Self-aldol condensation of aldehydes over Lewis acidic rare-earth cations stabilized by zeolites

The self-aldol condensation of aldehydes was investigated with rare-earth cations stabilized by [Si]Beta zeolites in parallel bulk metal oxides. Good catalytic performance achieved all Lewis acidic and yttrium appeared to be the best choice. According results several complementary techniques, i.e., temperature-programmed surface reactions, situ diffuse reflectance infrared Fourier transform spectroscopy, ultraviolet-visible reaction pathway mechanism aldehyde over Y/Beta catalyst were studied more detail. Density functional theory calculations revealed that aldol dehydration rate-limiting step. hydroxyl group at open site played an important role stabilizing transition state dimer reducing energy barrier for its hydration. Y(OSi)(OH)2 configurations identified as preferred active sites aldehydes.