CN102909037A

CN102909037A - Preparation method of porous cobalt selenide photocatalyst

Info

Publication number: CN102909037A
Application number: CN2012104108849A
Authority: CN
Inventors: 马建锋; 李良银; 李定龙; 杨彦
Original assignee: Changzhou University
Current assignee: Jiangyin Intellectual Property Operation Co., Ltd
Priority date: 2012-10-25
Filing date: 2012-10-25
Publication date: 2013-02-06
Anticipated expiration: 2032-10-25
Also published as: CN102909037B

Abstract

The invention discloses a preparation method of a porous cobalt selenide photocatalyst for catalyzing and degrading waste water or waste pollutants, comprising the following steps of: dissolving Cl2 and AlCl3 in water respectively and preparing two solutions with the concentration of 1-2mol/L, mixing the two solutions and keeping the mole ratio of Co to Al at 2-4, dropping NaOH into a water bath at the constant temperature of 70-80 DEG C, keeping the pH value at 12-13, reacting for 2-3h, aging, separating sediments and washing by using deionized water; adding the obtained solid into a sodium selenite solution with the concentration of 1-2mol/L according to a solid-to-liquid ratio of 1:20-1:50, washing the obtained solid and calcining at 400-500 DEG C; and adding the product obtained by calcining per one gramme of the solid into 20-40mL of hydrazine hydrate solution with the concentration of 20-40% to obtain the porous cobalt selenide photocatalyst, wherein the porous cobalt selenide photocatalyst has a good aperture structure and greater specific surface area and is beneficial to absorption and catalysis.

Description

A kind of preparation method of porous type cobaltous selenide photochemical catalyst

Technical field

The present invention relates to the development field of environmental pollution control new material, relate in particular to the preparation method of the porous type cobaltous selenide photochemical catalyst of a kind of catalytic degradation waste water or waste pollutant.

Background technology

1972, Fujishma and Honda wait found to carry out UV Light with nano titanium oxide as the light anode can decomposing H ₂O is H ₂And O ₂, this indicates that multiphase photocatalysis is from basic research to the application study New Times.Since then, be accompanied by the appearance of the outburst of energy crisis in the world wide and ecological deterioration problem etc., multiphase photocatalysis research causes people's concern day by day.Its target be utilize nature the abundantest the energy---solar energy is applied to energy conversion and utilization.

But because TiO ₂Forbidden band wide (Eg=3.2 eV) cause it can not effectively utilize visible light part in the sunshine and TiO ₂The right probability of recombination in light induced electron-hole is higher, has reduced its quantum efficiency, to such an extent as to there is not so far large-scale industrial application.

It is wider that cobalt class catalyst is used, and particularly aspect the pollutant of some difficult degradations of catalytic oxidation, preferably application prospect arranged, such as: the organic matter such as catalyze oxidation of formaldehyde, catalytic oxidation of cyclohexane at room temperature.Utilize liquid-phase synthesis process to obtain a kind of non-integer than cobaltous selenide (Co0.85Se) nanometer sheet, preparation process need not to use organic formwork and surfactant, and the thickness of sheet is less than 10 nanometers; Studies show that, the synthetic product that obtains can effectively adsorb the organic dyestuff methylene blue, can be used for adsorbing the organic dyestuff (" Chinese Chemical Society the 28th Annual Conference the 4th sub-venue summary collection " 2012) in the sewage.But this material granule is too little, and the Separation of Solid and Liquid difficulty need to load on the carrier and just can give full play to its catalytic effect; By a step low-temperature hydro-thermal synthesis, on electro-conductive glass growth in situ cobaltous selenide and nickelous selenide nanocrystalline, need not any post processing, directly apply to dye-sensitized solar cells, obtained good battery performance, particularly cobaltous selenide has the electrocatalysis characteristic (JACS, DOI:10.1021/ja303034w) higher than metal platinum.The catalyst of cobaltous selenide class is owing to needing carrier just larger specific area can be arranged at present, and therefore exploitation has the catalyst than bigger serface from pore-forming, and applying of such catalyst had positive effect.

