Synthesis of 'unfeasible' zeolites.

Michal Mazur,Russell E Morris,Paul S Wheatley,Marta Navarro,Jiří Čejka,Pavla Eliášová,Wieslaw J Roth,Alvaro Mayoral,Miroslav Položij,Petr Nachtigall

doi:10.1038/nchem.2374

Abstract

Zeolites are porous aluminosilicate materials that have found applications in many different technologies. However, although simulations suggest that there are millions of possible zeolite topologies, only a little over 200 zeolite frameworks of all compositions are currently known, of which about 50 are pure silica materials. This is known as the zeolite conundrum--why have so few of all the possible structures been made? Several criteria have been formulated to explain why most zeolites are unfeasible synthesis targets. Here we demonstrate the synthesis of two such 'unfeasible' zeolites, IPC-9 and IPC-10, through the assembly-disassembly-organization-reassembly mechanism. These new high-silica zeolites have rare characteristics, such as windows that comprise odd-membered rings. Their synthesis opens up the possibility of preparing other zeolites that have not been accessible by traditional solvothermal synthetic methods. We envisage that these findings may lead to a step change in the number and types of zeolites available for future applications.

Highlights

Zeolites are porous aluminosilicate materials that have found applications in many different technologies
The most recent criteria postulated are those based on local interatomic distances (LID) where feasible zeolite targets are only those that obey strict criteria describing limits on the values of the interatomic distances and angles.[8]
We present the structures of two new silica zeolites, IPC-9 and IPC-10

Summary

Introduction

Zeolites are porous aluminosilicate materials that have found applications in many different technologies. It has long been recognised that the known zeolites show a strong correlation between framework energy and density, a finding that was predicted computationally[9,10] and confirmed experimentally.[11] the largest sets of hypothetical zeolites, postulated by connecting SiO4 tetrahedra in as many ways as possible, do not show such a correlation and the potential structures cover a large region in energy-density space.[12] it has been noted that the known zeolites can all be found at the low-density edge of the energy-density distribution of hypothetical zeolites.[12,13] This suggests that known zeolites all obey the correlation not because of the properties of the zeolites formed but because of kinetic limitations of the synthesis procedure (or at the very least a combination of the two).[13] This means that solvothermal synthesis is the limiting factor in determining which zeolites are feasible or not This all suggests that the development of new synthetic pathways could overcome the limitations of solvothermal synthesis and prepare zeolites that are currently thought to be unfeasible.

Methods

Conclusion