CN101757912B

CN101757912B - Prepration method of Pt/TiO2 compound catalyst for low temperature combustion of methanol

Info

Publication number: CN101757912B
Application number: CN2010100231173A
Authority: CN
Inventors: 安保礼; 戴樊增
Original assignee: University of Shanghai for Science and Technology
Current assignee: University of Shanghai for Science and Technology
Priority date: 2010-01-21
Filing date: 2010-01-21
Publication date: 2012-01-04
Anticipated expiration: 2030-01-21
Also published as: CN101757912A

Abstract

The invention relates to a preparation method of a Pt/TiO2 compound catalyst for low temperature combustion of methanol. The method does not involve the prepration method of taking organic compounds and hydrogen as reducing agents during the prepration process. The prepared Pt nanoparticles are characterized by uniformity, monodisperse and the like. The prepared Pt/TiO2 compound catalyst can catalyze the combustion of methanol gas under the room temperature condition and has high catalytic activity for low-temperature catalytic combustion of the methanol. TiO2 in the synthesis method can not only reduce the using amount of Pt in the catalyst, but also improve the catalytic performance of the catalyst and improve the stability of the catalyst. Equipment used in the synthesis process is simple, and the preparation efficiency is high, so that the preparation method can be used for mass prepration of the Pt/TiO2 compound catalyst.

Description

Low temperature combustion of methanol is used Pt/TiO 2The preparation method of composite catalyst

Technical field

The present invention relates to a kind of low temperature combustion of methanol and use the Preparation of catalysts method, particularly a kind of low temperature combustion of methanol is used Pt/TiO ₂The preparation method of composite catalyst.

Technical background

The whole world surpasses 90% the energy from coal combustion, natural gas, oil and other combustible material such as timber etc.; But can produce the problem that many mankind have to face in the high-temp combustion process, like the poor efficiency utilization of global temperatures rising, environmental pollution and the energy.Along with rapid economy development, the China and the whole world also are faced with the immense pressure and the challenge of energy and environment protection aspect.If address this problem, just need start with from changing traditional this basic point of power conversion mode (like high-temp combustion) with wanting essence.

The energy conversion efficiency of present most of internal combustion engine is less than 20%, if we can improve 5% to energy conversion efficiency, can practice thrift the fuel that surpasses more than 25%.Improve energy conversion efficiency a very attractive spot arranged---itself no longer produce new greenhouse gases or increase new environmental pollution.Develop new high-energy conversion efficiency technology and it is promoted the use of, energy security, Environmental security, national defense safety and economic development are all had important meaning.

The energy that the low-temperature burning of methyl alcohol is emitted can convert electric energy into through thermoelectric conversion element, and electric energy drives motor again and makes machine works such as automobile.The low-temperature burning technology of methyl alcohol combines with thermoelectric conversion element, the miniature all solid state direct fuel TRT of processing, and the electric energy of generation is tens of times of chemical cell.

Research shows that the Pt nano particle is the good catalyst of low temperature combustion of methanol.Therefore the efficient production of Pt/ oxide composite catalyst is a hot research in recent years always.Because Pt is noble metal, expensive, and the Pt nano particle in catalytic process along with the temperature rising can be reunited, its particle diameter can constantly be grown up.Therefore seek preparation efficiency height, Pt nanometer particle process method that catalytic activity is high; The use amount that reduces Pt in the catalyst is to reduce use cost; Seek the appropriate catalyst carrier to improve the stability and the catalytic activity of catalyst; And helping efficient, the stable use of preparation of devices and device, is one of this technology popularization key in application problem.

Summary of the invention

The object of the present invention is to provide a kind of low temperature combustion of methanol to use Pt/TiO ₂The preparation method of composite catalyst.

For achieving the above object, the present invention adopts following technical scheme:

A kind of low temperature combustion of methanol is used Pt/TiO ₂The preparation method of composite catalyst is characterized in that the concrete steps of this method are:

1. a low temperature combustion of methanol is used Pt/TiO ₂The preparation method of composite catalyst is characterized in that the concrete steps of this method are:

A. with NaNO ₃Join in the ethylene glycol solution that concentration is the 0.02-0.05mol/L polyvinylpyrrolidone NaNO ₃With the mass ratio of polyvinylpyrrolidone be 1: 1, be warmed up to backflow under stirring; Implantation concentration is 0.05-0.15mol/L H rapidly again ₂PtCl ₆The aqueous solution, NaNO ₃With H ₂PtCl ₆Mass ratio be 3: 2, the faint yellow aterrimus that becomes of back flow reaction to reaction system, stop the reaction.After the cooling, use washing with acetone, separate obtaining the black product; This black product is used dissolve with ethanol, 10～30 minutes min of ultrasonic dispersion, and being mixed with concentration is 2 * 10 ^-4Mol/L nanometer Pt particle solution A.

