SERMACS Poster flyer
1
Core-Shell Nanoparticle Synthesis 1150 1400 1650 1900 2150 2400 %Transmittance cm -1 1 PVP eqv. ½ PVP eqv. 1150 1400 1650 1900 2150 2400 % Transmittance cm -1 ½ PVP eqv. 1 PVP eqv. Reducing Carbon Monoxide Emissions: A Core-Shell Bimetallic Nanoparticle Approach Z. Decker * , J. Oliveto § , T.M. Selby ¥ , R.K. Abhinavam Kailasanathan § , K. Pisane ‡ , M. Seehra ‡ , F. Goulay § * Department of Chemistry New College of Florida, Sarasota, Fl, 34243 § C. Eugene Bennett Department of Chemistry West Virginia University, Morgantown, WV, 26506 ¥ Department of Chemistry, University of Wisconsin-Washington County , West Bend, WI 53095 ‡ Department of Physics and Astronomy, West Virginia University, Morgantown, WV, 26506 Introduction Catalytic Converters Engines undergo incomplete combustion producing harmful carbon monoxide (CO) and nitrogen compounds (NO x ). Three-way catalytic converters (TWC) currently use expensive precious metal nanoparticles such as Pt, Rh, and Pd to reduce CO emissions. However, federal agencies have identified Pt to be of high supply risk and high economic importance 1 . In addition, these nanoparticles are only effective above 150°C. It takes ~15 s. to warm a cold TWC for conversion to occur. 1 During these ~15s hazardous CO is released into the atmosphere. Our goal is to develop nanoparticles which exhibit lower conversion temperatures while also using less expensive and more abundant transition metals. This may be accomplished using bimetallic core-shell nanoparticles combining a precious metal shell such as Pt with a less expensive transition metal core such as Fe. Fe Pt Results Anneal Under Air GC analysis displays decreasing Fe@Pt %CO conversion temperatures over time. It is hypothesized that the stabilizer, PVP, is obstructing the surface of the nanoparticles, and is burned over time. Pd/Pt and Pt are shown as reference Future Work References Contact Conclusions • XRD and ATR-FTIR spectra suggest Fe@Pt Nanoparticles are initially contaminated by PVP • ATR-FTIR and XRD spectra suggest annealing the nanoparticles under air (600 °C) removes any PVP • GC analysis continues to show an increasing catalytic efficiency over time suggesting an unknown factor is affecting catalytic efficiency • Preliminary Al@Pt & Sn@Pt XRD spectra show no PVP contamination, but their core-shell character are under further review • Further investigate Fe@Pt catalytic efficiency • Fully characterize Sn@Pt & Al@Pt nanoparticles • Test Sn@Pt & Al@Pt for catalytic efficiency • Begin testing nanoparticles with NO x gasses 1. U.S. Department of Energy, Critical materials strategy, 2011 2. Vayenas, C. G.; C., P.; S., B. and D., T. in Catalysis and electrocatalysis at nanoparticle surfaces; Wieckowski, A., Savinova, E. R., Vayenas, C.G., Eds.; CRC Press 2003:2003 3. Alayoglu, S.; Nilekar, A.; Mavrikakis, M.; Eichhorn, B. Nature 2008, 7, 333-338 Email: [email protected] Mail: 5800 Bayshore Rd. Sarasota FL 34243 Box# 181 Phone: (850) 529-8945 Home Institution: New College of Florida ↑ ↓ Core-shell nanoparticles exhibit increased catalytic efficiency due to the metal-metal interactions. A difference in Work Function () between each metal correlates to its efficiency. Two interacting metals align their Fermi levels and transfer − inducing an electric potential. The electric potential weakens the bond of electropositive absorbates (CO 2 ) and strengthens the bond of electronegative absorbates such as oxygen, which is needed to oxidize CO to CO 2 . Core-Shell nanoparticle synthesis occurs by a sequential reduction process 3 . Ethylene