Dendrimer templated synthesis of one nanometer Rh and Pt particles supported on mesoporous silica: catalytic activity for ethylene and pyrrole hydrogenation.
Monodisperse rhodium (Rh) and platinum (Pt) nanoparticles as small as approximately 1 nm were synthesized within a fourth generation polyaminoamide (PAMAM) dendrimer, a hyperbranched polymer, in aqueous solution and immobilized by depositing onto a high-surface-area SBA-15 mesoporous support. X-ray photoelectron spectroscopy indicated that the as-synthesized Rh and Pt nanoparticles were mostly oxidized. Catalytic activity of the SBA-15 supported Rh and Pt nanoparticles was studied with ethylene hydrogenation at 273 and 293 K in 10 torr of ethylene and 100 torr of H 2 after reduction (76 torr of H 2 mixed with 690 torr of He) at different temperatures. Catalysts were active without removing the dendrimer capping but reached their highest activity after hydrogen reduction at a moderate temperature (423 K). When treated at a higher temperature (473, 573, and 673 K) in hydrogen, catalytic activity decreased. By using the same treatment that led to maximum ethylene hydrogenation activity, catalytic activity was also evaluated for pyrrole hydrogenation.
Huang
Wenyu
W
Department of Chemistry, University of California, Berkeley, California 94720, USA.
Kuhn
John N
JN
Tsung
Chia-Kuang
CK
Zhang
Yawen
Y
Habas
Susan E
SE
Yang
Peidong
P
Somorjai
Gabor A
GA
D002384:Catalysis; D050091:Dendrimers / Q000737:chemistry*; D004583:Electrons; D005030:Ethylenes / Q000737:chemistry*; D006865:Hydrogenation; D053768:Metal Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D046529:Microscopy, Electron, Transmission; D015394:Molecular Structure; D010984:Platinum / Q000737:chemistry*; D016062:Porosity; D011758:Pyrroles / Q000737:chemistry*; D012238:Rhodium / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry*; D013057:Spectrum Analysis
D050091:Dendrimers; D005030:Ethylenes; D011758:Pyrroles; D010984:Platinum; D012822:Silicon Dioxide; C036216:ethylene; D012238:Rhodium