In the course of our attempts to replace harmful solvents in organic processes by environmentally favored media, we investigated the use of aqueous microemulsions for catalytic decarbonylation of different kinds of aldehydes. The aldehydes were solubilized in the microemulsions with the aid of the cationic surfactant, cetyltrimethylammonium bromide. The aldehydes were transferred into CO-free products by sol-gel entrapped catalysts. The best results were obtained in the presence of nanoparticles of Pd(0). The heterogenized catalyst could usually be recycled 7-8 times without loss of catalytic activity. At relatively low temperatures (140°C) the decarbonylation proceeds stepwise. Initially a mixture of saturated and unsaturated products is formed. At 180°C however, fast hydrogenation of the unsaturated compounds takes place. These investigations may be regarded as model studies for the conversion of biomass derived intermediates to fuels and chemicals.
Bibliographical noteFunding Information:
We gratefully acknowledge the financial support of this trilateral study by the Deutsche Forschungsgemainschaft (DFG) through grant SCHO687/8-2 . We also thank Dr. Inna Popov for her help in the TEM studies, Dr. Vitally Gutkin for his help in the XPS work and Gilad Zafriri for the BET and NJH measurements.
- Aldehyde decarbonylation
- Heterogeneous catalysis
- Palladium nanoparticles
- Sustainable chemistry