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Prof. Panias Dimitrios Krestou Athina, MSc 11/9/2014 SLM 2008, Belgrade National Technical University of Athens.

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Presentation on theme: "Prof. Panias Dimitrios Krestou Athina, MSc 11/9/2014 SLM 2008, Belgrade National Technical University of Athens."— Presentation transcript:

1 Prof. Panias Dimitrios Krestou Athina, MSc 11/9/2014 SLM 2008, Belgrade National Technical University of Athens

2 11/9/2014 SLM 2008, Belgrade National Technical University of Athens Construction Packaging Transportation Electrical Conductors Machinery & Equipment Ceramics Abrasives Medicinal Catalysts Bauxite Alumina

3 11/9/2014 SLM 2008, Belgrade National Technical University of Athens BAYER PROCESS to lower the SiO 2 concentration and control the level of phosphates may contain Al(OH) 3 or AlOOH for the extraction of all of the Al 2 O 3 in bauxite Al(OH)3 Calcination above 1380K 2Al(OH) 3 α-Al 2 O 3 +3H 2 O

4 11/9/2014 SLM 2008, Belgrade National Technical University of Athens γ- Al2O3 α- Al 2 O 3 Gibbsite γ-Al(OH)3 Bayerite α-Al(OH)3 Boehmite γ-AlOOH (energy saving, topotactic transformation into γ-Al 2 O 3 ) transformation into γ-Al 2 O 3 )

5 11/9/2014 SLM 2008, Belgrade National Technical University of Athens γ-AlΟΟΗ Nanosized High surface area Narrow distribution in mesoporous Controlled calcination γ-Al2O3 with the same microtructure as boehmite precursor

6 11/9/2014 SLM 2008, Belgrade National Technical University of Athens Bayer liquor (NaAlO4, NaOH, impurities) Precipitation γ-AlOOH rather than Al(OH)3 Calcination ( γ-, η-,δ-,θ-, α- Al2O3)

7 11/9/2014 SLM 2008, Belgrade National Technical University of Athens Properties Applications Microstructure

8 11/9/2014 SLM 2008, Belgrade National Technical University of Athens Applications (catalysis, adsorption) Microstructure (homogeneous, defect-free) Properties (high surface area, mesoporosity, proper crystallite size)

9 11/9/2014 SLM 2008, Belgrade National Technical University of Athens Applications of γ- Al 2 O 3 catalyst or catalyst support in heterogeneous catalysis catalyst or catalyst support in heterogeneous catalysis adsorbent in purification and bleaching processes adsorbent in purification and bleaching processes composite reinforcement composite reinforcement membrane in separation processes of industrial waste streams and food membrane in separation processes of industrial waste streams and food in biomedical and chemical processes in biomedical and chemical processes absence of defects Enhanced performance: homogeneous microstructure uniform size distribution uniform size distribution NANO-METER or SUB-MICROMETER sized particles

10 Previous research in the Laboratory of Metallurgy (NTUA)  Synthetic Bayer liquor (SSA)  Boehmite seeds  T<100 o C  precipitation of coarse γ-AlOOH particles by decreasing the free NaOH More information: D. Panias, A. Asimidis, I. Paspaliaris, Hydrometallurgy 15-29 (2001) 59. C.Skoufadis, D.Panias, I Papsaliaris, Hydrometallurgy 57 (2003) 68. D. Panias, Hydrometallurgy 203 (2004) 74. D. Panias, A. Krestou, Powder Technology 163-173 (2007) 175. 11/9/2014 SLM 2008, Belgrade National Technical University of Athens

11 This study: Precipitation of pure nano-boehmite by the destabilization of SSA through neutralization at atmospheric conditions without γ-AlOOH seed addition 11/9/2014 SLM 2008, Belgrade National Technical University of Athens

12 11/9/2014 SLM 2008, Belgrade National Technical University of Athens SSA (solution A) Acid (solution B) Reagents HNO3, HCl, H2SO4, H3PO4, CH3COOH BA AB Mode of mixing 30<T<100 o C 5<pH<13,6 Parameters Studied 0<t ag <2weeks addition rate calcination T Characterization of precipitates XRD TG ssa, ps, pv, psd by N 2 adsorption /desorption SEM, TEM

13 11/9/2014 SLM 2008, Belgrade National Technical University of Athens Precipitates: well crystallised gibbsite gibbsite/bayerite mixtures gibbsite/bayerite mixtures gibbsite/bayerite/boehmite mixtures gibbsite/bayerite/boehmite mixtures NO PURE γ-AlOOH with the BA experiments

14 11/9/2014 SLM 2008, Belgrade National Technical University of Athens PURE nano-crystallite γ-AlOOH with the AB experiments

15 11/9/2014 SLM 2008, Belgrade National Technical University of Athens Effect of Temperature and pH

16 11/9/2014 SLM 2008, Belgrade National Technical University of Athens Effect of ageing time

17 11/9/2014 SLM 2008, Belgrade National Technical University of Athens Effect of different acids

18 11/9/2014 SLM 2008, Belgrade National Technical University of Athens Effect of different acids (T90-pH7-t24h) Region ΙRegion ΙΙRegion ΙΙΙ Crystallites <50nm Transformation to γ-AlOOH of higher crystallinity Transformation of γ-AlOOH to γ-Al 2 O 3 Transformations

19 SLM 2008, Belgrade National Technical University of Athens Effect of different acids (T90-pH7-t24h)

20 SLM 2008, Belgrade National Technical University of Athens Effect of addition rate(T90-ph7-t0) Ab. add. 10ml/min7ml/min5ml/min3ml/min 1ml/mi n

21 Only the AB experiments resulted in γ-AlOOH precipitation : effect of Al-species 11/9/2014 SLM 2008, Belgrade National Technical University of Athens HCl : higher specific surface area addition rate 5ml/min: most promising for the precipitation of nanocrystallite γ-AlOOH and calcined products for catalytic applications T & pH: better crystallinity in less t ageing

22 11/9/2014SLM 2008, Belgrade

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