Thermal stability studies of zeolites A and X synthesized from South African coal fly ash
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The thermal stability of zeolites A and X synthesized from coal fly ash was studied by evaluation of TGA–DTA curves obtained on increasing the temperature and by in-situ temperature-programmed XRD analysis. It was found that zeolites A and X were both stable up to approximately 800 °C and retained their characteristic diffraction peaks up to 440 °C, meaning the crystal structure was still stable. Of particular interest was that zeolite X, which has a unique hierarchical morphology, was thermally stable and was, hence, suitable for applications requiring elevated temperatures, for example catalysis and pollution control.
KeywordsZeolites Fly ash Thermal stability In-situ XRD
The authors of this paper would like to acknowledge and thank DAAD for supporting Nicholas Musyoka during his research visit to the University of Erlangen-Nürnberg, Germany. Andreas Kuhnt and Wilhelm Schwieger appreciatively acknowledge funding by the German Research Council (DFG), which supports the Cluster Excellence “Engineering of Advanced Materials” at the University of Erlangen-Nürnberg. Assistance offered by Alexandra Inayat and Albert Machoke during the SEM analysis is also appreciated.
- 1.M.E. Brown, P.K. Gallagher, Handbook of Thermal Analysis and Calorimetry, Volume 5: Recent Advances, Techniques and Applications (Elsevier, Amsterdam, 2008)Google Scholar
- 2.D.W. Breck, Zeolite Molecular Sieves (Wiley, New York, 1974)Google Scholar
- 4.A. Auroux, in Catalyst Characterization: Physical Techniques for Solid Materials, ed. by B. Imelik, J.C. Vedrine (Plenum Press, New York, 1994), pp. 611Google Scholar
- 5.Z. Adamczyk, B. Bialecka, Hydrothermal synthesis of zeolites from Polish fly ash. Polish J. Environ. Stud. 14, 713–719 (2005)Google Scholar
- 7.I. Majchrzak-Kuceba, A simple thermogravimetric method for the evaluation of the degree of fly ash conversion into zeolite material. J. Porous Mater. (2012). doi: 10.1007/s10934-012-9610-1
- 9.B. Subotić, J. Bronić, in Theoretical and Practical Aspects of Zeolite Crystal Growth, ed. by M.A. Scott, A. Kathleen, Carrado, K.D. Prabir. Handbook of zeolite science and technology (Marcel Dekker, New York)Google Scholar
- 10.N.M. Musyoka, Zeolite A, X and Cancrinite from South African Coal Fly Ash: Mechanism of Crystallization, Routes to Rapid Synthesis and New Morphology, Unpublished PhD Thesis (University of the Western Cape, 2012b)Google Scholar
- 11.N.M. Musyoka, L.F. Petrik, E. Hums, H. Baser, W. Schwieger, In-situ ultrasonic diagnostic of zeolite X crystallization with novel (hierarchical) morphology from coal fly ash Submitted to be published (2012c)Google Scholar
- 14.S. Akbar, K. Dad, T.H. Shah, R. Shahnaz, Thermal studies of NaX zeolite with different degrees of cadmium exchange. J. Chem. Soc. Pak. 27, 456–461 (2005)Google Scholar
- 15.A. Pfenninger, Molecular Sieve, Science and Technology , vol. 2, ed. by H.G. Karge, J. Weitkamp (Springer, Berlin, 1999), p. 162Google Scholar