Nanosized Cu-SSZ-13 and Its Application in NH3-SCR

Ana Palčić,Roger Gläser,David Poppitz,Marko Bertmer,Magdalena Jabłońska,Andreas Pöppl,Kinga Góra-Marek,Kamila Pyra,Paolo Cleto Bruzzese

doi:10.3390/catal10050506

Abstract

Nanosized SSZ-13 was synthesized hydrothermally by applying N,N,N-trimethyl-1-adamantammonium hydroxide (TMAdaOH) as a structure-directing agent. In the next step, the quantity of TMAdaOH in the initial synthesis mixture of SSZ-13 was reduced by half. Furthermore, we varied the sodium hydroxide concentration. After ion-exchange with copper ions (Cu2+ and Cu+), the Cu-SSZ-13 catalysts were characterized to explore their framework composition (XRD, solid-state NMR, ICP-OES), texture (N2-sorption, SEM) and acid/redox properties (FT-IR, TPR-H2, DR UV-Vis, EPR). Finally, the materials were tested in the selective catalytic reduction of NOx with ammonia (NH3-SCR). The main difference between the Cu-SSZ-13 catalysts was the number of Cu2+ in the double six-membered ring (6MRs). Such copper species contribute to a high NH3-SCR activity. Nevertheless, all materials show comparable activity in NH3-SCR up to 350 °C. Above 350 °C, NO conversion decreased for Cu-SSZ-13(2–4) due to side reaction of NH3 oxidation.

Highlights

SSZ-13 and SAPO-34 are typical examples of zeolite materials with a chabazite (CHA) structure
Techniques such as ion-exchange [2], chemical vapor deposition [3], solid-state ion-exchange (SSIE) [4], one-pot preparation with Cu ions introduced by the structure-directing agent [5], and wet mixing and impregnation [6] have been examined for the preparation of Cu-CHA materials
SSZ-13 to study their activity in NH3 -SCR

Summary

Introduction

SSZ-13 and SAPO-34 are typical examples of zeolite materials with a chabazite (CHA) structure. Its structure can be represented as cha cages connected via double six-membered rings and is a member of the abc-six frameworks family. The incorporation of Cu ions into the CHA zeolite is a key factor in the preparation of the Cu-CHA catalysts. Techniques such as ion-exchange [2], chemical vapor deposition [3], solid-state ion-exchange (SSIE) [4], one-pot preparation with Cu ions introduced by the structure-directing agent [5], and wet mixing and impregnation [6] have been examined for the preparation of Cu-CHA materials. In Cu-SSZ-13, copper species are predominantly present as isolated Cu2+ ions, even at higher ion-exchange degrees [2]

Methods

Results

Conclusion