Davydenko L. Chemical transformations of chromium and manganese acetylacetonates on surface of alumina and silica

Transformations of Cr(acac)3 upon vapour phase modification of surface of fumed SiO2 and Al2O3 and subsequent thermal activation have been studied. Occurrence of adsorption complexes of Cr(acac)3 on SiO2 surface by means of hydrogen bonding of Cr(acac)3 molecules with ОН-groups of SiO2 surface has been found out. The mechanism of chemical transformations upon thermal activation of Cr(acac)3, adsorbed on SiO2 and Al2O3 surface upon vapour phase modification, has been studied. It has been proved that OH-groups of SiO2 surface and coordinatively unsaturated Al3+ ions of Al2O3 surface participate in thermal destruction of Cr(acac)3 molecules. The conditions of formation of amorphous highly-dispersed Mn2О3 phase upon oxidative thermal destruction of Mn(acac)3, adsorbed on precipitated Al2O3 surface from solution, have been cleared. It has been demonstrated that Mn(acac)3 is promising precursor for synthesis of effective and regenerable Mn2O3/Al2O3 sorbents for thigh temperature desulphurisation. The conditions of synthesis of SiO2 films, modified with Cr(acac)3, have been determined. It has been found out that SiO2 films, modified with Cr(acac)3, may be synthesised exclusively by direct doping of sol-gel composition with Cr(acac)3. Binding of Cr(acac)3 in sol-gel films due to interaction with ОН-groups of SiO2 matrice has been proved. It has been found out that thermal destruction of Cr(acac)3 in SiO2 films takes place at 473-613 К and is accompanied by elimination of acetylacetonate ligands due to their oxidation and with transformation of Cr(III) to Cr(VI) due to formation of dichromate species.