阅读说明：本技术 一种锡铌共掺杂二氧化钛光催化剂及其制备方法和应用 (Tin-niobium co-doped titanium dioxide photocatalyst and preparation method and application thereof ) 是由 陈加藏 张文琴 于 2020-04-13 设计创作，主要内容包括：本发明公开了一种锡铌共掺杂二氧化钛光催化剂的制备方法,具体如下步骤：将称量好的钛酸四丁酯、五水氯化锡、五水氯化铌于烧杯中混合搅拌均匀得到溶液A,然后向溶液A中加入一定量的冰醋酸,搅拌混合均匀得到溶液B；之后将溶液B转移到水热反应釜中于220℃水热反应12h,反应结束后将反应釜冷却至室温,最后通过离心、洗涤、干燥即得所述锡铌共掺杂二氧化钛光催化剂。本发明制备SnNb/TiO<Sub>2</Sub>光催化剂的方法简单,反应条件温和,适合大规模合成；将本发明催化剂材料用于光催化降解低浓度的VOCs气体-甲苯、丙酮及其混合物,最优掺杂量的光催化剂其催化降解效率可达到99％以上,降解效果十分显著。(The invention discloses a preparation method of a tin-niobium co-doped titanium dioxide photocatalyst, which comprises the following steps: mixing and stirring weighed tetrabutyl titanate, stannic chloride pentahydrate and niobium chloride pentahydrate uniformly in a beaker to obtain a solution A, then adding a certain amount of glacial acetic acid into the solution A, and stirring and mixing uniformly to obtain a solution B; and then transferring the solution B into a hydrothermal reaction kettle for hydrothermal reaction at 220 ℃ for 12 hours, cooling the reaction kettle to room temperature after the reaction is finished, and finally centrifuging, washing and drying to obtain the tin-niobium co-doped titanium dioxide photocatalyst. The invention prepares SnNb/TiO 2 The method of the photocatalyst is simple, the reaction condition is mild, and the photocatalyst is suitable for large-scale synthesis; the catalyst material of the invention is used for photocatalytic degradation of low-concentration VOCs gas-toluene, acetone and mixture thereof, and the optimal doping amount isThe catalytic degradation efficiency of the photocatalyst can reach more than 99 percent, and the degradation effect is very obvious.)

1. A preparation method of a tin-niobium co-doped titanium dioxide photocatalyst is characterized by comprising the following specific steps:

mixing and stirring weighed tetrabutyl titanate, stannic chloride pentahydrate and niobium chloride pentahydrate uniformly in a beaker to obtain a solution A, then adding a certain amount of glacial acetic acid into the solution A, and stirring and mixing uniformly to obtain a solution B; and then transferring the solution B into a hydrothermal reaction kettle for hydrothermal reaction at 220 ℃ for 12 hours, cooling the reaction kettle to room temperature after the reaction is finished, and finally centrifuging, washing and drying to obtain the tin-niobium co-doped titanium dioxide photocatalyst.

2. The method of claim 1, wherein the mass ratio of tetrabutyl titanate, tin chloride pentahydrate, niobium chloride pentahydrate, and glacial acetic acid is about 10: (0.0515-0.2060): (0.0529-0.2116): 3.5316.

3. the preparation method according to claim 2, wherein the mass ratio of the tetrabutyl titanate, the tin chloride pentahydrate, the niobium chloride pentahydrate and the glacial acetic acid is 10: 0.0515: 0.0529: 3.5316.

4. the method according to claim 1, wherein the washing is performed 2 to 3 times with absolute ethanol and deionized water, respectively.

5. The method of claim 1, wherein the drying is at 80 ℃ for 12 hours.

6. A tin-niobium co-doped titanium dioxide photocatalyst prepared by the method of any one of claims 1 to 5.

7. The application of the tin-niobium co-doped titanium dioxide photocatalyst disclosed by claim 6 in photocatalytic degradation of low-concentration toluene, acetone and mixed gas thereof.

Technical Field

The invention relates to the technical field of new material environmental protection, and more particularly relates to a tin-niobium co-doped titanium dioxide photocatalyst, and a preparation method and application thereof.

Background

How to treat pollutants, especially Volatile Organic Compounds (VOCs) efficiently and harmlessly is a research hotspot of broad researchers. Prolonged exposure to VOCs can have serious consequences such as carcinogenesis, teratogenesis, and mutagenesis. For high concentrations of VOCs, photocatalytic treatment is generally relatively easy, and the selectivity of the catalyst is also broader. This is because when the degradation efficiency is 90% or more, the high-concentration VOCs are not degraded and still reach the emission standard, and the degradation efficiency cannot be further improved for most catalysts. For low concentrations of VOCs, degradation efficiencies of over 90% are also achieved, and the requirements for photocatalysts are much higher and more difficult. However, in daily life, the need to treat low concentrations of VOCs is often greater. Therefore, how to find a suitable catalyst capable of degrading low-concentration VOCs efficiently and rapidly is a difficult problem in the field of photocatalysis. Due to the wide variety of VOCs, we selected several common contaminants identified as toxic as the study subjects-toluene and acetone.

