CN108855169A - Porous silicon carbide as filler/modifying titanium dioxide composite photo-catalyst preparation method - Google Patents

Abstract

The invention provides a method for preparing a porous silicon carbide/modified _TiO2 composite photocatalyst used as a filler, which belongs to the technical field of photocatalysts and solves the problems of narrow response spectrum range, easy agglomeration, easy loss, poor photocatalytic effect, and problems of nano- _TiO2 . Difficult to reproduce problem. In the present invention, graphene is first added to absolute ethanol and deionized water, and ultrasonically dispersed to obtain graphene solution A; then _TiO2 is added to absolute ethanol, and after ultrasonic dispersion, it is added to graphene solution A to adjust the pH of the solution value, to prepare solution B; add porous silicon carbide powder to absolute ethanol and deionized water, ultrasonically disperse and add it to solution B, and form a gel after stirring; transfer the gel to the reaction kettle and heat The reaction was carried out for 12 hours, and after drying, the powdery porous silicon carbide/modified _TiO2 composite photocatalyst was obtained by grinding. The preparation method of the invention improves the photocatalytic efficiency of TiO ₂ , enhances the catalytic degradation effect, and has good prospects for popularization and application.

Description

Preparation of Porous SiC/Modified TiO Composite Photocatalyst Used as Filler method

technical field

The invention relates to a method for preparing a porous silicon carbide/modified titanium dioxide (TiO ₂ ) composite photocatalyst used as a filler, and belongs to the technical field of photocatalysts.

Background technique

Photocatalytic reaction refers to the process in which semiconductor materials absorb external radiant light energy to excite holes in the conduction band and valence band, and then undergo a series of chemical reactions with the substances adsorbed on the surface of the catalyst. Photocatalytic technology has the following advantages: completely degrade organic pollutants into CO ₂ , H ₂ O, etc., and oxidize or reduce inorganic pollutants to harmless substances; no additional electron acceptor (such as H ₂ O ₂ ); suitable The photocatalyst has the advantages of cheap, non-toxic, stable and reusable; it can use the inexhaustible solar energy as a light source to activate the photocatalyst, the operating conditions are easy to control, the oxidation ability is strong, and there is no secondary pollution.

In recent years, the research on TiO ₂ has been increasing in different fields, and the benefits created by TiO ₂ products and its derivatives in the industrial field are also increasing exponentially. TiO ₂ is widely used in energy and environmental fields, such as sewage treatment, dye-sensitized solar cells, sensors, electrochromic devices, etc., due to its non-toxic, self-cleaning, safe, stable chemical properties, and high catalytic activity. It is considered to be one of the most ideal semiconductor catalysts in the field of photocatalysis.

Loading TiO ₂ on porous media is an effective way to solve the easy loss of photocatalysts and improve the ability of photocatalysts to absorb pollutants. TiO ₂ composite carrier material is a new method proposed to improve the photocatalytic activity of TiO ₂ in recent years. , diatomaceous earth, new carbon materials, etc. as carrier materials to form a composite system. When TiO ₂ is combined with insulators, insulators such as Al ₂ O ₃ , SiO ₂ , and ZrO ₂ also mostly act as carriers. However, due to the interaction between the carrier and the active components, special properties such as acidity changes , making composite oxides exhibit higher acidity than single component oxides.

Commonly used loading methods include powder sintering method, sol-gel method, deposition method, sputtering method, hydrothermal method, etc. The powder sintering method directly adopts ultrasonic dispersion and other methods to make TiO ₂ powder and a certain solution into a suspension and impregnates it with a carrier. After depositing a certain amount of TiO ₂ particles, it can be easily obtained by drying and roasting. This method can be mass-produced and has a high catalytic activity. Higher, but poorer in stability and reproducibility. The sol-gel method uses inorganic titanium salts or titanium alkoxides as precursors, which are hydrolyzed and condensed in a certain medium by external stirring to form a sol, and then aged into a gel, which is loaded onto the It can be obtained by calcination at high temperature after being placed on the carrier. Although the operation is relatively complicated, the reaction process is mild and easy to control.

The deposition method refers to a method in which _TiO2 becomes a vapor or a liquid phase with a high dispersion degree by means of laser, high temperature, etc., and then contacts the carrier at a low temperature, and condenses on the carrier to form a thin film. It can be carried out under normal pressure. The required equipment is simple but the uniformity of the film is poor. _The ^sputtering method is also called the plasma treatment method. _The plasma in the gas has a high speed and energy under the action of the electric field and the magnetic field. However, since the sputtering method needs to be operated in an electric field or a magnetic field, the required temperature is relatively high, so the carrier should be made of high-temperature-resistant materials.

In the past, the method of supporting TiO ₂ was usually to solve the problems of easy loss and difficult recycling of TiO ₂ after the reaction, easy agglomeration of TiO ₂ , and small contact area, or to prepare composite materials to improve catalytic performance. Related test results also show that, The synergistic effect of _TiO2 and supporting materials can effectively enhance the reactivity. Therefore, according to the strong adsorption capacity of porous silicon carbide and the good matching between its pore size and modified TiO ₂ , the present invention fully utilizes the synergistic effect of the two, improves the photocatalytic performance, and achieves a better catalytic degradation effect.

