CN113070073A

CN113070073A - PtCu/TiO for degrading toluene at low temperature2Photo-thermal catalyst, preparation method and application

Info

Publication number: CN113070073A
Application number: CN202110368650.1A
Authority: CN
Inventors: 王凤龙; 齐园; 刘久荣; 蒋妍彦; 吴莉莉; 杨正义
Original assignee: Shandong University
Current assignee: Shandong University
Priority date: 2021-04-06
Filing date: 2021-04-06
Publication date: 2021-07-06

Abstract

The invention relates to the technical field of photo-thermal coupling catalyst materials, in particular to PtCu/TiO for degrading toluene at low temperature₂Photothermal catalyst, preparation method and application thereof, and PtCu bimetal load of catalyst on TiO₂The preparation method adopts a sodium borohydride one-step reduction method to load the PtCu nano particles to TiO₂Of (2) is provided. The catalyst can greatly reduce the combustion temperature, reduce the cost of catalyst materials and promote the application of the bimetallic catalyst in the photo-thermal catalytic degradation of toluene.

Description

PtCu/TiO for degrading toluene at low temperature2Photo-thermal catalyst, preparation method and application

Technical Field

The invention relates to the technical field of photo-thermal coupling catalyst materials, in particular to PtCu/TiO for degrading toluene at low temperature₂A photo-thermal catalyst, a preparation method and application thereof.

Background

The information in this background section is only for enhancement of understanding of the general background of the invention and is not necessarily to be construed as an admission or any form of suggestion that this information forms the prior art that is already known to a person of ordinary skill in the art.

Volatile Organic Compounds (VOCs) are one of the main components responsible for air pollution, and the most common VOCs are halogenated compounds, aldehydes, alcohols, ketones, aromatics, and ethers. Most VOCs have foul odor and toxicity, and are directly harmful to human health. In the case of toluene, significant irritation symptoms of the eye and upper respiratory tract, redness of the conjunctiva and pharynx, dizziness, headache, nausea, vomiting, chest distress, weakness of the limbs, teetering during gait, and confusion can occur when toluene is inhaled at higher concentrations for a short period of time. Leukemia can be caused by long-term exposure to high-concentration toluene, and skin frequently exposed to toluene can become dry due to degreasing, and allergic eczema and even developmental toxicity can occur. Toluene is very common in human production activities, and especially in environments such as decorative materials, finishing materials, automobile exhaust and the like, threatens the living environment of human beings, so that the catalytic degradation of low-concentration toluene is very important for protecting the environment and human health.

In the prior art, the photo-thermal coupling catalytic degradation method is one of the most effective, economical and feasible technologies for removing toluene, and the nano titanium dioxide is a catalyst which is low in cost, easy to obtain and chemically stable, is suitable for removing various volatile organic compounds, and has outstanding advantages and wide application prospects in the field of VOCs treatment. The Pt-based titanium dioxide catalyst has higher activity and stability in the aspect of catalytic oxidation of volatile organic compounds, but noble metals are expensive and are easy to generate a poisoning phenomenon in the using process, so that the application of the noble metals in the technical field of catalysis is limited, and therefore, the development of a catalytic material with common cheap transition metals instead of the noble metals has important significance for realizing equivalent reduction of the noble metal catalytic material.

In addition, the inventor also finds that the existing photothermal coupling catalyst needs higher temperature for degrading the toluene, for example, the ignition temperature of the noble metal thermal catalyst is up to more than 200 ℃, and the higher ignition temperature is not beneficial to reducing the energy consumption.

Disclosure of Invention

To solve the above problems of the prior art, the present disclosure provides PtCu/TiO for low temperature degradation of toluene₂The catalyst can greatly reduce the combustion temperature, reduce the cost of catalyst materials, improve the conversion rate and promote the application of the bimetallic catalyst in the photo-thermal catalytic degradation of toluene.

Specifically, the technical scheme of the present disclosure is as follows:

in a first aspect of the disclosure, a PtCu/TiO for low temperature degradation of toluene₂Photo-thermal catalyst, PtCu bimetal supported on TiO₂A surface.

In a second aspect of the disclosure, a PtCu/TiO for low temperature degradation of toluene₂The preparation method of the photo-thermal catalyst adopts a sodium borohydride one-step reduction method to load PtCu nano particles on TiO₂Of (2) is provided.

