Papers by Keyword: Acetone Condensation

Abstract: Mg-Al composite oxide (MgAlY-LDO) solid base catalysts were prepared via the coprecipitation method, followed by calcinations at high temperatures. Isophorone synthesis from acetone condensation was also investigated. The catalysts were characterized via X-ray diffraction analysis, Fourier transform infrared spectroscopy, CO₂ temperature-programmed desorption, and Brunauer-Emmett-Teller analysis. After doping with Y, the MgAl-LDO showed higher catalytic activity at a reaction temperature of 300 °C, 100 kPa and WHSV 6.3 h^-1. Furthermore, the conversion of acetone and the selectivity of isophorone increased from 17.8% and 11.0% to 37.5% and 58.7%, respectively. These results indicate that the basicity of MgAlY-LDO as well as the number of its strong base centers increased after Y doping. The pore volume and size of MgAlY-LDO increased because of the increased hydrotalcite layer space caused by the big Y³⁺ ion. However, the crystal structure of hydrotalcite was remained. Y₂O₃ was evenly dispersed in MgAlY-LDO at low Y doping amounts. As the doping amount increased, the layer structure of hydrotalcite became distorted, thereby affecting the crystallinity of the hydrotalcite. Some Y³⁺ ions emerged from the Mg²⁺ lattice after doping with a high Y³⁺ concentration.

Abstract: Perovskite-type compounds such as alkali tantalates, ATaO3 (A = Li, Na and K), prepared by the sol-gel method are reported as heterogeneous basic catalysts for the acetone aldol condensation. It has been proposed that the activity order and the selectivity patterns (LiTaO3 > > KTaO3 > NaTaO3) depend on the octahedral arrangements of the TaO6 tantalates.