Preparation method of platinum-ruthenium catalyst for chlorine production

Abstract

This invention provides a method for preparing a platinum-ruthenium catalyst for chlorine production, comprising: mixing nitrosylruthenium nitrate, platinum nitrate solution, deionized water, and a dispersant; heating to reflux temperature to dissolve; continuing the reaction at reflux temperature for 1 hour after the system changes from brownish-red to brownish-black; filtering the system after cooling to room temperature; and mixing the platinum-ruthenium mixture, silica hydrosol, and silica powder. The mixture is extruded into cylindrical pieces with a diameter of 5 mm, dried at 100-120°C for 6 hours to a breakage length of approximately 3-5 mm, and calcined in air at 200-240°C for 12 hours to obtain the platinum-ruthenium catalyst. This method can prepare a platinum-ruthenium catalyst with low chlorine impurity content that easily leads to catalyst aging. Simultaneously, because the reaction system remains acidic, the occurrence of ruthenium hydrolysis side reactions is reduced, resulting in a platinum-ruthenium catalyst with high yield, high ruthenium dispersion, and high catalyst activity.

Description

Technical Field

[0001] This invention belongs to the field of precious metal catalyst preparation technology, and relates to a method for preparing a platinum-ruthenium catalyst for chlorine production. Background Technology

[0002] Ruthenium, a noble metal, has a unique electronic structure. Its unfilled d electron orbitals give it excellent adsorption properties for molecules, which is conducive to the formation of intermediate "active compounds" with platinum. Its catalysts have the advantages of high activity, good stability and high selectivity, and are widely used in chemical catalysts.

[0003] Chlorine (Cl2) is a basic chemical raw material with extensive applications in chemical, pesticide, and pharmaceutical fields. In chemical production processes, reactions involving chlorine account for 50%, and the vast majority of these reactions produce an equal amount of hydrogen chloride (HCl) as a byproduct, resulting in an atom utilization rate of less than 50% for chlorine. Methods for treating the byproduct HCl include water absorption to produce hydrochloric acid and neutralization with alkali solutions. However, producing hydrochloric acid has limited market applications, and neutralizing hydrogen chloride is costly and wasteful of chlorine resources. A process for producing chlorine from hydrogen chloride can achieve the recycling of hydrogen chloride, avoiding the waste of chlorine resources. Therefore, developing a method for preparing a highly active, long-life platinum-ruthenium catalyst is of great significance.

[0004] The method of catalytically oxidizing HCl to Cl2 was proposed by Henry Deacon in 1870, hence the process is also called the Deacon reaction. Since Henry Deacon used Cu-based catalysts to catalyze this reaction, the catalysts for this reaction have undergone more than 150 years of development and improvement. CN102513102A discloses a method for preparing a low-loading, high-activity supported ruthenium catalyst using titanium dioxide as a support. This invention uses titanium dioxide as a support and irradiates the aging solution with ultraviolet light during the precipitation-deposition aging process to enhance the interaction between the ruthenium precursor and titanium dioxide, improve the dispersion of the precursor, and thus obtain a highly dispersed titanium dioxide-supported ruthenium catalyst. CN112536032A discloses a high-temperature sintering-resistant catalyst for the production of chlorine from hydrogen chlorination and its preparation method. The high-temperature sintering-resistant catalyst consists of a tin-doped titanium dioxide support and highly dispersed ruthenium dioxide nanoparticles as active components. CN109453764A discloses a ruthenium dioxide catalyst for producing chlorine by chlorination and hydrogenation, comprising a support, an active component supported on the support, a co-catalytic component, and a support modifying agent. The support contains titanium dioxide, the active component is ruthenium dioxide, the co-catalytic component contains an alkali metal component and a transition metal component, and the support modifying agent is silicon dioxide.

[0005] The methods described above all suffer from poor high-temperature resistance and short service life of the catalysts. Furthermore, numerous domestic and international patents explicitly point out the problem of ruthenium loss due to thermal oxidation as the catalyst ages. There are reports both domestically and internationally of a gradual decrease in the ruthenium content of the ruthenium catalyst in hydrogen chloride treatment units, leading to production shutdowns due to excessive ruthenium levels in the chlorine gas transport pipeline. Ruthenium is extremely rare in the Earth's crust, and its mining, enrichment, and refining are costly. Moreover, due to its unique chemical properties, the cost of ruthenium recovery and refining is also high. Therefore, the preparation of highly active, long-life platinum-ruthenium catalysts for chlorination is of great significance. Summary of the Invention

[0006] The purpose of this invention is to address the problems existing in the prior art by providing a method for preparing a highly active, long-life platinum-ruthenium catalyst for chlorine production, thus solving the technical problems of low activity and short lifespan of existing ruthenium catalysts for chlorine production in the background art.