In a third aspect of the disclosure, a PtCu/TiO for low temperature degradation of toluene₂PtCu/TiO of photo-thermal catalyst and/or low-temperature degradation toluene₂The photo-thermal catalyst prepared by the preparation method of the photo-thermal catalyst is applied to catalytic degradation of toluene under the photo-thermal condition.

One or more technical schemes in the disclosure have the following beneficial effects:

(1) the photo-thermal catalytic degradation method adopted by the method can enable VOCs to be subjected to flameless combustion under the operation condition of lower temperature (25-200 ℃), organic matter oxidation occurs on the surface of a solid catalyst, and CO is generated at the same time₂And H₂O, which greatly suppresses N in the air due to its low oxidation reaction temperature₂Formation of high temperature NO_x。

(2)、PtCu/TiO₂Compared with the traditional titanium dioxide catalyst, the bimetallic catalyst realizes the transfer of photo-generated electrons from titanium dioxide to metal nanoparticles and promotes the separation of electron holes. In Cu metal-added catalysts, Pt_0.4Cu_0.1-TiO₂The temperature of the catalyst in 80% toluene degradation is 77 ℃ and is Pt/Pt_0.5-TiO₂The catalyst (100 ℃) is reduced by 23 ℃, the photo-thermal catalytic performance is greatly improved, and the synergistic catalytic effect between double metals is reflected.

(3) The titanium dioxide is easy to prepare, has stable property and is beneficial to mass production and storage; the PtCu nano particles are loaded on the titanium dioxide by a sodium borohydride one-step reduction method, and the method is simple and easy to operate.

(4) The catalyst has low metal content, low cost and reaction conditions lower than 100 ℃, is convenient to operate, saves energy, does not generate redundant harmful substances in the production process, is green and environment-friendly, and is beneficial to realizing industrial production.

Drawings

The accompanying drawings, which are included to provide a further understanding of the disclosure, illustrate embodiments of the disclosure and together with the description serve to explain the disclosure and are not to limit the disclosure.

Embodiments of the present disclosure are described in detail below with reference to the attached drawing figures, wherein:

FIG. 1 is Pt prepared in example 4_0.4Cu_0.1-TiO₂A TEM image of (B);

FIG. 2 is Pt_xCu_0.5-x-TiO₂And (x is 0-0.5), wherein the crystal form of the titanium oxide is mainly anatase and has a small amount of brookite crystal form.

FIG. 3 is Pt_xCu_0.5-x-TiO₂(x is 0-0.5) temperature-catalyst curve for photo-thermal catalytic degradation of 80% toluene, and Pt can be seen from the graph_0.4Cu_0.1-TiO₂The catalyst has better performance and degrades most of toluene gas at 77 ℃.

FIG. 4 is Pt_0.4Cu_0.1-TiO₂Compared with the conversion rate of the thermal catalysis of the catalyst and the conversion rate of the photo-thermal catalysis for degrading the toluene, the graph shows that the introduction of light greatly reduces the reaction temperature required by the catalyst, when the temperature reaches 110 ℃, the degradation rate of the photo-thermal coupling catalysis for catalyzing the toluene reaches 99 percent, and the degradation rate of the thermal catalysisLess than 5%.

Detailed Description

The disclosure is further illustrated with reference to specific examples. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present disclosure. The experimental procedures, in which specific conditions are not noted in the following examples, are generally carried out according to conventional conditions or according to conditions recommended by the manufacturers.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. The reagents or starting materials used in the present invention can be purchased from conventional sources, and unless otherwise specified, the reagents or starting materials used in the present invention can be used in a conventional manner in the art or in accordance with the product specifications. In addition, any methods and materials similar or equivalent to those described herein can be used in the methods of the present invention. The preferred embodiments and materials described herein are intended to be exemplary only.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present disclosure. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of the stated features, steps, operations, and/or combinations thereof, unless the context clearly indicates otherwise.

At present, the photo-thermal coupling catalytic degradation method has the problems that the photo-thermal catalyst for removing the toluene is high in cost, the combustion temperature is high, the conversion rate is low, and in order to solve the problems, the disclosure provides the PtCu/TiO for degrading the toluene at low temperature₂A photo-thermal catalyst, a preparation method and application thereof.

In one embodiment of the disclosure, a PtCu/TiO material for the low temperature degradation of toluene₂Photo-thermal catalyst, PtCu bimetal supported on TiO₂A surface.