Toluene (tolumen, C)₇H₈) Colorless clear liquid, benzene-like smell, strong refractivity, flammability, explosive mixture of vapor and air, and high concentration of gas with anesthetic property. Toluene is mainly used as a solvent and a high-octane gasoline additive, and is also an important raw material for organic chemical engineering. Toluene is irritant to skin and mucosa, and has anesthetic effect on central nervous system. Exposure to high concentrations of toluene can lead to acute toxicity and can also produce anesthetic effects. Inhalation of 100ppm toluene can have psychological effects on humans, and inhalation of 200ppm toluene can have effects on the human nervous center. The irritation to the eye mucous membrane and the upper respiratory tract can be caused under the environment of 200-570 ppm. About 48% of toluene is metabolized in vivo after entering the body and is discharged out of the body after passing through the liver, brain, lung and kidney, but in the process, the toluene can cause damage to the nervous system. The inhalation of toluene at higher concentration for a short period of time can cause significant irritation symptoms in the eye and upper respiratory tract, congestion in the conjunctiva and pharynx, dizziness, headache, nausea, vomiting, chest distress, weakness of limbs, teetering during gait, and blurred consciousness. Severe patients may have restlessness, convulsions and coma. The long-term contact can cause neurasthenia syndrome, hepatomegaly, dry skin, chapping, dermatitis and the like.

Acetone (acetone, CH)₃COCH₃) The name also known as dimethyl ketone,is a colorless transparent liquid with special pungent smell. Acetone is an important organic synthetic raw material and can be widely used for producing epoxy resin, polycarbonate, organic glass, medicines, pesticides and the like. The volatilized acetone gas has toxicity, anesthesia effect on nervous system, and irritation effect on mucous membrane. Under short-term conditions, the concentration below 500ppm has no influence and only stimulates eyes; 500-1000ppm can stimulate nose and throat, 1000ppm can cause headache and dizziness, and eyes can be slightly and temporarily stimulated; 10000ppm of 2000-. Skin contact can lead to dryness, redness and chapping upon prolonged contact. When the steam with the concentration of 1000ppm is inhaled 3 hours a day, the nasal cavity can be stimulated in 7-15 years, people can be dizzy and hypodynamia, and the high-concentration steam can also influence the functions of the kidney and the liver.

Toluene and acetone are very common gases of VOCs as two organic solvents which are very widely used industrially. It is of practical significance to find a suitable photocatalyst for efficiently degrading low-concentration toluene and acetone gases to the emission threshold specified in the national standard by means of photocatalysis. Meanwhile, VOCs discharged by common industry cannot be single gas but a mixture of a plurality of gases, so that the research on the photocatalytic degradation of the mixed gas of toluene and acetone has more practical application value.

Disclosure of Invention

The invention aims to provide a tin-niobium co-doped titanium dioxide photocatalyst and application of the catalyst in photocatalytic degradation of low-concentration toluene, acetone and mixed gas thereof.

In order to achieve the purpose, the invention adopts the following technical scheme:

a preparation method of a tin-niobium co-doped titanium dioxide photocatalyst comprises the following specific steps:

mixing and stirring weighed tetrabutyl titanate, stannic chloride pentahydrate and niobium chloride pentahydrate uniformly in a beaker to obtain a solution A, then adding a certain amount of glacial acetic acid into the solution A, and stirring and mixing uniformly to obtain a solution B; and then transferring the solution B into a hydrothermal reaction kettle for hydrothermal reaction at 220 ℃ for 12 hours, cooling the reaction kettle to room temperature after the reaction is finished, and finally centrifuging, washing and drying to obtain the tin-niobium co-doped titanium dioxide photocatalyst.

Preferably, the mass ratio of the tetrabutyl titanate, the tin chloride pentahydrate, the niobium chloride pentahydrate and the glacial acetic acid is 10: (0.0515-0.2060): (0.0529-0.2116): 3.5316.

preferably, the mass ratio of the tetrabutyl titanate, the tin chloride pentahydrate, the niobium chloride pentahydrate and the glacial acetic acid is 10: 0.0515: 0.0529: 3.5316.

preferably, the washing is 2-3 times by using absolute ethyl alcohol and deionized water respectively.

Preferably, the drying is at 80 ℃ for 12 h.

In addition, the invention also claims a tin-niobium co-doped titanium dioxide photocatalyst prepared by the method and application of the tin-niobium co-doped titanium dioxide photocatalyst in photocatalytic degradation of low-concentration toluene, acetone and mixed gas thereof.

