BORESKOV INSTITUTE OF CATALYSISSiberian Branch, Russian Academy of Sciences
Prof. Dr. Valerii I. Bukhtiyarov
Tel.: +7-(383)-330-67-71Fax: +7-(383)- 308-356E-mail: [email protected]
Pr.Akademika Lavrentieva, 5Novosibirsk, 630090Russia
CATALYSTS WITH NANOSTRUCTURED ACTIVE COMPONENT.
Synthesis, Investigation And Application in Processes of Environmental Protection,
Power Production and Refinery
Reduction of the size parameters of a substance to nanometer scale causes
appearance of unique properties which can be used in practice for development of novel
materials and technologiescalled as NANOMATERIALS and
NANOTECHNOLOGIES Not only physical properties, but also
reactivity of a substance in nanometer scale will be
changed.As consequence, new functional
nanomaterials such as chemical sensors, CATALYSTS, adsorbents, membranes, fillers
can be produced
Nanomaterials and Catalysis
Nanomaterials and CatalysisSize effects are known since the Boudart’s discovery of the structure-sensitive
and structure-insensitive reactions and have been studied for a long time
1.Bukhtiyarov V.I. Chemical Reactivity of Metal Clusters at Solid Surfaces, In: Interfacial Science, “Chemistry for the 21st Century” Monograph (Ed. M.W.Roberts), Blackwell Science, 1997, 109-128.
2.Bukhtiyarov V.I., Slinko M.G. Metallic nanosystems in catalysis. Russian Chemical Reviews, 2001, v. 70, n.2, 147-159.
3 10 100 1000
Particle Size, Å
Tu
rno
ver
num
ber
, s-1
Positive size effects
Structural insensitive reaction
Structural sensitive reactions
• Abatement of СО and CHx
• Reforming of gasoline• Hydrogenation of unsaturated
CxHy
• Hydrogen and methanol FC ….
Systematic investigation of the size effects in catalysis by metallic nanoparticles and, especially, their application in practice require:
1) to develop the methods of synthesis of nanosized metallic particles, which have to provide:
Homogeneous size distribution with the mean particle size which is optimal for catalytic properties;
Stability of the supported metallic particles against sintering; Economical practicability
2) to develop the methods of testing of catalytic properties:
with application of porous and planar supports; intensification of catalytic activity testing – the search of structure-
sensitive reactions using the testing protocols developed by catalysts producers
Nanomaterials and Catalysts
It has been shown that variation of pH and gas-phase composition during ageing of the solution of Pt metal precursor regulates the sizes of polynuclear platinum hydroxocompomlexes:
[Pt(OH)6]2- + nH+Pt
O
OH
O
O
H H
H
Pt
OH
O
H
Pt
OH
O
H
Pt
OH
O
H
[Pt(-OH)m]y
0.8-1.2 nm2.0-2.4 nmThis provides homogeneous size distribution of [Pt(OH)m]y collodidal particles
in impregnated solution (contrary to commercial solutions): SAXS data
0 2 4 6 8 10 12 14 16 18 20 22 24 26 280
20
40
60
80
100
Dv(
d)
dPt
, nm0 1 2 3 4 5 6 7 8 9 10
0
20
40
60
80
100
dPt, nm
Dv
(d)
0 1 2 3 4 5 6 7 8 9 100
20
40
60
80
100
dPt
, nmD
v(d
)
Commercial solutionCommercial solution Our solution (lower pH)Our solution (lower pH) Our solution (higher pH)Our solution (higher pH)
Preparation of supported metal nanoparticles with Preparation of supported metal nanoparticles with homogeneous size distribution. Colloid formationhomogeneous size distribution. Colloid formation
Scientific bases of preparation of platinum nanoparticles with the mean sizes of 0.5–10 nm on -alumina have been developed
Size effectsSize effects inin catalysis by metal nanoparticlescatalysis by metal nanoparticles. . Observation and investigationObservation and investigation
Application of the prepared solutions for impregnation of alumina allows us to prepare the series of Pt/-Al2O3 catalysts and shows the size effect in CH4 oxidation
0 2 4 6 8 100
5
10
15
20
25
30
35
0 5 10 15 20 25 30 35 400
10
20
30
40
50
d, nm d, nm
Nd/N
tota
l1
00
