Facile synthesis of mesoporous tungstated zirconia with improved acidity for solvent free Knoevenagel condensation and fine chemical synthesis

Single step surfactant assisted sol–gel technique was adapted to synthesize mesoporous tungstated zirconia (m-WZ). Amorphous WZs, with high surface area, were synthesized after calcination of as-synthesized materials at 550 °C for 6 h. These materials were well characterized by powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy. Textural properties were established from N₂ adsorption–desorption isotherm, Scanning electron microscope (SEM) and Transmission electron microscopy (TEM). Pyridine adsorbed FTIR and NH₃-TPD revealed reasonable amount of Brønsted and Lewis acid sites of m-WZs. m-WZs exhibited outstanding catalytic activities toward solvent free Knoevenagel condensation reaction of different aromatic aldehydes with malononitrile and ethyl cyanoacetate at room temperature. The developed catalysts were also employed to synthesize different industrially important fine chemicals. These catalysts had longer reusability and no visible drops were observed in catalytic activity even after several runs.