Ordered nanoporous materials have attracted much attention due to their unique pore architecture, tunable physicochemical properties, which find applications in a broad spectrum of catalysis, separation, adsorption, drug delivery, energy storage, and sensing. In the past decades, the amount of research on ordered nanoporous materials has grown incrementally, resulting in diverse types of these materials with unprecedented structures. Herein, this chapter presents the recent advances of ordered nanoporous materials, including zeolites, ordered mesoporous materials (OMMs), metal–organic frameworks (MOFs), and covalent organic frameworks (COFs). Several vital aspects, i.e., structural and physicochemical properties, synthesis, and applications, are comprehensively discussed. Finally, challenges and prospects for future improvement are also elaborated.

Advanced Ordered Nanoporous Materials

.................................................................................................................................... V List of abbreviations used in this thesis ................................................................................... VI 1 Project motivation and aim ................................................................................................ 1 2 Introduction ........................................................................................................................ 5 Microporous materials ................................................................................................. 5 What are zeolites and zeotypes? .................................................................................. 5 Historical development of zeolites .............................................................................. 6 Defining the framework ............................................................................................... 8 Properties ................................................................................................................... 11 2.5.1 Acid sites ............................................................................................................ 11 2.5.2 Shape selectivity ................................................................................................. 13 Catalysis and application of zeolitic materials .......................................................... 15 2.6.1 SAPO-11 as a heterogeneous catalyst for the conversion of methanol to olefins 19 3 Theory and Methodology ................................................................................................. 20 Kinetics and thermodynamics of crystal growth ....................................................... 20 3.1.1 Nucleation theory ............................................................................................... 20 3.1.2 Crystal growth theory – Conventional and recent published theory .................. 22 3.1.3 Nucleation and growth in zeolitic materials ....................................................... 22 Zeolite synthesis ........................................................................................................ 24 3.2.1 Hydrothermal method and HSE aspects. ............................................................ 24 3.2.2 Theoretical effect of important synthesis parameters ........................................ 26 3.2.3 Published work on synthesis of SAPO-11 ......................................................... 28 Theory of characterization techniques ....................................................................... 31 3.3.1 Powder X-ray diffraction ................................................................................... 31

SAPO-11 as a catalyst for the production of chemicals from methanol

For the first time, the structural investigation of a Pb-exchanged zeolite (Pb13.4(OH)10Al17.4Si54.6O144 ∙38H2O) with STI framework type, revealed a highly unusual and intriguing sudden volume increase under continuous heating. Understanding the fundamental mechanisms leading to such an unusual behaviour is essential for technological applications and interpretation of chemical bonding in zeolites. The dehydration was tracked in situ from 25 to 450 °C by single crystal X-ray diffraction, infrared and X-ray absorption spectroscopy. Further interpretation of the experimental observations was supported by ab initio molecular dynamics simulations. Initially, Pb-STI unit-cell volume contracts (ΔV = - 3.5%) from 25 to 100 °C. This agrees with the trend observed in STI zeolites. Surprisingly, at 125 °C, the framework expanded (ΔV = + 2%), adopting a configuration, which resembles that of the room temperature structure. Upon heating, the structure loses H2O but no de-hydroxylation occurred. The key mechanism leading to the sudden volume increase was found to be the formation of Pbx(OH)y clusters, which prevent the shrinking of the channels, rupture of the tetrahedral bonds and occlusion of the pores. This zeolite has therefore an increased thermal stability with respect to other STI metal-exchanged zeolites, with important consequences on its applications. 

/pdf/pbx-oh-y-cluster-formation-and-anomalous-thermal-behaviour-3cpzdq4k.pdf

Pbx(OH)y cluster formation and anomalous thermal behaviour in STI framework-type zeolites

The assembly–disassembly–organisation–reassembly (ADOR) approach extends the synthesis of new zeolites. Understanding the disassembly and organisation mechanism is important to optimise the post-treatment process on germanosilicate zeolites. In situ synchrotron X-ray...

In situ synchrotron X-ray diffraction reveals the disassembly-organisation mechanism of germanosilicate zeolites in HCl vapour

Synthesis and Catalytic Properties of Al-Itq-34

The performance of a zeolite is dictated by its framework structure Understanding the regular crystal arrangement is key to understanding why and how these materials function, in order to improve on the features that make them useful This chapter covers how zeolites are classified through their framework type, how they can be described in terms of common structural features, such as building units, and how small changes to the structure can affect the performance On the basis of several relevant examples of zeolite frameworks, the fundamental aspects of zeolite structural science are laid out Finally, crystallographic methods for structural analysis of zeolites, such as powder X-ray diffraction, electron diffraction, and high resolution transmission electron microscopy, are summarized

Chapter 2:Zeolite Structures

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Chapter 2:Zeolite Structures