Preparation method of supported ruthenium-based catalyst and application thereof

Abstract

This invention discloses a method for preparing a supported ruthenium-based catalyst and its application. The disclosed method involves fluorinating an oxide support with a fluoride-containing aqueous solution; loading a ruthenium component onto the fluorinated support; then performing a solvothermal treatment on the solid composite using an aqueous alcohol solution; and finally calcining to obtain the supported ruthenium-based catalyst. By fluorinating the oxide support, this invention increases the defects on the support surface, and fluoride ions participate in regulating the electronic structure of the ruthenium sites on the surface, which is beneficial for anchoring the ruthenium component and limiting its migration and sintering under heat treatment or high-temperature reaction atmospheres. Furthermore, the solvothermal treatment using an aqueous alcohol solution further reconstructs and fixes the ruthenium component and optimizes its electronic structure. The catalyst of this invention can be used as a catalyst for the production of chlorine from recycled hydrogen chloride, with significantly improved stability and activity.

Description

Technical Field

[0001] This invention belongs to the field of catalyst preparation, specifically relating to a method for preparing a supported ruthenium-based catalyst. Background Technology

[0002] In numerous chemical processes, over 50% of chemical reactions involve chlorine, with chlorine gas and hydrogen chloride being the most common. Chlorine-related industries encompass polyurethane, fluorochemicals, chlor-alkali, pharmaceuticals, electronics, cosmetics, and many other fields, becoming an indispensable part of modern industrial civilization. However, due to the widespread industrial application of chlorine gas, a large amount of hydrogen chloride byproduct is inevitably generated. To achieve high-quality development in chlorine-related industries, the efficient and resource-based utilization of this byproduct has become a critical challenge that urgently needs to be addressed.

[0003] Converting hydrogen chloride back into chlorine gas enables the recycling of chlorine resources and is a green approach to promote the sustainable development of chlorine-related industries. Catalytic oxidation is the most efficient method for producing chlorine from recycled hydrogen chloride, but current mainstream ruthenium-based catalysts still suffer from long-term stability issues. Ruthenium components migrate and sinter during high-temperature reactions, leading to a gradual decrease in activity. Summary of the Invention

[0004] To address the shortcomings or deficiencies in the stability and activity of existing ruthenium-based catalysts, this invention provides a method for preparing a supported ruthenium-based catalyst.

[0005] Therefore, the method for preparing the supported ruthenium-based catalyst provided by the present invention includes:

[0006] (1) Fluoride-containing aqueous solution is used to fluoride the oxide support to obtain a fluorinated support; the oxide support is one or a mixture of two or more of rutile titanium dioxide, anatase titanium dioxide, tin dioxide, γ-alumina and α-alumina.

[0007] (2) The Ru element is loaded onto the fluorinated carrier, and then a solid composite is obtained after a first calcination.

[0008] (3) Under sealed conditions, the solid composite was heat-treated in an aqueous solution of alcohol, and then a second calcination was performed to prepare a supported ruthenium-based catalyst.

[0009] Alternatively, the fluoride-containing aqueous solution may be an aqueous solution of one or more of the following fluorides: HF, NH4F, NaF, KF, and CsF.

[0010] Alternatively, the fluoride ion mass fraction in the fluoride-containing aqueous solution is 0.1% to 5.0%.

[0011] An alternative approach is that the mass ratio of the fluoride-containing aqueous solution to the oxide support is 100:1 to 60.

[0012] An alternative is that the Ru element loading in step (2) is performed by impregnation or alkaline precipitation.

[0013] An optional approach is that the first roasting temperature is 150–400℃ and the roasting time is 0.5–10h.

[0014] An optional approach is that the aqueous solution of the alcohol mentioned in step (3) is one or more of the following: methanol, ethanol, propanol, butanol, ethylene glycol, propylene glycol and glycerol.

[0015] An optional approach is that the mass ratio of alcohol to water in the aqueous solution of alcohol in step (3) is 100:20 to 600.

[0016] An alternative approach is that the mass ratio of the aqueous solution of the alcohol to the solid complex in step (3) is 100:1 to 80.

[0017] An optional approach is to use a heat treatment temperature of 30 to 200°C and a treatment time of 0.5 to 10 hours in step (3).

[0018] An optional approach is that the second roasting temperature in step (3) is 140-300℃ and the roasting time is 0.5-8h.

[0019] 12. A method for preparing chlorine gas, characterized in that the catalyst used in the method is the catalyst described in claim 1.

