Supported mesoporous solid base catalysts for condensation of carboxylic acids

New mesoporous base catalysts (CM-HMS and CM-MCM-41) were synthesized by generating uniform particles of cerium and manganese oxides (MnOx/CeO2) in situ within hexagonal mesoporous silica (HMS) and MCM-41 supports. These catalysts were characterized by N2 adsorption, X-ray diffraction (XRD), transmission electron microscopy (TEM), energy-dispersive X-ray spectrometry (EDX), FTIR, temperature-programmed desorption of CO2 (CO2-TPD), and diffuse reflectance UV–visible (UV–vis) spectroscopy. Spectroscopic studies reveal that some particles of MnOx/CeO2 are incorporated into the walls of the silica network of HMS and MCM-41, while others are highly dispersed onto the surface of the HMS or MCM-41. The catalytic activity of CM-HMS and CM-MCM-41 for the ketonization of carboxylic acids was confirmed; better utilization of Ce and Mn was observed than in unsupported MnOx/CeO2. The citrate-based preparation of MnOx/CeO2 catalyst supported on HMS and MCM-41 has not been previously reported in the literature.

New mesoporous solid base catalysts, abbreviated as CM-HMS and CM-MCM-41, were synthesized by incorporating active base centers of MnOx/CeO2 into two different mesoporous silica supports (HMS and MCM-41). CM-HMS and CM-MCM-41 are more efficient catalysts than unsupported MnOx/CeO2 in ketonization of carboxylic acids.Figure optionsDownload high-quality image (103 K)Download as PowerPoint slideResearch highlights
► Uniformly dispersed solid base catalysts prepared on mesoporous silicas (CM-HMS, CM-MCM-41).
► Characterization shows MnOx/CeO2 primarily present on walls and surface of silica supports.
► CM-HMS and CM-MCM-41 are highly selective catalysts for ketonization of carboxylic acids.