A comprehensive review of the recent progress in the applications of hierarchically structured porous materials is given.

Owing to their immense potential in energy conversion and storage, catalysis, photocatalysis, adsorption, separation and life science applications, significant interest has been devoted to the design and synthesis of hierarchically porous materials. The hierarchy of materials on porosity, structural, morphological, and component levels is key for high performance in all kinds of applications. Synthesis and applications of hierarchically structured porous materials have become a rapidly evolving field of current interest. A large series of synthesis methods have been developed. This review addresses recent advances made in studies of this topic. After identifying the advantages and problems of natural hierarchically porous materials, synthetic hierarchically porous materials are presented. The synthesis strategies used to prepare hierarchically porous materials are first introduced and the features of synthesis and the resulting structures are presented using a series of examples. These involve templating methods (surfactant templating, nanocasting, macroporous polymer templating, colloidal crystal templating and bioinspired process, i.e. biotemplating), conventional techniques (supercritical fluids, emulsion, freeze-drying, breath figures, selective leaching, phase separation, zeolitization process, and replication) and basic methods (sol–gel controlling and post-treatment), as well as self-formation phenomenon of porous hierarchy. A series of detailed examples are given to show methods for the synthesis of hierarchically porous structures with various chemical compositions (dual porosities: micro–micropores, micro–mesopores, micro–macropores, meso–mesopores, meso–macropores, multiple porosities: micro–meso–macropores and meso–meso–macropores). We hope that this review will be helpful for those entering the field and also for those in the field who want quick access to helpful reference information about the synthesis of new hierarchically porous materials and methods to control their structure and morphology.

Zeolites with hierarchically porous structures have garnered much attention due to their highly attractive properties. Hierarchically structured zeolites integrate at least two levels of porosity and present the advantages associated with each level of porosity, from selectivity to mass transport. They are categorized into three distinctly different types according to their hierarchical porosities: mesostructured zeolites, macrostructured zeolites, and micro–meso–macroporous structured zeolites. Most importantly, hierarchically structured zeolites offer an effective solution to the mass transport problem associated with conventional zeolites in catalysed reactions because they combine the catalytic features of micropores and the improved accessibility and increased molecular transport related to the addition of several porosities within a single body. In recent years, many strategies have been successfully developed to synthesize hierarchically structured zeolitic materials. This feature article thoroughly summarizes recent developments that have been achieved in the field of hierarchically structured zeolites, with the main focus on the synthesis strategies that are available, with examples given from the literature. Available approaches are reviewed for the preparation of micro–mesoporous structured zeolites, micro–macroporous structured zeolites and micro–meso–macroporous structured zeolites. Furthermore, the enhanced mass transport properties of hierarchically structured zeolites, featuring additional larger pores in addition to the crystalline micropores, have also been described. The significant improvement in catalytic properties in a range of important reactions resulting from enhanced mass transport properties have also been discussed through several representative cases. It is the intent of this work to stimulate intuition into the optimal design of related hierarchically organized zeolites with desired characteristics.