Supported Au nanoparticles as Heterogeneous Catalyst for Organic - - PowerPoint PPT Presentation
Supported Au nanoparticles as Heterogeneous Catalyst for Organic Reactions Hermenegildo Garca and Avelino Corma Instituto de Tecnologa Qumica, Technical University of Valencia Spain Outline: Au NPs and Nanoscience Au NPs as catalyst
SJNANO 2013
Au NPs and Nanoscience Au NPs as catalyst For aerobic oxidations For carbamoylation For tandem reactions Role of impurities Isolation of Au intermediates Conclusions and Acknowledgements
C + H2O CO + H2 syngas H2O CO2 + H2 water gas shift Hydrogen technology Low temperature, selective CO combustion:
the smaller the particle size, the higher the activity
M Haruta, N Yamada, T Kobayashi, S Iijima: J. Cat. 115 (1989) 301-09.
They can be easily obtained. “Bare” small Au NPs (1-2 nm) tend to
The key issue is to stabilize small Au NPs “Stabilized” nanoparticles are surrounded
Typically, for bulk materials, surface
20 nm
HAuCl4 PTC PPh3 NaBH4 1.4 nm Gold Particles Use of ligands (Brust method) Supporting on a solid: Deposition-Precipitation method
HAuCl4
CH3OH
Au(OH)3
H2 Pd/C
Hydrogenations
N OH N O H H2SO4 (oleum)
Brönsted acids
O CH3 (CH3CO)2O AlCl3
Lewis acids
CH3 CH3 O CH3 O CH3 CH3 NaOH Br B OH HO Pd
Bases Oxidations Transition metal catalysts
CH3 CH3 H OH CH3 CH3 O K2CrO4
CeO2 nanoparticles
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 20 40 Counts Diameter (nm)
Interplanar distance of Au Particle size distribution
Substrate Time [h] Conversion[a] [%] Product Selectivity[%] 1b 3-octanol 2.5 97 3-octanone 96 2b sec-phenylethanol 2.5 92 acetophenone 97 3b 2,6-dimethylcyclohexanol 2.5 78 2,6-dimethylcyclohexanone 94 4b 1-octen-3-ol 3.5 80 1-octen-3-ona >99 5b cinnamylalcohol 7 66 cinnamaldehyde 73 6b 3,4-dimethoxybenzyl alcohol 7 73 3,4-dimethoxybenzaldehyde 83 7b 3-phenyl-1-propanol 6 70 3-phenylpropyl- 3-phenylpropanoate 98 8c vanillin alcohol 2 96 vanillin 98 9c 2-hydroxybenzyl alcohol 2 >99 2-hydroxybenzaldehyde 87 10c 3,4-dimethoxybenzyl alcohol 2 >99 3,4-dimethoxybenzylic acid >99 11c cinnamyl alcohol 3 >99 cinnamylic acid 98 12d n-hexanol 10 >99 hexanoic acid >99 13e n-hexanol 10 >99 hexanoic acid >99 14c sec-phenylethanol 5 >99 acetophenone 51
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phosgene isocyanate polyurethanes
polyol
(Best selling industrial polymers)
25 50 75 100 1 2 3 4 5 6 7 t(ht) Product selectivity (%)
Final yield > 90%
CH3 NH2 NH2 CH3 O C O H3C O CH3 HN H N C O O CH3 C O O CH3 CH3 NO2 NO2 H2
Two steps, two processes:
CH3 NO2 NO2 CH3 H N HN O O O O DMC H2 (5 bar) T=150ºC t=12 hours Conversion = 95.2 Selectivity = 98.3
High purity Au is also active for Sonogashira coupling
to promote Sonogashira
Au catalyst