Preparation method of Ce-Ti-S catalyst for efficiently removing methylbenzene and NOx at low temperature

Abstract

The invention discloses a preparation method of a Ce-Ti-S catalyst for efficiently removing methylbenzene and NOx at a low temperature, and belongs to the technical field of catalysts. The preparation method comprises the following steps: dissolving titanyl sulfate in deionized water to obtain a titanium source solution, adding an ammonium carbonate solution to adjust the pH value to obtain a TiO2 precursor precipitate, washing with water, drying and roasting to obtain a TiO2 carrier; the preparation method comprises the following steps: mixing a TiO2 carrier with a Ce source precursor salt solution, uniformly depositing Ce ions on the surface of TiO2, filtering and drying the mixture, and roasting to obtain a CeO2-loaded Ce-Ti composite material; and mixing the Ce-Ti composite material with a concentrated sulfuric acid solution, reacting to introduce a sulfate group, and washing and drying after the reaction is completed to obtain the Ce-Ti-S catalyst. According to the present invention, the catalytic performance of the catalyst is optimized by reasonably regulating the oxygen vacancy, the acid site and the electronic structure in the catalyst, such that the efficient, stable and low-cost catalyst is provided, and the catalyst is used for efficiently and jointly removing toluene and NOx pollutants at the low temperature.

Description

Technical Field

[0001] The present invention relates to the field of catalyst technology, in particular to a method for removing toluene and NO with high efficiency at low temperature. x Preparation method of Ce-Ti-S catalyst. Background Art

[0002] With the advancement of industrialization, toluene and nitrogen oxides (NO x The emission of NOx is becoming increasingly serious, causing significant pollution to the environment. Toluene is a volatile organic compound (VOCs). Long-term presence in the air will have serious effects on human health and have an adverse impact on the ecological environment. x As the precursor of photochemical smog and acid rain, it also poses a serious threat to the ecological environment and human health. x The efficient removal of pollutants has become an important issue in current environmental governance.

[0003] Existing catalysts usually target toluene or NO x The removal of single pollutants was good, but the removal of toluene and NO x The coordinated governance of toluene and NO has not been effectively solved, and it is difficult to remove toluene and NO simultaneously and efficiently. x , and there are often competing adsorption and reaction problems. x The removal of chlorinated carbon often faces the following challenges:

[0004] 1. Insufficient low-temperature activity: Traditional catalysts often exhibit better catalytic performance only at higher temperatures, which makes them subject to temperature restrictions in practical applications. Especially in low-temperature environments, the activity and conversion rate of the catalysts drop significantly.

[0005] 2. Poor stability of catalysts: Existing catalysts will experience activity decline during long-term operation, especially in environments with high pollution loads. The stability of the catalysts is poor, resulting in a rapid decrease in the catalytic effect.

[0006] 3. Higher cost: Many existing catalysts use precious metals or high-cost materials. Although they have high removal efficiency, their high cost and poor stability in highly polluted environments limit their large-scale application.

[0007] Therefore, a low-cost, high-efficiency and long-term stable method for removing toluene and NO was developed. x catalyst, has become a problem that needs to be solved urgently. Summary of the invention

[0008] The purpose of the present invention is to provide a method for removing toluene and NO at low temperature and high efficiency. xPreparation method of Ce-Ti-S catalyst to solve the problem of toluene and NO x The problems existing in the combined removal process include low catalytic efficiency and poor long-term stability of the catalyst.

[0009] To achieve the above object, the present invention provides a method for removing toluene and NO at low temperature and high efficiency. x The preparation method of the Ce-Ti-S catalyst comprises the following steps:

[0010] S1、TiO 2 Preparation of vector

[0011] Titanyl sulfate was dissolved in deionized water to obtain a titanium source solution, and then ammonium carbonate solution was added to adjust the pH to obtain TiO 2 The precursor is precipitated, the precipitate is washed with water to remove impurities, and then dried and calcined to obtain TiO 2 Carrier;

[0012] S2、CeO 2 Introduction

[0013] TiO 2 The carrier is mixed with the Ce source precursor salt solution, and the Ce ions are uniformly deposited on the TiO 2 The mixture was filtered and dried, and then calcined to obtain CeO 2 Ce-Ti composite materials;

[0014] S3, catalyst sulfide modification

[0015] The Ce-Ti composite material is mixed with a concentrated sulfuric acid solution, and sulfate groups are introduced by reaction to increase surface acid sites. After the reaction is completed, deionized water is used to wash and remove residual sulfuric acid. After drying, the mixture is ground and sieved to obtain a Ce-Ti-S catalyst.