PtCu/TiO₂The photo-thermal bimetallic catalyst is a metal-loaded semiconductor catalyst, and the crystal form of titanium dioxide is mainly anatase. PtCu/TiO₂BimetalTiO in catalyst₂Has photosensitivity, when the intensity of incident light is larger than the forbidden bandwidth of titanium oxide, electrons in the valence band are excited and jump to the conduction band and are continuously transferred to the surface of PtCu metal nano-particles, and O₂Molecular reaction to form O₂ ^-Ions having a strong oxidizing action; at the same time, a large number of oxidative holes remain in the valence band, participating in the oxidation of toluene molecules. The Pt element is a noble metal, has stable property, can be used as an active site for catalytic reaction, and increases the separation efficiency of electron holes; the addition of Cu not only reduces the cost of the catalyst, but also changes the binding energy between metals to form an alloy with Pt, so that the catalyst is more stable in the catalysis process, and the performance is further improved. When the frequency of photons is matched with the vibration frequency of free electrons in metal, the metal nano particles generate a local surface plasma resonance phenomenon, so that the light energy is converted into heat energy, and the catalytic reaction is greatly promoted.

Further, TiO is added in an amount of 100% by weight based on the weight of the catalyst₂The mass fraction of (A) is 99.5%, and the mass fraction of the PtCu bimetal is 0.5%. The catalyst has low metal content and can greatly reduce the cost. In addition, the control of the content of the bimetal is good, on one hand, the control is helpful for improving the PtCu bimetal particle in TiO₂On the other hand, the catalyst is beneficial to providing rich adsorption sites for the catalyst and improving the catalytic effect.

Further, TiO₂Has a size of 20-55nm and PtCu particles have a size of 1-5 nm. In the photo-thermal catalytic degradation process, the catalyst can expose more active sites and adsorption sites, which is important for improving the catalytic efficiency. Therefore, the size of the bimetallic alloy particles is controlled to be 1-5nm, more active sites can be exposed, and the stability of the catalyst is improved.

In one embodiment of the disclosure, a PtCu/TiO material for the low temperature degradation of toluene₂The preparation method of the photo-thermal catalyst adopts a sodium borohydride one-step reduction method to load PtCu nano particles on TiO₂Of (2) is provided. In the traditional preparation method, hydrothermal reaction is mostly adopted, however, the hydrothermal reaction is not only complicated in reaction process, but also complicated in reaction processAnd takes a long time. By adopting a sodium borohydride one-step reduction method, the PtCu nano particles can be rapidly loaded on TiO₂The preparation efficiency is improved, and the PtCu/TiO prepared by the method₂The photo-thermal catalyst has a very stable structure, and the problems of stability reduction and rapid catalyst failure caused by falling of metal particles in the catalytic reaction process cannot occur.

Further, comprising: mixing titanium dioxide and H₂PtCl₆·6H₂O、CuCl₂·2H₂And O, uniformly mixing, adding a sodium borohydride solution with a certain concentration, and drying in an oven. Directly placing the mixed solution into an oven for drying to obtain the PtCu/TiO₂The photo-thermal catalyst has simple and high-efficiency preparation method.

Further, the preparation method of the titanium dioxide comprises the following steps: adding a tetraisopropyl titanate or tetrabutyl titanate precursor into deionized water, dissolving, drying to obtain titanium dioxide powder, and then placing the coarse titanium dioxide powder in air for roasting.

Furthermore, the roasting temperature of the crude titanium dioxide in the air is 500-600 ℃, and the reaction time is 2-5 h. By the calcination treatment in this temperature range, titanium dioxide having anatase as a main crystal form can be obtained, and the particle diameter of titanium dioxide is controlled to be within a desired range.

Further, H₂PtCl₆·6H₂O and CuCl₂·2H₂The concentration of O is 1-3 mmol/L; further, said H₂PtCl₆·6H₂The volume of O is 0-3.0mL but not 0; the CuCl₂·2H₂The volume of O is 0-8.0mL but not 0; further, the concentration of the sodium borohydride is 0.5-1.5 mol/L.

In one embodiment of the disclosure, a PtCu/TiO material for the low temperature degradation of toluene₂The photo-thermal catalyst and/or the photo-thermal catalyst obtained by the preparation method are applied to the catalytic degradation of toluene under the photo-thermal condition.

Further, the catalytic conditions were: the light source is a full-spectrum xenon lamp, the working current is 15A, and the light intensity is 1.1W cm^-2First, aThe flow rate of benzene is 50mL/min, the reaction temperature is 25-200 ℃, and the reaction device is a gas phase flow reactor; preferably, the reaction temperature is 77 ℃. The optimal reaction temperature is 77 ℃, the reaction temperature is greatly reduced, and the energy consumption is greatly reduced.

