REMOVAL OF DIQUATERNARY AMMONIUM CATIONS FROM AS-SYNTHESIZED SSZ-16 ZEOLITE

Tatana Supinkova,Ivan Jirka,Vlastimil Fila,Jan Langmaier,Jan Drahokoupil,Libor Brabec,Milan Kocirik

doi:10.14311/app.2017.9.0026

Abstract

Zeolites are stable microporous aluminosilicates with numerous applications in chemical technology such as separation of species and catalytic transformations. Our study is focused on a weakly explored zeolite SSZ-16 with pore constrictions defined by 8-membered oxygen rings. Key results are the preparation of Et6-diquat-5 dication used as a structure directing agent (SDA) and finding the optimum synthesis conditions with respect to zeolite phase purity. Stability of SDA was examined in conditions similar to those of autoclave synthesis (concentration, pH, temperature). Moreover, the content and location of SDA species in zeolite phase and conditions of SDA decomposition were investigated.

Highlights

Zeolites and zeolite-like materials consist of tetraedral building units TO4 where T are central atoms most frequently Si and Al+
A relatively novel zeolite SSZ-16 belongs to the class of small pore zeolites characterized by 8membered oxygen rings which may exhibit molecular sieve effect for gases with small molecules
Cu-SSZ-16 [7, 8] seems to be promising as a selective catalytic reduction catalyst for the direct conversion of NO into N2 and O2

Summary

Introduction

Zeolites and zeolite-like materials consist of tetraedral building units TO4 where T are central atoms most frequently Si and Al+. T-atoms can be replaced by isomorphous substitution, for example Ge, Ti, P, Fe, Ga, B and form zeolite analogues. Zeolites and their analogues are crystalline materials with regular microporous structure (with pore width < 2 nm). A relatively novel zeolite SSZ-16 belongs to the class of small pore zeolites characterized by 8membered oxygen rings which may exhibit molecular sieve effect for gases with small molecules. The principal aim of this work is to contribute to the knowledge of structure-directing agent (diquaternary ammonium dications) chemistry in relation to its (i) synthesis and purity, (ii) role in the synthesis of SSZ-16 zeolite, (iii) stability in synthesis batches and (iv) its thermal removal from the zeolite framework

Objectives

Results

Conclusion