WO2020073298A1

WO2020073298A1 - Niobium and vanadium-doped titanium tantalate-based photocatalyst, preparation method therefor and use thereof

Info

Publication number: WO2020073298A1
Application number: PCT/CN2018/109921
Authority: WO
Inventors: 黄彦林; 米龙庆; 刘宣宣; 魏东磊
Original assignee: 南通纺织丝绸产业技术研究院; 苏州大学
Priority date: 2018-10-11
Filing date: 2018-10-11
Publication date: 2020-04-16

Abstract

A niobium and vanadium-doped titanium tantalate-based photocatalyst, a preparation method therefor and a use thereof, which belong to the field of inorganic photocatalytic materials. According to the stoichiometric ratio of TiTa_18-x-yNb_xV_yO₄₇, x and y being respectively the molar weight of Ta doped and substituted with niobium Nb⁵⁺ ions and Ta doped and substituted with vanadium V⁵⁺ ions, x being 0.1-5.4, and y being 0.1-2, raw materials containing Ti⁴⁺, Nb⁵⁺, Ta⁵⁺ and V⁵⁺ ions are weighed and taken; an appropriate amount of a compound containing Li⁺ ions is weighed and taken as a sintering aid; and a stepwise sintering process is adopted, so as to obtain a pure-phase niobium and vanadium-doped titanium tantalate-based photocatalyst. The titanium tantalate photocatalyst obtained by doping with niobium Nb and vanadium V enhances the absorption in the visible light range; in addition, lattice disturbance greatly improves the separation efficiency of photoinduced charges, and enhances the photocatalytic ability. The photocatalyst has a simple preparation process, low costs and good photocatalytic material stability, and is able to degrade organic pollutants under the irradiation of ultraviolet light and near ultraviolet light, and particularly, is able to degrade organic pollutants in water, facilitating environmental protection.

Description

Titanium tantalate-based photocatalyst doped with niobium and vanadium, preparation method and application

[0001] The present invention relates to an inorganic photocatalyst and a preparation method thereof, in particular to a niobium and vanadium-doped titanium tantalate-based photocatalyst, preparation method and application thereof, and belongs to the field of inorganic photocatalytic materials.

Background technique

[0002] The development of industry in the world today brings serious environmental pollution and energy crisis, and seriously affects sustainable development and the improvement of people's quality of life. For example, in recent years, the problem of dye wastewater has become very prominent and has become a major concern for water pollution. How to remove dyes in water efficiently and without residues under green and environmental conditions has become a key technology for researchers to solve water pollution. Among them, using photocatalytic technology to solve water pollution caused by dyes is one of the promising technical solutions.

[0003] Photocatalysis refers to one or several semiconductor materials. Under the irradiation of a certain energy photon, electrons absorb a certain amount of energy, then they will jump from the valence band and absorb energy to the conduction band, which was originally in the valence band. A positively charged hole will appear where it exists, that is, light irradiation generates photo-generated electrons and photo-generated holes. This photo-generated charge has a strong reducing or oxidizing property, so that the substances on the semiconductor can undergo an oxidation-reduction reaction, thereby converting light energy into chemical energy. These semiconductor substances are called photocatalysts. Therefore, the separation efficiency of photogenerated electrons and holes plays a crucial role in photocatalysis. To improve the separation efficiency of charges, the researchers implemented some methods, such as impurity doping, surface treatment, heterojunction, etc .; Multi-element doping in the lattice can produce structural distortions or defects, and is an effective means to improve light absorption and enhance the ability to separate photogenerated electrons and holes.

Summary of the invention

technical problem

Solution to the problem

Technical solution

[0004] The object of the present invention is to provide a simple preparation method, high photocatalytic efficiency, niobium, vanadium doped titanium tantalate-based new photocatalyst, preparation method and application.

[0005] The technical solution to achieve the object of the present invention is to provide a niobium and vanadium-doped titanium tantalate-based photocatalyst, which The chemical formula is TiTa ^ NUO ^ where JC and y are the molar amounts of Ta replaced by niobium Nb and vanadium V ⁵⁺ ions, respectively, and the doping range JC is 0.1 to 5.4 and 0.1 to 2.

