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REU Final PresentationAugust 1st, 2013
Analysis of the Promoter-Catalyst interaction between Mn and Rh by Transmission Electron Microscopy
Ben GrahamDepartment of Materials Science and Engineering,
University of Alabama at Birmingham
Robert Klie, PhDDepartment of Physics, University of Illinois at Chicago
REU Final PresentationAugust 1st, 2013
Introduction• An alternative source of energy is a major concern for society.
• Draw Backs for traditional fermentation routes include:• Slow conversion process• Inefficient conversion process• By-products (such as ammonia)
• the Fischer-Tropsch mechanism can convert syngas(or bio-gas) to higher octane fuels such as ethanol.
• It is possible to increase the activity and selectivity of the mechanism by adding a catalyst and promoter. • Catalyst of interest is Rhodium promoted by Manganese
REU Final PresentationAugust 1st, 2013
IntroductionSEA strategy for increased promoter-metal interactions catalysts EELS mapping of SEA promoted catalyst
• Electron Energy Loss Spectroscopy (EELS) collects the inelastically-scattered electrons to determine chemical bonding.• J.R. Regalbuto, Catalyst Preparation: Science and Engineering, Taylor
& Francis/CRC Press, Boca Raton, 2006, pp. 297.
Sample was prepared in previous study
REU Final PresentationAugust 1st, 2013
2 4 6 8 10 12 14 160
5
10
15
20
25
30
35
40
Ethanol
1Mn3RhCNTs
2Mn3RhCNTs
CO Conversion %
Sel
ecti
vity
%
Introduction
• J. Liu and et al, Selective Absorption of Manganese onto Rhodium for optimized Mn/Rh/SiO2 Alcohol Synthesis Catalysts. print. 2013.
REU Final PresentationAugust 1st, 2013
TEM
• JEM 3010, basic TEM was used
• Transmitted elastically scattered electrons can be assembled into bright field images (composed of phase and mass contrast)
• D.B. Williams, C.B. Carter, Transmission Electron Microscopy. 1996, New York, Springer Science,7-141.
REU Final PresentationAugust 1st, 2013
TEM
• D.B. Williams, C.B. Carter, Transmission Electron Microscopy. 1996, New York, Springer Science,7-141.
REU Final PresentationAugust 1st, 2013
TEM Images3% Rh/CNT sample at 600Kx, atomic
resolution of particles3% Rh/CNT sample at 300Kx, ideal for
particle sampling
REU Final PresentationAugust 1st, 2013
TEM Images2% Mn/3%Rh/CNT sample at 600Kx, atomic
resolution of particles2% Mn/3%Rh/CNT sample at 300Kx, ideal for
particle sampling
• 1.96 nm total• 9 fringes • 0.22 nm each• (111) orientation
Emaps.mrl.uiuc.edu
REU Final PresentationAugust 1st, 2013
Particle Size Measurements• Average particle size for 3%Rh/CNT:
1.9 ± 0.6 nm
• Average Particle Size for 1%Mn/3%Rh/CNT
2.1 ± 0.5nm
3% Rh/CNT
1%Mn/3%Rh/CNT
Average Particle Size (nm)
Average Particle Size (nm)
Co
un
t
Co
un
t
REU Final PresentationAugust 1st, 2013
Particle Size Measurements• Average particle size for 2%
Mn/3%Rh/CNT:3.2 ± 0.6 nm
• Distribution for all samples were Gaussian or normal.
Catalyst Average Particle Size (nm)
Standard Deviation (±nm)
3% Rh/CNT 1.9 0.6
1% Mn/3% Rh/CNT
2.1 0.5
2% Mn/3% Rh/CNT
3.2 0.6
2%Mn/3%Rh/CNT
Average Particle Size (nm)
Co
un
t
REU Final PresentationAugust 1st, 2013
Particle Orientation
• 3.57nm• 16 Fringes• 0.223 nm each• In (111) plane
Catalyst Coordination Number(EXAFS)*
Bond Distance (Å)(EXAFS)*
Experimental
Lattice Parameter (Å)
(TEM)
3% Rh/CNT 4.9 2.67 4.1±0.1
1% Mn/3% Rh/CNT
5 2.67 4.2±0.1
2% Mn/3% Rh/CNT
4.8 2.67 3.8±0.1
• a= Lattice parameter
• d= measured d-spacing
• (hkl)= corresponding miller indices
• J. Liu and et al, Selective Absorption of Manganese onto Rhodium for optimized Mn/Rh/SiO2 Alcohol Synthesis Catalysts. print. 2013.
2%Mn/3%Rh/CNT image at 600k
REU Final PresentationAugust 1st, 2013
Discussion
Catalyst STEM* size (nm)
3%Rh/CNT 1.3 ±0.4
1%Mn/3%Rh/CNT 1.1±0.4
2%Mn/3%Rh/CNT 1.2 ±0.4
• STEM Dark Field Image of 2%Mn/3%Rh/CNTs (left)
• STEM Dark field image composed of Z-contrast
• TEM bright field image composed of phase and mass contrast
TEMCatalyst
Average Particle Size (nm)
Standard Deviation (±nm)
3% Rh/CNT 1.9 0.6
1% Mn/3% Rh/CNT
2.1 0.5
2% Mn/3% Rh/CNT
3.2 0.6
Rh
Mn
• J. Liu and et al, Selective Absorption of Manganese onto Rhodium for optimized Mn/Rh/SiO2 Alcohol Synthesis Catalysts. print. 2013.
REU Final PresentationAugust 1st, 2013
Conclusions & Future Work Determined nano-
particle size for promoted and un-promoted rhodium on carbon nano-tubes
Found evidence of manganese-rhodium interactions • Increase in particle size• Decrease in lattice
parameter
Examine Rh particles on a Mn substrate
Electron Diffraction analysis of samples
REU Final PresentationAugust 1st, 2013
Acknowledgments
NSF grant – EEC-NSF Grant #1062943 Nanoscale Physics Group Research Recourses Center East staff Dr. Takoudis, Dr. Jursich, and REU Staff
Thank You!Questions?