Abstract
Multiwalled carbon nanotube–supported Rh nanoparticles prepared by a simple sonochemical method are highly active for catalytic hydrogenation of dibenzo-18-crown-6 to dicyclohexyl-18-crown-6. The catalytic hydrogenation reaction shows a selectivity favoring the cis-syn-cis isomer over cis-anti-cis isomer of the product by a factor of ≥6. Conventional Rh catalysts supported by activated wood carbon, SiO2, or Al2O3 can only convert dibenzo-18-crown-6 to dicyclohexyl-18-crown-6 with an cis-syn-cis/cis-anti-cis ratio of <1.7. The Rh nanoparticle catalyst can be reused at least six times without losing its catalytic activity.
ACKNOWLEDGMENTS
We thank Thomas J. Williams and J. Franklin Bailey for assistance with XRD, TEM, and SEM/EDX analysis of our samples. Hsing-Jung Chen was supported by a scholarship from the National Chung-Hsing University, Taiwan, for her study in the USA.
Notes
Note. Metal/DB18C6 = 0.16 (mol ratio), 10 atm H2, 323 K, reaction time 60 min.
a Metal loading (wt%).
b Ratio of the isomers: cis-syn-cis/cis-anti-cis.
c Metal/DB18C6 = 0.18 (mol ratio).
a Reaction conditions: metal/DB18C6 = 0.16 (mol ratio), 10 atm H2, 323 K, reaction time 60 min.