Preparation method of hydrophobic cerium oxide-loaded platinum catalytic material and application of hydrophobic cerium oxide-loaded platinum catalytic material in CO catalytic oxidation in presence of water and sulfur dioxide

Abstract

The invention discloses a preparation method of a hydrophobic cerium oxide loaded platinum catalyst for CO catalytic oxidation in the presence of H2O and SO2. The method is characterized in that a Pt / CeO2 precursor material is prepared by taking platinum salt and cerium salt as main raw materials and alkali as a precipitator through a coprecipitation method. And carrying out surface modification by using an alkyl silane coupling agent to prepare the hydrophobic Pt / CeO2 catalytic material. The preparation method is simple and low in cost; the prepared catalyst has the advantages of high catalytic efficiency, good stability, strong hydrophobicity, strong sulfur dioxide poisoning resistance and the like. And the practical applicability is high, and the method has important significance on pollutant gas emission reduction, energy conservation and consumption reduction.

Description

Technical Field

[0001] The present invention relates to the technical field of catalyst preparation, and in particular to a method for preparing a hydrophobic Pt / CeO2 catalytic material by preparing a precursor material by a coprecipitation method and then surface-modifying the material with an alkylsilane coupling agent, and an application of the same in catalytic oxidation of CO under H2O and SO2 conditions. Background Art

[0002] With the continuous development of my country's industry, the production scale of steel mills has been continuously expanded, and the amount of flue gas generated has also been increasing. CO is the gas with the highest emission in sintering flue gas. CO not only affects the air quality, but also poses a serious threat to human health. Due to the complex composition, high temperature, high humidity, high oxygen and sulfur content, and high dust content of steel mill flue gas, high requirements are placed on the stability of flue gas treatment equipment and catalysts in the process of treating CO flue gas emissions. In order to prevent CO catalyst poisoning, it is generally placed after desulfurization for treatment. However, after desulfurization treatment, there will still be a low concentration of SO2. It will still cause catalyst poisoning, and the catalytic oxidation removal of CO in steel plant flue gas still faces huge challenges. In recent years, it has been found that trace platinum catalysts loaded on cerium oxide carriers have shown excellent catalytic activity for CO, and surface hydrophobic modification can greatly improve the catalytic stability and resistance to sulfur dioxide poisoning. This method is low-cost, simple to prepare, and has practical application value. Summary of the invention

[0003] The object of the present invention is to provide a method for preparing a hydrophobic cerium oxide-supported platinum catalyst by surface modification of an alkylsilane coupling agent for catalytic oxidation of CO under H2O and SO2 conditions. The present invention is achieved by the following technical solutions: The invention discloses a method for preparing a cerium oxide supported platinum catalyst modified by a silane coupling agent for catalytic oxidation of CO under the conditions of H2O and SO2. A cerium oxide supported platinum precursor material is prepared by a coprecipitation method using a base as a precipitant, platinum salt, cerium salt and a silane coupling agent as main raw materials, and a hydrophobic cerium oxide supported platinum catalyst material is prepared by surface modification with an alkyl silane coupling agent. The specific preparation steps are as follows: Step 1: prepare alkali solution, and heat and stir to obtain alkali solution at a certain temperature; Step 2: Dissolve the soluble cerium salt and platinum salt in deionized water in a certain proportion, then slowly add the mixed salt solution drop by drop into an alkaline solution at a certain temperature, and stir continuously to allow the mixed salt solution to react and precipitate completely; Step 3: After the reaction is completed, the precipitate is filtered, washed and dried to obtain the Pt / CeO2 precursor material.

[0004] Step 4: dissolve a certain amount of precursor material Pt / CeO2 in an organic solvent, add a certain amount of silane coupling agent dropwise therein, and then condense and reflux at a certain temperature until the reaction is complete.

[0005] Step 5: After the reaction is completed, the precipitate is filtered, washed and dried to obtain the Pt / CeO2-Si catalyst.

[0006] As a further improvement, the entire process of preparing the precursor material described in the present invention is carried out at a temperature of 60-90°C.

[0007] As a further improvement, the alkali solution described in the present invention is sodium hydroxide or potassium hydroxide.