[0006] The technical solution of the present invention also includes a method for preparing a niobium and vanadium-doped titanium tantalate-based photocatalyst, using a solid-phase synthesis method, including the following steps:

[0007] (1) According to the stoichiometric ratio of each element in the chemical formula TiTa uNb ^ _y CU, where, JC = 0.1 ~ 5.4

,

Weigh the compound containing titanium ion Ti ⁴⁺ , the compound containing niobium ion Nb ⁵⁺ , the compound containing tantalum ion Ta ⁵⁺ , the compound containing vanadium V ⁵⁺ ion; the compound containing Li ⁺ ion in proper amount is called sintering Auxiliaries, grind and mix well to obtain a mixture;

[0008] (2) The mixture obtained in step (1) is pre-sintered in an air atmosphere at a sintering temperature of 400 to 750 ° C

, The sintering time is 1 ~ 15 hours, after natural cooling, grinding and mixing to obtain a mixture;

[0009] (3) The mixture obtained in step (2) is calcined in an air atmosphere, the calcination temperature is 1000 ~ 1100 ° C

The calcination time is 1 ~ 15 hours, after natural cooling, grinding and mixing to obtain a mixture;

[0010] (4) The mixture obtained in step (3) is calcined in an air atmosphere at a calcination temperature of 950 to 1250 ° C

The calcination time is 1 to 15 hours, cooled to room temperature, and ground uniformly to obtain powdered niobium Nb and vanadium V-doped titanium tantalate photocatalyst.

[0011] The compound containing titanium ion Ti ⁴⁺ in the technical solution of the present invention is titanium dioxide Ti0 _2; the compound containing niobium ion Nb ⁵⁺ is niobium pentoxide Nb ₂ 0 ₅ , niobium pentachloride NbCl _{One of 5} ; the compound containing tantalum ion Ta ⁵⁺ is one of tantalum pentoxide Ta ₂ 0 ₅ and tantalum pentachloride TaCl ₅ ; the compound containing vanadium ion V ⁵⁺ is five One of vanadium oxide ₂ 0 ₅ and ammonium vanadate NH ₄ VO ₃ .

[0012] The compound containing Li ⁺ ions is one of lithium oxide Li ₂ 0, lithium carbonate Li ₂ CO ₃ or 1 ^; according to the mass percentage, the sintering aid is TiTa m _v Nb _x V _v 0 ₄₇ i ~ 5%, where, JC = 0.1 ~ 5.4,

: V = 0.1 2

[0013] A preferred solution of the sintering process of step (3) of the present invention is: the sintering temperature is 750 ~ 950 ° C, and the sintering time is 5 ~ 8 hours.

[0014] The application of a niobium and vanadium-doped titanium tantalate-based photocatalyst provided by the present invention is used to degrade organic pollutants under ultraviolet or near ultraviolet light irradiation, especially to degrade organic matter in water Pollutants.

Beneficial effects of invention

Beneficial effect [0015] Compared with the existing technical solutions, the significant advantages of the technical solutions of the present invention are:

[0016] 1. The niobium Nb and vanadium V-doped titanium tantalate-based photocatalyst provided by the present invention, the matrix of which is a basic framework constructed from a Ta0 ₆ A polyhedron, this transition metal polyhedron has a natural polarization effect, The invention realizes the doping of multiple elements in the crystal lattice, the octahedron is strongly disturbed, therefore, it can generate a strong electrostatic field, and generate directional polarization in the crystal lattice, which is conducive to the separation of photogenerated charges And transmission, increase the life of the carrier, improve the efficiency of photocatalysis; At the same time, a variety of doping can improve light absorption, achieve absorption of visible light, and has excellent photocatalytic performance.

[0017] 2. The niobium and vanadium doped titanium tantalate-based photocatalyst provided by the present invention has simple preparation process and low production cost

As a photocatalytic material, it can degrade organic pollutants under ultraviolet or near-ultraviolet light. It is especially suitable for degrading organic pollutants in water and is conducive to environmental protection.

