جستجوی مقالات مرتبط با کلیدواژه « اپوکسایش » در نشریات گروه « شیمی »

Er2Ti2O7 pyrochlore structure was successfully prepared by solid-state method. The prepared microstructure mixed-metal oxide was characterized by XRD, SEM, EDX, FT-IR and BET. X-ray powder diffraction revealed a Cubic crystal system with Fd-3m space group for Er2Ti2O7. The morphology and mean particle size of the sample was characterized by the scanning electron microscope. The elemental analysis or chemical characterization of the sample was determined by Energy Dispersive X-ray microanalysis. The absorption bands between the A and B sites in the pyrochlore structure were confirmed by Fourier transmission infrared spectra in (400–4000 cm-1) range. The specific surface area and the pore size distributions of the sample were calculated using Brunauer–Emmett–Teller (BET) method and Barrett–Joyner–Halenda (BJH) method respectively. The complex has been used as a catalyst for epoxidation of cyclooctene with TBHP (tert-butyl hydroperoxide). Various parameters including catalyst amount, solvent type and amount, oxidant/substrate ratio and time have been optimized and almost. Considerable catalytic activity and high epoxide selectivity has been found.

The present work describes the synthesis، characterization and the investigation of electrochemical and catalytic performance of a series of new N2O2type oxidovanadium (IV) Schiff base complexes. The Schiff base ligands had salophen type structure and were derived from the condensation of 4-methyl or 4- nitro-1،2-phenylenediamine with salicylaldehyde. The catalytic ability of the complexes was studied in the process of epoxidation of cyclooctene with tert-butylhydroperoxide (TBHP). Several factors affecting this catalytic ability was optimized such as solvent type، catalyst amount، substrate to oxidant ratio، and reaction time. Electrochemical studies revealed that in the presence of electron withdrawing groups، the VIV/VV redox potentials shifted to more positive values. Besides، the catalytic performance of the complexes was increased by this increase.