CN105457629A - Load type nano precious metal catalyst and preparation method and application thereof - Google Patents

Abstract

The invention relates to a load type nano precious metal catalyst which comprises a carrier and nano precious metal particles loaded on the carrier. The average particle size of the nano precious metal particles is 1.5-4.5 nm, and the quality percentage of the precious metal in the catalyst is 1-10%; the specific surface area of the carrier is 40-190 m<2>/g, and the pore volume is 0.06-0.4 ml/g. The preparation method of the catalyst includes the steps that a reduction method is adopted to prepare nano precious metal colloid particles, then a colloidal deposition method is adopted, the nano precious metal particles are loaded to different carriers, and the load type nano precious metal catalyst with the particle size and the size distribution being the same is prepared. The load type nano precious metal catalyst can be widely applied to an industrial catalytic reaction, and the emission load of the pollutant CO can be lowered.

Description

A kind of loaded nano noble metal catalyst and its preparation method and application

Technical field

The present invention relates to nanocatalyst preparing technical field, be specifically related to a kind of loaded nano noble metal catalyst and its preparation method and application.

Background technology

Nano particle makes to which create much distinctive optics, electricity, catalytic performance etc. because of the quantum size effect of its uniqueness, skin effect and macro quanta tunnel effect etc., the fields such as chemical industry, electronic circuit, optical check, instrument manufacturing, bio-sensing, pharmaceutical carrier can be widely used in, there is important using value.

Air pollution problems inherent more and more receives the concern of people, and many researchers start to be devoted to research and develop efficient, safe, economic material for air purification.Wherein the efficient performance of loaded nano noble metal granule causes the attention of researcher.Nano-noble metal particle because of its valuable rare characteristic, can not individually, a large amount of stable existence, be therefore loaded on cheap inert carrier, generate loaded nano noble metal catalyst and catalytic action is carried out to industrial reaction.

The method of loaded nano noble metal catalyst is generally infusion process, deposition-precipitation etc.In these conventional methods, even if preparation condition (as pH value, aging, roasting etc.) is identical, but due to the difference of oxide carrier kind, also can impact the formation of nano metal particles, make the size of nano noble metal particles and Size Distribution different and produce larger difference.Wherein on loaded nano noble metal catalyst, nano particle plays catalytic effect, and because the particle diameter of nano noble metal particles is different, its performance can be greatly affected, and therefore the loaded nano noble metal catalyst prepared of conventional method is unsatisfactory.

Summary of the invention

In order to overcome prior art deficiency, the invention provides a kind of loaded nano noble metal catalyst and its preparation method and application.Preparation method of the present invention first adopts reducing process to prepare nano-noble metal colloidal particle, then by colloidal deposition method, nano noble metal particles is loaded on different carriers, prepares grain size and the identical loaded nano noble metal catalyst of Size Distribution.

Technical solution of the present invention is as follows:

A kind of loaded nano noble metal catalyst, comprise carrier and be carried on the nano-noble metal particle on described carrier, the average grain diameter of wherein said nano-noble metal particle is 1.5-4.5nm, and in catalyst, the mass percentage of noble metal is 1%-10%; The specific area of described carrier is 40-190m²/ g, pore volume is 0.06-0.4ml/g.

Preferably, the average grain diameter of described nano-noble metal particle is 1.5-3nm, more preferably 2nm;

Preferably, in described catalyst, the mass percentage of noble metal is 1%-1.5%, more preferably 1%;

Preferably, the specific area of described carrier is specific area is 40-60m²/ g, pore volume is 0.06-0.1ml/g.

Preferably, described noble metal comprises one or more in Pt, Pd, Au, Rh, Ag, Ru etc.; More preferably Pt and/or Au.

Preferably, described carrier is TiO₂, CeO₂, ZrO₂, Al₂o₃deng one or more in oxide; More preferably TiO₂and/or CeO₂.

The present invention also provides the preparation method of above-mentioned loaded nano noble metal catalyst, comprises the steps:

1) be dissolved in by precious metal salt in PVP (i.e. polyvinylpyrrolidone) solution, add the ethylene glycol solution containing NaOH, continue to pass into inert gas, after stirring, cooling, obtains the nano-sized colloidal solution of described noble metal;

2) add acid to receiving in colloidal solution of described noble metal, add inert carrier after centrifugation, after leaving standstill, dry process, obtains loaded nano noble metal catalyst.