Hydrotalcite-based compound (LDHs) is to pile up the compound that forms by interlayer anion and positively charged laminate.The hydrotalcite chemical structure of general formula is: [M ²⁺ _1-xM ³⁺X (OH) ₂] ^X+[(A ^N-) _X/nMH ₂O], M wherein ²⁺And M ³⁺Be respectively the divalence and the trivalent metal cation that are positioned on the main body laminate, such as Mg ²⁺, Ni ²⁺, Zn ²⁺, Mn ²⁺, Cu ²⁺, Co ²⁺, Pd ²⁺, Fe ²⁺Deng bivalent cation and Al ³⁺, Cr ³⁺, Co ³⁺, Fe ³⁺All can form hydrotalcite Deng Tricationic; A ^{N –}Be interlayer anion, can comprise inorganic anion, organic anion, complex anion, same many and heteropolyanion; X is M ³⁺/ (M ²⁺+ M ³⁺) molar ratio, approximately be that 4:1 is to 2:1; M is the number of intermediary water molecule.Its structure is similar to shepardite Mg (OH) ₂, share seamed edge and form the main body laminate by octahedron.Be positioned at the divalent metal M on the laminate ²⁺Can be by the close trivalent metal cation M of ion half price in certain proportion ³⁺The isomorphous replaces so that laminate is positively charged, interlayer exist can exchange anion and the positive charge balance on the laminate so that the overall structure of LDHs is electroneutral.The anion of interlayer can be exchanged, and through a series of modifications, hydrotalcite material can obtain the many kinds of materials that performance is different.

Summary of the invention

The objective of the invention is provides a kind of preparation method of porous type cobaltous selenide photochemical catalyst for overcoming the deficiency that the carrier price is high in the prior art, load process is responsible for.

The technical solution used in the present invention is in turn include the following steps: 1) with CoCl ₂And AlCl ₃Be dissolved into respectively in the water, be configured to concentration and be two kinds of solution of 1 ~ 2 mol/L, two kinds of solution are mixed, Co in the maintenance mixed solution and the mol ratio of Al are 2 ~ 4, splash into NaOH in 70 ~ 80 ℃ of water-baths of constant temperature, and keeping the pH value is 12 ~ 13, reaction 2 ~ 3 h, aging 12 ~ 24 h, precipitate and separate is washed 2 ~ 3 times with deionized water; 2) solid that step 1) is obtained joins in the sodium selenite solution that concentration is 1 ~ 2 mol/L, and solid-to-liquid ratio is 1:20 ~ 1:50, stirs 4 ~ 5 h, and precipitate and separate is after the solid of acquisition washs 2 ~ 3 times with deionized water, at 400 ~ 500 ℃ temperature lower calcination; 3) it is in 20% ~ 40% the hydrazine hydrate solution, to obtain porous type cobaltous selenide catalyst that the product that per 1 g calcining is obtained joins 20 ~ 40 mL concentration.

Advantage of the present invention is:

(1) passes through coprecipitation reaction, form the larger lamellar structure of specific area that cobalt is being mingled with aluminium, enter the selenous acid ion at Inter layer exchange again, form supporting construction by high-temperature calcination again, make and separate between lamella and the lamella and fixing, can not separate or closure, make this material have good pore space structure and larger specific area, be conducive to absorption and catalysis.

(2) after calcining, form oxide, at last this oxide is utilized hydrazine hydrate reduction, obtain being doped with the cobaltous selenide that aluminium supports.

(3) be doped with part aluminium in this catalyst, in catalyst, form skeleton function, and between catalyst and skeleton, stronger active force is arranged, can prevent that catalyst from coming off or reunite and reduce the catalysis area and affect catalytic action.

The specific embodiment

With CoCl ₂And AlCl ₃Be dissolved into respectively in the water, be configured to concentration and be the solution of 1 ~ 2 mol/L, two kinds of solution are mixed, keeping the mol ratio of Co and Al is 2 ~ 4, in 70 ~ 80 ℃ of water-baths of constant temperature, splash into a certain amount of NaOH, keeping the pH value is 12 ~ 13, reaction 2 ~ 3 h, aging 12 ~ 24 h, in this process, form the precipitation with layer structure, precipitate and separate, deionization washing 2 ~ 3 times prepares Co-Al type houghite in this process.This houghite is joined in the sodium selenite solution that concentration is 1 ~ 2 mol/L, and solid-to-liquid ratio is 1:20 ~ 1:50, stirs 4 ~ 5 h, precipitate and separate, and the solid of acquisition is after with deionized water washing 2 ~ 3 times, at 400 ~ 500 ℃ temperature lower calcination; It is in 20% ~ 40% the hydrazine hydrate solution that the product that per 1 g calcining is obtained joins 20 ~ 40 mL concentration, utilizes the reduction of hydrazine hydrate, and the selenium cobalt/cobalt oxide is reduced into cobaltous selenide, obtains porous type cobaltous selenide catalyst.

3 embodiment of the present invention below further are provided:

Embodiment 1

With CoCl ₂And AlCl ₃Be dissolved into respectively in the water, be configured to the solution that concentration is 1 mol/L, two kinds of solution are mixed, and keeping the mol ratio of Co and Al is 2, splashes into a certain amount of NaOH in 70 ℃ of water-baths of constant temperature, keeping the pH value is 12, react 2 h, aging 12 h form the precipitation with layer structure in this process, precipitate and separate, deionization washing 2 times; The solid that precipitation is obtained joins in the sodium selenite solution that concentration is 1 mol/L, and solid-to-liquid ratio is 1:50, stirs 4h, precipitate and separate, and the solid of acquisition is after with deionized water washing 2 times, at 400 ℃ temperature lower calcination; It is in 40% the hydrazine hydrate solution, to obtain porous type cobaltous selenide catalyst that the product that 1 g calcining is obtained joins 20 mL concentration.

