SSZ-13 (framework type code CHA) is an aluminosilicate zeolite mineral possessing 0.38 × 0.38 nm micropores. It belongs to the ABC-6 family of zeolites as well as offretite, cancrinite, erionite and other related minerals. 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. The material was patented by Chevron research Company in 1985, and has a potential use as a solid catalyst for the methanol-to-olefins (MTO) process and the selective catalytic reduction (SCR) of NOx.
Contents
Synthesis
SSZ-13 can be synthesized from the following method. 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. Actually copper-loading SSZ-13 is industrially applied to the emission control of diesel engines.