CN1768931A

CN1768931A - Method for preparing nano-catalyst of Cu2+/TiO2-SiO2

Info

Publication number: CN1768931A
Application number: CN 200510015342
Authority: CN
Inventors: 张国亮; 王贤亲; 张凤宝
Original assignee: Tianjin University
Current assignee: Tianjin University
Priority date: 2005-10-09
Filing date: 2005-10-09
Publication date: 2006-05-10
Anticipated expiration: 2025-10-09
Also published as: CN100387336C

Abstract

The invention discloses a method for preparing nanometer catalyst of Cu2+/TiO2-SiO2, belonging to the vapor phase photo-catalyst technique. Said method comprises: adding de-ionized water into the mixture of silicic acid n-hexanoic, alcohol, and acetic acid to be mixed and attaining the SiO2 sol; adding butyl titanate into SiO2 sol to be mixed to attain the TiO2-SiO2 sol; adding cupric nitrate solution to be mixed to attain the Cu2+/TiO2-SiO2 sol, which is processed by drying, sintering and milling to attain the Cu2+/TiO2-SiO2 catalyst at 10-15nm. The inventive Cu2+/TiO2-SiO2 can realize the full-frequency absorption of visible light, to improve the optical quantum efficiency significantly, while the degradation rate of photo-catalysis dimethoxybenzene can reach more than 95%, with anatase crystal structure with high purity, uniform particle distribution, and larger specific surface. And the invention has reasonable process, simple producing processes, normal reaction conditions, and lower producing cost.

Description

Cu 2+/ TiO 2-SiO 2The preparation method of nanocatalyst

Technical field

The present invention relates to a kind of Cu ²⁺/ TiO ₂-SiO ₂The preparation method of nanocatalyst belongs to gas-phase photocatalysis agent technology.

Background technology

In recent years, utilize TiO ₂For the airborne VOCs of method oxidative degradation of the multiphase photocatalysis of catalyst is that of coming into one's own day by day administers the new technology of polluting.In order to improve TiO ₂Photocatalysis performance, concrete approach has the mode of finishing to mainly contain: the deposition of noble metal, the doping of transition metal ions, semi-conductive compound, surface light sensitization, chelated surface and derivatization etc.People such as Hu Chun report that in Catalysis Today 90 (2004) 325～330 with butyl titanate, silica gel be primary raw material, at logical N ₂Utilize the light deposition method to prepare 1%Cu under the atmosphere ²⁺/ TiO ₂-SiO ₂Nanocatalyst the peak occurs at 600～800nm place in the UV-Vis absorption spectrum, and illustrating has had certain absorption to visible light; But light deposition method complex process, apparatus expensive belongs to the liquid phase photocatalysis technology, 1.5gCu ²⁺/ TiO ₂-SiO ₂Photochemical catalytic oxidation 275ml concentration is that the degradation rate of K-2G, the CBX of 20mg/L only reaches 30%, 60% respectively, active TiO relatively ₂-SiO ₂32%, 60% not improve, therefore prepare Cu with the light sedimentation ²⁺/ TiO ₂-SiO ₂Cost height, activity are not high.

Summary of the invention

The object of the invention provides a kind of Cu ²⁺/ TiO ₂-SiO ₂The preparation method of nanocatalyst.It is reasonable that this method has technology, and preparation equipment is simple, reaction condition gentleness, the characteristics that production cost is low.

To achieve these goals, the present invention is realized by following technical scheme, a kind of Cu ²⁺/ TiO ₂-SiO ₂The preparation method of nanocatalyst is characterized in that may further comprise the steps:

1, be 1: 40～60: 20～30: 60～80 the own ester of positive silicic acid to be added in ethanol and the acetate by the own ester of positive silicic acid and ethanol and acetate and deionized water mol ratio, splash into deionized water then, under 20～30 ℃, generate SiO through the stirring of 10～20min with 60～100 commentaries on classics/min ₂Colloidal sol;

2, be butyl titanate to be added above-mentioned SiO in 1: 4: 0.02 by the own ester of positive silicic acid and butyl titanate and copper nitrate mol ratio ₂In the colloidal sol, under 20～30 ℃, stir 10～20min and form TiO with 60～100 commentaries on classics/min ₂-SiO ₂Colloidal sol splashes into copper nitrate solution again, stirs 30～60min, obtains Cu ²⁺/ TiO ₂-SiO ₂Colloidal sol;

3, the Cu that step 2 is prepared ²⁺/ TiO ₂-SiO ₂Colloidal sol is at 20～30 ℃ down after dry 48～72 hours, and 70～90 ℃ of dryings 36～48 hours in drying box obtain Cu again ²⁺/ TiO ₂-SiO ₂Xerogel;

4, with the Cu of step 3 ²⁺/ TiO ₂-SiO ₂Xerogel is calcined under 500～600 ℃, constant temperature 2～3 hours;

5, after the cooling product is ground the Cu that obtains 10～15nm ²⁺/ TiO ₂-SiO ₂Catalyst.

