitate is separated, washed, and dried. Finally, under a protective atmosphere, it is calcined at 500-600℃ for 3-6 h to obtain an Fe-B based catalyst. The boron-alkali mixed solution is prepared from a boron source reducing agent, a strong base, and water, wherein the concentration of the boron source reducing agent is 1.6-2 mol / L, and the molar ratio of the ions is B3-:OH- = 10:
1. The ratio of the amount of boron-alkali mixed solution to the amount of iron salt solution is 3-4, based on the molar ratio of boron to iron contained therein.
10. The application of the Fe-B based catalyst as described in any one of claims 1-8 in the production of chlorine gas by chlorination and hydrogenation.