The preparation method of above-mentioned loaded nano noble metal catalyst, wherein:

Step 1) described precious metal salt comprises chloroplatinic acid (H₂ptCl₆6H₂o), gold chloride (HAuCl₄4H₂o), palladium bichloride (PdCl₂nH₂o), ruthenium trichloride (RuCl₃nH₂etc. O) one or more in;

Described polyvinylpyrrolidonesolution solution concentration is 1 × 10^-6-1 × 10^-5mol/L;

The concentration of described precious metal salt in polyvinylpyrrolidonesolution solution is 0.003-0.03mmol/L, is preferably 0.025-0.029mmol/L;

The concentration of described NaOH in ethylene glycol is 0.02-0.05mmol/L, is preferably 0.02-0.03mmol/L;

Described inert gas is one or more in argon gas, nitrogen, helium etc.;

Step 2) described acid is one or more in hydrochloric acid, nitric acid, carbonic acid etc.; Be preferably hydrochloric acid.

The consumption of described acid is 0.02-0.03mmol/L;

Described inert carrier comprises TiO₂, CeO₂, ZrO₂, Al₂o₃deng one or more in oxide; More preferably TiO₂and/or CeO₂.

The present invention also comprises the obtained loaded nano noble metal catalyst of said method.

The present invention also provides the purposes of above-mentioned loaded nano noble metal catalyst, and described purposes comprises for hydrogen manufacturing, methane vapor reforming legal system synthesis gas etc. in hydrogen/methanol oxidation in fuel cell or redox, water gas shift reaction.

If no special instructions, specific area method of testing of the present invention is static capacity method.

The present invention obtains grain size and the identical nano-noble metal particle of Size Distribution by reducing process, then loads on different inert carriers, obtains the catalyst that nano-noble metal seed activity is identical.Method is reduced the nano-noble metal grain diameter obtained and is about 2nm thus, and domain size distribution is more even.By nano-noble metal particulate load on identical indifferent oxide carrier, obtained loaded nano noble metal catalyst, can be widely used in industrial catalytic reaction.Loaded nano noble metal catalyst involved in the present invention, can be applicable in small-sized even medium-sized fuel cell, reduces the discharge capacity of pollutant CO.

Accompanying drawing explanation

Fig. 1 is embodiment 1Pt/TiO₂tEM figure (i.e. transmission electron microscope picture) of catalyst.

Fig. 2 is different preparation method Pt/CeO in experimental example 1₂catalyst carries out the CO conversion ratio figure of water gas shift reaction.

Detailed description of the invention

Following examples for illustration of the present invention, but are not used for limiting the scope of the invention.

If no special instructions, specific area method of testing described in following examples is static capacity method.

Embodiment 1

A kind of loaded nano precious metals pt catalyst (Pt/TiO₂catalyst), nano-noble metal Pt particle diameter is 2nm, and carrier is TiO₂, the specific area of this carrier is 40m²/ g, pore volume is 0.06ml/g, and in catalyst, the mass percentage of precious metals pt is 1%.

Embodiment 2

A kind of loaded nano precious metals pt catalyst (Pt/CeO₂catalyst), nano-noble metal Pt particle diameter is 2nm, and carrier is CeO₂, the specific area of this carrier is 60m²/ g, pore volume is 0.1ml/g, and in catalyst, the mass percentage of precious metals pt is 1%.

Embodiment 3

A kind of loaded nano noble metal Au catalyst (Au/TiO₂catalyst), nano-noble metal Au particle diameter is 2nm, and carrier is TiO₂, the specific area of this carrier is 40m²/ g, pore volume is 0.06ml/g, and in catalyst, the mass percentage of noble metal Au is 1%.

Embodiment 4

A kind of loaded nano precious metals pd catalyst (Pd/TiO₂catalyst), nano-noble metal Pd particle diameter is 2nm, and carrier is TiO₂, the specific area of this carrier is 40m²/ g, pore volume is 0.06ml/g, and in catalyst, the mass percentage of precious metals pd is 1%.

Embodiment 5

A kind of loaded nano precious metals pd catalyst (Pd/CeO₂catalyst), nano-noble metal Pd particle diameter is 2nm, and carrier is CeO₂, the specific area of this carrier is 60m²/ g, pore volume is 0.1ml/g, and in catalyst, the mass percentage of precious metals pd is 1%.