[0016] Preferably, in S1, the amount of titanyl sulfate is 10-100 mmol, the concentration of the titanium source solution is 0.1-1 mol / L; the concentration of the ammonium carbonate solution is 5-10 mol / L, and the amount is 100-200 mL.

[0017] Preferably, in S1, the pH value is adjusted to 9-11; the drying temperature is 60-80°C, and the drying time is 12-48 hours; the roasting temperature is 300-500°C, and the roasting time is 4-6 hours.

[0018] Preferably, in S2, the Ce source precursor salt is one of cerium nitrate, cerium sulfate, cerium chloride, and ammonium cerium nitrate.

[0019] Preferably, in S2, CeO 2The loading amount is 1-30wt.%, the calcination temperature is 300-600°C, and the calcination time is 3-6h.

[0020] Preferably, in S3, the concentration of concentrated sulfuric acid solution is 0-2 mol / L, the dosage is 1-30 mL; the drying temperature is 60-80° C., and the drying time is 12-48 h.

[0021] Therefore, the present invention provides a low-temperature and high-efficiency combined synergistic removal of toluene and NO x The preparation method of Ce-Ti-S catalyst improves its catalytic activity and stability by rationally regulating the oxygen vacancies, acidic sites and electronic structure in the catalyst.

[0022] This highly efficient, stable and low-cost catalyst can achieve efficient synergistic removal of toluene and NO at lower temperatures. x This new catalyst can overcome the defects of existing technologies, show high catalytic efficiency and long-term stability under low temperature environment, and has broad industrial application prospects.

[0023] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The catalytic performance curve of the Ce-Ti-S catalyst prepared in the embodiment of the present invention for single removal of toluene at different temperatures;

[0025] Figure 2 The Ce-Ti-S catalyst prepared in the present invention has a NO conversion rate of 2.3 % at different temperatures. x Catalytic performance curve for single removal;

[0026] Figure 3 The Ce-Ti-S catalyst prepared in the present invention has a good effect on toluene and NO at different temperatures. x Catalytic performance curves for combined removal;

[0027] Figure 4 The Ce-Ti-S catalyst prepared in the present invention has a high activity for toluene and NO at 350°C. x The conversion rate curve of toluene in the 50-hour stability test of combined removal is shown;

[0028] Figure 5 The Ce-Ti-S catalyst prepared in the present invention has a high activity for toluene and NO at 350°C. x Conduct a 50-hour stability test on the combined removal of NO x Conversion rate curve diagram. DETAILED DESCRIPTION

[0029] The technical solution of the present invention is further described below by means of the accompanying drawings and embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention. Any other changes, modifications, substitutions, combinations, simplifications made without violating the spirit and principle of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention. In addition, it should be understood that after reading the content of the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the claims attached to this application and belong to the scope of protection of the present invention.

[0030] Reference to "embodiment" herein means that the specific features, structures or characteristics described in conjunction with the embodiment may be included in at least one embodiment of the present application. The term "embodiment" appearing in various places in the specification does not necessarily refer to the same embodiment, nor does it particularly limit its independence or association with other embodiments. In principle, in the present application, as long as there is no technical contradiction or conflict, the various technical features mentioned in the embodiments can be combined in any way to form a corresponding implementable technical solution.

[0031] Unless otherwise defined, the technical terms used in this document have the same meanings as those generally understood by those skilled in the art to which this application belongs; the use of relevant terms in this document is only for describing specific embodiments and is not intended to limit this application.

[0032] Unless otherwise specified in the present invention, the reagents, instruments, and equipment used are those commonly used by technicians in this field.

[0033] Example

[0034] This embodiment provides a method for preparing a Ce-Ti-S catalyst, comprising the following steps:

[0035] Step 1: TiO 2 Preparation of vector

[0036] 20 mmol of titanyl sulfate (TiOSO 4 ) was dissolved in deionized water to obtain a titanium source solution with a concentration of 0.2 mol / L. Then 100 mL of 8 mol / L ammonium carbonate solution was added to the solution and the pH value of the solution was adjusted to 9.5 to obtain TiO 2 The precursor was precipitated. The precipitate was washed with water to remove impurities in the solution. The precipitate was then dried at 80°C for 24 hours. Finally, it was calcined at 500°C for 3 hours to obtain TiO 2 carrier.