In order to make the technical solutions of the present disclosure more clearly understood by those skilled in the art, the technical solutions of the present disclosure will be described in detail below with reference to specific embodiments.

Example 1

(1) Dropwise adding tetraisopropyl titanate into deionized water to obtain a solution A;

(2) carrying out ultrasonic treatment on the solution A, standing for 3 days, and drying at 90 ℃ to obtain crude titanium dioxide powder;

(3) placing the crude titanium dioxide powder in a muffle furnace, and roasting for 2 hours at 500 ℃ in the air to obtain the final titanium dioxide powder;

(4) 199mg of titanium dioxide and 0.51mL of chloroplatinic acid hexahydrate solution (concentration: 0.002 mol. L.) were weighed out^-1) And 6.29mL of a copper chloride dihydrate solution (concentration: 0.002 mol. L)^-1) Adding deionized water into a beaker, keeping the volume to 200mL to obtain a solution B, and stirring for 1 h;

(5) preparing 1mol/L sodium borohydride solution, adding 5mL sodium borohydride solution into the solution B, stirring for 2h, performing centrifugal separation, and putting the solution into an oven to be dried to obtain Pt_0.1Cu_0.4-TiO₂A catalyst.

Example 2

(2) carrying out ultrasonic treatment on the solution A, standing for one day, and drying at 90 ℃ to obtain crude titanium dioxide powder;

(4) 199mg of titanium dioxide and 1.03mL of chloroplatinic acid hexahydrate solution (concentration: 0.002 mol. L.) were weighed out^-1) And 4.72mL of a copper chloride dihydrate solution (concentration: 0.002 mol. L)^-1) Adding deionized water into a beaker, keeping the volume to 200mL to obtain a solution B, and stirring for 1 h;

(5) preparing 1mol/L sodium borohydride solution, and adding 5mL of the solutionB, stirring for 2 hours, centrifugally separating, and putting into an oven for drying to obtain Pt_0.2Cu_0.3-TiO₂A catalyst.

Example 3

(4) 199mg of titanium dioxide and 1.54mL of chloroplatinic acid hexahydrate solution (concentration: 0.002 mol. L.) were weighed out^-1) And 3.15mL of a copper chloride dihydrate solution (concentration: 0.002 mol. L)^-1) Adding deionized water into a beaker, keeping the volume to 200mL to obtain a solution B, and stirring for 1 h;

(5) preparing 1mol/L sodium borohydride solution, adding 5mL sodium borohydride solution into the solution B, stirring for 2h, performing centrifugal separation, and putting the solution into an oven to be dried to obtain Pt_0.3Cu_0.2-TiO₂A catalyst.

Example 4

(4) 199mg of titanium dioxide and 2.05mL of chloroplatinic acid hexahydrate solution (concentration: 0.002 mol. L.) were weighed out^-1) And 1.57mL of a copper chloride dihydrate solution (concentration: 0.002 mol. L)^-1) Adding deionized water into a beaker, keeping the volume to 200mL to obtain a solution B, and stirring for 1 h;

(5) preparing 1mol/L sodium borohydride solution, adding 5mL sodium borohydride solution into the solution B, stirring for 2h, performing centrifugal separation, and putting the solution into an oven to be dried to obtain Pt_0.4Cu_0.1-TiO₂A catalyst.

Example 5

(4) 199mg of titanium dioxide and 2.56mL of chloroplatinic acid hexahydrate solution (concentration: 0.002 mol. L.) were weighed out^-1) Adding deionized water into a beaker, keeping the volume to 200mL to obtain a solution B, and stirring for 1 h;

(5) preparing 1mol/L sodium borohydride solution, adding 5mL sodium borohydride solution into the solution B, stirring for 2h, performing centrifugal separation, and putting the solution into an oven to be dried to obtain Pt_0.5-TiO₂A catalyst.

Example 6

(4) 199mg of titanium dioxide and 7.87mL of a copper chloride dihydrate solution (concentration: 0.002 mol. L) were weighed out^-1) Adding deionized water into a beaker, keeping the volume to 200mL to obtain a solution B, and stirring for 1 h;

(5) preparing 1mol/L sodium borohydride solution, adding 5mL sodium borohydride solution into the solution B, stirring for 2h, performing centrifugal separation, and putting into an oven for drying to obtain Cu_0.5-TiO₂A catalyst.