Brief description of the drawings

BRIEF DESCRIPTION

[0018] FIG. 1 is a ray powder diffraction pattern of a sample TiTa „ _.7 Nb _4.5 V i _.8 0 ₄₇ prepared according to the technical scheme of Example 1 of the present invention;

[0019] FIG. 2 is a scanning electron microscope pattern of the sample TiTa „ _.7 Nb _4.5 V i _.8 0 ₄₇ prepared according to the technical solution of Example 1 of the present invention;

[0020] FIG. 3 is an ultraviolet-visible absorption spectrum of a sample TiTa prepared in accordance with the technical solution of Example 1 of the present invention. _.7 Nb _4.5 V i _.8 0 ₄₇ ;

[0021] FIG. 4 is the degradation curve of the organic dye methylene blue prepared by the sample prepared according to the technical solution of Example 1 of the present invention;

[0022] FIG. 5 is a scanning electron micrograph of the sample TiTa _12.5 Nb ₄ V _1.5 O ₄₇ prepared according to the technical solution of Example 4 of the present invention

[0023] FIG. 6 is an ultraviolet-visible absorption spectrum of a sample TiTa _12.5 Nb ₄ V _1.5 O ₄₇ prepared according to the technical solution of Example 4 of the present invention;

[0024] FIG. 7 is a degradation curve of the organic dye methylene blue of the sample TiTa _12.5 Nb ₄ V _1.5 O ₄₇ prepared according to the technical scheme of Example 4 of the present invention.

Invention Example

Embodiments of the invention

[0025] The technical solution of the present invention will be further described below in conjunction with the accompanying drawings and embodiments. [0026] Embodiment 1:

[0027] According to the stoichiometric ratio of each element in the chemical formula TiTa, _.7 Nb ₄₅ V uO ₄₇ , weigh 0.2 g TiO ₂

, 6.486 g Ta ₂ 0 ₅ , 1.49 g Nb ₂ 0 ₅ , 0.526 g NH ₄ VO _3; Weigh 0.348 g Li ₂ 0 as a sintering aid, grind and mix well.

[0028] The obtained mixture was pre-sintered for the first time in an air atmosphere, with a sintering temperature of 650 ° C and a sintering time of 6 hours, naturally cooled, ground and mixed evenly.

[0029] The mixture obtained after the first pre-sintering continues to be calcined a second time in an air atmosphere, the calcination temperature is 850 ° C., the calcination time is 5 hours, natural cooling, grinding and mixing are uniform.

[0030] The mixture obtained after the second calcination was calcined a third time in an air atmosphere, the calcination temperature was 1 100 ° C, the calcination time was 8 hours, and cooled to room temperature to obtain powdered niobium Nb and vanadium V doped Titanium heterotantalate photocatalyst.

[0031] Referring to FIG. 1, is the ray powder diffraction pattern of niobium Nb and vanadium V-doped titanium tantalate TiTa „ _.7 Nb 4.5 _{5 18} 0 ₄₇ prepared according to the technical scheme of this embodiment, the test results show that the sample It is a single phase with good crystallinity

[0032] Referring to FIG. 2, which is a scanning electron microscope pattern of a sample prepared according to the technical solution of this embodiment, it can be seen from the figure that the sample particles are uniform and well dispersed.

[0033] Referring to FIG. 3, is the UV-Vis absorption spectrum of the sample TiTa prepared in accordance with the technical scheme of this embodiment, _.7 Nb ₄₅ V i ₈ 0 _47. For comparison, the undoped sample TiTa _{18 is} listed The light absorption spectrum of 0 ₄₇ can be seen from the figure. The absorption of the doped sample is greatly red-shifted and has a strong absorption in the visible light range.

