Loading...

Investigation of the Kinetics of Zirconium Oxide Synthesis Reactions by Co-Precipitation Method and Design of an Appropriate Reactor in Pilot Scale

Abdollahi, Mohsen | 2020

726 Viewed
  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 52554 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Ghotbi, Cyrus; Fotovat, Farzam
  7. Abstract:
  8. To study the kinetics of the yttria-stabilized zirconia produced by co-precipitation method from the chemical engineering point of view, this process was studied in two parts of hydrolysis and precipitation. the hydrolysis reaction was studied by titration method, and the rate constant and fraction of formation of hydrous zirconia was determined by applying Avrami equation. The results showed that the percentage of zirconia formation until the boiling time of 12 hours was zero and after 48 hours boiling was 2.81%. moment definitions were used In order to study the kinetics of precipitation. changes in precipitated powder concentration with pH of the solution was obtained based on the particle size distribution for the powders obtained at different reaction times. Using these concentrations, the mass of precipitated powder in different pH values was calculated and a mathematical equation was fitted for mass diagram. According to the mathematical equation, the mass of the precipitate at the end of reaction was predicted to be 12.98 grams. Reactor operating parameters were determined in three steps: studying the reactor dimensions, choosing the type and speed of the stirrer, and obtaining reaction parameters such as feed concentration, flow rate, reaction time, and temperature. Due to the high impact of the reaction parameters on the product characteristics, determining and optimization of these parameters were done by investigating the changes of the product characteristics with operational parameters. According to optimization experiments, 0.81M were obtained for zirconyl chloride concentration, 3% for molar percentage of yttria in the final product and 3 wt% for dispersant concentration in solution. Also, the optimum process time was 30 min and the final pH of solution was 7. Based on the values obtained for reaction time and final solution pH, the open flow rate of 90 ml / h for the initial volume of 100 ml was determined. The dimensional characteristics of the stirred reactors were obtained through a set of relationships expressing the ratio between the different dimensions of the reactor. The type and speed of the stirrer were also determined according to the type of flow regime and the specifications expected for the product. Properties of suitable reactor at pilot scale were determined based on empirical rules and using scale-up relationships
  9. Keywords:
  10. Zirconia ; Kinetics Study ; Yttria-Stabilized Zirconia (YSZ) ; Co-Precipitation ; Scale Up method ; Stirred Tank Reactor ;

 Digital Object List

 Bookmark

No TOC