glycol is both a solvent and reducing agent. Polyvinyl pyrrolidone (PVP) is used as a stabilizer to form iron cores. Platinum Chloride coats the iron cores to form core-shell nanoparticles. The nanoparticles are finally annealed at 600 °C under N 2 . Oven Injector Switch Flow Control Intensity Retention Time CO O 2 Catalytic efficiency is measured using an in-lab built flow tube. CO, He, and O 2 gasses are injected through quartz tubing inside an oven which holds a nanoparticle sample and a reference (carbon black). The CO exhaust is analyzed by a Gas Chromatographer, and the %CO difference (conversion) between sample and reference is recorded as a function of temperature. XRD spectra (left) shows Pt and PVP present. Iron core is shielded by the platinum surface and thus does not show in the XRD spectra. TEM shows primarily spherical particles with a diameter <10nm. Magnetic measurements (right) show a hysteresis loop characteristic of ferromagnetic samples. While XRD shows no iron on the surface, magnetic studies suggest a magnetic metal is present. To investigate PVP poisoning, nanoparticles were synthesized using 1 & ½ PVP equivalents. ATR-FTIR spectra before annealing under air (top left) exhibits amide, carbonyl, and hydrocarbon peaks consistent with PVP. Moreover, Adsorbed CO before annealing (2065cm -1 ) appears to increase with decreasing PVP. After annealing, (top right) all peaks disappear. Acknowledgments • Sponsored by NSF Divisions of Materials Research and Chemistry (DMR-1262075). • Project funded by the Award for Research Team Scholarship (ARTS) from The Eberly College of Arts and Sciences at WVU. • Recreational activities funded by WVU Research Corporation and the WVU Eberly College of Arts and Sciences. Core-Shell Nanoparticles Synergistic Effects 2 Methods Nanoparticle Catalytic Analysis Carbon Black Reference Nanoparticle Sample Gas Flow He Gas O 2 Gas CO Gas Nanoparticle Characterization M (emu/g) Field (kOe) 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 -0.1 -0.2 -0.3 -0.4 -0.5 -0.6 -0.7 -80 -60 -40 -20 0 20 40 60 80 Decreasing CO Concentration over time PVP Cleaning Intensity (Arbitrary Units) 2 (degrees) 20 40 60 80 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 175 195 215 235 255 275 % CO Conversion Temperature °C Day 1 Day 2 Preliminary Sn@Pt & Al@Pt Data Al@Pt XRD is similar to Fe@Pt and shows only platinum peaks with no indication that PVP is present. Iron acetylacetonate Ethylene glycol Polyvinyl pyrrolidone (PVP) Reflux 3h Reflux 2h Centrifuge Anneal 600°C, 2h, N 2 Platinum Chloride 2 (degrees) Intensity (Arbitrary Units) 20 30 70 60 50 40 80 90 Pt Pt Pt Pt XRD spectra (left) shows only platinum peaks with no indication that PVP or Fe is present. GC analysis (right) continues to show decreasing %CO conversion temperatures over time. Electric Potential − − − Energy Fermi Levels Exhaust CO CO 2 Engine Al 2 O 3 Supported Nanoparticles TWC Catalytic Converter Day 3 Intensity (Arbitrary Units) 20 30 40 50 60 70 80 90 2 (degrees) Al@Pt Intensity (Arbitrary Units) 20 30 40 50 60 70 80 90 2 (degrees) Sn@Pt Sn@Pt XRD shows Pt and PtSn 4 peaks suggesting the sample may not be in a core-shell configuration. 0% 20% 40% 60% 80% 100% 100 150 200 250 300 350 % CO Conversion Temperature °C Fe@PT Day 1 Fe@Pt Day 2 Fe@Pt Day 3 Pd/Pt Pt He Gas Gas Chromatograph 2-way Switch
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Transcript of SERMACS Poster flyer
Core-Shell Nanoparticle Synthesis
115014001650190021502400
%Tr
ansm
itta
nce
cm-1
1 PVP eqv.½ PVP eqv.
115014001650190021502400
% T
ran
smit
tan
ce
cm-1
½ PVP eqv.