[0034] In this embodiment, the photodegradation activity of methylene blue is used as an example to evaluate the performance of the photocatalyst. The light source lamp of the photocatalytic reaction device is a 500-watt cylindrical xenon lamp, the reaction tank is a cylindrical photocatalytic reaction instrument made of borosilicate glass, the light source lamp is inserted into the reaction tank, and condensed water is passed through to cool the temperature. The temperature is room temperature. The amount of catalyst was 100 mg, the volume of solution was 250 ml, and the concentration of methylene blue was 10 mg / L.

[0035] The catalyst provided in this embodiment is placed in the reaction liquid, the catalytic time is set to 120 minutes, the condensed water is turned on, and the light is started. After the light is taken, the sample is taken at intervals, centrifuged, and the supernatant is used The ultraviolet-visible spectrophotometer measures the absorbance of the methylene blue solution at a wavelength of 663 to 665 nanometers. According to Lambert-Beer law, the absorbance of a solution is proportional to the concentration, so the absorbance can be used instead of the concentration to calculate the removal rate This is the removal rate of methylene blue solution. Calculation formula: Degradation rate = (1-C / C _Q ) X100% = (1-A / A _q ) X100%, where C p C is the concentration before and after photocatalytic degradation, and A p A is the absorbance before and after degradation value.

[0036] Referring to FIG. 4, it is a degradation curve of the organic dye methylene blue prepared by the technical solution of this example. As can be seen from the figure, compared with the undoped sample, the degradation rate of the photocatalytic degradation of methylene blue provided by the present invention can reach 93% in 120 minutes, and has a good photocatalytic activity.

Example 2:

[0038] According to the stoichiometric ratio of each element in the chemical formula _{TiTa ia6} Nb _5.4 V ₂ 0 ₄₇ , 0.2 grams of TiO ₂ were weighed separately

, 9.493 g TaCl ₅ , 3.588 g NbCl ₅ , 0.455 g V ₂ 0 _5; Weigh 0.13 g Li ₂ CO ₃ as a sintering aid 1 Grind and mix well. The obtained mixture was pre-sintered for the first time in an air atmosphere, with a sintering temperature of 650 ° C and a sintering time of 6 hours, naturally cooled, ground and mixed evenly. The mixture obtained after the first pre-sintering continues to be calcined for a second time in an air atmosphere, the calcination temperature is 850 ° C, the calcination time is 5 hours, natural cooling, grinding and mixing are uniform; after the second calcination The mixture was calcined a third time in an air atmosphere. The calcination temperature was 1100 ° C, the calcination time was 8 hours, and the mixture was cooled to room temperature to obtain powdered niobium Nb and vanadium V-doped titanium tantalate photocatalyst. Its main crystal structure, ultraviolet-visible absorption spectrum, SEM image, and degradation curve of methylene blue are similar to those in Example 1.

Embodiment 3:

[0040] According to the stoichiometric ratio of each element in the chemical formula _TiTa _17.8 Nb _0.i V o _.i O ₄₇ , 0.399 g TiO ₂ , 19.669 g Ta ₂ 0 ₅ , 0.067 g Nb ₂ 0 ₅ , 0.0665 g NH ₄ VO _3; Weigh 0.196 g LiF as sintering aid, grind and mix evenly. The obtained mixture was pre-sintered for the first time in an air atmosphere, with a sintering temperature of 650 ° C and a sintering time of 6 hours, naturally cooled, ground and mixed evenly. The mixture obtained after the first pre-sintering continues to be calcined for a second time in an air atmosphere, the calcination temperature is 850 ° C, the calcination time is 5 hours, natural cooling, grinding and mixing are uniform; it will be obtained after the second calcination The mixture was calcined a third time in an air atmosphere at a calcination temperature of 1100 ° C, a calcination time of 8 hours, and cooled to room temperature to obtain powdered niobium Nb and vanadium V-doped titanium tantalate photocatalyst. Its main crystal structure, ultraviolet-visible absorption spectrum, SEM image, and degradation curve of methylene blue are similar to those in Example 1.

