SSZ-13

SSZ-13 (framework type code CHA) is an aluminosilicate zeolite mineral possessing 0.38 × 0.38 nm micropores.[1] It belongs to the ABC-6 family of zeolites as well as offretite, cancrinite, erionite and other related minerals.[2] The framework topology is the same as that of chabazite but SSZ-13 has high-silica composition with Si/Al > 5 which leads to low cation exchange capacity. The typical chemical formula of the unit cell can be described as QxNayAl2.4Si33.6O72•zH2O (1.4 < x <27)(0.7 < y < 4.3)(1 < z <7), where Q is N,N,N-1-trimethyladamantammonium.[1] The material was patented by Chevron research Company in 1985,[3] and has a potential use as a solid catalyst for the methanol-to-olefins (MTO) process and the selective catalytic reduction (SCR) of NOx.

Synthesis

SSZ-13 can be synthesized from the following method.[4] The material is synthesized from the following batch composition:

10 Na2 : 2.5 Al2O3 : 100 SiO2 : 4400 H2O : 20 QOH.

2 g 1N NaOH, 2,78 g 0.72 M N,N,N-1-trimethyladamantammonium hydroxide (QOH) and 3.22 g deionized water are mixed. 0,1 g Al2O3 is added to the solution and mixed with 0.6 g fumed silica. The resulting viscous gel is aged for two hours and heated for 4 days at 160oC in a teflon lined steel autoclave. The crystallized product can be recovered by filtration.

Uses

SSZ-13 is a high silica zeolite with the CHA topology. Materials with this topology are of industrial interest, as potential catalysts for application in the methanol to olefins (MTO) reaction.

Recently SSZ-13 has attracted attention as the catalyst for selective catalytic reduction (SCR) of NOx.[5] Actually copper-loading SSZ-13 is industrially applied to the emission control of diesel engines.

See also

References

  1. 1 2 Baerlocher, Ch.; McCusker, L.B..; Olson, D.H. Atlas of Zeolite framework Types, Elsevier, Amsterdam, 6th edn., 2007, see also: http://www.iza-structure.org/databases/.
  2. ↑ G.R. Millward, S. Ramdas, J.M. Thomas, Proc. R. Soc. Lond. A, 399, 57 (1985)
  3. ↑ Zones, S.I. US Patent 4 544 538, 1985,
  4. ↑ Robson, H., Lillerud, K.P. (2001). Verified Synthesis of Zeolitic Materials. Elsevier. ISBN 0-444-50703-5
  5. ↑ Bull, I.; Boorse, R. S.; Jaglowski, W. M.; Koermer, G. S.; Moini, A.;Patchett, J. A.; Xue, W. M.; Burk, P.; Dettling, J. C.; Caudle, M. T. U.S. Patent 0,226,545, 2008.
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