CN102936037A

CN102936037A - Process for preparing stable high-dispersion Au/TiO2 catalyst

Info

Publication number: CN102936037A
Application number: CN 201210457050
Authority: CN
Inventors: 安会琴
Original assignee: Tianjin Polytechnic University
Current assignee: Tianjin Polytechnic University
Priority date: 2012-11-15
Filing date: 2012-11-15
Publication date: 2013-02-20

Abstract

The invention relates to a process for preparing a stable high-dispersion Au/TiO2 supported catalyst of which the particle size is controllable. A TiO2 nanotube which is synthesized through a hydrothermal process serves as a carrier, by the aid of a large amount of -ONa bonds on the surface of the TiO2 nanotube which is synthesized through the hydrothermal process, and nano gold particles are anchored at active positions of the carrier through a chemical reaction, so that the Au/TiO2 catalyst which is high in dispersion and controllable in particle size is obtained. Active components of Au particles are controllable in size, the catalyst is stable, agglomeration is avoided during roasting and catalyzing, and the catalyst has good application prospects in terms of industrial catalysis.

Description

A kind of stable high dispersive Au/TiO 2The preparation method of catalyzer

Technical field

The present invention relates to a kind of stable high dispersive Au/TiO ₂Catalyzer, the invention still further relates to the concrete grammar and the characteristics that prepare this catalyzer.

Background technology

Nano-Au catalyst has good application prospect in fields such as environment protection, the energy, biomedicine and fine chemistry industries.The Au catalyzer can be used for the elimination of pollution gas, as the elimination of low temperature CO, and the perfect combustion reaction of alkane and the elimination of oxynitride etc.Since Hutchings and Haruta reported first since the high reactivity of high dispersive Au to the CO oxidizing reaction, Au catalyst starts to be paid close attention to widely.Particularly when nano Au particle, be deposited on the surface of metal oxide carrier, it significantly increases the activity of CO oxidation, and many heterogeneous organic synthesis are also demonstrated to higher catalytic activity, therefore is subject to paying close attention to more widely.

TiO ₂As a kind of important inorganic functional material, nontoxic with it, catalytic activity is high, good stability and the advantage such as resistance of oxidation is strong and enjoy favor.Nano-TiO ₂Not only self there is excellent catalytic performance, and also obtain broad research as carrier.With general T iO ₂Nano-powder is compared, by TiO ₂The titanyl nanotube be transformed has special tubular structure, and high specific surface area and stronger adsorptive power, be more suitable for doing support of the catalyst.At present, about Au/TiO ₂The report of loaded catalyst synthetic method has a lot, mainly contains deposition-precipitation method, coprecipitation method, photochemical precipitation method and pickling process etc.A general general character of these methods is that gold particle loads on TiO by physical adsorption ₂On carrier, that is, there do not is chemical bonding force between nano Au particle and titanium dioxide.

Research shows, the size of nano Au particle is one of principal element determined its catalytic activity height, and gold particle is less, and its catalytic activity is higher, and by traditional preparation method's physical adsorption at TiO ₂Its size of particles of gold particle on carrier is uncontrollable, and particularly, in roasting process, the reunion of the nanometer Au of physical adsorption is quite serious, and the Au nanoparticle is also very easily reunited in catalytic process simultaneously, causes the load type gold catalyst catalytic activity to reduce.In addition, also there is some other inevitable defect in the tradition preparation method, for example, the more difficult accurate control of coprecipitation method synthesis condition, poor repeatability, on the catalyzer made, a lot of Au particles all are embedded in carrier particle inside, cause surfaces A u content lower, only have and just can show activity preferably when charge capacity is larger.And the nano Au particle size that pickling process is prepared is uncontrollable, and Cl ^-Easily be adsorbed onto the gold particle surface, cause golden active site position to be reduced.Therefore, the controlled polymolecularity Au/TiO of synthetic gold particle size ₂Catalyzer is current problem demanding prompt solution.The present invention is anchored on TiO by chemical reaction by nano Au particle ₂Thereby obtain stable high-dispersion loading type Au catalyst on the activity site of carrier.

Summary of the invention

For realizing that technical scheme provided by the present invention is:

The synthetic titanate nanotube of the hydrothermal method of take is carrier, by means of hydrothermal method synthetic titanate nanotube surface a large amount of-the ONa key, form by itself and dithiocarbonic anhydride the titanate nanotube that the xanthogen chemical reaction obtains the dithiocarbonic anhydride modification, after acidifying, nanotube surface contains a large amount of-SH base.Due to the characteristic of Au and S ,-SH base can be by Au-S key assemble nanometer gold to TiO ₂On nano-tube support.Thereby stablized, high dispersing and the controlled Au/TiO of size of particles ₂Catalyzer.

The hydrothermal synthesis method of wherein said titanate nanotube is: general～1.5gTiO ₂Powder (Detitanium-ore-type) is sealed in 70mL tetrafluoroethylene reactor with 10mol/LNaOH solution, be heated to～150 ℃ of reaction 12h of oil bath under agitation condition.Centrifugal, the floss of gained white is titanate nanotube.