, %
Nd/N
tota
l1
00
, %
Tcalcination = 400оС Tcalcination = 600оС
TEM images and Pt particle size TEM images and Pt particle size distribution for the Pt/distribution for the Pt/-Al-Al22OO33
catalysts with smallest platinum catalysts with smallest platinum nanoparticesnanopartices
TEM images and Pt particle size TEM images and Pt particle size distribution for the Pt/distribution for the Pt/-Al-Al22OO33
catalysts with smallest platinum catalysts with smallest platinum nanoparticesnanopartices
- TOF or turn-over frequency is rate of a catalytic reaction, normalized to the number of surface atoms of active compoment
TO
F, s
ec-1
0 2 4 6 8 10
0.00
0.01
0.02
0.03
0.04
0.05
0.06
0.07
Size effect in methane Size effect in methane oxidationoxidation
<d>, nm
Preparation of supported metal nanoparticles Preparation of supported metal nanoparticles with homogeneous size distribution. Epitaxial growthwith homogeneous size distribution. Epitaxial growth
Scientific bases of preparation of gold nanoparticles with the mean sizes of 1–10 nm on high-surface aluminas have been developed
Au [111] faceAu
OAlAl2O3 [111]
face
x 600 000
HRTEMHRTEM images ofimages of gold nanoparticlesgold nanoparticles onon AlAl22OO33The modelThe model ( (molecular dynamics methodmolecular dynamics method)) of of
epitaxialepitaxial growth of gold nanoparticles on Algrowth of gold nanoparticles on Al22OO33
results in epitaxial growth of gold nanoparticles, that provides the best results in preparation of the particles with homogeneous size distribution
and improved stability against sintering
[AuCl4]-
+ Al2O3
+ NaOH Au(OH)3·[AuCl4-n(OH)n]-/MOx
Al 2O3
Aumetal
O2
It has been shown, that «deposition-presipitation»:
Size effectsSize effects inin catalysis by metal nanoparticlescatalysis by metal nanoparticles. . Observation and investigationObservation and investigation
We have observed the size effect in reaction of low-temperature CO oxidation over Au/Al2O3 catalysts, which is appeared as sharp increase of TOF for the gold
supported particles with the mean sizes of 1-2 nm
0 5 10 15 20 250
20
40
60
80
100
120
140
TO
F (
sec-1
)10
-4
dvs(nm)
0 2 4 6 8 10 12 14 16 18 200
50
100
150
Dl = 1.8 nm
Dvs
= 2.0 nm
Th
e p
art
icle
nu
mb
er
Particle size, nm
Size distribution of Au nanoparticles
TEMTEM imagesimages
Flow reactorТ = 293 K; 0.05%CO, 2% of H2O, air for balance
We have shown the perspectives of application of the catalysts – gold nanoparticles supported on alumina – to solve the «cold start» problem for car engines
Catalysts on the bases of metallic nanoparticlesCatalysts on the bases of metallic nanoparticles for for afterburning afterburning
of exhaust gases from car enginesof exhaust gases from car engines
standard neutralization of standard neutralization of
exhaust gases (from CHexhaust gases (from CHxx and and
CO at high temperatures)CO at high temperatures), ,
while the deeper layerwhile the deeper layer ( (Au) Au)
burns up CO on cold engineburns up CO on cold engine..
Au/AlAu/Al22OO33
Pt/AlPt/Al22OO33
(commercial)(commercial)
5050 100100 150150 250250 30030020020000
2020
4040
6060
8080
100100
1 run 2 run 3 run
Temperature, Temperature, 00CC
CO
co
nve
rsio
n,
CO
co
nve
rsio
n, %%
The method of preparationThe method of preparation of honeycomb of honeycomb
catalystscatalysts for afterburning of exhaust gases for afterburning of exhaust gases
from car enginesfrom car engines, ,
front layer of whichfront layer of which ( (Pt) providesPt) provides
Observation andObservation and study of the nature of the size effectsstudy of the nature of the size effects in practically important in practically important catalytic reactionscatalytic reactions with further development and scaling-up of more effective with further development and scaling-up of more effective
((nanonano-)-)catalystscatalysts withwith lower loading of the noble metalslower loading of the noble metals
