Zeolites are crystalline sodium aluminosilicate materials with a 3D microporous structure. They are used as catalysts, ion exchangers and adsorbents due to their unique properties such as crystallinity, thermal stability, large specific surface area, ordered microporous structure, presence of catalytically active acid sites, ion exchange properties and ability to selectively separate according to molecular size. ZSM-5 is one of the most widely used zeolite catalyst (T/year, income in mio EUR/$).