[0007] Therefore, the present invention adopts the following technical solution:

[0008] A method for preparing a platinum-ruthenium catalyst for chlorine production includes the following steps:

[0009] Step 1, Mixing: In a three-necked flask equipped with a reflux condenser, add 10-15 grams of ruthenium nitrite with a ruthenium content of 30-32%, 3-10 grams of platinum nitrate solution with a platinum content of 10-12%, 60-150 grams of deionized water, and 0.1-0.3 grams of dispersant, and stir to mix evenly;

[0010] Step 2, Dissolution: Add 0.1~0.3 ml of co-solvent to the mixed solution prepared in Step 1, and reflux at a temperature of 100~110℃ to dissolve. When the solution changes from brownish-red to brownish-black, continue the reaction at a reflux temperature of 100~110℃. After stirring the reaction for 1 hour, stop heating and cool to room temperature.

[0011] Step 3, mixing: Add 140-250g of silica, 8-16g of silica hydrosol and 0.1-0.6g of oxalic acid to the solution prepared in Step 2 and mix for 6-8 hours;

[0012] Step 4, Drying: Extrude the mixture from Step 3 into cylindrical shapes with a diameter of 5mm, dry at 100~120℃ for 6~8 hours until the broken length is about 3-5mm;

[0013] Step 5, calcination: The cylindrical mixture from step 4 is calcined in air at 200-240°C for 12-18 hours to obtain a platinum-ruthenium catalyst.

[0014] Further, in step one, the nitrosyl ruthenium nitrate is a brownish-red solid with a ruthenium content of 31-32%; the amount of deionized water added in step one is such that the ruthenium content in the diluted nitrosyl ruthenium nitrate solution is 2-4%; the platinum nitrate in step one is a brownish-red solution with a platinum content of 10-11%, and the amount of platinum nitrate added is such that the mass ratio of platinum to ruthenium is 0.1-0.2; the dispersant in step one is ethylene glycol, and the amount of dispersant added is such that the dispersant content is 0.1-0.2%.

[0015] Furthermore, in step two, the co-solvent is hydrogen peroxide, and the mass percentage concentration of the hydrogen peroxide is 30-40%.

[0016] Furthermore, in step three, the silica is a white powder with a particle diameter of 100 μm, and the amount of silica added is 1.5-1.8 times the mass of the platinum-ruthenium mixed solution; in step three, the silica hydrosol is a pale yellow solution with a silica content of 10%, and the amount of silica hydrosol added is 5-6% of the mass of silica.

[0017] The beneficial effects of this invention are as follows:

[0018] 1. This invention uses platinum nitrate solution as both a reactant and a solvent, which keeps the dissolution process of nitrosyl ruthenium nitrate in an acidic system, avoiding side reactions such as hydrolysis of ruthenium compounds under moderately alkaline conditions, thereby improving ruthenium dispersibility and catalyst activity.

[0019] 2. This invention uses non-chloride nitrosyl ruthenium nitrate as the ruthenium precursor, and the entire reaction process is free of chloride sources, ensuring no chloride ion residue inside the platinum-ruthenium catalyst, which is beneficial for improving catalytic activity. Simultaneously, nitrosyl ruthenium nitrate and platinum nitrate decompose at relatively low drying and calcination temperatures, reducing product production costs. Attached Figure Description

[0020] Figure 1 This is a process flow diagram for the preparation of the platinum-ruthenium catalyst of the present invention;

[0021] Figure 2 The infrared spectrum of ruthenium trichloride prepared according to the present invention. Detailed Implementation

[0022] The technical solution of the present invention will be described below with reference to the accompanying drawings and implementation methods.

[0023] Example 1

[0024] like Figure 1 As shown, a method for preparing a platinum-ruthenium catalyst for chlorine production includes the following steps:

[0025] Step 1, Mixing: In a three-necked flask equipped with a reflux condenser, add 10 g of ruthenium nitrite with a ruthenium content of 31.38%, 3.138 g of platinum nitrate solution with a platinum content of 10%, 143.762 g of deionized water and 0.157 g of dispersant and stir to mix evenly;

[0026] Step 2, Dissolution: Add 0.1 ml of a co-solvent to the mixed solution prepared in Step 1, and reflux at 100°C to dissolve. When the solution changes from brownish-red to brownish-black, continue the reaction at 100°C under reflux for 1 hour, then stop heating and cool to room temperature. Specifically, the co-solvent is hydrogen peroxide, and the mass percentage concentration of the hydrogen peroxide is 30%.