[0008] As a further improvement, the concentration of the alkali solution of the present invention is 0.3-0.8 mol·L -1 .

[0009] As a further improvement, the molar ratio of the alkali contained in the alkali solution of the present invention to the cerium salt is 3:1 to 8:1.

[0010] As a further improvement, the platinum salt added in the present invention is chloroplatinic acid, sodium chloroplatinate or potassium chloroplatinate.

[0011] As a further improvement, the loading amount of the precious metal described in the present invention is 0.1 wt%~0.5 wt%.

[0012] As a further improvement, the solvent for washing the precursor material in the present invention is deionized water; and the drying temperature is 80°C.

[0013] As a further improvement, the silane coupling agent described in the present invention is one of methyltrimethoxysilane, dimethyldimethoxysilane, trimethylmethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, trimethylethoxysilane or a mixture thereof.

[0014] As a further improvement, the organic solvent described in the present invention is toluene.

[0015] As a further improvement, the amount of the precursor material used in the present invention is 0.5-2 g; the amount of the silane coupling agent used is: 0.5-2 ml.

[0016] As a further improvement, the condensation reflux temperature in the present invention is 110-120°C.

[0017] As a further improvement, the catalyst washing solvent of the present invention is toluene; and the drying temperature is 110°C.

[0018] Positive effects of the present invention: Using alkali as a precipitant, cheap cerium salt, silane coupling agent and a small amount of platinum salt as raw materials, the cerium oxide-loaded platinum precursor material is prepared by co-precipitation method, and the hydrophobic cerium oxide-loaded platinum catalyst is prepared by surface modification with an alkyl silane coupling agent. The preparation process is simple, the cost is low, the catalyst has high catalytic efficiency, good stability, high sulfur resistance, and has practical significance for production application. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is the X-ray diffraction pattern of the catalyst prepared in the embodiment provided by the present invention.

[0020] Figure 2 It is a graph of CO conversion rate of the catalyst prepared by the embodiment provided in the present invention.

[0021] Figure 3 It is a stability test spectrum of the catalyst prepared in the embodiment provided by the present invention.

[0022] Note: The gas composition is: 1% CO, 100 ppm SO2, 15% O2, the rest of the gas is N2, the catalyst dosage is 100 mg, and the space velocity is 30000 mL•g -1 •h -1 . Specific implementation methods The technical solution of the present invention is further described below by means of specific embodiments: Example

[0024] First, dissolve 2.4 g NaOH in 100 ml deionized water to prepare 0.6 mol·L -1 6H2O and 4.95 mg of Na2PtCl6·6H2O were added to 10 ml of deionized water, stirred evenly, and then slowly added to the above NaOH solution, and then stirred continuously for 2 hours. After the reaction was completed, the precipitate was filtered, washed and dried to obtain a Pt / CeO2 precursor material with a Pt loading of 0.1 wt%. Then 50 mg of the precursor material was dissolved in 50 ml of toluene, and then 0.5 ml of methoxytrimethylsilane was slowly added to the above precursor solution and condensed and refluxed at 110 °C for 2 hours. After the reaction was completed, the precipitate was filtered, washed and dried to obtain a 0.1 wt% Pt / CeO2-Si catalyst material modified with a silane coupling agent.

[0025] Example 2 The same operation as in Example 1 was used except that the base was changed to 2.2 g KOH and the mixture was prepared to 0.4 mol·L -1of KOH solution, the platinum salt was changed to 9.13 mg of H2PtCl6·6H2O, the amount of precursor material was changed to 1.5 g, and the silane coupling agent was changed to 1.5 ml of dimethyldiethoxysilane. The Pt loading in the catalyst was 0.2 wt%.

[0026] Example 3 The same operation as in Example 1 was used except that the base was changed to 1.7 g KOH and the mixture was prepared to 0.3 mol·L -1 The KOH solution was replaced with 12.84 mg of K2PtCl6 for platinum salt, 1 g of precursor material, and 0.5 ml of a mixture of dimethyldimethoxysilane and trimethylmethoxysilane for silane coupling agent. The Pt loading in the catalyst was 0.3 wt%.