The chemical reaction that titanate nanotube and dithiocarbonic anhydride form xanthogen is: take quantitative titanate nanotube, add excessive CS ₂, stirring at room 12 hours.Color by colourless become gradually orange-yellow.Centrifugal, remove mother liquor, with distilled water and ethanol repetitive scrubbing, use afterwards rare HNO ₃Solution is adjusted to the acid rear 12h of stirring, and centrifugal, room temperature vacuum-drying obtains the titanate nanotube (after acidifying) that dithiocarbonic anhydride is modified.

The preparation method of gold colloid solution is: the precursor that the hydrochloro-auric acid of take is nanometer gold, polyvinylpyrrolidone (PVP), Trisodium Citrate are dispersion agent, with the sodium borohydride reduction chlorauric acid solution, obtain nano Au particle.

Afterwards quantitative dithiocarbonic anhydride is modified to titanate nanotube and be scattered in gold sol solution stirring at room 12 hours, with after the distilled water repetitive scrubbing, centrifugal, dry.The gained sample is the Au/TiO of chemical anchoring ₂Catalyzer.。

Ultimate principle of the present invention is the TiO that utilizes hydrothermal method synthetic ₂Nanotube surface has a large amount of-ONa key, prepare dithiocarbonic anhydride and modify titanate nanotube by forming the xanthogen chemical reaction, and take dithiocarbonic anhydride, to modify titanate nanotube be carrier, by chemical reaction grappling nanometer gold thereon.Due to the nano Au particle prepared in the present invention be chemical anchoring on nano-tube support, its degree of scatter on carrier depends on TiO ₂On nano-tube support-and the distribution of ONa group, therefore, in roasting and catalytic process gold particle, do not reunite, thereby can synthesize the controlled Au/TiO of size of particles of high dispersive ₂Loaded catalyst.

Embodiment

For better understanding the present invention, below in conjunction with embodiment, the present invention is done further and describes in detail, but the scope of protection of present invention is not limited to the scope that embodiment means.

Embodiment:

By 1.5g TiO ₂Powder (Detitanium-ore-type) is sealed in 70mL tetrafluoroethylene reactor with 10mol/L NaOH solution, be heated to～150 ℃ of reaction 12h of oil bath under agitation condition.Centrifugal, vacuum-drying obtains titanate nanotube.Take the 2.0g titanate nanotube in a round-bottomed flask, add 10ml CS ₂, stirring at room 12 hours.Color by colourless become gradually orange-yellow.Centrifugal, remove mother liquor, with after the distilled water repetitive scrubbing, then use washing with alcohol twice, use afterwards rare HNO ₃Solution stirs 12h after being adjusted to acidity (pH 2-3), centrifugal, and room temperature vacuum-drying obtains the titanate nanotube (after acidifying) that dithiocarbonic anhydride is modified.Take the titanate nanotube (after acidifying) of 1.0g dithiocarbonic anhydride modification in a round-bottomed flask, add PVP 0.20g in round-bottomed flask, 0.01mol/L HAuCl ₄Solution 18mL, Trisodium Citrate 0.06g, be placed in ice-water bath stir about 10min.The sodium borohydride solution that slowly adds afterwards in advance cooling 15ml 0.07mol/L, continue stir about 12h, centrifugal, uses the distilled water repetitive scrubbing, and vacuum-drying must be stablized, the Au/TiO of high dispersive ₂Catalyzer.

Claims

1. a titanate nanotube is characterized in that: it is the white floss that adopts hydrothermal method to prepare, and this floss is alkalescence, during use without repeatedly cleaning with distilled water.

2. the titanate nanotube that dithiocarbonic anhydride is modified, is characterized in that: the CS that 2.0g titanate nanotube claimed in claim 1 is joined to 10ml ₂In, stirring at room 12 hours, color becomes orange-yellowly, centrifugal by colourless gradually, removes mother liquor, with distilled water and ethanol repetitive scrubbing, uses afterwards rare HNO ₃Solution is adjusted to the acid rear 12h of stirring, centrifugal, room temperature vacuum-drying, wherein said CS ₂Consumption is excessive, and dilute nitric acid solution concentration is about 1mol/L, is adjusted to acid rear pH value of solution between 2-3.

3. the stable high dispersive Au/TiO of a chemical anchoring ₂Catalyzer is characterized in that: quantitative dithiocarbonic anhydride claimed in claim 2 modified to titanate nanotube and is scattered in gold sol solution stirring at room 12 hours, and with after the distilled water repetitive scrubbing, centrifugal, dry.

4. the stable high dispersive Au/TiO of chemical anchoring according to claim 3 ₂Catalyzer is characterized in that: described gold sol solution manufacturing method is for take the precursor that hydrochloro-auric acid is nanometer gold, and polyvinylpyrrolidone (PVP), Trisodium Citrate are dispersion agent, and sodium borohydride is reductive agent.

5. according to the stable high dispersive Au/TiO of chemical anchoring claimed in claim 3 ₂The preparation method of catalyzer is characterized in that comprising following steps:

1) titanate nanotube (after acidifying) that takes the modification of 1.0g dithiocarbonic anhydride, in a round-bottomed flask, adds PVP 0.20g, 0.01mol/L HAuCl in round-bottomed flask ₄Solution 18mL, Trisodium Citrate 0.06g, be placed in ice-water bath stir about 10min;

2) slowly add afterwards the sodium borohydride solution of in advance cooling 15ml 0.07mol/L, continue stir about 12h;

3) centrifugal, use the distilled water repetitive scrubbing, vacuum-drying.