Adopt L shaped pipe (internal diameter 10 mm) continuous-flow reaction evaluating device, in the synthetic catalyst disposed tubes that obtains of weighing 100 mg, the coaxial quartz ampoule that is provided with in the vertical part glass jar of L shaped pipe, it is the uviol lamp of 6W that power is arranged in the pipe, the flow velocity of regulating air is 40 mL/min, Air Flow drives formaldehyde gas and enters in the U-shaped pipe reactor, and the gas volume (being air speed) that per hour flows through every liter of catalyst is 55000 h ^-1Under 25 ℃ of conditions, it is that the formaldehyde gas complete oxidation of 100 ppm is carbon dioxide and water that this catalyst can make 85% concentration.

Embodiment 2

With CoCl ₂And AlCl ₃Be dissolved into respectively in the water, be configured to the solution that concentration is 2 mol/L, two kinds of solution are mixed, and keeping the mol ratio of Co and Al is 4, splashes into a certain amount of NaOH in 80 ℃ of water-baths of constant temperature, keeping the pH value is 13, react 3 h, aging 24 h form the precipitation with layer structure in this process, precipitate and separate, deionization washing 3 times; The solid that precipitation is obtained joins in the sodium selenite solution that concentration is 2 mol/L, and solid-to-liquid ratio is 1:20, stirs 5 h, precipitate and separate, and the solid of acquisition is after with deionized water washing 3 times, at 500 ℃ temperature lower calcination; It is in 20% the hydrazine hydrate solution, to obtain porous type cobaltous selenide catalyst that the product that 1 g calcining is obtained joins 40 mL concentration.

The catalyst 0.5g that obtains is joined in the Orange II waste water that 500 mL concentration are 50mg/L, under the irradiation of 500w Metal halogen lamp, react 3 h, percent of decolourization is 95%, illustrates that this catalyst also can catalytic reaction oxidation removal pollutant under visible light.

Embodiment 3

With CoCl ₂And AlCl ₃Be dissolved into respectively in the water, be configured to the solution that concentration is 2 mol/L, two kinds of solution are mixed, and keeping the mol ratio of Co and Al is 3, splashes into a certain amount of NaOH in 75 ℃ of water-baths of constant temperature, keeping the pH value is 13, react 3 h, aging 18 h form the precipitation with layer structure in this process, precipitate and separate, deionization washing 3 times; The solid that precipitation is obtained joins in the sodium selenite solution that concentration is 1.5 mol/L, and solid-to-liquid ratio is 1:30, stirs 4 h, precipitate and separate, and the solid of acquisition is after with deionized water washing 3 times, at 450 ℃ temperature lower calcination; It is in 30% the hydrazine hydrate solution, to obtain porous type cobaltous selenide catalyst that the product that 1 g calcining is obtained joins 30 mL concentration.

The catalyst 0.5g that obtains is joined in the methylene blue waste water that 500 mL concentration are 50mg/L, under the irradiation of 500w Metal halogen lamp, react 3 h, percent of decolourization is 90%, illustrates that this catalyst can catalytic reaction oxidation removal pollutant under visible light.

Claims

1. the preparation method of a porous type cobaltous selenide photochemical catalyst is characterized in that in turn including the following steps:

1) with CoCl ₂And AlCl ₃Be dissolved into respectively in the water, be configured to two kinds of solution that concentration is 1 ~ 2 mol/L, two kinds of solution are mixed, Co in the maintenance mixed solution and the mol ratio of Al are 2 ~ 4, splash into NaOH in 70 ~ 80 ℃ of water-baths of constant temperature, and keeping the pH value is 12 ~ 13, reaction 2 ~ 3 h, aging 12 ~ 24 h, precipitate and separate is washed 2 ~ 3 times with deionized water;

2) solid that step 1) is obtained joins in the sodium selenite solution that concentration is 1 ~ 2 mol/L, and solid-to-liquid ratio is 1:20 ~ 1:50, stirs 4 ~ 5 h, and precipitate and separate is after the solid of acquisition washs 2 ~ 3 times with deionized water, at 400 ~ 500 ℃ temperature lower calcination;

3) it is in 20% ~ 40% the hydrazine hydrate solution, to obtain porous type cobaltous selenide catalyst that the product that per 1 g calcining is obtained joins 20 ~ 40 mL concentration.