Preparation of supported metal nanoparticles Preparation of supported metal nanoparticles with homogeneous size distribution.Epitaxial growthwith homogeneous size distribution.Epitaxial growth
HRTEM study of Pd+Rh/Al2O3+CeO2-ZrO2 automobile catalyst produced by UECPallowed us to identify epitaxial growth of Pd particels on ceria-containing phase
Preparation of supported metal nanoparticles Preparation of supported metal nanoparticles with homogeneous size distribution. MMM as with homogeneous size distribution. MMM as
supportssupportsHomogeneous distribution of Ag nanoparticles have been reached with application of
mesophase mesoporous silica (SBA-15) – data of DICP CAS and FHI der MPG
There is a possibility to vary fluently the pore sizes of these There is a possibility to vary fluently the pore sizes of these materials materials ((silicasilica, , carboncarbon) ) via variation of the preparation via variation of the preparation conditionsconditions
Internal location of metal particles allows limitation of the Internal location of metal particles allows limitation of the particle sizes by pore diametersparticle sizes by pore diameters
Nanomaterials and Catalysis
4) to elucidate the reasons of unique catalytic properties of nanoparticles and search of the ways for the their practical applications
Systematic investigation of the size effects in catalysis by metallic nanoparticles and, especially, their application in practice require:
3) to develop the physical methods for characterization of supported metallic nanoparticles:
Transmission electron microscopy with high resolution (HR TEM) Scanning electron (SEM) and probe microscopy (STM, AFM) X-ray absorption and scattering (EXAFS, XANES, SAXS) Surface Science methods for in situ measurement (IRAS, SFG, UV-Vis,
XPS, XAS)
Combined application of Combined application of in-situin-situ XPS and MS for XPS and MS for operando study of operating nanostructured operando study of operating nanostructured
catalystscatalysts
LensesX-raytubes
Sample holder
sample
0
2
4
6
0 200 400 600 800 1000
Kinetic energy of photoelectrons (eV)T
he
mea
n f
ree
pat
h o
f p
ho
toel
ectr
on
s (t
orr
×m
m)
Gas cell
Bukhtiyarov V.I., Kaichev V.V., Prosvirin I.P. X-ray Photoelectron Spectroscopy as a Tool for In situ Study of the Mechanisms of Heterogeneous Catalytic Reactions. Topics in Catalysis 32 (2005) 3-15
Photoelectrons (Еkin = h – Eb)
X-rays
To perform in-situ XPS measurements, it is necessary:
to decrease the path of photoelectrons in high-pressure zone;
to provide the differential pumping of X-ray source and energy analyzer.
VG photoelectron spectrometer has been reconstructed for operando measurements in millibar pressure range
68 72 76 80 84
68 72 76 80 84
Pt4f + Al2p
PtO2
Ptmet
Binding energy, eV
Binding energy, eV
Inte
nsi
ty,
arb
.un
.
Inte
nsi
ty,
arb
.un
.
Pt4f + Al2pPt+
Binding energy, eV
P(CH4) = 0.02; P(O2) = 0.04 mbarT = 430oC
68 72 76 80 84
Combined application of Combined application of in-situin-situ XPS and MS for XPS and MS for operando study of operating nanostructured operando study of operating nanostructured
catalystscatalystsUsing this spectrometer, the chemical state of platinum nanoparticles
in Pt/Al2O3 catalysts for total oxidation of methane were studied
Investigation of the nature of active sites in Investigation of the nature of active sites in nanostructured catalysts with physical methods nanostructured catalysts with physical methods
Identification of active sites in Au/Al2O3 catalysts for low-temperature CO oxidation: XRD and UV-VIS spectroscopy for
10000 20000 30000 40000 50000 600000
1
2
3
4
Wavenumber, cm-1
0.13%
0.05%
0.02%F
(R)
10000 30000 5000020000 40000 60000
0.3%
Au, wt.%
Au
AuAu [Au-O-Au]m
Al2O3
500oC
Au/Al2O3
800oC
600oC
72 74 76 78 80 82 84
Au [2.2.2.]
Au [3.1.1.]
