Base catalysis for the synthesis of α,β-unsaturated ketones from the vapor-phase aldol condensation of acetone

Consequences of MgO activation procedures on its catalytic performance for acetone self-condensation

“…However, magnesium oxide presents an important drawback in comparison to other common catalysts, its low surface area. Furthermore, the selectivity towards isophorones is reduced in comparison to, for example, Li/MgO [10]. This effect was attributed to the low concentration of high-strength basic sites in the non-promoted catalyst.…”

“…Gas phase self-condensation of acetone yields to isophorones (cyclic trimers) as the most valuable product, with applications in paints, pesticides, adhesives, resins, etc., whereas liquid phase condensations (usually performed in presence of H 2 ) are mainly devoted to manufacturing methyl-isobutyl ketone (MIBK).Different basic catalysts have been proposed for this condensation, such as niobium oxides [6], Mg-Al mixed oxides [7,8], Mg-Zr mixed oxides and Mg-Zr oxides dispersed on carbonaceous materials to increase the exposed surface area [9] and even MgO,non-promoted and promoted with alkaline or alkaline-earth metal ions [10]. Among all these catalysts, bulkMgO is the cheapest alternative and very attractive due to its preparation easiness.…”

Isobutanol-Methanol Mixtures From Synthesis Gas

“…Then, as 13 CO 2 is depleted from the surface, vacant adsorption sites are occupied by the majority 12 CO 2 species in the gas phase; therefore, readsorption of desorbed 13 CO 2 is minimized. It is well known that readsorption will shift the desorption peak to higher temperatures (101). Thus, it is not surprising that higher gas phase 12 CO 2 concentrations, which minimize readsorption, lead to a shift of desorption peaks to lower temperatures.…”

“…This assumption is based on the infrared results of adsorbed CO 2 on MgO reported by Di Cosimo et al [101]. Only unidnetate and bidentate species exist on MgO at 573 K. By applying mole balance on 13 CO 2 in gas phase and each surface compartment subjected to a 13 CO 2 to 12 CO 2 switch, one can get:…”

CuPd Bimetallic Nanoparticles Supported on Magnesium Oxide as an Active and Stable Catalyst for the Reduction of 4-Nitrophenol to 4-Aminophenol

“…Thus, magnesium oxide has been extensively employed not only as a catalysts support but also directly as catalyst itself, taking advantage of its basic nature. For example, it has been widely used in basecatalyzed reactions such as aldol-condensation [17], Cannizzaro [18] or Tischenko [19] reactions, and the Knoevenagel condensation [20].…”