A method for regenerating an RCO honeycomb platinum catalyst

Abstract

The present application belongs to the technical field of noble metal recovery, and relates to a regeneration method of RCO honeycomb platinum catalyst, which comprises the steps of calcination, pickling, activation, drying and roasting. The method can sequentially remove the carbon deposition, organic sulfur and nitrogen compounds and metal particles in the honeycomb platinum catalyst, complete the regeneration of the honeycomb platinum catalyst without destroying the honeycomb structure, and has low processing cost and complete impurity treatment.

Description

Technical Field

[0001] This invention relates to the field of precious metal recycling technology, and in particular to a method for regenerating RCO honeycomb platinum catalyst. Background Technology

[0002] Catalytic combustion, or Regenerative Catalytic Oxidation (RCO), is one of the most effective processes for treating VOCs (volatile organic compounds). It mainly consists of a pretreatment unit, adsorption unit, desorption unit, heat exchange system, and catalytic combustion unit. Platinum catalyst is the core material in catalytic combustion. Platinum is a precious metal and is relatively expensive. In practical applications, it is usually prepared as a uniformly sized solution and then loaded onto a carrier. Platinum catalysts exhibit high catalytic combustion activity for benzene and toluene, and higher CO2 selectivity when treating chlorine-containing VOCs. Its lifespan is approximately 1.5 years, and the replacement cost is 170,000 RMB / m³. 3 To save costs, platinum catalysts need to be recycled.

[0003] The platinum catalysts used in the above processes generally have a honeycomb structure, which allows organic waste gas passing through it to be oxidized into carbon dioxide and water at a relatively low temperature (from 700-800℃ to 500-600℃). During catalytic combustion, some side reactions occur, producing carbon deposits, organic sulfur and nitrogen compounds, and platinum sulfide. Additionally, the organic waste gas may contain entrained metal elements, which can also remain in the honeycomb structure due to the high temperature. All these factors contribute to clogging of the honeycomb structure, with the contact surfaces becoming covered by impurities, thus reducing the catalytic effect. Furthermore, the honeycomb structure is inconvenient to clean mechanically.

[0004] CN115275241A provides a method for recycling and regenerating spent platinum catalysts. This method involves ball milling the platinum catalyst, adding a pore-forming agent for hydrothermal reaction, drying, calcining, washing, adding chloroplatinic acid, and calcining again to obtain a regenerated platinum catalyst. However, the honeycomb structure is completely destroyed during ball milling, and chloroplatinic acid is also very expensive, making the processing cost too high in this method.

[0005] Therefore, it is necessary to develop a new regeneration method to solve the above problems. Summary of the Invention

[0006] The main objective of this invention is to provide a method for regenerating RCO honeycomb platinum catalyst, which can remove internal impurities without damaging the honeycomb structure of the platinum catalyst, and at a low cost.

[0007] This invention achieves the above objective through the following technical solution: a method for regenerating an RCO honeycomb platinum catalyst, comprising the following steps:

[0008] S1. Calcination: The honeycomb platinum catalyst is calcined at 600-850℃ for 3-4 hours;

[0009] S2. Acid washing: Immerse the honeycomb platinum catalyst in an acid solution in which platinum is insoluble for 0.5-1 hour, and then wash it with pure water;

[0010] S3. Activation: Soak the honeycomb platinum catalyst in a strong alkali and add hydrazine to react for 2-3 hours. The mass ratio of hydrazine to honeycomb platinum catalyst is 0.5-1.5. Finally, wash with pure water.

[0011] S4. Drying: Dry the honeycomb platinum catalyst at a temperature of 100-150℃;

[0012] S5. Calcination: The honeycomb platinum catalyst is calcined at 400-800℃ for 2-3 hours, and then cooled to obtain the regenerated honeycomb platinum catalyst.

[0013] Specifically, the acid solution is 10-20 wt% hydrochloric acid.

[0014] Specifically, the strong alkali is a 5 g / L sodium hydroxide solution.

[0015] Specifically, the water washing step and the activation step each involve rinsing with pure water 3 times.

[0016] Specifically, the drying time for the drying step is 3-4 hours.

[0017] The beneficial effects of the technical solution of this invention are:

[0018] This method can sequentially remove carbon deposits, organic sulfur and nitrogen compounds, and metal particles from the honeycomb platinum catalyst, regenerating the honeycomb platinum catalyst without damaging the honeycomb structure. It has low processing costs and thoroughly removes impurities. Detailed Implementation

[0019] The present invention will be further described in detail below with reference to specific embodiments.

[0020] Example:

[0021] A method for regenerating RCO honeycomb platinum catalyst, comprising the following steps:

[0022] S1. Calcination: Place the honeycomb platinum catalyst in an oven and calcine it at 600-850℃ for 3-4 hours.

