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Regulating the size and acidity of SAPO-34 zeolites using dual templates to enhance the selectivity of light olefins in MTO.
- Source :
- New Journal of Chemistry; 7/14/2021, Vol. 45 Issue 26, p11812-11822, 11p
- Publication Year :
- 2021
-
Abstract
- To understand the relationship between the catalytic performance, crystallite size, and acidity of SAPO-34 zeolites better, a series of SAPO-34 zeolites were prepared by hydrothermal crystallization using palygorskite as silicon and partial aluminum source, and selecting two kinds of triethylamine, morpholine and tetraethylammonium hydroxide as dual templates. The obtained SAPO-34 zeolites were characterized via the methods of XRD, SEM, N<subscript>2</subscript>-adsorption–desorption, NH<subscript>3</subscript>-TPD, FTIR, XRF, <superscript>29</superscript>Si MAS NMR, <superscript>27</superscript>Al MAS NMR and TG. The properties of the templates affected the crystal growth rate that triethylamine and morpholine can cause a larger crystallite size while tetraethylammonium hydroxide can form small crystallite size particles. The number of acid sites of SAPO-34 zeolites first decreased and then increased with the increase of morpholine. The formation of Si islands can enhance the number of acid sites of SAPO-34 zeolites. The catalytic performance of SAPO-34 zeolites in methanol-to-olefins (MTO) reaction was investigated in a fixed bed reactor. Under reaction conditions, when the reaction temperature was 400 °C, the feed WHSV was 2.0 h<superscript>−1</superscript>, the mass of the catalyst was 0.5 g, at atmospheric pressure, the sample with an amount of acid sites of 0.85 mmol g<superscript>−1</superscript> and crystallite size of 0.84 μm exhibited the optimum catalytic performance with methanol conversion at 100%, light olefin selectivity at 97.15% and catalytic lifetime at more than 1050 min. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 11440546
- Volume :
- 45
- Issue :
- 26
- Database :
- Complementary Index
- Journal :
- New Journal of Chemistry
- Publication Type :
- Academic Journal
- Accession number :
- 151248912
- Full Text :
- https://doi.org/10.1039/d1nj01845k