Synthesis and characterization of Al2O3–SiO2–MgO nanocomposite prepared by sol–gel process as an efficient catalyst for the Knoevenagel condensation of aldehydes with malononitrile

Abstract

The composite of Al2O3–SiO2 and Al2O3–SiO2–MgO nanocomposite were synthesized by sol–gel method and FT-IR, XRD, FE-SEM, EDAX, TEM, and BET surface area analysis were used to characterize the as-prepared samples. XRD results show the formation of MgO phase in the nanocomposite. FE-SEM images indicate uniform distribution of MgO nanoparticles in the Al2O3–SiO2 matrix and also amorphous and spherical-like structures for Al2O3–SiO2 and Al2O3–SiO2–MgO nanocomposite, respectively. An increase in the surface area of the nanocomposite compared to Al2O3–SiO2 composite is observed with adding MgO. The catalytic activity of Al2O3–SiO2–MgO nanocomposite was tested by using them as an efficient base catalyst for the Knoevenagel condensation of different aromatic aldehydes with malononitrile at room temperature. The nanocomposite can be easily separated and reused for several cycles.