Titanium dioxide-based catalyst, preparation method thereof and application of titanium dioxide-based catalyst in catalytic ozonation of VOCs toluene

Abstract

The invention discloses a titanium dioxide-based catalyst, a preparation method thereof and application of the titanium dioxide-based catalyst in catalytic ozonation of VOCs toluene, and belongs to the technical field of low-temperature catalytic oxidation. The preparation method of the titanium dioxide-based catalyst comprises the following steps: mixing titanium dioxide with a soluble metal solution to obtain a turbid liquid; and drying the turbid liquid, and calcining to obtain the titanium dioxide-based catalyst. The soluble metal solution is one or more of a soluble copper salt solution, a soluble platinum salt solution, a soluble cobalt salt solution and a soluble palladium salt solution. In addition, the invention also provides the titanium dioxide-based catalyst which is prepared by the preparation method. In addition, the invention also provides an application of the titanium dioxide-based catalyst in catalytic ozonation of toluene. The titanium dioxide-based catalyst provided by the invention can efficiently catalyze VOCs at low temperature, especially has 100% catalytic activity at 75 DEG C, and realizes low-temperature removal of toluene.

Description

Technical Field

[0001] The invention relates to the technical field of low-temperature catalytic oxidation, and in particular to a titanium dioxide-based catalyst and a preparation method thereof, and application thereof in catalytic ozonation of VOCs toluene. Background Art

[0002] In recent years, volatile organic compounds (VOCs) emitted from fixed and mobile sources have seriously threatened the environment and human health. Therefore, developing a technology to eliminate volatile organic compounds is an urgent and challenging task to protect environmental sustainability and human health. Single-atom catalysts are widely used in catalytic reactions due to their special coordination environment, extremely high atomic utilization, and highly uniform catalytic sites. Titanium dioxide has three crystal forms: brookite, anatase, and rutile. Among them, brookite is a good catalyst carrier because of its diverse surface oxygen species and easy surface modification. Loading metals on the carrier can increase the reaction active sites and improve the efficiency of the catalytic reaction. Currently, copper-based, cobalt-based, platinum-based, etc. are commonly used to load on metal carriers to improve the catalytic reaction activity. At present, traditional catalytic oxidation technology eliminates VOCs at a high temperature and consumes a lot of energy.

[0003] Therefore, how to develop catalysts with high activity at low temperatures is also one of the key technical issues that we urgently need to solve. Summary of the invention

[0004] The purpose of the present invention is to overcome the above technical deficiencies, provide a titanium dioxide-based catalyst and its preparation method and its application in catalytic ozonation of VOCs toluene, and solve the technical problems of high temperature and high energy consumption of the catalyst in the prior art for catalyzing VOCs.

[0005] In order to achieve the above technical objectives, the technical solution of the present invention provides a method for preparing a titanium dioxide-based catalyst, comprising the following steps: mixing titanium dioxide with a soluble metal solution to obtain a suspension; drying the suspension, and then calcining to obtain the titanium dioxide-based catalyst; the soluble metal solution is one or more of a soluble copper salt solution, a soluble platinum salt solution, a soluble cobalt salt solution and a soluble palladium salt solution.

[0006] In any embodiment, the titanium dioxide is titanium dioxide with oxygen vacancies, and the titanium dioxide with oxygen vacancies is prepared by the following steps: a mixed gas is introduced into the titanium dioxide, and the temperature is raised to 550-600°C and calcined to obtain the titanium dioxide with oxygen vacancies; the mixed gas is a mixed gas of hydrogen and nitrogen; the volume ratio of the hydrogen and nitrogen is 1:(8-9).

[0007] In any embodiment, the calcination time at 550-600° C. is 4-5 hours.

[0008] In any embodiment, the calcination temperature is 400-450°C.

[0009] In any embodiment, the calcination time is 3-4 hours.

[0010] In any embodiment, in the suspension, the mass ratio of the metal in the soluble metal solution to the titanium dioxide is (2-8):100.