B. by 1: the volume ratio of (2～6) is with TiCl ₄Slowly be added drop-wise in the frozen water, treat that violent hydrolysis tends towards stability after, be diluted to 85mL (0.53mol/L) with deionized water, stirred 200 ℃ of constant temperature 2～3 hours 10～30 minutes; After the centrifugation, filter residue use deionized water to pH be 7, use absolute ethanol washing again, obtain TiO ₂White gels; This white gels oven dry, grinding are obtained TiO ₂White powder;

C. with adding step b gained TiO among the Pt nano-particle solution A of step a preparation ₂White powder, Pt nano particle and TiO ₂The mass ratio of white powder is 1: 500; Fully be ground to fully evenly, after the drying with solid product 350～500 ℃ of temperature lower calcinations 1～5 hour, obtain the Pt/TiO of grey black ₂Catalyst fines.

Above-mentioned step c replaces with: with adding step b gained TiO among the Pt nano-particle solution A of step a preparation ₂White powder, Pt nano particle and TiO ₂The mass ratio of white powder is 1: 500; Fully be ground to fully evenly, after the drying with solid product 350～500 ℃ of temperature lower calcinations 1～5 hour, obtain the Pt/TiO of grey black ₂Composite catalyst; Get the Pt/TiO of this grey black of a part ₂Composite catalyst was dissolved in the ethanolic solution ultrasonic dispersion 10～30 minutes, obtained Pt/TiO ₂Complex catalyst solution B.Get Pt/TiO ₂It is 10 that composite catalyst uses methyl alcohol to be diluted to concentration ^-4Mol/L (calculating with Pt) is with Al ₂O ₃Fiber is immersed in this dilution 5～20 minutes, takes out and treats solvent evaporates, and burning obtains Al ₂O ₃The Pt/TiO of fiber appendix ₂Composite catalyst C.

Advantage of the present invention is:

1. the Pt nano particle of preparation has homogeneous, characteristics such as single dispersion.

2. the Pt/TiO for preparing ₂Composite catalyst is high to the catalytic activity of low-temperature methanol catalytic combustion.

3. use equipment is simple, and the efficient of preparation is high, in the preparation process, does not include organic compounds and hydrogen as reducing agent.Can be used for preparing more in large quantities Pt/TiO ₂Composite catalyst.

4. active high for synthesis catalytic, the preparation method is simple, and applications such as the catalyst of lower-cost low temperature combustion of methanol have practical significance.

Description of drawings

Fig. 1 is the TEM photo of nanometer Pt particle.

Fig. 2 is Pt/TiO ₂The TEM photo of composite catalyst.

The specific embodiment

Embodiment one: concrete steps are:

1. dispose earlier 0.08mol/L H respectively ₂PtCl ₆The aqueous solution and 0.03mol/L PVP (polyvinylpyrrolidone) ethylene glycol solution.0.1122 gram NaNO ₃Join in the 35mL PVP ethylene glycol solution and dissolve, under electromagnetic agitation, be warmed up to 160 ℃ and boil, inject 3～5mL H with pipette rapidly to solution is little ₂PtCl ₆The aqueous solution, back flow reaction 5～20 minutes, solution stops reaction by the faint yellow aterrimus that becomes.After the cooling, with a large amount of acetone soln washings, 3900 left the heart 1 minute, obtained the black product.Add 5～10mL ethanolic solution, ultrasonic dispersion 10～30min obtains homogeneous, mono-dispersed nano Pt particle A solution at last.

2. with 5mL TiCl ₄Slowly be added drop-wise in 10～30mL frozen water, treat that violent hydrolysis tends towards stability after, be diluted to 85mL with deionized water, electromagnetic agitation 10～30min.Solution is transferred in the 100ml agitated reactor 200 ℃ of constant temperature 2～3h.3900 spend deionised water earlier 3～4 times after leaving the heart 10～30min, to pH ≈ 7, use absolute ethanol washing again 1～2 time, obtain TiO ₂White gels.Product is put to 80 ℃ of oven for drying.The product of oven dry is put in agate mortar, grinds, weighing, dress appearance obtains TiO at last ₂White powder.