[0020] In the supported ruthenium-based catalyst of this invention, fluorination of the oxide support increases the defects on the support surface. Simultaneously, fluoride ions participate in regulating the electronic structure of the ruthenium sites on the surface, which is beneficial for anchoring the ruthenium component and limiting its migration and sintering under heat treatment or high-temperature reaction atmospheres. Further solvothermal treatment using an alcohol-water solution promotes further reconstruction and fixation of the ruthenium component and optimizes the electronic structure. The preparation method of this invention can significantly improve the stability and activity of the supported ruthenium-based catalyst. The catalyst of this invention is particularly suitable as a catalyst for the catalytic oxidation of hydrogen chloride to produce chlorine. Detailed Implementation

[0021] Unless otherwise specified, the terminology used herein is for the understanding of one of ordinary skill in the art. It should also be understood that the temperatures and durations mentioned herein are approximate values ​​used for illustrative purposes. While methods and materials similar to or equivalent to those described herein can be used in the implementation of this disclosure, some suitable methods and materials are described below. Furthermore, the materials, methods, proportions, and embodiment schemes described are merely exemplary and not intended to be limiting. In specific embodiments, those skilled in the art can optimize the proportions of substances and the values ​​of operating parameters involved in the methods using conventional experimental periods based on the disclosure of this invention to achieve the objectives of this invention.

[0022] It should be noted that the Ru element supplier in this invention can be ruthenium trichloride, hydrated ruthenium trichloride, ruthenium acetylacetonate, or other ruthenium salts.

[0023] In the following examples, the elemental content of the catalyst was determined using inductively coupled plasma atomic emission spectrometry.

[0024] Example 1:

[0025] After thoroughly mixing 3.12g of rutile TiO2 and 1.03g of anatase TiO2, the mixture was added to 20.21g of HF aqueous solution (HF content 0.8wt%) and magnetically stirred at 100r / min for 2.0h. The mixture was then filtered and the filter residue was washed three times with deionized water. After drying at 100±10℃ for 4.0h, 3.82g of fluorinated carrier A was obtained.

[0026] 0.16 g RuCl3·3H2O was dissolved in 50 mL of deionized water; then 2.03 g of fluorinated carrier A was added, and the mixture was stirred vigorously and impregnated for 16 h; the solvent was then evaporated under vacuum at 50±5 °C, and the mixture was dried at 80 °C for 3 h and calcined at 350±10 °C for 4 h to obtain 2.01 g of solid composite A.

[0027] 2.01 g of solid composite A was added to an aqueous solution of 6.56 g ethanol, 12.35 g ethylene glycol, and 8.82 g deionized water. After stirring and mixing, the solid-liquid mixture was transferred to a PTFE liner in a stainless steel autoclave. The autoclave was then sealed and placed in a furnace for solvothermal treatment at 120±10 °C for 4 h. Subsequently, the mixture was cooled, filtered, washed three times each with deionized water and ethanol, dried at 80±5 °C for 4 h, and calcined at 150±10 °C for 3 h to obtain 1.97 g of supported ruthenium-based catalyst A, in which the mass content of Ru was 2.96%.

[0028] Example 2:

[0029] After thoroughly mixing 3.57g of rutile TiO2, 1.01g of SnO2 and 0.65g of α-alumina, the mixture was added to 27.86g of HF aqueous solution (HF content 0.72wt%) and magnetically stirred at 120r / min for 2.5h. The mixture was then filtered and the filter residue was washed three times with deionized water. After drying at 100±10℃ for 5.0h, 5.02g of fluorinated carrier B was obtained.

[0030] 0.16 g RuCl3·3H2O was dissolved in 50 mL of deionized water; then 2.01 g of fluorinated carrier B was added, and the mixture was stirred vigorously and impregnated for 16 h; the solvent was then evaporated under vacuum at 50±5 °C, and the mixture was dried at 80±5 °C for 3 h and calcined at 350±10 °C for 4 h to obtain 2.02 g of solid composite B.

[0031] 2.02 g of solid composite B was added to an alcohol-water solution containing 10.96 g methanol, 4.63 g glycerol, and 11.31 g deionized water. After stirring thoroughly for 10 min, the solid-liquid mixture was transferred to a PTFE liner in a stainless steel autoclave. The autoclave was then sealed and placed in a furnace for solvothermal treatment at 100±10 °C for 3 h. Subsequently, the mixture was cooled, filtered, washed three times each with deionized water and methanol, dried at 80±5 °C for 4 h, and calcined at 180±10 °C for 2 h to obtain 1.94 g of supported ruthenium-based catalyst B, in which the mass content of Ru was 2.99%.

[0032] Comparative Example 1:

[0033] 0.16 g RuCl3·3H2O was dissolved in 50 mL of deionized water; then 1.52 g rutile TiO2 and 0.50 g anatase TiO2 were added, and the mixture was stirred vigorously and impregnated for 16 h; the solvent was then evaporated under vacuum at 50±5 °C, and the mixture was dried at 80±5 °C for 3 h and calcined at 350±10 °C for 4 h to obtain 2.01 g of supported ruthenium-based catalyst C, in which the mass content of Ru element was 3.01%.

[0034] Comparative Example 2:

[0035] 0.16 g RuCl3·3H2O was dissolved in 50 mL of deionized water; then 1.37 g rutile TiO2, 0.39 g SnO2, and 0.25 g α-alumina were added, and the mixture was stirred vigorously and impregnated for 16 h; the solvent was then evaporated under vacuum at 50±5 °C, dried at 80±5 °C for 3 h, and calcined at 350±10 °C for 4 h to obtain 1.93 g of supported ruthenium-based catalyst D, in which the mass content of Ru element was 3.04%.

