Eco-friendly detoxification of aromatic compounds with highly active and reusable Pd/PDMS catalyst in supercritical carbon dioxide

• Main Authors: Hsing-Jung Chen, 陳幸容
• Other Authors: 鄭政峯
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/43313262845032987678

博士 === 國立中興大學 === 化學系所 === 100 === A hydrogenation method for degradation of polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) in supercritical carbon dioxide catalyzed by palladium nanoparticles stabilized in polydimethylsiloxane (Pd/PDMS) is described. The process of synthesizing metal nanoparticles embedded in PDMS polymer involves preparation of a homogenous mixture of metal salt, silicone elastomer and a curing agent, followed by hydrogen reduction. In TEM image, it is shown that Pd nanoparticles are dispersed well in the PDMS materials, and the average size is 12.9 ± 7.5 nm. PCBs and PAHs can be effectively hydrogenated to saturated hydrocarbons with greater than 99 % efficiency in an hour under 200 atm of CO2 containing 10 atm of H2 at 40℃ using the Pd/PDMS catalyst. Kinetic studies reveal that the catalytic hydrodechlorination of 4-chlorobiphenyl to biphenyl is pseudo-first-order. The subsequent hydrogenation of biphenyl to cyclohexylbenzene as an intermediate, and then reduced to the bicyclohexyl. These two hydrogenation reactions also follow pseudo-first-order kinetics. The initial hydrogenation of benzene and four PAH compounds are pseudo-first-order reactions. The Pd/PDMS catalysts can be reused without losing its activity and are more active than a previously reported Pd nanoparticle catalyst stabilized in high density polyethylene. This method is eco-friendly and efficient, and may lead to significant environmental remediation applications.