1. Full name: Le Thi Kim Huyen 2. Sex: Female
3. Date of birth: 04/02/1980 4. Place of birth: Phu Yen
5. Admission decision number: Decision No 2875/QĐ-ĐHKHTN dated on 07/08/2015 by the Rector of University of Science - Vietnam National University, Hanoi.
6. Changes in academic process: None
7. Official thesis title: “Synthesis and characterization of catalytic activity of Cu, Ni and Cr doped hydrotalcites for the oxidation of styrene”
8. Major: Petrochemistry 9. Code: 9520301.02
10. Supervisor: Prof. Dr. Nguyen Tien Thao
11. Summary of the new findings of the thesis:
- It was proven that the location of Cu2+, Ni2+ and Cr3+ cations, i.e., intra and extra framework in the octahedral hydroxide sheets Mg-Al-(OH)x, has different roles effects in the heterogeneously catalyzed oxidation of styrene.
- It was concluded that Cu2+ cations, located in the framework of hydrotalcite structure, are the catalytic active sites for the selective oxidation of styrene to styrene oxide using tert-butyl hydrogen peroxide as oxidation agent, whereas, Ni2+ cations facilitate the formation of benzaldehyde under identical reaction conditions.
- The modification of Mg-Al-CO3 by replacing Al in the brucite sheets with Cr3+ results in the formation of Cr (III) and Cr (VI) cations inside and outside of the layered-double hydroxide Mg-Al-(OH)x of hydrotalcites. The extra-framework Cr (III) are the active sites catalyzing the oxidation of styrene to benzaldehyde and other products, e.g., benzoic acid, phenyl glycol …, while Cr (III) cations sitting within hydrotalcite framework favor the epoxidation of styrene to styrene oxide. Additionally, it was proven that extra-framework Cr (VI) cations exhibit poor catalytic activity in the oxidation of styrene to benzaldehyde. The Cr leaching is marginal in the oxidation of styrene in hydrogen peroxide at low temperatures. The current study obtained the optimal reaction conditions for the oxidation of styrene over Mg-Cr-Al-CO3 catalysts.
12. Pratical applicability, if any:
Styrene oxide and benzaldehyde are precursors of many chemicals that are widely applied in industries, e.g., chemistry, pharmaceutics, fragnance, cosmetics, agricultural chemicals and additives. The use of the catalysts supported on hydrotalcite Mg-Al-CO3 modified with the transition metals, i.e., Cu2+, Ni2+and Cr3+, via coprecipitation allows the selective oxidation of styrene into these desired products to occur under mild conditions and thus more economically.
13. Further research directions, if any:
Further investigations in modifying hydrotalcite materials with various transition metals forming catalysts for the oxidation of different aromatic hydrocarbons.
14. Thesis-related publications:
[1] Nguyen Tien Thao, Le Thi Kim Huyen (2015), “Catalytic activity of Mg-Cu-Al hydrotalcite catalysts in the styrene oxidation”, Viet Nam Journal of chemistry, Vol. 53(4e1), pp. 64-69.
[2] Nguyen Tien Thao, Le Thi Kim Huyen (2015), “Catalytic oxidation of styrene over Cu-doped hydrotalcites”, Chemical Engineering Journal, Vol 279, Pages. 840 – 850.
[3] Le Thi Kim Huyen, Nguyen Tien Thao (2017), “Comparative activity of Cu and Ni-doped Mg/Al hydrotalcite – like catalysts in the oxidation of styrene”, Viet Nam Journal of chemistry, Vol. 55(5E3,4), pp. 489-493.
[4] Le Thi Kim Huyen, Nguyen Tien Dat, Nguyen Tien Thao (2018), “Synthesis and characteristics of Mg-Ni-Al-CO3 hydrotalcites for the oxidation of styrene”, Viet Nam Journal of chemistry, Vol. 56(2), pp. 203-207.
[5] Le Thi Kim Huyen, Nguyen Tien Thao (2018), “Influence of pH in the synthesis of hydrotalcite Mg-Ni-Al as catalysts in the oxidation of styrene”, Viet Nam Journal of chemistry, Vol. 56(3), pp. 312-317.
[6] Le Thi Kim Huyen, Tran Le Huy, Nguyen Tien Thao (2018), “Liquid oxidation of styrene Mg-Cu-Al layered double hydroxide catalysts”, Viet Nam Journal of Catalysis and Adsorption, Vol. 7(3), pp. 25-30.
[7] Le Thi Kim Huyen, Hoang Phuong Anh, Nguyen Tien Thao (2018), “Liquid-phase oxidation of styrene in H2O2 over layered double hydroxidedouble containing anion [CO32-] or [Cr2O72-]”, Viet Nam Journal of chemistry, Vol. 56(6E1), pp. 235-238.
[8] Nguyen Tien Thao, Le Thi Kim Huyen (2019), “Enhanced catalytic performance of Cr-inserted hydrotalcites in the liquid oxidation of styrene”, Journal of Industrial and Engineering Chemistry, Vol 73, Pages. 221-232.
|