Calcium Oxide Supported on Monoclinic Zirconia as a Highly Active Solid Base Catalyst

Abstract

Calcium oxide supported on ZrO2 is a highly active catalyst for base‐catalyzed reactions such as aldol‐type reactions and transesterification reactions. The role of key parameters during preparation, that is, impregnation versus precipitation, heat treatment, and metal oxide loading on the basicity and catalytic activity were investigated for CaO supported on ZrO2. An impregnation of 10 wt % CaO on monoclinic zirconia followed by heat treatment at 600 °C resulted in high activity for the self‐condensation reaction of acetone. An evaluation of a series of CaO/ZrO2 samples with different loadings showed that the activity increased for impregnated amounts per gram catalyst of 0–10 wt % CaO, and at higher loading the activity decreased as a result of a decrease in dispersion. The number of strong base sites (calculated from CO2 desorbed at temperatures higher than 625 °C) correlated with the activity. For MgO, CaO, SrO, and BaO on zirconia the catalytic activity increased as the ionic radius of the metal cation increased, suggesting the impact of base strength on catalytic performance.

Acid–base characterization of heterogeneous catalysts: an up-to-date overview

“…As an example, for catalytic oxidation of iso-mercaptans on pure MgO or MgO or doped with Cu and Ni to create defects, it has been shown [65] temperature larger than 923 K), have been shown [66] to be related to aldol-type and transesterification reactions. For MgO, CaO, SrO, and BaO on zirconia the catalytic activity was observed to increase as the ionic radius of the metal cation increased, suggesting the impact of base strength on catalytic performance, as described below (''FTIR analysis'' section and Figs.…”

Design and fabrication of mesoporous heterogeneous basic catalysts

“…[173][174][175][176] Inspired by this sophisticated method, inorganic basic species were used to modify mesoporous silica, aiming to obtain mesoporous solid bases with a high strength. Introduction of inorganic basic species.…”

Low‐Temperature Preparation of a Mesoporous Silica Superbase by Employing the Multifunctionality of a La2O3 Interlayer

“…These unique properties make it potentially suitable for various applications. Therefore the mesoporous SBA‐15 materials modified with active sites had high potentials as environmentally friendly catalysts in diverse reactions . However, it is relatively difficult to generate superbasic sites on mesoporous silica because of their weak guest–host (precursor–silica) interaction and the poor alkali‐resistant capacity of siliceous frameworks.…”