3. configuration 2 * 10 earlier ^-6The Pt nano particle A solution of mol/L.Take by weighing 0.1～0.5 gram TiO ₂Nanometer rods places agate mortar, adds the Pt nano particle A solution of 2～5mL, fully is ground to fully evenly.After the infrared lamp drying solid product is put into crucible, under air atmosphere, calcine 1～5h in 350～500 ℃ the Muffle furnace.Obtain the Pt/TiO of grey black at last ₂Powder.Get a part and add the ultrasonic 10～30min of 3～10mL ethanolic solution, obtain Pt/TiO ₂Complex catalyst solution B, its TEM photo sees also Fig. 2.

4. with above-mentioned Pt/TiO ₂The composite catalyst powder, using absolute methanol to be diluted to concentration is 10 ^-4Mol/L is with Al ₂O ₃Fiber soaks wherein to soak after 5 minutes and takes out, and after the equal solvent volatilization, burning obtains Al ₂O ₃The Pt/TiO of fiber appendix ₂Composite catalyst C.The catalytic performance test

At ambient temperature, be in the Pt/TiO that does not have grey black under the aqueous condition fully ₂Splash into several absolute methanols in the powder, have Mars to produce.At ambient temperature, on catalyst C, drip several absolute methanols, methyl alcohol carries out catalytic combustion apace on catalyst C, no flame but red light is arranged.

Repeat above experiment, catalyst C catalysis methanol burning has soon repeated 5 times, and the catalytic performance of catalyst does not fall as follows.Catalyst C is placed in the drier, and cooling is 30 minutes under the room temperature.And then repeat above test, and catalyst C is catalysis methanol burning soon still, and the catalytic performance of catalyst does not fall as follows.

In a water white vial, add about 4 milliliters of absolute methanols, capped is shaken bottle and is volatilized naturally by methyl alcohol, in bottle, is full of methanol gas.At ambient temperature, clamp catalyst C with tweezers and put into bottle, catalyst C does not contact methanol solution, and the methanol gas that can be observed volatilization is burnt on catalyst C soon, sends red light, produces water smoke on the vial wall.This combustion process continues tens minutes, and methyl alcohol volatilizees and all burnt just stops fully in bottle.The The performance test results explanation: the prepared low temperature combustion of methanol of the present invention is used Pt/TiO ₂Composite catalyst can catalysis be lighted methanol gas at ambient temperature, and catalytic activity is high; And good stability can continuous catalysis combustion methanol gas, and catalytic performance does not fall as follows; And still have high catalytic activity after at room temperature placing a period of time, Pt/TiO is described ₂Composite catalyst has stronger water absorption resistance and stability.

Claims

A. with NaNO ₃Join in the ethylene glycol solution that concentration is the 0.02-0.05mol/L polyvinylpyrrolidone NaNO ₃With the mass ratio of polyvinylpyrrolidone be 1: 1, be warmed up to backflow under stirring; Implantation concentration is 0.05-0.15mol/L H rapidly again ₂PtCl ₆The aqueous solution, NaNO ₃With H ₂PtCl ₆Mass ratio be 3: 2, the faint yellow aterrimus that becomes of back flow reaction to reaction system, stop the reaction; After the cooling, use washing with acetone, separate obtaining the black product; This black product is used dissolve with ethanol, ultrasonic dispersion 10～30 minutes, and being mixed with concentration is 2 * 10 ^-4Mol/L nanometer Pt particle solution A;

B. by 1: the volume ratio of (2～6) is with TiCl ₄Slowly be added drop-wise in the frozen water, treat that violent hydrolysis tends towards stability after, be diluted to 85mL with deionized water, stirred 200 ℃ of constant temperature 2～3 hours 10～30 minutes; After the centrifugation, it is 7 that filter residue uses deionized water to be washed till pH, uses absolute ethanol washing again, obtains TiO ₂White gels; This white gels oven dry, grinding are obtained TiO ₂White powder;

2. low temperature combustion of methanol according to claim 1 is used Pt/TiO ₂The preparation method of composite catalyst is characterized in that described step c is replaced with: with adding step b gained TiO among the Pt nano-particle solution A of step a preparation ₂White powder, Pt nano particle and TiO ₂The mass ratio of white powder is 1: 500; Fully be ground to fully evenly, after the drying with solid product 350～500 ℃ of temperature lower calcinations 1～5 hour, obtain the Pt/TiO of grey black ₂Composite catalyst; Get Pt/TiO ₂It is 10 that composite catalyst uses methyl alcohol to be diluted to the concentration of calculating with Pt ^-4Mol/L is with Al ₂O ₃Fiber is immersed in this dilution 5～20 minutes, takes out and treats solvent evaporates, and burning obtains Al ₂O ₃The Pt/TiO of fiber appendix ₂Composite catalyst C.