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Preparation, Characterization and Catalytic Application of Some Polyoxometalates for Esterification Reaction

Nazari, Pegah | 2014

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 46311 (03)
  4. University: Sharif University of Technology
  5. Department: Chemistry
  6. Advisor(s): Rahman Setayesh, Shahrbanoo
  7. Abstract:
  8. Catalytic esterification of acetic acid with 1-hexanol was investigated over polyoxometalates. H3PW12O40 and H3PMo6W6O40 polyoxometalates with keggin structures were synthesized. Catalytic activity and recyclability of them were improved by loading on the γ-Al2O3 with impregnation method and Cs, K and NH4 salts preparing.Catalysts were characterized by XRD, SEM, FT-IR, BET, DRS and NMR techniques. According to XRD's results, catalysts have ace-centered cubic crystal systems. Loading on supports and preparing the salts do not destroy the structures of polyoxometalates. SEM images show the uniformity of catalysts' surface and catalysts' fixing on the support. It was seen that the keggin structure of polyoxometalates has remained after loading on the support and preparing the salts of them. Increasing in surface area has been proved by BET's results during the modification of the catalysts. The effect of various parameters such as reaction time, amount of loading on support, reaction temperature, amount of catalyst, acid/alcohol mole ratio, various catalysts and different alcohols was studied and the optimized condition was determined. Recyclability of catalysts was examined. High stability of polyoxometalates by leaching test was found. Kinetics study on the esterification of acetic acid with 1-hexanol was done and the rate constant and the activation energy were calculated. Finally esterification of a dicarboxylic acid (malonic acid) and ethanol was investigated
  9. Keywords:
  10. Esterification ; Kinetics Study ; Polyoxometalates ; Hexyl Acetate ; Malonic Acid ; Inoculation

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