Embodiment 6

The present embodiment provides loaded nano precious metals pt catalyst (Pt/TiO described in embodiment 1₂catalyst) preparation method, comprise the following steps:

By a certain amount of H₂ptCl₆6H₂o solid is dissolved in PVP solution that (PVP solution concentration is 1 × 10^-5mol/L), add the ethylene glycol solution containing NaOH, after mixing, be placed in three hole round-bottomed flasks, described H₂ptCl₆6H₂the concentration of O in PVP solution is 0.029mmol/L; The concentration of described NaOH in ethylene glycol is 0.02mmol/L; Continue to pass into inert gas argon gas, after stirring, cooling obtains the nano-colloid particle solution of precious metals pt.This nano-colloid particle solution is added the HCl of 0.02mmol/L amount, after centrifugation, add inert carrier TiO₂, stir, carry out drying process after leaving standstill, obtain loaded nano precious metals pt catalyst.

Embodiment 7

The present embodiment provides loaded nano precious metals pt catalyst (Pt/CeO described in embodiment 2₂catalyst) preparation method, comprise the following steps:

By a certain amount of H₂ptCl₆6H₂o solid is dissolved in PVP solution that (PVP solution concentration is 1 × 10^-5mol/L), add the ethylene glycol solution containing NaOH, after mixing, be placed in three hole round-bottomed flasks, described H₂ptCl₆6H₂the concentration of O in PVP solution is 0.029mmol/L; The concentration of described NaOH in ethylene glycol is 0.02mmol/L; Continue to pass into inert gas argon gas, after stirring, cooling obtains the nano-colloid particle solution of precious metals pt.This nano-colloid particle solution is added the HCl of 0.02mmol/L amount, after centrifugation, add inert carrier CeO₂, stir, carry out drying process after leaving standstill, obtain loaded nano precious metals pt catalyst.

Embodiment 8

The present embodiment provides loaded nano noble metal Au catalyst (Au/TiO described in embodiment 3₂catalyst) preparation method, comprise the following steps:

By a certain amount of HAuCl₄4H₂o solid is dissolved in PVP solution that (PVP solution concentration is 1 × 10^-6mol/L), add the ethylene glycol solution containing NaOH, after mixing, be placed in three hole round-bottomed flasks, described HAuCl₄4H₂the concentration of O in PVP solution is 0.03mmol/L; The concentration of described NaOH in ethylene glycol is 0.02mmol/L; Continue to pass into inert nitrogen gas, after stirring, cooling obtains the nano-colloid particle solution of noble metal Au.This nano-colloid particle solution is added the HCl of 0.02mmol/L amount, after centrifugation, add inert carrier TiO₂, stir, carry out drying process after leaving standstill, obtain loaded nano precious metals pt catalyst.

Embodiment 9

The present embodiment provides loaded nano precious metals pd catalyst (Pd/TiO described in embodiment 4₂catalyst) preparation method, comprise the following steps:

By a certain amount of PdCl₂nH₂o solid is dissolved in PVP solution that (PVP solution concentration is 1 × 10^-6mol/L), add hydrochloric ethylene glycol solution, after mixing, be placed in three hole round-bottomed flasks, described PdCl₂nH₂the concentration of O in PVP solution is 0.03mmol/L; The concentration of described NaOH in ethylene glycol is 0.02mmol/L; Continue to pass into inert nitrogen gas, after stirring, cooling obtains the nano-colloid particle solution of noble metal Au.This nano-colloid particle solution is added the NaOH of 0.02mmol/L amount, after centrifugation, add inert carrier TiO₂, stir, carry out drying process after leaving standstill, obtain loaded nano precious metals pt catalyst.

Embodiment 10

The present embodiment provides loaded nano noble metal Au catalyst (Au/TiO described in embodiment 3₂catalyst) preparation method, comprise the following steps:

By a certain amount of HAuCl₄4H₂o solid is dissolved in PVP solution that (PVP solution concentration is 1 × 10^-5mol/L), add the ethylene glycol solution containing NaOH, after mixing, be placed in three hole round-bottomed flasks, described HAuCl₄4H₂the concentration of O in PVP solution is 0.03mmol/L; The concentration of described NaOH in ethylene glycol is 0.02mmol/L; Continue to pass into inert nitrogen gas, after stirring, cooling obtains the nano-colloid particle solution of noble metal Au.This nano-colloid particle solution is added the HCl of 0.02mmol/L amount, after centrifugation, add inert carrier CeO₂, stir, carry out drying process after leaving standstill, obtain loaded nano precious metals pt catalyst.

Comparative example 1

A kind of loaded nano precious metals pt catalyst (Pt/CeO₂catalyst), by prior art loaded catalyst conventional impregnation methods, by carrier (CeO₂) put liquid (H containing active material into₂ptCl₆solution) middle dipping, active material (Pt ion) is adsorbed in carrier surface gradually, and when after dipping balance, the liquid that removing is left, carries out the process such as drying, roasting and prepare.

