Papers by Keyword: Diluents

Abstract: The performance of methanol to gasoline (MTG) reaction was apparently influenced by the addition of diluents to ZSM-5. The lifetime of catalyst was prolonged when appropriate amount of diluents was added into the catalyst. The yield of MTG oil improved with the addition of diluents, while the initial conversion of methanol decreased slightly，and the total amount of oil product increased. At the same time, the content of dimethyl ether (DME) and light olefins obviously increased when large amount of diluents was added into the catalyst.

Abstract: Alumina-Tungsten Carbide (Al₂O₃-WC) composites were synthesized by self-propagating high temperature synthesis (SHS) from a powder mixture of WO₃-C-Al. The reaction was carried out in a SHS reactor under static argon gas at a pressure of 0.5 MPa. The standard Gibbs energy minimization method was used to calculate the equilibrium composition of the reacting species. The effects of carbon mole ratio in precursor mixture and diluents of NaCl and Al₂O₃ on the Al₂O₃-WC conversion were investigated using X-ray diffraction and scanning electron microscope technique. The as-synthesized products of Al₂O₃-WC₂-WC powders were concurrently formed and the reduction of W₂C phase was found when added diluents in precursors.

Abstract: Post-reaction sintering as a technique for the fabrication of Si3N4 ceramics has received much attention as a cost-effective process due to the use of cheap Si powder as a raw material. In this method, the rapid exothermic nitridation of Si results in local melting of Si to cause its agglomeration, which is expected to be a flaw after densification. Therefore, control of the exothermic reaction is needed to improve the reliability of post-reaction sintered Si3N4 ceramics. In this study, Si3N4 ceramics were fabricated by post-reaction sintering with Si3N4 or SiO2 powders in order to control the exothermic reaction. As a result, the microstructure and bending strength of Si3N4 ceramics was changed by adding these additives. In particular, the addition of SiO2 resulted in the high strength of Si3N4 ceramics. Consequently, it was found that Si3N4 and SiO2 particles played the role of diluents, and SiO2 was effective in post-reaction sintering as an oxygen donor.