[0011] In any embodiment, the copper salt in the soluble copper salt solution is one or both of copper nitrate trihydrate and copper sulfate pentahydrate; and / or, the platinum salt in the soluble platinum salt solution is one or both of tetraammine platinum nitrate and chloroplatinic acid; and / or, the cobalt salt in the soluble cobalt salt solution is cobalt nitrate hexahydrate.

[0012] In any embodiment, drying the suspension comprises: subjecting the suspension to rotary evaporation and vacuum drying; the rotary evaporation temperature is 60-70° C.; the vacuum drying temperature is 55-65° C., and the time is 8-12 hours.

[0013] In addition, the present invention also provides a titanium dioxide-based catalyst prepared by the above preparation method.

[0014] In addition, the present invention also proposes a titanium dioxide-based catalyst prepared by the above preparation method or the use of the above titanium dioxide-based catalyst in catalytic ozonation of toluene.

[0015] Compared with the prior art, the beneficial effects of the present invention include: mixing titanium dioxide with a soluble metal solution to obtain a suspension; drying the suspension and then calcining to obtain the titanium dioxide-based catalyst; the soluble metal solution is one or more of a soluble copper salt solution, a soluble platinum salt solution, a soluble cobalt salt solution and a soluble palladium salt solution; the obtained titanium dioxide-based catalyst can efficiently catalyze VOCs at low temperature, especially has 100% catalytic activity at 75°C, and realizes low-temperature removal of toluene. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The TiO2 of Example 1 and the TiO2-O of Example 2 are v And the XRD patterns of the catalysts prepared in Examples 1-2, Example 5 and Example 7.

[0017] Figure 2 The TiO2 of Example 1 and the TiO2-O of Example 2 are v And the Raman spectra of the catalysts prepared in Examples 1-2, Example 5 and Example 7.

[0018] Figure 3The TiO2 of Example 1 and the TiO2-O of Example 2 are v , Cu / TiO2 prepared in Example 1, Cu / TiO2-O prepared in Example 2 v Catalytic activity test results.

[0019] Figure 4 1 is a graph showing the catalytic activity test results of the catalysts prepared in Examples 6 and 7 of the present invention. DETAILED DESCRIPTION

[0020] The "range" disclosed in the present application is defined in the form of a lower limit and an upper limit, and a given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundaries of the particular range. The range defined in this way can be inclusive or exclusive of the end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a range. For example, if a range of 60 to 120 and 80 to 110 is listed for a particular parameter, it is understood that a range of 60 to 110 and 80 to 120 is also expected. In addition, if the minimum range values ​​1 and 2 are listed, and if the maximum range values ​​3, 4 and 5 are listed, the following ranges can all be expected: 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4 and 2 to 5. In the present application, unless otherwise specified, the numerical range "a to b" represents an abbreviation of any real number combination between a and b, where a and b are both real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0021] If there is no special explanation, the "include" and "comprising" mentioned in this application are open-ended or closed-ended. For example, the "include" and "comprising" may mean that other components not listed may also be included or only the listed components may be included or only the listed components may be included.

[0022] If not specifically stated, in this application, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, any of the following conditions satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0023] The present specific embodiment provides a method for preparing a titanium dioxide-based catalyst, comprising the following steps: mixing titanium dioxide with a soluble metal solution to obtain a suspension; drying the suspension, and then calcining at 400-450° C. for 3-4 hours to obtain the titanium dioxide-based catalyst; the soluble metal solution is one or more of a soluble copper salt solution, a soluble platinum salt solution, a soluble cobalt salt solution, and a soluble palladium salt solution; in the suspension, the metal in the soluble metal solution and the titanium dioxide The mass ratio of titanium is (2-8):100; the copper salt in the soluble copper salt solution is one or both of copper nitrate trihydrate and copper sulfate pentahydrate; the platinum salt in the soluble platinum salt solution is one or both of tetraammine platinum nitrate and chloroplatinic acid; the cobalt salt in the soluble cobalt salt solution is cobalt nitrate hexahydrate; drying the suspension comprises: rotary evaporation of the suspension and vacuum drying; the rotary evaporation temperature is 60-70°C; the vacuum drying temperature is 55-65°C and the time is 8-12 hours.