[0037] Step 2: CeO 2 Introduction

[0038] TiO 2 The carrier is mixed with cerium nitrate solution, and the Ce ions are uniformly deposited on the TiO 2 The mixture was filtered and dried, and then calcined at 500 °C for 3 hours to obtain CeO 2 Ce-Ti composite material with a loading of 15wt.%.

[0039] Step 3: Catalyst sulfidation modification

[0040] 2 g of the obtained Ce-Ti composite material was mixed with 25 mL of a 0.5 M concentrated sulfuric acid solution to introduce sulfate groups in the reaction to increase surface acid sites. After the reaction, the catalyst surface was washed with deionized water to remove residual sulfuric acid. The modified catalyst was then dried at 80 ° C for 24 hours. The dried Ce-Ti-S catalyst was ground and sieved to obtain the final catalyst.

[0041] Removal of toluene and NO x Verification of catalytic performance and stability:

[0042] The Ce-Ti-S catalyst prepared in this example was placed at a temperature of 150°C to 450°C to react with toluene and NO. x Single and combined removal experiments were conducted to verify its catalytic removal efficiency and low temperature stability. Figure 1-Figure 5 shown.

[0043] like Figure 1-Figure 3 It can be seen that the Ce-Ti-S catalyst can efficiently remove toluene and NO simultaneously in the temperature range of 350°C to 450°C. x .

[0044] like Figure 4-Figure 5 It can be seen that the toluene conversion rate of the catalyst decreased by less than 0.2% during the 50-hour stability test at 350°C ( Figure 4 ), NO x The removal rate is maintained above 90% ( Figure 5 ). This indicates that the catalyst has better activity at low temperatures and is more stable in long-term use.

[0045] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A low-temperature and efficient method for removing toluene and NO x The method for preparing a Ce-Ti-S catalyst is characterized in that: The following steps are involved: Preparation of S1 and TiO2 carrier Dissolve titanyl sulfate in deionized water to obtain a titanium source solution, then add an ammonium carbonate solution, adjust the pH to obtain a TiO2 precursor precipitate, wash with water to remove impurities, dry the precipitate, and calcine to obtain a TiO2 carrier; Introduction of S2 and CeO2 The TiO2 carrier is mixed with a Ce source precursor salt solution, and Ce ions are uniformly deposited on the TiO2 surface by a liquid phase impregnation method, and the mixture is filtered and dried, and then calcined to obtain a Ce-Ti composite material loaded with CeO2; S3, catalyst sulfide modification The Ce-Ti composite material is mixed with a concentrated sulfuric acid solution to introduce sulfate groups through reaction. After the reaction is completed, it is washed with deionized water, dried, ground and sieved to obtain a Ce-Ti-S catalyst.

2. A method for removing toluene and NO at low temperature and high efficiency according to claim 1 x The preparation method of Ce-Ti-S catalyst is characterized by: In S1, the amount of titanyl sulfate is 10-100 mmol, the concentration of the titanium source solution is 0.1-1 mol / L; the concentration of the ammonium carbonate solution is 5-10 mol / L, and the amount is 100-200 mL.

3. A method for removing toluene and NO at low temperature and high efficiency according to claim 1 x The preparation method of Ce-Ti-S catalyst is characterized by: In S1, the pH value is adjusted to 9-11; the drying temperature is 60-80°C, and the drying time is 12-48h; the roasting temperature is 300-500°C, and the roasting time is 4-6 hours.

4. A method for removing toluene and NO at low temperature and high efficiency according to claim 1 x The preparation method of Ce-Ti-S catalyst is characterized by: In S2, the Ce source precursor salt is one of cerium nitrate, cerium sulfate, cerium chloride, and ammonium cerium nitrate.

5. A method for removing toluene and NO at low temperature and high efficiency according to claim 1 x The preparation method of Ce-Ti-S catalyst is characterized by: In S2, the CeO2 loading is 1-30wt.%, the calcination temperature is 300-600°C, and the calcination time is 3-6h.

6. A method for removing toluene and NO at low temperature and high efficiency according to claim 1 x The preparation method of Ce-Ti-S catalyst is characterized by: In S3, the concentration of concentrated sulfuric acid solution is 0-2 mol / L, the dosage is 1-30 mL; the drying temperature is 60-80° C., and the drying time is 12-48 h.

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