Synthesis of nanosized mesoporous Co-Al spinel and its application as solid base catalyst

A novel mesoporous Co-Al spinal catalyst with high surface area and suitable basicity was prepared by the thermal decomposition of Co-Al hydrotalcite-like compound. The properties of the solid base catalyst were characterized by XRD, FTIR, TEM, nitrogen sorption and CO2-TPD. The formation mechanism of the mesopores and the Co-Al spinel structure was also investigated by TG/DTA and mass-spectrometer, respectively. This is due to the partial oxidation of Co2+ ions and the dehydration of the interface OH groups in precursor. The formed Co3+ ions collapsed into the interlayer space, coordinated with the adjacent oxygen atoms (tetrahedral or octahedral), worked as pillars between layers and made the interlayer space to be almost opened (mesopores formed). The partial oxidation of Co2+ ions plays a critical role in the phase transformation and the formation of mesopores. The as-obtained mesoporous Co-Al spinel-type solid base catalyst was first used in the aldol condensation of furfural with acetone and the self-condensation of acetone and found that it had good activity and excellent selectivity in both reactions. The stability studies showed that the catalyst can be completely regenerated easily by calcination. (C) 2010 Elsevier Inc. All rights reserved.