反应详情

WO 2003/047747 and WO 2003/047748 (publ. Jun. 12, 2003) describe metal oxide catalysts based on γ-aluminum oxide, their use during the aldol condensation of citral and acetone to give pseudoionone, and also special columns for carrying out the reaction by reactive distillation. The metal oxides are oxides of the elements with the atomic numbers 39 (Y) and 57 (La)-71 (Lu), with yttrium oxide and praseodymium oxide being emphasized as being preferred. When using a catalyst of 5% Pr on γ-Al2O3, in the 24 hour operation, pseudoionone was obtained with a yield of 66.7% and a selectivity of 97.3% based on citral. The concentration of the active components based on the total weight of the supported catalyst is in the range of 5 to 12% by weight, preferably 7.5 to 10% by weight. Whereas, as a result of extensive screening investigations, γ-Al2O3 has proven to be a particularly suitable support material, which relates to the activity of the catalyst, it is emphasized that both the geometry of the catalyst support and also the maintenance of the aforementioned concentrations are of decisive importance for obtaining good space-time yields.