[0024] In some embodiments, the titanium dioxide is titanium dioxide with oxygen vacancies, and the titanium dioxide with oxygen vacancies is prepared by the following steps: a mixed gas is introduced into the titanium dioxide, the temperature is raised to 550-600°C and calcined for 4-5 hours to obtain the titanium dioxide with oxygen vacancies; the mixed gas is a mixed gas of hydrogen and nitrogen; the volume ratio of hydrogen to nitrogen is 1:(8-9).

[0025] This specific embodiment also provides a titanium dioxide-based catalyst prepared by the above preparation method.

[0026] In addition, this specific embodiment also proposes a titanium dioxide-based catalyst prepared by the above preparation method or the use of the above titanium dioxide-based catalyst in catalytic ozonation of toluene.

[0027] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0028] In the present invention, reference is made to “some embodiments”, “this embodiment”, examples, etc., which describe a subset of all possible embodiments, but it can be understood that “some embodiments” may be the same subset or different subsets of all possible embodiments and may be combined with each other without conflict.

[0029] If similar descriptions of "first / second" appear in the application documents, the following instructions are added. In the following description, the terms "first\second\third" involved are merely used to distinguish similar objects and do not represent a specific ordering of the objects. It can be understood that "first\second\third" can be interchanged in a specific order or sequence where permitted, so that the embodiments described herein can be implemented in an order other than that illustrated or described herein.

[0030] In this embodiment, the term "and / or" is merely a description of the association relationship between associated objects, indicating that three relationships may exist. For example, object A and / or object B may represent three situations: object A exists alone, object A and object B exist at the same time, and object B exists alone.

[0031] Hereinafter, the embodiments of the present application will be described. The embodiments described below are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. If no specific techniques or conditions are indicated in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. If the manufacturer is not indicated in the reagents or instruments used, they are all conventional products that can be obtained commercially.

[0032] Example 1

[0033] This embodiment provides a titanium dioxide-based catalyst, which is prepared by the following steps:

[0034] Weigh 100 mg of copper nitrate trihydrate and add it to a 250 mL beaker. Then add a certain amount of distilled water and pour it into the beaker. After uniform dispersion under ultrasonic conditions for 10 minutes, pour the liquid into a 250 mL volumetric flask and adjust the volume to obtain solution A.

[0035] Use a 1 / 10,000 analytical balance to weigh 200 mg of brookite titanium dioxide powder (labeled as TiO2) into an eggplant-shaped bottle, add a stirring magnet, and then use a 50 mL measuring cylinder to measure 10 mL of solution A and add it to the above eggplant-shaped bottle. Use a pipette to add 10 mL of distilled water under stirring at room temperature at a speed of 300 rpm, and fully stir the reaction at room temperature for 2 hours to obtain dispersion B. At this time, the metal atoms have been successfully loaded on the brookite titanium dioxide carrier without oxygen vacancies;

[0036] The stirring bar was removed, and the dispersion B was evaporated to dryness at 65°C, and then transferred to a vacuum dryer and dried at a constant temperature of 60°C for 10 hours to obtain solid C; solid C was placed in a tubular furnace and calcined at 400°C in a nitrogen atmosphere for 4 hours to obtain a single-atom copper titanium dioxide catalyst without oxygen vacancies. The obtained catalyst was labeled Cu-TiO2.

