Metal–organic frameworks represent a class of porous materials which have developed considerably over the past few years. Their highly porous structure makes them outperform conventional adsorbents in hot topics such as dihydrogen and methane storage, and carbon dioxide capture. Their consequent modularity, based on the assembly of organic linkers and metal ions or clusters, also brings novel perspectives in catalysis, sensing and drug delivery just to name a few. However, one of the main bottlenecks to their broader use remains their shaping. Especially, shaped materials should present long-term mechanical stability as well as preserve their physical and chemical properties. This makes shaping of MOFs a special case as their thermal and chemical stabilities remain a downside as compared to other traditional porous materials such as silicas and zeolites today. Therefore, ever-increasing efforts have been devoted to the shaping of these materials. In this review, the state of the art for the preparation of shaped 3D MOF-based materials will be presented. Emphasis will be given to the final physical and chemical properties of the shaped solids comparatively to the initial powders, when data are available. In the first part, traditional techniques based on applying a significant force to MOF-based powders will be reviewed. These include pelletization, granulation, and extrusion, which generally lead to an increase of the final volumetric gas uptake of the objects. At the same time, the advantages and disadvantages of each technique will be discussed as well as the main outcome on the final objects. In the second part, the focus will be on newly-emerging techniques such as 3D printing and spray drying. The former also maximizes the volumetric gas uptake of the final materials, and for both techniques the quality of the final objects heavily relies on the working parameters. Finally, the third part will include the so-called “phase separation” shaping techniques which are for the most part performed without using special techniques. This implies shaping via physical and chemical phenomena such as sublimation and precipitation. Subsequently, a discussion on the performance of these materials for adsorption-based applications will be provided. Finally, perspectives and future outlook will be discussed.

Hierarchical macroporous–mesoporous SBA-15 silicas have been synthesised via dual-templating routes employing liquid crystalline surfactants and polystyrene beads. These offer high surface areas and well-defined, interconnecting macro- and mesopore networks with respective narrow size distributions around 300 nm and 3–5 nm for polystyrene:tetraethoxysilane ratios ≥2:1. Subsequent functionalisation with propylsulfonic acid yields the first organized, macro-mesoporous solid acid catalyst. The enhanced mass transport properties of these new bi-modal solid acid architectures confer significant rate enhancements in the transesterification of bulky glyceryl trioctanoate, and esterification of long chain palmitic acid, over pure mesoporous analogues. This paves the way to the wider application of hierarchical catalysts in biofuel synthesis and biomass conversion.

A series of propylsulfonic (MCM–SO₃H) and octyl co-functionalised propylsulfonic (MCM–Oc–SO₃H) catalysts have been prepared by post modification of MCM-41 with mercaptopropyltrimethoxysilane (MPTS) to achieve SO₃H surface coverages spanning the range 0.12–1 monolayer. Within the MCM–Oc–SO₃H series, samples with submonolayer MPTS coverages were further grafted with octyltrimethoxysilane to cap bare hydroxyl sites and tune the hydrophobicity of the support. For the MCM–SO₃H series NH₃ calorimetry revealed acid strength increases as a function of sulfonic acid loading, with -ΔH_ads(NH₃) increasing from 87 to 118 kJ mol⁻¹. In contrast, MCM–Oc–SO₃H exhibits a dramatic enhancement of acid strength for submonolayer SO₃H coverages, with -ΔH_ads(NH₃) found to increase to 103 kJ mol⁻¹. In line with these acid strength measurements the per-site activity of the MCM–SO₃H series in the esterification of butanol with acetic acid was found to increase with SO₃H content. Incorporation of octyl groups further promotes esterification activity of all the samples within the MCM–Oc–SO₃H series, such that the turn over frequency of the sample with the lowest loading of SO₃H more than doubles. Molecular dynamic simulations indicate that the interaction of isolated sulfonic acid groups with the pore walls is the primary cause of the decrease in acid strength and activity of submonolayer samples within the MCM–SO₃H series. Incorporation of octyl groups results in a combination of increased hydrophobicity and lateral interactions between adjacent sulfonic acid head groups, resulting in a striking enhancement of acid strength and esterification activity.