[0041] Example 4:

[0042] According to the stoichiometric ratio of each element in the chemical formula TiTa mNluV uO ^, weigh 0.2 g TiO ₂ , 6.9 G Ta ₂ 0 ₅ , 1.325 g Nb ₂ 0 ₅ , 0.44 g NH ₄ V0 _3; weigh 0.445 g Li ₂ CO sf as sintering aid

, Grind and mix well. The obtained mixture was pre-sintered for the first time in an air atmosphere, with a sintering temperature of 6 50 ° C and a sintering time of 6 hours, naturally cooled, ground and mixed evenly. The mixture obtained after the first pre-sintering continues to be calcined a second time in an air atmosphere, the calcination temperature is 850 ° C, the calcination time is 5 hours, natural cooling, grinding and mixing are uniform; The mixture was calcined a third time in an air atmosphere at a calcination temperature of 1100 ° C, a calcination time of 8 hours, and cooled to room temperature to obtain niobium Nb and vanadium V-doped titanium tantalate photocatalyst. The structure of this sample is the same as in Example 1.

[0043] Referring to FIG. 5, it is a scanning electron microscope pattern of the sample TiTa _12.5 Nb ₄ V _1.5 O ₄₇ prepared according to the technical solution of this embodiment. From the figure, it can be seen that the sample particles are uniform and well dispersed.

[0044] Referring to FIG. 6, is the UV-Vis absorption spectrum of the sample prepared according to the technical solution of this embodiment. For comparison, the optical absorption spectrum of the undoped sample TiTa ₁₈ 0 ₄₇ is listed. It can be seen that the absorption of the doped sample is greatly red-shifted and has strong absorption in the visible range.

[0045] According to the photocatalyst performance evaluation method provided in Example 1, the sample provided in this example is subjected to organic dye methylene blue degradation treatment, and the degradation curve of the sample to the organic dye methylene blue is shown in FIG. 7. As can be seen from FIG. 7, compared with the undoped sample, the degradation rate of the doped sample prepared in this example for photocatalytic degradation of methylene blue can reach 90% in 120 minutes, and has a good photocatalytic activity.

Example 5:

[0047] According to the stoichiometric ratio of each element in the chemical formula TiTa _13.2 Nb _3.5 V _1.3 O ₄₇ , 0.2 g TiO ₂ was weighed separately

, 7.29 g Ta ₂ 0 ₅ , 1.159 g Nb ₂ 0 ₅ , 0.38 g NH ₄ V0 _3; Weigh 0.27 g Li ₂ 0 as sintering aid 1J, grind and mix well. The obtained mixture was pre-sintered for the first time in an air atmosphere, with a sintering temperature of 650 ° C and a sintering time of 6 hours, naturally cooled, ground and mixed evenly. The mixture obtained after the first pre-sintering continues to be calcined for a second time in an air atmosphere, the calcination temperature is 850 ° C, the calcination time is 5 hours, natural cooling, grinding and mixing are uniform; it will be obtained after the second calcination The mixture was calcined a third time in an air atmosphere at a calcination temperature of 1100 ° C, a calcination time of 8 hours, and cooled to room temperature to obtain a niobium Nb and vanadium V-doped titanium tantalate photocatalyst. The structure of this sample is the same as in Example 1. The ultraviolet-visible absorption spectrum, the SEM spectrum, and the degradation curve of methylene blue are similar to those in Example 4.

Example 6:

[0049] According to the stoichiometric ratio of each element in the chemical formula TiTa _14.2 Nb _2.5 V0 ₄₇ , 0.2 g of TiO ₂ was weighed separately, 8.01 Gram Ta ₂ 0 ₅ , 1.66 grams NbCl ₅ , 0.293 grams NH ₄ VO _3; Weigh 0.41 grams Li ₂ CO ₃ as a sintering aid, grind and mix well. The obtained mixture was pre-sintered for the first time in an air atmosphere with a sintering temperature of 650 ° C and a sintering time of 6 hours, naturally cooled, ground and mixed evenly. The mixture obtained after the first pre-sintering continues to be calcined for a second time in an air atmosphere, the calcination temperature is 850 ° C, the calcination time is 5 hours, natural cooling, grinding and mixing are uniform; it will be obtained after the second calcination The mixture was calcined a third time in an air atmosphere at a calcination temperature of 1100 ° C, a calcination time of 8 hours, and cooled to room temperature to obtain a niobium Nb and vanadium V-doped titanium tantalate photocatalyst. The structure of this sample is the same as in Example 1. The ultraviolet-visible absorption spectrum, the SEM spectrum, and the degradation curve of methylene blue are similar to those in Example 4.

