Papers by Keyword: Basic

Abstract: A promising basic microporous catalytic material is prepared by nitridation of dehydrated NaY zeolite. The base strength of zeolite framework is enhanced due to the replacement of oxygen by nitrogen with lower electronegativity. Various characterization methods, including XRD, CHN elemental analysis, SEM and FTIR spectra of CO adsorption, are employed to analyze the physico-chemical properties of the nitrogen-incorporated NaY zeolite. High crystallinity and high specific surface areas of NaY are well preserved in nitrogen-incorporated NaY. Compared to parent NaY zeolite, the nitridized materials exhibit improved basic catalytic performances in Knoevenagel condensation reaction and side-chain monomethylation reaction of phenylacetonitrile.

Abstract: The corrosion behavior of silicon nitride materials in aqueous media strongly depends on the composition and amount of the grain boundary. But there exist no systematic investigations of the relation between the corrosion behavior and the composition and amount of the grain-boundary phase. The subject of this study is based on the evaluation of the corrosion mechanisms of Si3N4 ceramics and YSiAlON glasses, both with defined and characterized compositions, in acidic and basic environments with different concentrations. Special effort has been made in describing the compositions of grain boundary phases in the sintered Si3N4 ceramics. A model to describe structural features of YSiAlON-glasses was developed which allows the correlation of the corrosion behavior of the ceramics and the glasses with their compositions. In combination with SEM and TEM investigations it became possible to give structural reasons for the different observed corrosion mechanisms.