Various nano-size iron oxide polymorphs on mesoporous supports I. New mesoporous catalyst supports synthesized in acidic and alkaline media

摘要: Abstract A fairly large number (altogether 12) of new mesoporous silica catalyst supports have been synthesized mainly in alkaline media using ionic (CTAB) and non-ionic Aldrich-type triblock poly(alkylene oxide) copolymers polyglycol mixtures. Preference was given to water–glass as the silicon source. This study aiming at setting up an own carrier repertory be able select with “good” characteristics for investigation deconvoluted Mossbauer EPR spectra. task could not carried out on compact oxides. The physical characterization (N2 adsorption, XRD, SEM, HRTEM, SAED, Mossbauer, 29Si-NMR spectroscopy) supplemented by activity testing, well, N2O-mediated selective oxidation benzene synthesis (carbon) nanotubes very high temperature. first part planned two publications deals description various recipes carriers a few novel observations obtained during their characterization. It seems important know that so called amorphous silicas are always never fully amorphous. Their structure consists crystalline SiO2 polymorph grains (β-tridymite or quartz) embedded randomly oriented agglomeration particles similar (15–20 nm) size. final state genesis is preceded separation viscous, tacky liquid droplets from aqueous phase when “surfactant + silicate” complex becomes insoluble slurry. Later solidify such experience slight deformation if ordering continues even after separation. no hexagonal pore structure, thus, walls either. extreme heat– hydrothermal stability due this fact. They can wide range specific surface areas diameters, possession testing data information respective spectra, selection literature rather promising perspective.