[0027] Step 3, mixing: Add 235.35 g of silica, 11.76 g of silica hydrosol and 0.1 g of oxalic acid to the solution prepared in Step 2 and mix for 6 hours;

[0028] Step 4, Drying: Extrude the mixture from Step 3 into cylindrical shapes with a diameter of 5mm, dry at 100℃ for 6 hours, and the broken length is about 3-5mm.

[0029] Step 5, calcination: The cylindrical mixture from step 4 is calcined in air at 200°C for 12 hours to obtain a platinum-ruthenium catalyst.

[0030] Example 2

[0031] A method for preparing a platinum-ruthenium catalyst for chlorine production includes the following steps:

[0032] Step 1, Mixing: In a three-necked flask equipped with a reflux condenser, add 10 g of ruthenium nitrite with a ruthenium content of 31.38%, 4.0 g of platinum nitrate solution with a platinum content of 10%, 130.0 g of deionized water, and 0.18 g of dispersant, and stir to mix evenly;

[0033] Step 2, Dissolution: Add 0.1 ml of a co-solvent to the mixed solution prepared in Step 1, and reflux at 105°C to dissolve. When the solution changes from brownish-red to brownish-black, continue the reaction at 105°C under reflux for 1 hour, then stop heating and cool to room temperature. Specifically, the co-solvent is hydrogen peroxide, and the mass percentage concentration of the hydrogen peroxide is 30%.

[0034] Step 3, mixing: Add 230.4 g of silica, 12.76 g of silica hydrosol and 0.1 g of oxalic acid to the solution prepared in Step 2 and mix for 6 hours;

[0035] Step 4, Drying: Extrude the mixture from Step 3 into cylindrical shapes with a diameter of 5mm, dry at 105℃ for 6 hours until the broken length is about 3-5mm;

[0036] Step 5, calcination: The cylindrical mixture from step 4 is calcined in air at 210°C for 12 hours to obtain a platinum-ruthenium catalyst.

[0037] Example 3

[0038] A method for preparing a platinum-ruthenium catalyst for chlorine production includes the following steps:

[0039] Step 1, Mixing: In a three-necked flask equipped with a reflux condenser, add 10 g of ruthenium nitrite with a ruthenium content of 31.38%, 3.82 g of platinum nitrate solution with a platinum content of 10%, 110 g of deionized water, and 0.15 g of dispersant, and stir to mix evenly;

[0040] Step 2, Dissolution: Add 0.1 ml of a co-solvent to the mixed solution prepared in Step 1, and reflux at 106°C to dissolve. When the solution changes from brownish-red to brownish-black, continue the reaction at 106°C under reflux for 1 hour, then stop heating and cool to room temperature. Specifically, the co-solvent is hydrogen peroxide, and the mass percentage concentration of the hydrogen peroxide is 30%.

[0041] Step 3, mixing: Add 235.0 g of silica, 12.98 g of silica hydrosol and 0.1 g of oxalic acid to the solution prepared in Step 2 and mix for 6 hours;

[0042] Step 4, Drying: Extrude the mixture from Step 3 into cylindrical shapes with a diameter of 5mm, dry at 108℃ for 6 hours until the broken length is about 3-5mm;

[0043] Step 5, calcination: The cylindrical mixture from step 4 is calcined in air at 220°C for 12 hours to obtain a platinum-ruthenium catalyst.

[0044] Example 4

[0045] A method for preparing a platinum-ruthenium catalyst for chlorine production includes the following steps:

[0046] Step 1, Mixing: In a three-necked flask equipped with a reflux condenser, add 10 grams of ruthenium nitrite with a ruthenium content of 31.38%, 5 grams of platinum nitrate solution with a platinum content of 10%, 120 grams of deionized water, and 0.12 grams of dispersant, and stir to mix evenly;

[0047] Step 2, Dissolution: Add 0.1 ml of a co-solvent to the mixed solution prepared in Step 1, and reflux at 107°C to dissolve. When the solution changes from brownish-red to brownish-black, continue the reaction at 107°C under reflux for 1 hour, then stop heating and cool to room temperature. Specifically, the co-solvent is hydrogen peroxide, and the mass percentage concentration of the hydrogen peroxide is 30%.