1 PVP eqv.
Reducing Carbon Monoxide Emissions: A Core-Shell Bimetallic Nanoparticle Approach
Z. Decker *, J. Oliveto§, T.M. Selby ¥, R.K. Abhinavam Kailasanathan§, K. Pisane ‡, M. Seehra ‡, F. Goulay§
*Department of Chemistry New College of Florida, Sarasota, Fl, 34243§C. Eugene Bennett Department of Chemistry West Virginia University, Morgantown, WV, 26506¥Department of Chemistry, University of Wisconsin-Washington County , West Bend, WI 53095
‡Department of Physics and Astronomy, West Virginia University, Morgantown, WV, 26506Introduction
Catalytic Converters
Engines undergo incomplete combustion producing harmful
carbon monoxide (CO) and nitrogen compounds (NOx).
Three-way catalytic converters (TWC) currently
use expensive precious metal nanoparticles such as Pt, Rh,
and Pd to reduce CO emissions. However, federal
agencies have identified Pt to
be of high supply risk and high economic importance1.In addition, these nanoparticles are only effective above 150°C. It takes ~15 s. to warm a cold TWC for conversion to occur. 1
During these ~15s hazardous CO is released into the atmosphere.
Our goal is to develop nanoparticles which exhibit lower conversion temperatures while also using less expensive and more abundant transition metals. This may be accomplished using bimetallic core-shell nanoparticles combining a precious metal shell such as Pt with a less expensive transition metal core such as Fe.
Fe
Pt
Results
Anneal Under Air
GC analysis displays decreasing Fe@Pt %CO conversion temperatures over time. It is hypothesized that the stabilizer, PVP, is obstructing the surface of the nanoparticles, and is burned over time. Pd/Pt and Pt are shown as reference
Future Work
References
Contact
Conclusions• XRD and ATR-FTIR spectra suggest Fe@Pt
Nanoparticles are initially contaminated by PVP
• ATR-FTIR and XRD spectra suggest annealing the
nanoparticles under air (600 °C) removes any PVP
• GC analysis continues to show an increasing catalytic
efficiency over time suggesting an unknown factor is
affecting catalytic efficiency
• Preliminary Al@Pt & Sn@Pt XRD spectra show no
PVP contamination, but their core-shell character
are under further review
• Further investigate Fe@Pt catalytic efficiency
• Fully characterize Sn@Pt & Al@Pt nanoparticles
• Test Sn@Pt & Al@Pt for catalytic efficiency
• Begin testing nanoparticles with NOx gasses
1. U.S. Department of Energy, Critical materials strategy, 2011
2. Vayenas, C. G.; C., P.; S., B. and D., T. in Catalysis and electrocatalysis at nanoparticle surfaces; Wieckowski, A., Savinova, E. R., Vayenas, C.G., Eds.; CRC Press 2003:2003
3. Alayoglu, S.; Nilekar, A.; Mavrikakis, M.; Eichhorn, B. Nature 2008, 7, 333-338
Email: [email protected]: 5800 Bayshore Rd. Sarasota FL 34243 Box# 181 Phone: (850) 529-8945Home Institution: New College of Florida
𝝓 ↑𝝓 ↓
Core-shell nanoparticles exhibit increased catalytic efficiency due to the metal-metal interactions. A difference in Work Function (𝜙) between each metal correlates to its efficiency. Two interacting metals align their Fermi levels and transfer 𝑒− inducing an electric potential. The electric potential weakens the bond of electropositive absorbates (CO2) and strengthens the bond of electronegative absorbates such as oxygen, which is needed to oxidize CO to CO2.
Core-Shell nanoparticle synthesis occurs by a sequential reduction process3. Ethylene glycol is both a solvent and reducing agent. Polyvinyl pyrrolidone (PVP) is used as a stabilizer to form iron cores. Platinum Chloride coats the iron cores to form core-shell nanoparticles. The nanoparticles are finally annealed at 600 °C under N2.