[0037] Example 2

[0038] This embodiment provides a titanium dioxide-based catalyst, which is prepared by the following steps:

[0039] The brookite titanium dioxide powder was placed in a tube furnace, and a gas mixture with a flow rate of H2:N2 of 20 mL:180 mL was introduced. The temperature was raised to 600 °C and calcined for 5 hours to obtain brookite titanium dioxide with oxygen vacancies (labeled as TiO2-O v );

[0040] Weigh 100 mg of copper nitrate trihydrate and add it to a 250 mL beaker. Then add a certain amount of distilled water and pour it into the beaker. After uniform dispersion under ultrasonic conditions for 10 minutes, pour the liquid into a 250 mL volumetric flask and adjust the volume to obtain solution A.

[0041] 200 mg of brookite titanium dioxide with oxygen vacancies was weighed using a 1 / 10,000 analytical balance and added to an eggplant-shaped bottle, a stirring magnet was added, and 10 mL of solution A was measured using a 50 mL measuring cylinder and added to the eggplant-shaped bottle, 10 mL of distilled water was added using a pipette under stirring at room temperature at a speed of 300 rpm, and the mixture was stirred for 2 h at room temperature to obtain dispersion B, at which point the metal atoms had been successfully loaded on the brookite titanium dioxide carrier with oxygen vacancies;

[0042] The stirring bar was removed, and the dispersion B was evaporated to dryness at 65°C, and then transferred to a vacuum dryer and dried at a constant temperature of 60°C for about 10 hours to obtain solid C; solid C was placed in a tube furnace and calcined at 400°C in a nitrogen atmosphere for 4 hours to obtain a single-atom copper-titanium dioxide catalyst with oxygen vacancies. The obtained catalyst was labeled Cu-TiO2-O v .

[0043] Example 3

[0044] This embodiment provides a titanium dioxide-based catalyst, which is prepared by the following steps:

[0045] The brookite titanium dioxide powder was placed in a tube furnace, and a mixed gas with a flow rate of H2:N2 of 20 mL:180 mL was introduced, and the temperature was raised to 600° C. and calcined for 5 hours to obtain brookite titanium dioxide with oxygen vacancies;

[0046] Weigh 100 mg of tetraammine platinum nitrate and add it to a 250 mL beaker. Then add a certain amount of distilled water and pour it into the beaker. After uniform dispersion under ultrasonic conditions for 10 minutes, pour the liquid into a 250 mL volumetric flask and adjust the volume to obtain solution A.

[0047] 200 mg of brookite titanium dioxide with oxygen vacancies was weighed using a 1 / 10,000 analytical balance and added to an eggplant-shaped bottle, a stirring magnet was added, and 10 mL of solution A was measured using a 50 mL measuring cylinder and added to the eggplant-shaped bottle, 10 mL of distilled water was added using a pipette under stirring at room temperature at a speed of 200 rpm, and the mixture was stirred for 2 h at room temperature to obtain dispersion B, at which point the metal atoms had been successfully loaded on the brookite titanium dioxide carrier with oxygen vacancies;

[0048] The stirring bar was removed, and the dispersion B was evaporated to dryness at 65°C, and then transferred to a vacuum dryer and dried at a constant temperature of 55°C for 12 hours to obtain solid C; solid C was placed in a tubular furnace and calcined at 450°C in a nitrogen atmosphere for 3 hours to obtain a single-atom platinum titanium dioxide catalyst with oxygen vacancies.

[0049] Example 4

[0050] This embodiment provides a titanium dioxide-based catalyst, which is prepared by the following steps:

[0051] The brookite titanium dioxide powder was placed in a tube furnace, and a mixed gas with a flow rate of H2:N2 of 20 mL:180 mL was introduced, and the temperature was raised to 550° C. and calcined for 4 hours to obtain brookite titanium dioxide with oxygen vacancies;

[0052] Weigh 100 mg of cobalt nitrate hexahydrate and add it to a 250 mL beaker. Then add a certain amount of distilled water and pour it into the beaker. After uniform dispersion under ultrasonic conditions for 10 minutes, pour the liquid into a 250 mL volumetric flask and adjust the volume to obtain solution A.