[0036] Catalyst evaluation:

[0037] Catalyst evaluation was conducted using a fixed-bed reactor with dimensions of 350 mm × Φ10 mm × 1 mm. The reaction was carried out under atmospheric pressure with a catalyst loading of 1.50 g and a catalyst particle size of 0.1-0.18 mm. Hydrogen chloride gas and oxygen were used as reactants, which first passed through a mass flow meter and then through a preheater before entering the fixed-bed reactor.

[0038] The fixed-bed reactor uses a three-stage electric heating method, with a reaction temperature of 350±10℃, a hydrogen chloride flow rate of 80 ml / min, and an oxygen flow rate of 160 ml / min, resulting in a reaction space velocity of 9600 L / (kg·kg⁻¹). cat ·h);

[0039] After the reaction stabilized for 1 hour, samples were taken for analysis. Chlorine and unreacted hydrogen chloride in the samples were titrated using iodometric titration and acid-base titration, respectively. The specific operating steps are as follows: After the system stabilized, 100 mL of 20% KI solution was prepared at regular intervals. The three-way valve at the outlet of the oxidation reactor was switched, and the mixed gas after the reaction was passed into a fixed volume (100 mL) of potassium iodide solution. The solution was absorbed for 2 minutes. After absorption, the absorbent was transferred to an Erlenmeyer flask and titrated with 0.1 mol / L sodium thiosulfate standard solution, using starch as an indicator. Then, using phenolphthalein as an indicator, the unreacted HCl was titrated with 0.1 mol / L sodium hydroxide standard solution.

[0040] The catalysts obtained in Examples 1 and 2 and Comparative Examples 1 and 2 were evaluated in a fixed-bed reactor under the above-mentioned high space velocity reaction conditions. The catalytic oxidation performance of hydrogen chloride is shown in Table 1 below. The catalyst stability in the table is expressed as the percentage of Cl2 space-time yield after 100 h of reaction to the Cl2 space-time yield after 1 h of reaction.

[0041] Table 1

[0042]

[0043] As shown in Table 1 above, when the Ru content in the catalysts is the same or substantially the same, the catalytic activity and stability of the chlorination-hydrogenation catalysts A and B prepared by the method described in this invention are higher than those of catalysts C and D prepared by conventional methods. This method has a significant enhancing effect on the performance of supported ruthenium-based catalysts, especially on their stability. For example, the above examples show that at a high space velocity of 9600 L / (kg·h ... cat At ·h), the catalyst described in this invention was used for continuous reaction for 100h, and the catalytic activity showed virtually no decay.

Claims

1. A process for the preparation of a supported ruthenium-based catalyst, characterized in that the process comprises the steps of The method comprises the following steps: (1) fluoridating an oxide carrier with a fluorine-containing ion aqueous solution to obtain a fluoridated carrier; the oxide carrier is one or a mixture of two or more of rutile titanium dioxide, anatase titanium dioxide, tin dioxide, gamma-alumina and alpha-alumina; (2) loading Ru element on the fluoridated carrier, and then performing first calcination to obtain a solid composite; (3) under sealed conditions, performing heat treatment on the solid composite in an alcohol aqueous solution, and then performing second calcination to prepare a supported ruthenium-based catalyst; the alcohol aqueous solution is one or a mixture of two or more of methanol, ethanol, propanol, butanol, ethylene glycol, propylene glycol and glycerol; the heat treatment temperature is 30-200 ℃, and the treatment time is 0.5-10 h.

2. The method for preparing a supported ruthenium-based catalyst according to claim 1, wherein the fluorine-containing ion aqueous solution is one or a mixture of two or more of fluoride HF, NH4F, NaF, KF and CsF.

3. The method for preparing a supported ruthenium-based catalyst according to claim 1, wherein the mass fraction of fluorine ions in the fluorine-containing ion aqueous solution is 0.1-5.0%.

4. The method for preparing a supported ruthenium-based catalyst according to claim 1, wherein the mass ratio of the fluorine-containing ion aqueous solution to the oxide carrier is 100:1-60.

5. The method for preparing a supported ruthenium-based catalyst according to claim 1, wherein in step (2), the Ru element loading is performed by impregnation or alkali precipitation.

6. The method for preparing a supported ruthenium-based catalyst according to claim 1, wherein the first calcination temperature is 150-400 ℃, and the calcination time is 0.5-10 h.

7. The method for preparing a supported ruthenium-based catalyst according to claim 1, wherein in step (3), the mass ratio of alcohol to water in the alcohol aqueous solution is 100:20-600.

8. The method for preparing a supported ruthenium-based catalyst according to claim 1, wherein in step (3), the mass ratio of the alcohol aqueous solution to the solid composite is 100:1-80.

9. The method of preparing a supported ruthenium-based catalyst according to claim 1, wherein in step (3), the second calcination temperature is 140-300 ℃, and the calcination time is 0.5-8 h.

10. A method for producing chlorine gas by catalytic oxidation of hydrogen chloride, characterized in that, the catalyst used in the method is the catalyst prepared by the method of claim 1.

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