Testing of photo-thermal catalytic degradation of toluene:

the toluene degradation experiment is carried out in a photo-thermal catalysis micro-reaction system, and the reaction system is a flowing system. The catalysis conditions are as follows: the light source is a full-spectrum xenon lamp, the working current is 15A, and the light intensity is 1.1W cm^-2The flow rate of toluene is 50mL/min, and the reaction temperature is 25-200 ℃. Taking a catalyst with the mass of 50mg, fully mixing the catalyst with 1.3g of quartz sand, placing the mixture into a transparent quartz tube, placing the quartz tube into a heating furnace, introducing methylbenzene, turning on a light source, obtaining the concentration data of the methylbenzene through a gas chromatograph connected together, and further comparing the photo-thermal data of the catalysts with different proportionsThe performance of catalyzing and degrading toluene. Wherein, Pt_0.4Cu_0.1-TiO₂Optimum catalyst performance, T_80％It was 77 ℃. The performances of the catalysts with different proportions for the photo-thermal catalytic degradation of toluene are Pt from high to low in sequence_0.4Cu_0.1-TiO₂>Pt_0.5-TiO₂>Pt_0.3Cu_0.2-TiO₂>Pt_0.2Cu_0.3-TiO₂>Pt_0.1Cu_0.4-TiO₂>Cu_0.5-TiO₂。

Although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that changes may be made in the embodiments and/or equivalents thereof without departing from the spirit and scope of the invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. PtCu/TiO for degrading toluene at low temperature₂A photothermal catalyst, characterized in that PtCu bimetal is loaded on TiO₂A surface.

2. The PtCu/TiO of claim 1 for the low temperature degradation of toluene₂Photothermal catalyst, characterized in that TiO is present in an amount of 100% by weight based on the weight of the catalyst₂The mass fraction of (A) is 99.5%, and the mass fraction of the PtCu bimetal is 0.5%.

3. The PtCu/TiO of claim 1 for the low temperature degradation of toluene₂Photothermal catalyst, characterized in that TiO₂Has a size of 20-55nm and PtCu particles have a size of 1-5 nm.

4. PtCu/TiO for degrading toluene at low temperature₂The preparation method of the photo-thermal catalyst is characterized in that a sodium borohydride one-step reduction method is adopted to load PtCu nano particles to TiO₂Of (2) is provided.

5. The PtCu/TiO of claim 4 for the low temperature degradation of toluene₂A method for preparing a photothermal catalyst, comprising: mixing titanium dioxide and H₂PtCl₆·6H₂O、CuCl₂·2H₂And O, uniformly mixing, adding a sodium borohydride solution with a certain concentration, and drying in an oven.

6. The PtCu/TiO of claim 4 for the low temperature degradation of toluene₂The preparation method of the photo-thermal catalyst is characterized in that the preparation method of the titanium dioxide comprises the following steps: adding a tetraisopropyl titanate or tetrabutyl titanate precursor into deionized water, dissolving, drying to obtain titanium dioxide powder, and then placing the coarse titanium dioxide powder in air for roasting.

7. The PtCu/TiO of claim 6 for the low temperature degradation of toluene₂The preparation method of the photo-thermal catalyst is characterized in that the roasting temperature of the crude titanium dioxide in the air is 500-600 ℃, and the reaction time is 2-5 h.

8. The PtCu/TiO of claim 5 for the low temperature degradation of toluene₂A process for preparing a photothermal catalyst, characterized in that H₂PtCl₆·6H₂O and CuCl₂·2H₂The concentration of O is 1-3 mmol/L; further, said H₂PtCl₆·6H₂The volume of O is 0-3.0mL but not 0; the CuCl₂·2H₂The volume of O is 0-8.0mL but not 0; further, the concentration of the sodium borohydride is 0.5-1.5 mol/L.

9. PtCu/TiO for the low-temperature degradation of toluene according to any one of claims 1 to 3₂Use of a photothermal catalyst and/or a photothermal catalyst obtained by the method of any one of claims 4-9 for the catalytic degradation of toluene under photothermal conditions.

10. As in claimThe use according to claim 9, characterized in that the catalytic conditions are: the light source is a full-spectrum xenon lamp, the working current is 15A, and the light intensity is 1.1W cm^-2The flow rate of toluene is 50mL/min, the reaction temperature is 25-200 ℃, and the reaction device is a gas phase flow reactor; preferably, the reaction temperature is 77 ℃.