[0053] 200 mg of brookite titanium dioxide with oxygen vacancies was weighed using a 1 / 10,000 analytical balance and added to an eggplant-shaped bottle, a stirring magnet was added, and 20 mL of solution A was measured using a 50 mL measuring cylinder and added to the eggplant-shaped bottle, 10 mL of distilled water was added using a pipette under stirring at room temperature at a speed of 400 rpm, and the mixture was stirred for 2 h at room temperature to obtain dispersion B, at which point the metal atoms had been successfully loaded on the brookite titanium dioxide carrier with oxygen vacancies;

[0054] The stirring bar was removed, and the dispersion B was evaporated to dryness at 70°C, and then transferred to a vacuum drying machine and dried at a constant temperature of 65°C for 8 hours to obtain solid C; solid C was placed in a tubular furnace and calcined at 450°C in a nitrogen atmosphere for 3.5 hours to obtain a single-atom cobalt titanium dioxide catalyst with oxygen vacancies.

[0055] Example 5

[0056] The preparation method of the titanium dioxide-based catalyst of this embodiment is different from that of Example 2 only in that solution A contains tetraammine platinum nitrate in addition to copper nitrate, and the other reaction steps and raw materials are the same as those of Example 2. Specifically, 80 mg of copper nitrate trihydrate and 20 mg of tetraammine platinum nitrate are weighed and added to a 250 mL beaker, and then a certain amount of distilled water is added to the beaker. After uniform dispersion for 10 minutes under ultrasonic conditions, the liquid is poured into a 250 mL volumetric flask, and the volume is fixed to obtain solution A;

[0057] The obtained catalyst is labeled as Pt-Cu / TiO2-O v .

[0058] Example 6

[0059] The preparation method of the titanium dioxide-based catalyst of this embodiment is different from that of Example 1 only in that solution A contains tetraammine platinum nitrate in addition to copper nitrate, and the other reaction steps and raw materials are the same as those of Example 1. Specifically, 80 mg of copper nitrate trihydrate and 20 mg of tetraammine platinum nitrate are weighed and added to a 250 mL beaker, and then a certain amount of distilled water is added to the beaker. After uniform dispersion for 10 minutes under ultrasonic conditions, the liquid is poured into a 250 mL volumetric flask, and the volume is fixed to obtain solution A;

[0060] The obtained catalyst was labeled as Pt-Cu / TiO2.

[0061] Example 7

[0062] The preparation method of the titanium dioxide-based catalyst of this embodiment is different from that of Example 1 only in that solution A contains tetraammine platinum nitrate and cobalt nitrate, and the other reaction steps and raw materials are the same as those of Example 1. Specifically, 80 mg of cobalt nitrate hexahydrate and 20 mg of tetraammine platinum nitrate are weighed and added to a 250 mL beaker, and then a certain amount of distilled water is added to the beaker. After uniform dispersion for 10 min under ultrasonic conditions, the liquid is poured into a 250 mL volumetric flask, and the volume is fixed to obtain solution A;

[0063] The obtained catalyst was labeled as Pt-Co / TiO2.

[0064] For the prepared catalyst samples, the following Figure 1-2 Characterization of catalyst structure and morphology. Figure 1 XRD patterns and Figure 2 Raman spectra all confirmed that the catalyst samples of Example 1, Example 2, Example 5 and Example 7 all had typical TiO2 characteristic peaks, belonging to the brookite crystal phase, further indicating that the prepared catalyst was TiO2 in the brookite crystal phase.

[0065] Then we tested the catalytic ozonation of toluene on the prepared titanium dioxide-based catalyst. The test conditions were as follows: 200 mg of catalyst sample was placed in a quartz tube glass reactor with an inner diameter of 6 mm and an outer diameter of 8 mm. The test gas was 100 ppm toluene, the total gas flow rate was controlled to 100 mL / min, the volume space velocity was 30000 mL / (g·h), the oxygen flow rate was 30 mL / min, the ozone concentration was 480 ppm, the N2 balance gas flow rate was 36.7 mL / min, and the toluene gas flow rate was 33.3 mL / min. The toluene concentration in the tail gas was detected and analyzed by gas chromatography. Heating from 35°C to 200°C (10°C / section interval), each temperature section was kept warm for 30 minutes.

