Search

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.

The Mobil Composition of Matter No. 41 (MCM-41) containing Cu and Al with Si/Al ratios varying from 100 to 10 and 1 to 6wt.% of Cu was synthesized under hydrothermal and impregnation conditions, respectively. The samples were characterized by nitrogen adsorption-desorption measurements, X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS), temperature-programmed reduction (TPR), temperature-programmed desorption (TPD), and (29)Si and (27)Al magic-angle spinning-nuclear magnetic resonance (MAS-NMR) spectra. X-ray diffraction patterns indicate that the modified materials retain the standard MCM-41 structure. TPR patterns show the two-step reduction of Cu species. TPD study shows that Cu-impregnated Al-MCM-41 samples are more acidic than Al-MCM-41. From the MAS-NMR it was confirmed that most of the Al atoms are present tetrahedrally within the framework and some are present octahedrally in extraframework position. Impregnation of Cu shifted Al to the extraframework position. The catalytic activity of the samples toward hydroxylation of phenol in aqueous medium was evaluated using H(2)O(2) as the oxidant at 80 degrees C. The effects of reaction parameters such as temperature, catalyst amount, amount of H(2)O(2), and solvent were also investigated. Sample containing 4wt.% copper-loaded Al-MCM-41-100 showed high phenol conversion (78%) with 68% catechol and 32% hydroquinone selectivity.