Experimental example 1

Adopt Pt/CeO described in embodiment 1 and comparative example 1 respectively₂catalyst carries out Water gas shift/WGS (CO+H₂o=CO₂+ H₂) reaction, result (as shown in Figure 2) shows, CO conversion ratio raises with the rising of temperature, under same temperature, catalyst described in the embodiment of the present invention 1 in the reaction CO conversion ratio apparently higher than the catalyst prepared by conventional infusion process (comparative example 1).In Fig. 2, abscissa represents temperature, and ordinate represents CO conversion ratio, and " Xeqco " represents the thermodynamical equilibrium conversion ratio of water gas shift reaction, " Pt/CeO₂infusion process " represent comparative example 1, " Pt/CeO₂method therefor of the present invention " represent embodiment 1.

Although above the present invention is described in detail with a general description of the specific embodiments, on basis of the present invention, can make some modifications or improvements it, this will be apparent to those skilled in the art.Therefore, these modifications or improvements without departing from theon the basis of the spirit of the present invention, all belong to the scope of protection of present invention.

Claims (10)

1. a loaded nano noble metal catalyst, comprise carrier and be carried on the nano-noble metal particle on described carrier, the average grain diameter of wherein said nano-noble metal particle is 1.5-4.5nm, and in catalyst, the mass percentage of noble metal is 1%-10%; The specific area of described carrier is 40-190m²/ g, pore volume is 0.06-0.4ml/g.

2. loaded nano noble metal catalyst according to claim 1, is characterized in that, the average grain diameter of described nano-noble metal particle is 1.5-3nm, is preferably 2nm;

Preferably, in described catalyst, the mass percentage of noble metal is 1%-1.5%, more preferably 1%;

Preferably, the specific area of described carrier is 40-60m²/ g, pore volume is 0.06-0.1ml/g.

3. loaded nano noble metal catalyst according to claim 1 and 2, is characterized in that, described noble metal comprises one or more in Pt, Pd, Au, Rh, Ag, Ru; Be preferably Pt and/or Au.

4. loaded nano noble metal catalyst according to claim 1 and 2, is characterized in that, described carrier is TiO₂, CeO₂, ZrO₂, Al₂o₃in one or more; Be preferably TiO₂and/or CeO₂.

5. the preparation method of loaded nano noble metal catalyst described in any one of claim 1-4, is characterized in that, comprise the steps:

1) be dissolved in polyvinylpyrrolidonesolution solution by precious metal salt, add the ethylene glycol solution containing NaOH, continue to pass into inert gas, after stirring, cooling, obtains the nano-sized colloidal solution of described noble metal;

2) add acid to receiving in colloidal solution of described noble metal, add inert carrier after centrifugation, after leaving standstill, dry process, obtains loaded nano noble metal catalyst.

6. preparation method according to claim 5, is characterized in that, step 1) described in precious metal salt comprise in chloroplatinic acid, gold chloride, palladium bichloride, ruthenium trichloride one or more;

Preferably, the concentration of described precious metal salt in polyvinylpyrrolidone is 0.003-0.03mmol/L, more preferably 0.025-0.029mmol/L;

Preferably, described polyvinylpyrrolidonesolution solution concentration is 1 × 10-6-1 × 10-5mol/L.

7. the preparation method according to claim 5 or 6, is characterized in that, step 1) described in the concentration of NaOH in ethylene glycol be 0.02-0.05mmol/L, be preferably 0.02-0.03mmol/L;

Preferably, inert gas is one or more in argon gas, nitrogen, helium.

8. the preparation method according to any one of claim 5-7, is characterized in that, step 2) described in acid be one or more in hydrochloric acid, nitric acid, carbonic acid; Be preferably hydrochloric acid; Preferably, the consumption of described acid is 0.02-0.03mmol/L.

9. the preparation method according to any one of claim 5-8, is characterized in that, step 2) described in inert carrier comprise in TiO2, CeO2, ZrO2, Al2O3 one or more; Be preferably TiO2 and/or CeO2.

10. the purposes of loaded nano noble metal catalyst prepared by method described in the loaded nano noble metal catalyst described in any one of claim 1-4 or any one of claim 5-9, described purposes comprises for hydrogen manufacturing in hydrogen/methanol oxidation in fuel cell or oxygen reduction, water gas shift reaction, methane vapor reforming method preparing synthetic gas.