Claims

Claims [Claim 1] A niobium and vanadium-doped titanium tantalate-based photocatalyst, characterized in that its chemical formula is Ti TamvNbxV v047, where JC and y are niobium Nb 5+ and vanadium V 5 respectively + Ion doping replaces the molar amount of Ta, and the doping range JC is 0.1 ~ 5.4, which is 0.1 ~ 2. [Claim 2] A method for preparing titanium tantalate-based photocatalyst doped with niobium and vanadium, characterized in that the solid-phase synthesis method is adopted and includes the following steps:

(1) According to the stoichiometric ratio of each element in the chemical formula TiTanNb _x V _v 0 ₄₇ , where JC = 0.1 ~ 5.4,

Weigh the compound containing titanium ion Ti ⁴⁺ , the compound containing niobium ion Nb ⁵⁺ , the compound containing tantalum ion Ta ⁵⁺ , the compound containing vanadium V ⁵⁺ ion; the compound containing Li ⁺ ion in proper amount is called sintering Additives, grind and mix well

, To obtain a mixture;

(2) The mixture obtained in step (1) is pre-sintered in an air atmosphere with a sintering temperature of 40 to 750 ° C and a sintering time of 1 to 15 hours. After natural cooling, it is ground and mixed to obtain a mixture;

(3) The mixture obtained in step (2) is calcined in an air atmosphere with a calcination temperature of 1000 to 1100 ° C and a calcination time of 1 to 15 hours. After natural cooling, it is ground and mixed to obtain a mixture;

(4) The mixture obtained in step (3) is calcined in an air atmosphere at a calcination temperature of 950 to 1250 ° C, a calcination time of 1 to 15 hours, cooled to room temperature, and uniformly ground to obtain powdered niobium Nb and vanadium V doped Titanium heterotantalate photocatalyst.

[Claim 3] The method for preparing a niobium and vanadium doped titanium tantalate-based photocatalyst according to claim 2, characterized in that: the compound containing titanium ion Ti ⁴⁺ is titanium dioxide Ti0 _2; The compound containing niobium ion Nb ⁵⁺ is niobium pentoxide Nb ₂ 0 ₅

, One of niobium pentachloride NbCl ₅ ; said compound containing tantalum ion Ta ⁵⁺ is one of tantalum pentoxide Ta ₂ 0 ₅ , one of tantalum pentachloride TaCl ₅ ; said containing vanadium ion V ^{The 5+} compound is one of vanadium pentoxide ₂ 0 ₅ and ammonium vanadate NH ₄ VO ₃ .

[Claim 4] The method for preparing a niobium and vanadium doped titanium tantalate-based photocatalyst according to claim 2, wherein the compound containing Li ⁺ ion is lithium oxide Li ₂ 0, Carbonic acid One of lithium Li ₂ CO ₃ or 1 ^; in terms of mass percentage, the sintering aid is 1 ~ 5% of TiTa _{18 v} Nb, V '0 ₄₇ , where JC = 0.1 ~ 5.4, y = 0.1 ~ 2 .

[Claim 5] The method for preparing a niobium and vanadium doped titanium tantalate-based photocatalyst according to claim 2, characterized in that: the sintering temperature in step (3) is 750 ~ 950 ° C, and the sintering time 5 to 8 hours.

[Claim 6] The application of a niobium and vanadium doped titanium tantalate-based photocatalyst according to claim 1 is used to degrade organic pollutants under ultraviolet or near ultraviolet light irradiation.

[Claim 7] The application of a niobium and vanadium doped titanium tantalate-based photocatalyst according to claim 6, characterized in that it is used to degrade organic pollutants in water.