[0023] The above temperatures will not melt the honeycomb platinum catalyst. In the presence of airflow, calcination can oxidize the carbon deposits and organic sulfur and nitrogen compounds in the honeycomb platinum catalyst into CO2, SO2, and N2. x O yThese are all gaseous substances, so they can escape from the gaps in the honeycomb platinum catalyst.

[0024] S2. Acid washing: Immerse the honeycomb platinum catalyst in an acid solution that does not dissolve platinum for 0.5-1 hour, and then wash it with pure water.

[0025] For reactive metals and their oxides trapped in the gaps, an acid solution can be used to convert them into metal cations, which then flow out of the honeycomb platinum catalyst with the solution. To avoid consuming the alkali solution due to residual acidic solution, the catalyst is washed three times with pure water.

[0026] Acids are used to dissolve active metals and their oxides; hydrochloric acid, dilute sulfuric acid, and dilute nitric acid can be used. However, to save costs and facilitate subsequent processing, 10-20 wt% hydrochloric acid is preferred.

[0027] S3. Activation: Soak the honeycomb platinum catalyst in a strong alkali and add hydrazine to react for 2-3 hours. The mass ratio of hydrazine to honeycomb platinum catalyst is 0.5-1.5. Finally, wash with pure water.

[0028] Strong bases are used to provide OH- - For anions, sodium hydroxide solution, potassium hydroxide solution, sodium carbonate solution, etc. can be used. Here, a 5g / L sodium hydroxide solution is used.

[0029] The main reaction that occurs in this step is:

[0030] PtS + N₂H₄ + OH⁻ - +H₂O→Pt+NH₃·H₂O+SO₃ 2- .

[0031] The above reaction reduces platinum sulfide to platinum, while sulfur is oxidized to sulfite ions which enter the solution. The byproduct ammonia gas mainly dissolves in water to form ammonia water, while a small portion forms a platinum-ammonia complex with platinum. After the reaction, the catalyst should be rinsed three times with pure water to remove sulfite ions and ammonia water from the honeycomb platinum catalyst.

[0032] S4. Drying: Place the honeycomb platinum catalyst in an oven and dry it at a temperature of 100-150℃.

[0033] After washing, water residue will inevitably remain in the pores of the honeycomb platinum catalyst, so the moisture must be evaporated at a temperature slightly above the boiling point of water. To ensure dryness, the drying time is 3-4 hours. This also ensures that the honeycomb platinum catalyst is in an anhydrous state during calcination.

[0034] S5. Calcination: The honeycomb platinum catalyst is placed in a calcination furnace and calcined at 400-800℃ for 2-3 hours. After cooling, the regenerated honeycomb platinum catalyst is obtained.

[0035] The small amount of platinum-ammonia complex remaining in the honeycomb platinum catalyst will decompose into platinum and ammonia at this temperature. Since ammonia is a gas, it will escape and not remain in the structure, thus eliminating new impurities introduced by the use of hydrazine.

[0036] In summary, this method can sequentially remove carbon deposits, organic sulfur and nitrogen compounds, and metal particles from the honeycomb platinum catalyst, regenerating the honeycomb platinum catalyst without damaging the honeycomb structure. It has low processing costs and thoroughly removes impurities.

[0037] The above are merely some embodiments of the present invention. For those skilled in the art, various modifications and improvements can be made without departing from the inventive concept of the present invention, and all such modifications and improvements fall within the scope of protection of the present invention.

Claims

1. A method for regenerating an RCO honeycomb platinum catalyst, characterized in that the steps include... include: S1. Calcination: The honeycomb platinum catalyst is calcined at 600-850℃ for 3-4 hours, and the calcination is carried out under air flow conditions. S2. Acid washing: Immerse the honeycomb platinum catalyst in an acid solution in which platinum is insoluble for 0.5-1 hour, and then wash it with pure water; S3. Activation: Soak the honeycomb platinum catalyst in a strong alkali and add hydrazine to react for 2-3 hours. The mass ratio of hydrazine to honeycomb platinum catalyst is 0.5-1.

5. Finally, wash with pure water. S4. Drying: Dry the honeycomb platinum catalyst at a temperature of 100-150℃; S5. Calcination: The honeycomb platinum catalyst is calcined at 400-800℃ for 2-3 hours, and then cooled to obtain the regenerated honeycomb platinum catalyst.

2. The regeneration method for the RCO honeycomb platinum catalyst according to claim 1, characterized in that: The acid solution is 10-20 wt% hydrochloric acid.

3. The regeneration method for the RCO honeycomb platinum catalyst according to claim 1, characterized in that: The strong alkali is a 5 g / L sodium hydroxide solution.

4. The regeneration method for the RCO honeycomb platinum catalyst according to claim 1, characterized in that: The washing and activation steps each involve rinsing with pure water three times.

5. The regeneration method for the RCO honeycomb platinum catalyst according to claim 1, characterized in that: The drying time for the drying step is 3-4 hours.