MFI/∗BEA hybrid coating on aluminum alloys

[Display omitted] ► New MFI/∗BEA hybrid film on aluminum substrates. ► The importance of the secondary growth method. ► Potential applications of the hybrid films in VOCs adsorption and corrosion resistance. Hybrid bi-layered film composed of a thick layer of ZSM-5 zeolite (MFI structure-type) and a thin layer of Beta zeolite (∗BEA structure-type) is synthesized on aluminum alloys widely used in aerospace industry. In the first step, the bottom MFI layer is formed by direct hydrothermal synthesis on aluminum substrates. In the second step, the ZSM-5 film is seeded with zeolite Beta nanocrystals followed by a secondary growth of the ∗BEA layer using two starting gel compositions. Depending on the Si/Al molar ratio of the starting solution, ZSM-12 zeolite can also crystallise as an impurity phase. It is shown that the crystallisation step of the top layer is faster using zeolite Beta seeds. The sorption capacity of the hybrid film determined by nitrogen adsorption–desorption measurements is promising for technological uses in space decontamination.