October 17, 2012 Carry le Rouet, France. Valentin Valtchev

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1 Laboratoire Catalyse & Spectrochimie October 17, 2012 Carry le Rouet, France Zeolite formation a particular case of hydrothermal crystallization Valentin Valtchev ENSICAEN, Université de Caen, CNRS 6 bd du Maréchal Juin, Caen, France

2 Outlines I. Zeolites general information II. Zeolite formation - questions to be answered III. Zeolite nucleation in alkali metal containing hydrogel systems Example: LTL-type nucleation V. Zeolite growth Example: LTL-type zeolite growth VI. Concluding remarks 2

3 Zeolites basic characteristics Crystalline microporous solids Chemical composition: (Mn+)x/n [AlxSiy-xO2y].zH2O (Si4+O4) = (Al3+O4) + M+ M H, Li, Na, K, Cs, Ba, Ca, Mg, organic cation Microporous crystals able to display molecule recognition, discrimination, and organization properties with a resolution of less than 1 Å. Pore size : 3 20 Å Pore systems : 1-, 2- and 3dimensional pore systems Classification IUPAC (h 0 0) (h k 0) b a

4 Zeolites basic characteristics 201 Framework type Framework composition (Si, Al, Ge, Ga, Ti, Fe, B, P,..) High specific surface area ( m2 g-1) Channel systems with different size and geometry Controllable hydrophilic / hydrophobic properties Acid and base properties Very high thermal stability (> 1000 C) Very high chemical stability Ion exchange properties 4 The total length of the channels of 1 g MFI-type zeolite is 4 times the distance Earth Sun. MFI

5 Fluid Catalytic Cracking Catalysts and catalysts consumption Market: billions US$ per year

6 Control of zeolite crystal size External surface / Micropore surface ratio

7 Control of zeolite crystal morphology Zeolite Beta (BEA) c BEA + BAB polymorphs Tetragonal P4122 <100> 6.6 x 6.7 Å [001] 5.6 x 5.6 Å a BEA Slow growth rate of pinacoidal face Rapid growth rate of pinacoidal face Development of a crystal face privileges the access to a particular channel. O. Larlus & V. Valtchev, Chem. Mater. 2005,17,

8 Zeolite formation - nucleation Gel composition Structure directing agent Mineralizing agent Nature and ratio between framework cations (Si, Al, Si, Ge, Ga, P, Ti, Zn, ) Impurities Temperature Time Stirring Aging Supersaturation: Δµs =µs - µc µs chemical potential of a molecule in solution µc chemical potential of a molecule in the bulk crystal Δµ = k T ln S K Boltzmann constant T - absolute temperature S - supersaturation ratio Nucleation: Δµ > 0 Zeolite nucleation in alkali metal rich aluminosilicate hydrogel systems : 8 V. Valtchev & K. Bozhilov J. Phys. Chem. B (2004) 108, Langmuir (2005) 21, J. Am. Chem. Soc. (2005), 126, J. Am. Chem. Soc. (2009), 131, Kossel, W. Nachr. Ges. Wiss Göttingen, Math.-Physik. Kl. (1927) 135 Stranski, I.N. Physik. Chem. 136 (1928) 259

9 Zeolite A nucleation in a TMATMAcontaining colloidal system (c) 1400 (f) 1200 Intensity 1000 f e d c b a 400 (d) Theta, degrees Synthesis time : (a) - 5 min, (b) 1 day, (c) 3 days, (d) 4 days, (e) 5 days, (f) 7 days 9 S. Mintova, N. H. Olson, V. Valtchev & T. Bein, Science 1999, 283,

10 General scheme of zeolite formation Structure directing agent: Na+, K+, Organic cations,.. Mineralizing agent: OH- ; FFramework building units: TO4 = SiO4 ; AlO4 Solvent: H2O Low temperature ( C) hydrothermal crystallization. 10 Schematic presentation of the zeolite synthesis process showing the evolution of nucleation and growth rates.

11 Motivation Questions to be answered: -Which stage of gel evolution are the viable nuclei formed at? -What is the spatial and temporal locations of the nucleation events? Gel formation 11 Re-organization and nucleation Growth

12 Effect of the composition of the gel structure 12 Zeolite A Zeolite X Zeolite P ZSM-5 Zeolite L Zeolite Beta

13 A question to be answered: What are the factors controlling the number of nuclei in a zeolite yielding system? Crystal size Comparative study of zeolite L crystal size formation Number of nuclei Micron crystals 13 Nano crystals

14 Crystal growth kinetics of zeolite L Nano 24 h 16 h Two theta ( ) 40 4h 3h 2.5 h 2h 0h 50 Gel A: 0.5K2O:0.05Al2O3:1.0SiO2:20H2O h Intensity (a.u.) Intensity (a.u.) Micron Two theta ( ) h 14 h 10 h 8h 4h 0h 50 Gel B:0.3K2O:0.09Al2O3:1.0SiO2:16H2O

15 0,0 15 Nanocrystals 24 h 16 h 4h 3h 2.5 h 2h 0h 0,2 0,4 0,6 0,8 Relative pressure (P/P0) 1,0 Adsorbed Volume (cm3g-1) STP Adsorbed volume (cm3g-1) STP Nitrogen adsorption isotherms Microcrystals 24 h 12 h 8h 4h 2h 0h 0,0 0,2 0,4 0,6 0,8 Relative pressure (P/P0) 1,0

