SBA-15 obtained from rice husk ashes wet-impregnated with metals (Al, Co, Ni) as efficient catalysts for 1,4-dihydropyridine three-component reaction

Abstract

We report the preparation and full characterization of Al, Co and Ni–SBA-15 materials that were easily prepared from rice-industry wastes as a silicon source, followed by the impregnation of metal salts. The materials were successfully employed as heterogeneous catalysts for the 1,4-dihydropyridine multicomponent synthesis in ethanol as the solvent. They featured a number of advantages, such as low metal load due to mesoporous catalytic sites (4 nm), low reaction times, high yields and simple catalyst isolation and purification process, which resulted in high efficiency and low environmental impact. Al–SBA-15 showed weaker Lewis acid sites and the best performance as a catalyst, affording higher product conversion (>80% in 10 minutes) and higher TOF values.