A family of zeolites with controlled pore size prepared using a top-down method

Abstract

The properties of zeolites, and thus their suitability for different applications, are intimately connected with their structures. Synthesizing specific architectures is therefore important, but has remained challenging. Here we report a top-down strategy that involves the disassembly of a parent zeolite, UTL, and its reassembly into two zeolites with targeted topologies, IPC-2 and IPC-4. The three zeolites are closely related as they adopt the same layered structure, and they differ only in how the layers are connected. Choosing different linkers gives rise to different pore sizes, enabling the synthesis of materials with predetermined pore architectures. The structures of the resulting zeolites were characterized by interpreting the X-ray powder-diffraction patterns through models using computational methods; IPC-2 exhibits orthogonal 12- and ten-ring channels, and IPC-4 is a more complex zeolite that comprises orthogonal ten- and eight-ring channels. We describe how this method enables the preparation of functional materials and discuss its potential for targeting other new zeolites.

Layered zeolitic materials: an approach to designing versatile functional solids

“…It could also be re-converted to 3D zeolite with regular stacking of previously swollen ferrierite-like layers with octylamine (ICP-4), after calcination process, showing the versatility of this type of layered zeolitic precursors ( Figure 29). 196,197 On the contrary, direct calcination of layered precursor ICP-1P, without intercalated organic compounds, only led to a poorly ordered lamellar material (IPC-1).However, in the case of pillared solids, it was possible the formation of undesirable M41S mesoporous amorphous phases, cohabitating with layered ICP-type zeolites due to the strongly alkaline conditions used during the pillarization process in presence of surfactants as swelling agents.…”

The importance of T⋯T⋯T angles in the feasibility of zeolites

“…In addition to the classic solvothermal approach, where new gel compositions and new families of templates have contributed, among other, to the rising number of zeolites, novel methods such as 'inverse sigma' and 'ADOR (assembly, disassembly, organisation, reassembly)' approaches have been recently presented [13,14]. They start from existing zeolites containing individual layers interconnected by D4Rs (double four rings) where a high concentration of Ge favours delamination by selective removal of the D4Rs, and where subsequent condensation may lead to one or several new fully condensed phases.…”

“…It may be thought that the latter is a small number, but this depends T angles in the feasibility of zeolites on the efforts dedicated to try to synthesise new zeolites. The narrow differences in their relative free energies [15] is a factor against increasing their number, although some new synthesis methods allow to overcome certain energetic barriers by following a less straight synthesis path [13,14]. Assessing zeolite feasibility is a challenging issue and several attempts have been made [16][17][18].…”

In situ solid-state NMR and XRD studies of the ADOR process and the unusual structure of zeolite IPC-6

“…1,4 The process comprises four distinct steps. The assembly (A) process involves the preparation of a parent zeolite with suitable chemical and topological properties for…”

“…3 One consequence of the organisation step is the possibility of using different structural units to link the layers to form the different zeolites, leading to isoreticular families. 1,4 Controlling these linkages offers an important tool by which the final structures can be precisely tuned, and leads to, amongst other things, the possibility of continuously tuneable porosity. 4 The isoreticular family of structures discussed in this manuscript are IPC-4, IPC-2 and IPC-6, which contain the same UTL layer types linked by oxygen atoms (which we call PCR linkages, as they are present in the PCR zeolite topology), single four ring units (called OKO linkages) and 50%/50% PCR/OKO linkages respectively.…”