2
0 50 100 150 200 2500
20
40
60
80
100
H2O on
H2O off
H2O on
Time-on-stream (min)
CО
co
nve
rsio
n (
%)
The influence of water on the The influence of water on the activity of gold in CO oxidationactivity of gold in CO oxidation
Investigation of the nature of active sites in Investigation of the nature of active sites in nanostructured catalysts with physical methods nanostructured catalysts with physical methods
Suggestion about the nature of active sites and experiments about influence
of water is in agreement with the proposed mechanism of this reactionThe proposed mechanism of The proposed mechanism of
CO oxidation over gold CO oxidation over gold nanoparticlesnanoparticles
M.C. Kung, R.J. Davis, H.H. Kung
J. Phys. Chem. C: 111 (2007) 11767
CATALYSISCATALYSIS
Industrial catalysis has involved nanoparticles since beginning of the 20-th century
NANOSCIENCENANOSCIENCE
Addition of the “nano” prefix to many technical terms is not simple replacement of the unit of Ångstroms
Nanoscience gives a great contribution
to a fundamental approach for optimization of the catalyst performance
Nanomaterials and catalysis
Scientific basesScientific bases of the preparation of nanocompositeof the preparation of nanocomposite (Со)(Со)MoSMoS22 phase phase supported on aluminasupported on alumina
Methodology of synthesis of the mixed Со-Мо sulfide phase with high dispersity and location of cobalt ions on the lateral phase of the layered MoS2 phase
has been developed and realized
Preparation of the support (Al2O3) with optimal texture
properties and its impregnation with Co-Mo
solutions
Preparation of impregnating solutions with bimetallic Co-
Mo compounds
Preparation of bimetallic Co-Mo compound
in oxide form of the catalysts
Catalysts with active component in sulfide form
Synthesis of the proposed Synthesis of the proposed structurestructure of active sites in of active sites in hydrodesulfurization catalysts:hydrodesulfurization catalysts:
Со
S
Mo
Co-MoS2
Preparation and physical-chemical characterization of the catalysts
All steps of the catalyst preparation have been studied with a number of physical methods: NMR, EXAFS, IR-spectroscopy, HRTEM
DBT
4-МMDBT 4,6-DMDBT
3200С406 ppmS
3400C54 ppmS
3600C14 ppmS
Testingthe catalytic properties
Optimization of the catalyst working conditions
Study of catalytic properties ofStudy of catalytic properties of Со- Со-Mo-S/AlMo-S/Al22OO33
catalystscatalysts in hydrodesulfurization ofin hydrodesulfurization of diesel fractiondiesel fraction
Systematic investigation of catalytic activity of Со-Мо sulfide catalysts in hydrogenolysis of С-S bond have been performed depending on the support nature and sulfidation conditions of oxide precursors
The catalytic data were used to optimize the conditions ofThe catalytic data were used to optimize the conditions of catalyst activationcatalyst activation ( (sulfidationsulfidation) ) andand operationoperation, , as well as the proceduresas well as the procedures of active component supporting on specific types of alumina oxidesof active component supporting on specific types of alumina oxides,, prepared by the companyprepared by the company ( (JSCJSC “Industrial catalysts”“Industrial catalysts”), ), production facilities of which have being production facilities of which have being
apply for apply for industrial productionindustrial production of the catalystsof the catalysts
To test the catalytic performance of the synthesized samples, To test the catalytic performance of the synthesized samples, technological set-up for performing the catalytic testing under the technological set-up for performing the catalytic testing under the representative conditionsrepresentative conditions andand unique (for Russia) analytical unit unique (for Russia) analytical unit allowing not onlyallowing not only definition of total content of the residual sulfurdefinition of total content of the residual sulfur, , but alsobut also identification of individual sulfur-containing compounds identification of individual sulfur-containing compounds
have been created at the Boreskov Institute of Catalysishave been created at the Boreskov Institute of Catalysis
• StudyStudy of interaction ofof interaction of individualindividual (first of all, very stable)(first of all, very stable) sulfur-sulfur-containingcontaining organic compounds with new series of sulfide catalystsorganic compounds with new series of sulfide catalysts..
• Optimization of the methods and conditions for sulfidation Optimization of the methods and conditions for sulfidation of active of active componentcomponent ..
• Development of the hydrodesulfurization catalysts of diesel fraction Development of the hydrodesulfurization catalysts of diesel fraction to sulfur content in several ppmto sulfur content in several ppm..
NanocompositeNanocomposite of Co-Mo sulfide catalystsof Co-Mo sulfide catalysts for deep hydrotreating of straight-run gas-oil for deep hydrotreating of straight-run gas-oil
Industrial testing of pilot batch (30 tons)* of nanocomposite catalysts in hydrotreating reactor on Saratov oil-refinery plant decreases the sulfur content
from S < 1800 ppm to S < 50 ppm (Euro-4 standard)
Independent expertise of the catalytic properties of the synthesized catalyst in comparison with imported catalysts
0
100
200
300
400
500
0 5 10 15 20 25 30 35 40
Pro
du
ct s
ulp
hu
r (p
pm
wt)
Scaling up of the catalyst production
- preparation of pilot batch of the catalysts were performed by JSC “Industrial catalysts”
Siberian Branch of RAS: interdisciplinary project №79 «Size effects in catalysis by metals. Development of preparation methods and study of nano-sized metallic particles»Russian Ministry of Education and Science: state contract 2007-3-1.3-28-03-127 «Development of technological bases of application of nanosize effects to produce nanostructured catalysts of new generation»
Russian Foundation for Basic Researchproject # 08-03-01016 “The influence of the size effects on activity of Pt nanoparticles in various heterogeneous catalytic reaction”
Russian Foundation for Basic Research (joint Call with China)project # 07-03-92117-GFEN “Size effects in adsorption and catalysis over metals: from individual atoms and nanoparticles to nanostructured catalysts»
Acknowledgement for financial support