Magnetic zeolite composites: Classification, synthesis routes, and technological applications

Given their numerous remarkable properties such as chemical stability, high surface areas, and well-organized porous systems, zeolites have long been explored in a variety of important industrial applications, mainly those related to adsorption and catalysis. The zeolite polycrystalline nature imposes some limitations for the practical purposes, requiring for example its compression in form of pellets which usually leads to a drop of performance. One interesting alternative that has been subject of many studies is the incorporation of magnetic nanoparticles to zeolite crystals so that the formed composite can respond to an external magnetic field. In this review we have identified and organized the different types of magnetic zeolite composites, discussing the effectiveness of the synthetic methods reported, from the very simple routes until very sophisticated approaches, and classifying these materials in five groups according to the way the magnetic nanoparticles interact with the zeolites.