The application of the tin-niobium co-doped titanium dioxide photocatalyst in photocatalytic degradation of low-concentration toluene, acetone and mixed gas thereof comprises the following specific steps:

1) light source selection: because the prepared photocatalyst absorbs ultraviolet light, the selected light source is an ultraviolet lamp tube with 30W Philips power and quartz material;

2) loading a catalyst: weighing SnNb/TiO₂Adding 200mg of catalyst into 2m of L distilled water, fully stirring to form slurry, coating the slurry on an ultraviolet lamp tube with a quartz tube in the step 1), and drying at 50 ℃ for 2 hours;

3) assembling a reaction device: connecting an ultraviolet lamp tube loaded with a catalyst, an outer tube, an air mixing cylinder for supplying air, a flowmeter, an air cylinder, an air pump and the like, and checking whether the air tightness is good or not;

4) the concentration of toluene, acetone and their mixed gas before reaction was analyzed: VOCs gas with constant concentration is obtained in a laboratory in a simulation mode; the specific operation is that liquid toluene, acetone and deionized water are respectively filled in different reagent bottles in a constant-temperature water bath mode (so that the concentration of VOCs can be kept stable), and the reagent bottles are placed in a water bath kettle at a certain temperature, and after the reagent bottles are covered, holes are punched in a cover and are connected to the same gas mixing bottle through a hose. Uniformly mixing VOCs, steam and decompressed bottled compressed air through a gas mixing cylinder, connecting a flowmeter to control the flow rate, then introducing the mixture into a photocatalytic reactor, and detecting the concentration of the VOCs gas in the initial gas through a gas chromatography (model Haixin GC-950: used for detecting the concentration of the VOCs gas) at the gas inlet of the reactor; meanwhile, mixed gas mixed with low-concentration VOCs with different flow rates and different concentrations is obtained by adjusting the flow meter and the temperature of the water bath;

5) reacting and analyzing the components and concentration of the reacted gas: after all the products are ready, the ultraviolet lamps are electrified, the mixed gas containing low-concentration VOCs enters the reactor to react, the gas outlet of the reactor is detected by gas chromatography (type Haixin GC-950: used for detecting the concentration of the reacted VOCs gas and type Fuli-9790: used for detecting the concentration of the degraded products CO and CO 2), the concentration of the reacted main product gas is obtained, and the degradation efficiency of the VOCs is calculated.

Compared with the prior art, the invention has the following obvious beneficial effects:

(1) the invention prepares SnNb/TiO₂The method of the photocatalyst is simple, the reaction condition is mild, and the photocatalyst is suitable for large-scale synthesis;

(2) according to the invention, the concentration of carriers can be obviously improved through the synergistic effect of Sn and Nb codoping, and Sn is doped by a solvothermal method⁴⁺、Nb⁵⁺With TiO₂Solid solution is formed, and surface defects and surface oxygen active species are increased after doping. As the number of oxygen vacancies increases, the number of adsorption sites on the catalyst surface also increases, which facilitates the adsorption of volatile organics and water on the catalyst surface. The organic contaminants adsorbed on the surface of the catalyst can be directly oxidized by the holes and also by hydroxyl radicals generated by the holes and water. The concentration of carriers is increased after doping, the number of electrons is increased, the number of superoxide radicals generated by electrons and oxygen is increased, and then the organic pollution is realized by utilizing the strong oxidizing capability of the superoxide radicalsAnd (4) oxidizing the substance. However, when the doping amount is too high, the surface defect state is too much, and the recombination probability of the photon-generated carriers is increased, so that the catalytic efficiency is reduced. Therefore, the synergistic effect of co-doping Sn and Nb and the proper doping amount can effectively improve the efficiency of degrading VOCs.

(3) The invention is used for photocatalytic degradation of VOCs gas with low concentration, namely toluene, acetone and a mixture thereof, the degradation efficiency of tin-niobium co-doped titanium dioxide with the optimal doping amount can reach 99%, the catalytic efficiency is very obvious, and the relevant emission concentration limit value in the existing GB16297-1996 integrated emission Standard for atmospheric pollutants is reached.

Drawings

FIG. 1 shows SnNb/TiO of examples 1 to 3₂And undoped TiO₂XRD pattern of (a). From the figure, it can be seen that the main component is anatase-type titanium dioxide. Since the doping amounts of Sn and Nb are small, no significant diffraction peaks of Sn and Nb are observed in the figure.

FIG. 2 is a plot of 0.5% Sn0.5% Nb/TiO prepared according to example 1 of the present invention₂XPS chart of (a). The success of doping is demonstrated, and the sample contains Sn and Nb.

FIG. 3 is a plot of 0.5% Sn0.5% Nb/TiO prepared according to example 1 of the present invention₂A TEM image of (a). As can be seen from the figure, the prepared catalyst has agglomeration, irregular shape and particle size of about 10 nm.

Detailed Description

The invention is further illustrated by the following specific examples. The following examples are intended to illustrate the invention only and are not intended to limit the scope of the invention.