[0027] Example 4 The same operation as in Example 1 was used except that the base was changed to 1.6 g NaOH and the mixture was prepared to 0.4 mol·L -1 The NaOH solution was used, the platinum salt was changed to 19.80 mg of Na2PtCl6·6H2O, the amount of precursor material was changed to 1.0 g, and the silane coupling agent was changed to a mixture of 0.5 ml of trimethylmethoxysilane and 0.5 ml of trimethylethoxysilane. The Pt loading in the catalyst was 0.4 wt%.

[0028] Example 5 The same operation as in Example 1 was used except that the base was changed to 3.2 g NaOH and the mixture was prepared to 0.8 mol·L -1 The NaOH solution was used, the platinum salt was changed to 22.83 mg of H2PtCl6·6H2O, the amount of precursor material was changed to 2.0 g, and the silane coupling agent was changed to 2 ml of dimethyldiethoxysilane. The Pt loading in the catalyst was 0.5 wt%.

[0029] Finally, it should be noted that the above examples are only a few specific embodiments of the present invention. Obviously, the present invention is not limited to the above embodiments, and there are many variations. All variations that can be directly derived or associated with the content disclosed by a person skilled in the art should be considered as the protection scope of the present invention.

Claims

1. A method for preparing a hydrophobic cerium oxide-supported platinum catalyst for catalytic oxidation of CO in the presence of H2O and SO2. The method is characterized by: Using alkali as precipitant, platinum salt and cerium salt as main raw materials, the Pt / CeO2 precursor material is prepared by co-precipitation method, and then the hydrophobic Pt / CeO2 catalytic material is prepared by surface modification with alkyl silane coupling agent. The specific preparation steps are as follows: Step 1: Prepare alkali solution at a certain temperature; Step 2: Dissolve the soluble cerium salt and platinum salt in deionized water in a certain proportion, then slowly add the mixed salt solution drop by drop into an alkaline solution at a certain temperature, and stir continuously to allow the mixed salt solution to react and precipitate completely; Step 3: Filter the precipitate, wash and dry to obtain the Pt / CeO2 precursor material; Step 4: dissolving a certain amount of Pt / CeO2 precursor material in an organic solvent at a certain temperature, then slowly adding a certain amount of silane coupling agent dropwise into the above solution, and condensing and refluxing; Step 5: Filter the precipitate, wash and dry to obtain the Pt / CeO2-Si catalyst.

2. A method for preparing a catalytic material for catalytic oxidation of CO under H2O and SO2 conditions according to claim 1, characterized in that: The alkali solution is NaOH or KOH.

3. The method for preparing a catalytic material for catalytic oxidation of CO under H2O and SO2 conditions according to claim 1, characterized in that: The alkali solution temperature is controlled at 60-90°C.

4. The method for preparing a catalytic material for catalytic oxidation of CO under H2O and SO2 conditions according to claim 1, characterized in that: The concentration of the alkali solution is 0.3-0.8 mol·L -1 .

5. The method for preparing a catalytic material for catalytic oxidation of CO under H2O and SO2 conditions according to claim 1, characterized in that: The cerium salt is cerium nitrate or cerium chloride.

6. The method for preparing a catalytic material for catalytic oxidation of CO under H2O and SO2 conditions according to claim 1, characterized in that: The added platinum salt is chloroplatinic acid, sodium chloroplatinate or potassium chloroplatinate.

7. The method for preparing a catalytic material for catalytic oxidation of CO under H2O and SO2 conditions according to claim 1, characterized in that: The molar ratio of the alkali contained in the alkali solution to the cerium salt is 3:1 to 8:

1.

8. The method for preparing a catalytic material for catalytic oxidation of CO under H2O and SO2 conditions according to claim 1, characterized in that: The added silane coupling agent is one of methyltrimethoxysilane, dimethyldimethoxysilane, trimethylmethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, trimethylethoxysilane or a mixture thereof.

9. The method for preparing a catalytic material for catalytic oxidation of CO under H2O and SO2 conditions according to claim 1, characterized in that: The precious metal loading is 0.1 wt%~0.5 wt%.

10. Use of the cerium oxide-supported platinum catalyst modified with a silane coupling agent prepared by the preparation method of claim 1 in catalytic oxidation of CO under H2O and SO2 conditions.

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