To the above-mentioned Cu that makes ²⁺/ TiO ₂-SiO ₂Evaluating catalyst method: be by the conversion ratio situation of gas phase dimethylbenzene photocatalytic degradation is estimated.Cu ²⁺/ TiO ₂-SiO ₂The activity experiment of photocatalytic degradation dimethylbenzene is to carry out in the glass chamber reaction unit of a 26L.Detailed process is as follows: the Cu that takes by weighing 0.2g ²⁺/ TiO ₂-SiO ₂Nanocatalyst, add an amount of 2ml distilled water, after stirring the formation pulpous state, be applied to (260mm * 50mm) after 100 ℃ of dryings, be placed in the reaction unit on the glass plate, a certain amount of dimethylbenzene that reinjects makes the concentration in its reaction system reach 50ppm, opening aerofoil fan makes gas in reaction system behind the circulation 20min, sampling is as the initial concentration of photocatalytic degradation, carry out light-catalyzed reaction under the ultraviolet germicidal of 8w (wavelength 254nm) then, with the variation of GC7900 type gas chromatograph test paraxylene concentration.Behind the reaction 240min, finish experiment.

The present invention compared with prior art, prepared Cu ²⁺/ TiO ₂-SiO ₂The energy gap that has the visible radiation of being subjected to also can excite has realized the full range of visible light is absorbed, and can significantly improve Cu ²⁺/ TiO ₂-SiO ₂Photo-quantum efficiency, and this catalyst has highly purified anatase crystal structure, particle diameter is little, distribution of particles is even, bigger specific area is active high; It is reasonable to have technology simultaneously, and it is simple to produce preparation flow, the reaction condition gentleness, and production cost is low.

Description of drawings

Fig. 1 is the Cu of embodiment 1 gained ²⁺/ TiO ₂-SiO ₂Nanocatalyst and TiO ₂(P25) ultraviolet-visible absorption spectrum figure is the Lambda35 ultraviolet-visible spectrophotometer that utilizes PE company carries out UV-Vis to catalyst and detects and obtain.

Fig. 2 is the Cu of embodiment 1 gained ²⁺/ TiO ₂-SiO ₂Nanocatalyst and TiO ₂(P25) infrared light printing opacity spectrogram obtains by the detection of Thermo Nicolet NEXUS FT infrared spectrometer.

Fig. 3 is the Cu of embodiment 1 gained ²⁺/ TiO ₂-SiO ₂Nanocatalyst and TiO ₂(P25) the change in concentration tendency chart of photocatalytic degradation dimethylbenzene.

The specific embodiment

Embodiment 1

Measure 20ml absolute ethyl alcohol, 15ml glacial acetic acid and 1.64ml ethyl orthosilicate and join in the conical flask, mix down evenly, the 8ml deionized water is splashed into conical flask with the speed of 5/min, drip and finish the back, obtain transparent SiO with 60 commentariess on classics/min stirring 15min at 25 ℃ ₂Colloidal sol.Take by weighing the speed adding SiO of 10ml butyl titanate with 8/min ₂In the colloidal sol, drip and finish to obtain TiO behind the 60 commentaries on classics/min stirring 15min ₂-SiO ₂Colloidal sol.Again the copper nitrate solution (concentration is 0.5mol/L) of 2.94ml is splashed into TiO with the speed of 5/min ₂-SiO ₂Colloidal sol drips and finishes with behind the 60 commentaries on classics/min stirring 40min, leaves standstill colloidal sol under the nature, obtains translucent Cu ²⁺/ TiO ₂-SiO ₂Gel, under the room temperature behind the dry 48h, 80 ℃ of dry 36h in drying box.At last with dried Cu ²⁺/ TiO ₂-SiO ₂Xerogel is heated to 500 ℃ in Muffle furnace, heating voltage 110V, and 5 ℃/min of programming rate, constant temperature 2h, taking-up obtains the Cu that average grain diameter is 11nm after grinding ²⁺/ TiO ₂-SiO ₂Catalyst 4.8g.Then catalyst is carried out XRD, UV-Vis, BET, FTIR sign and activity rating.Specific area (BET) is detected Cu by Sorptomatic 1990 ²⁺/ TiO ₂-SiO ₂Specific area be 291m ²G ^-1, the catalyst surface that the catalyst that the present invention makes has bigger serface has more active sites, can adsorb more organic matter, more helps active raising.

Catalyst that present embodiment 1 makes and existing TiO ₂Catalyst photon absorbing intensity comparison curves as shown in Figure 1, as can be seen from Figure at visible region, Cu ²⁺/ TiO ₂-SiO ₂The light absorption of nanocatalyst is apparently higher than TiO ₂, realized the full range of visible light is absorbed; As can be seen from Figure 2 the catalyst that makes of present embodiment 1 is at 3408cm ^-1With 1630cm ^-1The peak value at place is obviously than existing TiO ₂(P25) strong, illustrate that water imbibition is strong, active high; As can be seen from Figure 3 the catalyst activity that makes of present embodiment 1 is obviously than TiO ₂(P25) height, the degradation rate of photochemical catalytic oxidation 50ppm dimethylbenzene is 96.5%, compares TiO ₂The degradation rate of photocatalysis dimethylbenzene 67.88% has improved 28.62%.

