Zeolites have been widely used as catalysts, ion exchangers, and adsorbents since their industrial breakthrough in the 1950s and continue to be state-of the-art adsorbents in many separation processes. Furthermore, their properties make them materials of choice for developing and emerging separation applications. The aim of this review is to put into context the relevance of zeolites and their use and prospects in adsorption technology. It has been divided into three different sections, i.e., zeolites, adsorption on nanoporous materials, and chemical separations by zeolites. In the first section, zeolites are explained in terms of their structure, composition, preparation, and properties, and a brief review of their applications is given. In the second section, the fundamentals of adsorption science are presented, with special attention to its industrial application and our case of interest, which is adsorption on zeolites. Finally, the state-of-the-art relevant separations related to chemical and energy production, in which zeolites have a practical or potential applicability, are presented. The replacement of some of the current separation methods by optimized adsorption processes using zeolites could mean an improvement in terms of sustainability and energy savings. Different separation mechanisms and the underlying adsorption properties that make zeolites interesting for these applications are discussed.

Purifying ethylene with flexible zeolites: Ethylene is a key feedstock for many chemicals and polymers, but its production requires cryogenic separation from ethane, an energy-consuming step. In theory, pure silica zeolites are well suited to separate olefins from paraffins. Bereciartua et al. synthesized a pure silica zeolite with very small pores, which, if static, would not adsorb either of these hydrocarbons. However, molecular dynamics suggested that the pores should be flexible. Indeed, in competitive adsorption experiments, the zeolite preferentially adsorbed ethylene from a mixed stream of ethylene and ethane. Science , this issue p. 1068