[0066] TiO2, TiO2-O v , Cu / TiO2 prepared in Example 1, Cu / TiO2-O prepared in Example 2 v The catalytic activity of Figure 3 From the comparison of the activity curves of different catalysts, it can be seen that the copper / titanium dioxide catalyst with oxygen vacancies prepared in Example 2 can achieve 100% catalytic ozonation activity of toluene at 75°C, and the other three catalyst samples can achieve 100% catalytic ozonation activity of toluene below 150°C, among which the catalytic ozone oxidation activity of toluene is Cu / TiO2-Ov>Cu / TiO2>TiO2-Ov≈TiO2.

[0067] According to the above method, the catalysts prepared in Example 6 and Example 7 were tested. Figure 4 Comparison of the activity curves of different catalysts shows that the prepared Pt-Co titanium dioxide-based catalyst and Pt-Cu titanium dioxide-based catalyst can both achieve 100% toluene removal efficiency below 110°C.

[0068] The catalysts prepared in Examples 3-5 have catalytic performance comparable to that of the catalyst in Example 2.

[0069] The specific implementation of the present invention described above does not constitute a limitation on the protection scope of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A method for preparing a titanium dioxide-based catalyst, characterized in that: The method comprises the following steps: mixing titanium dioxide with a soluble metal solution to obtain a suspension; drying the suspension, and then calcining to obtain the titanium dioxide-based catalyst; the soluble metal solution is one or more of a soluble copper salt solution, a soluble platinum salt solution, a soluble cobalt salt solution and a soluble palladium salt solution.

2. The method for preparing a titanium dioxide-based catalyst according to claim 1, wherein the titanium dioxide is titanium dioxide with oxygen vacancies, and the titanium dioxide with oxygen vacancies is prepared by the following steps: introducing a mixed gas into the titanium dioxide, heating the temperature to 550-600°C and calcining to obtain the titanium dioxide with oxygen vacancies; the mixed gas is a mixed gas of hydrogen and nitrogen, and the volume ratio of hydrogen to nitrogen is 1:(8-9).

3. The method for preparing a titanium dioxide-based catalyst according to claim 2, wherein the calcination time at 550-600°C is 4-5 hours.

4. The method for preparing a titanium dioxide-based catalyst according to claim 1, characterized in that: The calcination temperature is 400-450°C.

5. The method for preparing a titanium dioxide-based catalyst according to claim 4, characterized in that: The calcination time is 3-4 hours.

6. The method for preparing a titanium dioxide-based catalyst according to claim 1, characterized in that: In the suspension, the mass ratio of the metal in the soluble metal solution to the titanium dioxide is (2-8):

100.

7. The method for preparing a titanium dioxide-based catalyst according to claim 1, characterized in that: The copper salt in the soluble copper salt solution is one or both of copper nitrate trihydrate and copper sulfate pentahydrate; and / or, the platinum salt in the soluble platinum salt solution is one or both of tetraammine platinum nitrate and chloroplatinic acid; and / or, the cobalt salt in the soluble cobalt salt solution is cobalt nitrate hexahydrate.

8. The method for preparing a titanium dioxide-based catalyst according to claim 1, characterized in that: Drying the suspension includes: rotary evaporating the suspension and vacuum drying; the rotary evaporation temperature is 60-70° C.; the vacuum drying temperature is 55-65° C. and the time is 8-12 hours.

9. A titanium dioxide-based catalyst, characterized in that The invention is prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the titanium dioxide-based catalyst prepared by the preparation method according to any one of claims 1 to 8 or the titanium dioxide-based catalyst according to claim 9 in catalytic ozonation of toluene.

Images