[0048] Step 3, mixing: Add 198.4 g of silica, 10 g of silica hydrosol and 0.1 g of oxalic acid to the solution prepared in Step 2 and mix for 6 hours;

[0049] Step 4, Drying: Extrude the mixture from Step 3 into cylindrical shapes with a diameter of 5mm, dry at 109℃ for 6 hours until the broken length is about 3-5mm;

[0050] Step 5, calcination: The cylindrical mixture from step 4 is calcined in air at 230°C for 12 hours to obtain a platinum-ruthenium catalyst.

[0051] Example 5

[0052] A method for preparing a platinum-ruthenium catalyst for chlorine production includes the following steps:

[0053] Step 1, Mixing: In a three-necked flask equipped with a reflux condenser, add 10 grams of ruthenium nitrite with a ruthenium content of 31.38%, 6 grams of platinum nitrate solution with a platinum content of 10%, 132 grams of deionized water, and 0.17 grams of dispersant, and stir to mix evenly.

[0054] Step 2, Dissolution: Add 0.1 ml of a co-solvent to the mixed solution prepared in Step 1, and reflux at 105°C to dissolve. When the solution changes from brownish-red to brownish-black, continue the reaction at 105°C under reflux for 1 hour, then stop heating and cool to room temperature. Specifically, the co-solvent is hydrogen peroxide, and the mass percentage concentration of the hydrogen peroxide is 30%.

[0055] Step 3, mixing: Add 220g of silica, 11g of silica hydrosol and 0.1g of oxalic acid to the solution prepared in Step 2 and mix for 6 hours;

[0056] Step 4, Drying: Extrude the mixture from Step 3 into cylindrical shapes with a diameter of 5mm, dry at 106℃ for 6 hours until the broken length is about 3-5mm;

[0057] Step 5, calcination: The cylindrical mixture from step 4 is calcined in air at 215°C for 12 hours to obtain a platinum-ruthenium catalyst.

[0058] Example 6

[0059] A method for preparing a platinum-ruthenium catalyst for chlorine production includes the following steps:

[0060] Step 1, Mixing: In a three-necked flask equipped with a reflux condenser, add 10 grams of ruthenium nitrite with a ruthenium content of 31.38%, 5 grams of platinum nitrate solution with a platinum content of 10%, 100 grams of deionized water, and 0.1 grams of dispersant, and stir to mix evenly;

[0061] Step 2, Dissolution: Add 0.1 ml of a co-solvent to the mixed solution prepared in Step 1, and reflux at 107°C to dissolve. When the solution changes from brownish-red to brownish-black, continue the reaction at 107°C under reflux for 1 hour, then stop heating and cool to room temperature. Specifically, the co-solvent is hydrogen peroxide, and the mass percentage concentration of the hydrogen peroxide is 30%.

[0062] Step 3, mixing: Add 150g of silica, 8.98g of silica hydrosol and 0.1g of oxalic acid to the solution prepared in Step 2 and mix for 6 hours;

[0063] Step 4, Drying: Extrude the mixture from Step 3 into cylindrical shapes with a diameter of 5mm, dry at 108℃ for 6 hours until the broken length is about 3-5mm;

[0064] Step 5, calcination: The cylindrical mixture from step 4 is calcined in air at 225°C for 12 hours to obtain a platinum-ruthenium catalyst.

[0065] Example 7

[0066] A method for preparing a platinum-ruthenium catalyst for chlorine production includes the following steps:

[0067] Step 1, Mixing: In a three-necked flask equipped with a reflux condenser, add 10 g of ruthenium nitrite with a ruthenium content of 31.38%, 6.2 g of platinum nitrate solution with a platinum content of 10%, 80 g of deionized water, and 0.12 g of dispersant, and stir to mix evenly;

[0068] Step 2, Dissolution: Add 0.1 ml of a co-solvent to the mixed solution prepared in Step 1, and reflux at 102°C to dissolve. When the solution changes from brownish-red to brownish-black, continue the reaction at 102°C under reflux for 1 hour with stirring. Then stop heating and cool to room temperature. Specifically, the co-solvent is hydrogen peroxide, and the mass percentage concentration of the hydrogen peroxide is 30%.

[0069] Step 3, mixing: Add 146.4 g of silica, 9.07 g of silica hydrosol and 0.1 g of oxalic acid to the solution prepared in Step 2 and mix for 6 hours;

[0070] Step 4, Drying: Extrude the mixture from Step 3 into cylindrical shapes with a diameter of 5mm, dry at 108℃ for 6 hours until the broken length is about 3-5mm;

[0071] Step 5, calcination: The cylindrical mixture from step 4 is calcined in air at 232°C for 12 hours to obtain a platinum-ruthenium catalyst.