16 Crystal growth kinetics Nano Micron 24 h 3h 2h 1h Intensity (a.u.) Intensity (a.u.) 20 h 7h 6.5 h 6h 4h 0h Raman shift (cm ) Raman study Raman shift (cm ) 600 2h 0h

17 Physical features of z. L precursor gels N2 adsorption (0.3K2O:0.09Al2O3:1.0SiO2: 16.0H2O) micron-sized crystals Hydrothermal treatment (h) S BET (m²g-1) Micropore area (m²g-1) External surface area (m²g -1) Total pore Volume (cm³g-1) Micropore volume (cm³g-1) N2 adsorption (0.5K2O:0.05Al2O3:1.0SiO2: 20.0H2O) nano-sized crystals 17 Hydrothermal treatment (h) S BET (m²g-1) Micropore area (m²g-1) External surface area (m²g -1) Total pore Volume (cm³g-1) Micropore volume (cm³g-1) TEM TEM

18 TEM study Ludox HS Aerodisp W1226

19 TEM study Nano 0 h 19 Micro 0 h Initial gels yielding nano- (left) and micron- (right) sized crystals.

20 TEM study Nano 1h 20 Micro 4h Induction period: nano- (left) and micron- (right) sized crystals.

21 TEM study Nano LTL 3h 21 Micro LTL 20h

22 Gel morphology Gel chemistry Gel A mother liquor: Si 940 ppm Al 5850 ppm K ppm gel A: 0.5K2O:0.05Al2O3:1.0SiO2:20H2O Solid phase gel B: 0.3K2O:0.09Al2O3:1.0SiO2:14H2O 22 L. Itani, K. N. Bozhilov, G. Clet, L. Delmotte, V. Valtchev Chemistry A European Journal 2011, 17,

23 Chemical homogenization of the systems Pogress of reaction (%) x n (Gel A) x m (Gel 40 B) Time (min) The chemical homogenization is reckoned to be defined by, the progress of the reaction in terms of approaching the stoichiometric zeolite L composition. By definition = (ct-c0)/(c0-cf), where ct is the K/Si ratio at a specific reaction time t, c 0 at the beginning of the reaction, and cf is the final stoichiometric K/Si ratio of

24 Nanosized zeolite L precursor SiO2 / K2O =

25 Micron-sized zeolite L precursor SiO2 / K2O = 0.25 SiO2 / K2O =

26 Conclusions The polymerization reaction at room temperature predetermines to a great extent the reaction pathway during hydrothermal treatment: The morphological characteristics of initial gels remained unchanged throughout the induction period. The gel composition changed gradually to reach values close to the final zeolite composition. The size of the final zeolite crystals can be directed by careful and systematic control of the starting gel chemistry, which enables synthesis of nanometer- or micronsized zeolite particles with uniform crystal size distribution. 26

27 Mechanism of zeolite growth as a function of supersaturation

28 Mechanism of zeolite growth as a function of supersaturation Supersaturation evaluation as a function of time for zeolite A synthesis: (b-d) correspond to time interval 1, 2 and 3, respectively.

29 Aggregation around a crystallization center 29

30 Aggregation around a crystallization center 30

31 31

32 LTL-type zeolite growth Cancrinite cages Haxagonal (001) face Terrace 1.4 nm Prismatic (100) face Terrace nm Terrace nm

33 Zeolite L crystal morphology View along <001> H2O C LTL-type P6/mmm [001] 7.1 x 7.1 Å 1 SiO2 : 0,25 K2O : 0,08 Al2O3 : x H2O O. Larlus & V. Valtchev, Chem. Mater. 2004,16, 3381 H2O C 1 SiO2 : 0,25 K2O : 0,08 Al2O3 : x H2O 33

34 Effect of zeolite crystal morphology on film orientation C 34

35 Summary A) Zeolite crystal size Determines the ration external / internal surface area. Nanocrystals: useful tool for preparation of complex polycrystalline zeolite macrostructures. B) Zeolite crystal morphology Preferential development of a desired crystal face: - privileges the access to a particular channel system; - determines the number of pore opening per unit crystal surface. Important factor in the preparation of complex functional surfaces comprising extended zeolite layers. C) Structured zeolite materials Materials with new functionality Synergy between different type of materials Extend the area of application of microporous materials 35

36 Acknowledgements Colleagues Postdocs PhD students Svetlana Mintova Christian Fernandez S. Roy Chowdhury L. Tosheva Normandy: Halloween November, 2011 F. Gaslain O. Larlus Lubomira Tosheva L. Tosheva F. Guillou Thomas Bein Y. Bouizi Y. Bouizi Krassimir Bozhilov N. Mahé Y. Mathieu Jean-Pierre Gilson F. Gao A. Jacob Georgi Vayssilov L. Lakiss A. Darwiche Maguy Jaber Zh. Qin L. Itani Javier Perez-Ramirez M. El Roz A. Palcic Avelino Corma X. Zou Tatsuya Okubo K.G. Haw Sponsors: CNRS, TOTAL, Grace Davison, IFP, CNES, CEA, DGA, ANR,.. 36