Contents of the invention

(1) Technical issues

The object of the present invention is to provide a preparation method of porous silicon carbide/modified _TiO2 composite photocatalyst used as filler, which utilizes the synergistic effect of porous silicon carbide adsorption and nano- _TiO2 photocatalysis to solve the current response spectrum range of nano- _TiO2 Narrow, easy to agglomerate, easy to lose, poor photocatalytic effect, difficult to regenerate, so as to effectively improve the photocatalytic degradation effect of TiO ₂ .

(2) Technical solution

In view of the current problems that _TiO2 is easy to agglomerate, easy to lose, poor in photocatalytic effect, and difficult to regenerate, the present invention provides a A method for preparing a porous silicon carbide/modified _TiO2 composite photocatalyst used as a filler, thereby improving the catalytic degradation effect of the photocatalytic material, so that the photocatalytic material can be used effectively for a long time without loss and the like. The technical scheme of the present invention is as follows: first, graphene oxide is added to absolute ethanol and deionized water, and ultrasonically dispersed to obtain graphene oxide solution A; then _TiO is added to absolute alcohol, and added to graphene oxide after ultrasonic dispersion In solution A, use ammonia water to adjust the pH value of the solution, and continue ultrasonic dispersion to obtain solution B; add the porous silicon carbide powder after cleaning and drying to absolute ethanol and deionized water, and add it to solution B after ultrasonic dispersion treatment, Stir until a gel is formed; transfer the gel to a closed reaction kettle, react at 200°C for 12 hours, dry for 12, wash with deionized water and dry, and grind to obtain powdery porous silicon carbide/modified _TiO2 composite photocatalyst.

(3) Beneficial effect

TiO ₂ is a commonly used photocatalyst. It has attracted people's attention because of its non-toxicity, strong oxidation ability, complete degradation, stable chemical properties and no secondary pollution. It is considered to be the photocatalyst with the most development potential. catalytic material. However, when TiO ₂ is used directly, it has defects such as narrow response spectrum range, poor adsorption performance, easy agglomeration, and difficulty in recycling, which greatly limit its application. Therefore, most of the existing research focuses on loading it on porous carrier materials. The research on loading TiO ₂ on activated carbon, porous silica gel, natural ore, sepiolite and other supports has been reported, but most of these supports have defects such as high cost, low efficiency, and low comprehensive utilization rate. The porous silicon carbide/modified TiO ₂ composite photocatalyst prepared by the present invention can be used as a filler to improve the photocatalytic efficiency of TiO ₂ and enhance the catalytic degradation effect. It has a good application prospect and is very important for the development of photocatalytic materials in the future. significance.

Detailed ways

The invention provides a method for preparing a porous silicon carbide/modified titanium dioxide composite photocatalyst used as a filler. The specific implementation steps are as follows:

(1) 20 milligrams of graphene oxide were added to 5 milliliters of absolute ethanol and 15 milliliters of deionized water, and ultrasonically dispersed for 20 minutes to prepare graphene oxide solution A;

(2) 60 milligrams of nano- _TiO2 were added in 5 milliliters of absolute ethanol, ultrasonically dispersed for 30 minutes, added to the graphene oxide solution A, and the pH value of the solution was adjusted to 9 with ammonia water, and ultrasonically dispersed for 1 hour to obtain Solution B;

(3) Add 500 mg of porous silicon carbide powder washed and dried with deionized water to 5 ml of absolute ethanol and 25 ml of deionized water, ultrasonically disperse for 1 hour, add to solution B, and stir evenly to obtain gel;

(4) Transfer the gel to a closed reaction kettle, heat it up to 200°C at a heating rate of 1°C/min, react in a homogeneous phase at 200°C for 12 hours, dry it in an environment box at 100°C for 12 hours, and grind to obtain a powder Shaped Porous SiC/Modified TiO ₂ Composite Photocatalyst.

Claims (1)

1. a kind of porous silicon carbide as filler/modifying titanium dioxide composite photo-catalyst preparation method, it is characterised in that should Specific step is as follows for method：

(1) 20 milligrams of graphene oxides are added in 5 milliliters of dehydrated alcohols and 15 ml deionized waters, ultrasonic disperse processing 20 Minute, graphene oxide solution A is made；

(2) by 60 milligrams of nano-TiOs₂It is added in 5 milliliters of dehydrated alcohols, ultrasonic disperse is handled 30 minutes, is added to graphene oxide In solution A, solution ph is adjusted with ammonium hydroxide and reaches 9, continue ultrasonic disperse and handle 1 hour, obtained solution B；

(3) 500 milligrams of porous silicon carbide Si powders after deionized water washes and dries be added to 5 milliliters of dehydrated alcohols and In 25 ml deionized waters, ultrasonic disperse is handled 1 hour, is added in solution B, is stirred evenly, and gel is made；

(4) gel is transferred in closed reactor, is heated to 200 DEG C with 1 DEG C/min heating rate, is contrary at 200 DEG C It answers 12 hours, 12 hours dry in 100 DEG C of environmental cabinets, ground obtained powdery porous silicon carbide/modification TiO₂Complex light Catalyst.