AI-Guided Design and Property Prediction for Zeolites and Nanoporous Materials

5 Co-templating in the Designed Synthesis of Small-pore Zeolite Catalysts

Ruxandra G. Chitac¹, Mervyn D. Shannon^2,3, Paul A. Cox³, James Mattock³, Paul A. Wright¹, and Alessandro Turrina²

¹ EaStCHEM School of Chemistry, University of St Andrews, St Andrews, United Kingdom² Johnson Matthey Technology Centre, Billingham, United Kingdom³ School of Pharmacy and Biomedical Sciences, University of Portsmouth, Portsmouth, United Kingdom

5.1 Introduction

The importance of small-pore zeolites and zeotypes in catalytic reactions such as methanol-to-olefins (MTO) catalysis and the selective catalytic reduction (SCR) of NO_x from diesel exhausts using ammonia, and in selective adsorption of small molecules such as carbon dioxide, has led to intense study of their synthesis and structure-property relationships. This is well-covered in a number of excellent recent reviews [1,2]. Small-pore zeolites are defined as having a pore size, or window diameter of 3–4 Å, which usually results from their porosity being accessible only via 8-membered rings (bounded by 8 tetrahedrally-coordinated framework cations and 8 oxygen atoms, 8MRs). As a class of zeolites or zeotypes, they make up 41% of the total number of known framework structures (Figure 5.1) and a third of them have three-dimensionally-connected porosity that makes them highly desirable for applications [3]. Thus, it is useful to consider what methodology is the most efficient for synthesizing these structures in a controlled manner. An in-depth ...