[0072] Example 8

[0073] A method for preparing a platinum-ruthenium catalyst for chlorine production includes the following steps:

[0074] Step 1, Mixing: In a three-necked flask equipped with a reflux condenser, add 10 g of ruthenium nitrite with a ruthenium content of 31.38%, 6.276 g of platinum nitrate solution with a platinum content of 10%, 62.17 g of deionized water, and 0.124 g of dispersant, and stir to mix evenly;

[0075] Step 2, Dissolution: Add 0.1 ml of a co-solvent to the mixed solution prepared in Step 1, and reflux at 110°C to dissolve. When the solution changes from brownish-red to brownish-black, continue the reaction at 110°C under reflux for 1 hour, then stop heating and cool to room temperature. Specifically, the co-solvent is hydrogen peroxide, and the mass percentage concentration of the hydrogen peroxide is 30%.

[0076] Step 3, mixing: Add 141.21 g of silica, 8.47 g of silica hydrosol and 0.1 g of oxalic acid to the solution prepared in Step 2 and mix for 6 hours;

[0077] Step 4, Drying: Extrude the mixture from Step 3 into cylindrical shapes with a diameter of 5mm, dry at 120℃ for 6 hours until the broken length is about 3-5mm;

[0078] Step 5, calcination: The cylindrical mixture from step 4 is calcined in air at 240°C for 12 hours to obtain a platinum-ruthenium catalyst.

[0079] The ruthenium recovery rate and analysis results are shown in Table 1.

[0080] Table 1 Product Yield and Analysis Results

[0081]

[0082] Based on the data in Table 1, it can be concluded that Examples 1-8, using the platinum-ruthenium catalyst preparation method provided by the present invention, can achieve the goal of obtaining platinum-ruthenium catalysts with high yield and low impurity content.

[0083] The ruthenium trichloride product prepared in Example 7 of this invention was tested using an ATP-HC208 catalyst activity evaluation platform, and the test results are as follows: Figure 2 As shown, when the temperature reaches 310℃, the hydrogen chloride conversion rate reaches over 95%, which fully meets the industry requirements.

Claims

1. A method for preparing a platinum-ruthenium catalyst for chlorine production, characterized in that, Includes the following steps: Step 1, Mixing: In a three-necked flask equipped with a reflux condenser, add 10-15 grams of ruthenium nitrite with a ruthenium content of 30-32%, 3-10 grams of platinum nitrate solution with a platinum content of 10-12%, 60-150 grams of deionized water, and 0.1-0.3 grams of dispersant, and stir to mix evenly; Step 2, Dissolution: Add 0.1~0.3 ml of co-solvent to the mixed solution prepared in Step 1, and reflux at a temperature of 100~110℃ to dissolve. When the solution changes from brownish-red to brownish-black, continue the reaction at a reflux temperature of 100~110℃. After stirring the reaction for 1 hour, stop heating and cool to room temperature. Step 3, mixing: Add 140-250g of silica, 8-16g of silica hydrosol and 0.1-0.6g of oxalic acid to the solution prepared in Step 2 and mix for 6-8 hours; Step 4, Drying: Extrude the mixture from Step 3 into cylindrical pieces with a diameter of 5 mm, dry at 100~120℃ for 6~8 hours until the broken length is 3-5 mm; Step 5, calcination: The cylindrical mixture from step 4 is calcined in air at 200-240°C for 12-18 hours to obtain a platinum-ruthenium catalyst; In step one, ruthenium nitrite with nitrosyl group is a brownish-red solid; In step one, the amount of deionized water added is such that the ruthenium content in the diluted nitrosyl ruthenium nitrate solution is 2-4%. In step one, the platinum nitrate is a brownish-red solution, and the amount of platinum nitrate added is such that the mass ratio of platinum to ruthenium is 0.1-0.

2. In step one, the dispersant is ethylene glycol, and the amount of dispersant added is such that the content of the dispersant is 0.1-0.2%. In step two, the solvent is hydrogen peroxide, and the mass percentage concentration of the hydrogen peroxide is 30-40%. In step three, the silica is a white powder with a particle diameter of 100 μm, and the amount of silica added is 1.5-1.8 times the mass of the platinum-ruthenium mixed solution. In step three, the silica hydrosol is a pale yellow solution with a silica content of 10%, and the amount of silica hydrosol added is 5-6% of the silica mass.

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