Sujata Mallick

Cesium salts of heteropoly acid immobilized mesoporous silica: An efficient catalyst for acylation of anisole

A series of Cs salt of phosphotungstic acid (Cs-PTA) supported on MCM-41 (Cs-PTA/MCM-41) was synthesized by a wet impregnation method and thoroughly characterized by using various analytical techniques, viz. X-ray diffraction, UV-Vis diffused reflectance spectroscopy (UV-Vis DRS), nitrogen adsorption desorption, scanning electron microscopy (SEM), Infrared spectra (FTIR), temperature programmed reduction (TPR), and temperature programmed desorption (TPD). The spectroscopic results revealed that Cs-PTA is highly dispersed on a MCM-41 surface. The 50 wt.% Cs-PTA supported on MCM-41 showed remarkable catalytic performance toward acylation of anisole reaction. The catalyst is regenerable by simple calcinations without appreciable loss in catalytic activity.

Selective oxidation of benzaldehyde by molecular oxygen over molybdovanadophosphoric acid supported MCM-41

A series of molybdovanadophosphoric acid (MVPA) supported on mesoporous silica was synthesized by an incipient wetness impregnation method. The catalysts were characterized by nitrogen adsorption–desorption, X-ray powder diffraction, Fourier-Transform Infra red spectroscopy (FT-IR), UV–Vis Diffused reflectance spectroscopy (UV–Vis DRS), Temperature programmed reduction (TPR) and 31P MAS Nuclear magnetic resonance(NMR) study. The characterization data reveals the incorporation of vanadium in phosphomolybdic acid and retention of intact Keggin ion on the support. The catalytic activities were evaluated for oxidation of benzaldehyde using molecular oxygen as oxidant as the new green reaction system. Among all the promoted catalysts, 50wt% molybdovanadophosphoric acid supported on MCM-41 exhibits highest catalytic activity in oxidation of benzaldehyde, giving 95% conversion. Other oxidants like H2O2 and tert-butyl hydrogen peroxide (TBHP) were also tested for benzaldehyde oxidation reaction.

Characterization of novel Cs and K substituted phosphotungstic acid modified MCM-41 catalyst and its catalytic activity towards acetylation of aromatic alcohols

AbstractThe MCM-41 supported Cs2.5H0.5PW12O40 and K2.5H0.5PW12O40 salts were synthesized by incipient wetness impregnation method. The solids were characterized by N2 adsorption–desorption isotherms, FT-IR, XRD, and temperature programmed desorption, etc. This catalyst has been found to exhibit excellent activity for acetylation of phenolic compounds. The catalyst is stable and reusable giving 96% conversion with 100% selectivity towards acetate products. Graphical AbstractPhosphotungstic acid and its cesium and potassium salts supported on MCM-41 are found to be very active and an efficient catalyst for acetylation of aromatic alcohols. Inexpensive and easily available acetic acid as acetylating agent was used. The catalyst 50CsPTA/MCM-41 showed highest conversion (yield 96%).

Characterization of Nano-Crystalline Nickel Supported Zirconia and its Catalytic Activity of Hydrogenation of Nitrophenol

Mesoporous zirconia was prepared by the surfactantassisted route, using cetyltrimethylammonium bromide as cationic surfactant. The synthesized zirconia was employed as support for nickel catalysts in reduction reaction of nitrophenol at room temperature. The catalysts were characterized by nitrogen adsorption-desorption, X-ray powder diffraction, Fourier-transfer infrared spectroscopy (FTIR), Transmittance electron micrograph (TEM), UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS), temperature programmed reduction (TPR) and X-ray photoelectron spectroscopy (XPS). The nitrogen adsorption-desorption studies revealed that the modified samples retain the mesoporosity. Key word