Oven
Injector Switch
Flow
Co
ntro
l
Inte
nsi
ty
Retention Time
CO
O2
Catalytic efficiency is measured using an in-lab built flow tube. CO, He, and O2 gasses are injected
through quartz tubing inside an oven which holds a nanoparticle sample and a reference
(carbon black). The CO exhaust is analyzed by a Gas Chromatographer, and the %CO difference (conversion) between sample and reference is recorded as a function of temperature.
XRD spectra (left) shows Pt and PVP present. Iron core is shielded by the platinum surface and thus
does not show in the XRD spectra. TEM shows primarily spherical particles with a diameter <10nm.
Magnetic measurements (right) show a hysteresis loop characteristic of ferromagnetic samples. While XRD shows no iron on the surface, magnetic studies suggest a magnetic metal is present.
To investigate PVP poisoning, nanoparticles were synthesized using 1 & ½ PVP equivalents. ATR-FTIR
spectra before annealing under air (top left) exhibits amide, carbonyl, and hydrocarbon peaks
consistent with PVP. Moreover, Adsorbed CO before annealing (2065cm-1) appears to increase with decreasing PVP. After annealing, (top right) all peaks disappear.
Acknowledgments• Sponsored by NSF Divisions of Materials Research
and Chemistry (DMR-1262075). • Project funded by the Award for Research Team
Scholarship (ARTS) from The Eberly College of Arts and Sciences at WVU.
• Recreational activities funded by WVU Research Corporation and the WVU Eberly College of Arts and Sciences.
Core-Shell Nanoparticles
Synergistic Effects2
Methods
Nanoparticle Catalytic Analysis
Carb
on
Black R
eferenceN
ano
par
ticl
e S
amp
le
Gas FlowHe Gas
O2 Gas
CO Gas
Nanoparticle Characterization
M (
em
u/g
)
Field (kOe)
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
-0.1
-0.2
-0.3
-0.4
-0.5
-0.6
-0.7-80 -60 -40 -20 0 20 40 60 80
Decreasing CO Concentration over time
PVP Cleaning
Inte
nsi
ty (
Arb
itra
ry U
nit
s)
2𝜃 (degrees)20 40 60 80
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
175 195 215 235 255 275
% C
O C
on
vers
ion
Temperature °C
Day 1
Day 2
Preliminary Sn@Pt & Al@Pt Data
Al@Pt XRD is similar to Fe@Pt and shows only platinum peaks with no indication that PVP is present.
Iron acetylacetonate
Ethylene glycol
Polyvinyl pyrrolidone
(PVP)
Reflux 3h
Reflux 2h
Centrifuge
Anneal 600°C, 2h, N2
Platinum Chloride
2𝜃 (degrees)
Inte
nsi
ty (
Arb
itra
ry U
nit
s)
20 30 70605040 80 90
Pt
PtPt
Pt
XRD spectra (left) shows only platinum peaks with no indication that PVP or Fe is present.
GC analysis (right) continues to show decreasing %CO conversion temperatures over time.
Electric Potential
𝒆−
𝒆−
𝒆−
Ener
gy
Fermi Levels
𝝓 𝝓
Exhaust
CO CO2
Engine
Al2O3 Supported Nanoparticles TWC Catalytic Converter
Day 3
Inte
nsi
ty (
Arb
itra
ry U
nit
s)
20 30 40 50 60 70 80 90
2𝜃 (degrees)
Al@Pt
Inte
nsi
ty (
Arb
itra
ry U
nit
s)
20 30 40 50 60 70 80 90
2𝜃 (degrees)
Sn@Pt
Sn@Pt XRD shows Pt and PtSn4 peaks suggesting the sample may not be in a core-shell configuration.
0%
20%
40%
60%
80%
100%
100 150 200 250 300 350
% C
O C
on
vers
ion
Temperature °C
Fe@PTDay 1
Fe@PtDay 2
Fe@PtDay 3Pd/Pt Pt
He G
as
Gas Chromatograph
2-waySwitch
