Synthesis of corrosion-resistant MFI-type zeolite coatings by solid-conversion secondary growth without solvent.

The hydrothermal synthesis for the fabrication of zeolite coatings is the most effective route and has been extensively studied, in which a large amount of water is indispensable to ensure efficient transport of nutrition. The disposal of waste solvent and chemicals remains a big challenge in practice and an alternative route is highly desired. Herein, we present an unprecedented solid-conversion secondary growth route for the fabrication of corrosion-resistant MFI-type zeolite coatings by mixing, grinding, and heating the mixture of silica source (Na 2 SiO 3 ·9H 2 O and SiO 2), template (TPABr) and acidity regulator (NH 4 Cl) without addition of water. The ZSM-5 zeolite seeded aluminum alloy 1060 plates were prepared by spray-coating method where water glass as a binder between seed and substrate was used to increase the adhesion of seeds to the substrate. The continuity of the coatings was investigated by manipulating the molar composition of synthesis mixture and the optimized molar composition is 1.0Na 2 SiO 3 ·9H 2 O: 1.19SiO 2 : 0.58TPABr: 1.82NH 4 Cl. The corrosion protection performance of MFI-type zeolite coatings on aluminum alloy plates was evaluated by a direct current polarization technique. The excellent corrosion-resistant was demonstrated in severely corrosive medium including in 0.5 M H 2 SO 4 aqueous solution and 0.5 M NaCl aqueous solution, which is comparable to the performance of zeolite coatings synthesized by hydrothermal synthesis. The features are also briefly discussed, which make this route highly attractive from a good perspective. Image 1 ● The synthesis of MFI-type zeolite coatings by solid-conversion secondary growth route. ● Spray-coating was introduced to produce a continuous seed layer. ● Significant effect of the composition of synthesis mixture in solid-conversion method. ● MFI-type zeolite coatings are corrosion-resistant in severely corrosive medium. [ABSTRACT FROM AUTHOR]