Significant Improvement of Thermal Stability for CeZrPrNd Oxides Simply by Supercritical CO2 Drying
نویسندگان
چکیده
Pr and Nd co-doped Ce-Zr oxide solid solutions (CZPN) were prepared using co-precipitation and microemulsion methods. It is found that only using supercritical CO(2) drying can result in a significant improvement of specific surface area and oxygen storage capacity at lower temperatures for CZPN after aging at 1000°C for 12 h in comparison with those using conventional air drying and even supercritical ethanol drying. Furthermore, the cubic structure was obtained in spite of the fact that the atomic ratio of Ce/(Ce+Zr+Pr+Nd) is as low as 29%. The high thermal stability can be attributed to the loosely aggregated morphology and the resultant Ce enrichment on the nanoparticle surface, which are caused by supercritical CO(2) drying due to the elimination of surface tension effects on the gas-liquid interface.
منابع مشابه
Improvement of Thermal Stability of BCG Vaccine
Background: Thermal stability (TS) is a part of the BCG vaccine characterization by which the consistency of process in BCG vaccine production could be confirmed. To enhance the TS of the vaccine, some prevalent stabilizers in different concentrations were added to the final formulation of BCG bulk prior to Freeze-drying process. We found a formulation more effective than the current stabilizer...
متن کاملThe Effects of Secondary Oxides on Copper‐Based Catalysts for Green Methanol Synthesis
Catalysts for methanol synthesis from CO2 and H2 have been produced by two main methods: co-precipitation and supercritical anti-solvent (SAS) precipitation. These two methods are compared, along with the behaviour of copper supported on Zn, Mg, Mn, and Ce oxides. Although the SAS method produces initially active material with high Cu specific surface area, they appear to be unstable during rea...
متن کاملA Review of Aerogel Applications in Adsorption and Catalysis
Aerogels are a special class of porous material, which have excellent physicochemical properties such as low density, high porosity, high surface area and adjustable surface chemistry. Aerogels were first prepared several decades ago, but never truly commercialized due to their high cost. Technological advancements in the production and quality of different types of aerogel cut costs down and m...
متن کاملA Continuous Extraction and Pumpless Supercritical CO2 Drying System for Laboratory-Scale Aerogel Production
Production of aerogels starts with solution chemistry and may end with supercritical carbon dioxide drying, which both require a specialized system. Here we present a complete aerogel production system that was developed and used in our laboratory over the last nine years. Our aim was to develop a supercritical dryer and a protocol, whereby the CO2 pump can be left out, and the entire flow syst...
متن کاملEffect of Supercritical Carbon Dioxide on the Ordering and Aggregation of Polystyrene Latex Particles
Monodisperse latex particles microspheres of controlled size and variable composition have been produced in three-dimensional ordered arrays.[1] These materials can be used as templates for structured porous material including inorganic oxides, carbons, metals and polymers. Structure of the polymeric template can be altered by compressed gases and supercritical fluids. In this communication, we...
متن کامل