Embodiment 2

Measure 18ml absolute ethyl alcohol, 14ml glacial acetic acid and 1.64ml ethyl orthosilicate and join in the conical flask, mix down evenly, the 7ml deionized water is splashed into conical flask with the speed of 5/min, drip and finish the back, obtain transparent SiO with 80 commentariess on classics/min stirring 20min at 30 ℃ ₂Colloidal sol.Take by weighing the speed adding SiO of 10ml butyl titanate with 8/min ₂In the colloidal sol, obtain TiO behind the complete stirring 20min ₂-SiO ₂Colloidal sol.Again the copper nitrate solution (concentration is 0.5mol/L) of 2.94ml is splashed into TiO with the speed of 5/min ₂-SiO ₂Colloidal sol behind the complete stirring 60min, leaves standstill colloidal sol under the nature, obtains translucent Cu ²⁺/ TiO ₂-SiO ₂Gel, under the room temperature behind the dry 72h, 80 ℃ of dry 48h in drying box.At last with dried Cu ²⁺/ TiO ₂-SiO ₂Xerogel is heated to 500 ℃ in Muffle furnace, heating voltage 110V, and 5 ℃/min of programming rate, constant temperature 2h, taking-up obtains the Cu that average grain diameter is 13nm after grinding ²⁺/ TiO ₂-SiO ₂Catalyst 4.7g, Cu ²⁺/ TiO ₂-SiO ₂Specific area be 278m ²G ^-1, the degradation rate of photochemical catalytic oxidation 50ppm dimethylbenzene is 95.4%.

Embodiment 3

Measure 40ml absolute ethyl alcohol, 30ml glacial acetic acid and 3.28ml ethyl orthosilicate and join in the conical flask, mix down evenly, the 15ml deionized water is splashed into conical flask with the speed of 5/min, drip and finish the back, obtain transparent SiO with 100 commentariess on classics/min stirring 10min at 20 ℃ ₂Colloidal sol.Take by weighing the speed adding SiO of 20ml butyl titanate with 8/min ₂In the colloidal sol, obtain TiO behind the complete stirring 10min ₂-SiO ₂Colloidal sol.Again the copper nitrate solution (concentration is 0.5mol/L) of 5.88ml is splashed into TiO with the speed of 5/min ₂-SiO ₂Colloidal sol behind the complete stirring 30min, leaves standstill colloidal sol under the nature, obtains translucent Cu ²⁺/ TiO ₂-SiO ₂Gel, under the room temperature behind the dry 64h, 80 ℃ of dry 42h in drying box.At last with dried Cu ²⁺/ TiO ₂-SiO ₂Xerogel is heated to 500 ℃ in Muffle furnace, heating voltage 110V, and 5 ℃/min of programming rate, constant temperature 3h, taking-up obtains the Cu that average grain diameter is 12nm after grinding ²⁺/ TiO ₂-SiO ₂Catalyst 9.7g, specific area are 285m ²G ^-1, the degradation rate of photochemical catalytic oxidation 50ppm dimethylbenzene is 96.2%.

Claims

1. Cu ²⁺/ TiO ₂-SiO ₂The preparation method of nanocatalyst is characterized in that may further comprise the steps:

1) be 1: 40～60: 20～30: 60～80 the own ester of positive silicic acid to be added in ethanol and the acetate, by the own ester of positive silicic acid and ethanol and acetate and deionized water mol ratio, splash into deionized water then, under 20～30 ℃, generate SiO through the stirring of 10～20min with 60～100 commentaries on classics/min ₂Colloidal sol;

2) be butyl titanate to be added above-mentioned SiO in 1: 4: 0.02, by the own ester of positive silicic acid and butyl titanate and copper nitrate mol ratio ₂In the colloidal sol, under 20～30 ℃, stir 10～20min and form TiO with 60～100 commentaries on classics/min ₂-SiO ₂Colloidal sol splashes into copper nitrate solution again, stirs 30～60min, obtains Cu ²⁺/ TiO ₂-SiO ₂Colloidal sol;

3), with step 2) Cu for preparing ²⁺/ TiO ₂-SiO ₂Colloidal sol is at 20～30 ℃ down after dry 48～72 hours, and 70～90 ℃ of dryings 36～48 hours in drying box obtain Cu again ²⁺/ TiO ₂-SiO ₂Xerogel;

4), with the Cu of step 3) ²⁺/ TiO ₂-SiO ₂Xerogel is calcined under 500～600 ℃, constant temperature 2～3 hours;

5), after the cooling product is ground the Cu that obtains 10～15nm ²⁺/ TiO ₂-SiO ₂Catalyst.