MEL Zeolites: Synthesis, Properties, and CatalyticApplications

The review provides an analysis of the synthesis design features and the acidic and catalytic properties of MEL-type zeolites. Practicable methods for MEL zeolite synthesis are discussed, including one-step and two-step implementations of hydrothermal crystallization, crystal seed assisted synthesis, dual template synthesis, and vapor-phase crystallization to obtain nanocrystalline zeolites as isolated nanocrystals or binderless pellets. The study also provides an overview of methods for targeted control of the phase purity, chemical composition, crystal morphology/size, and acidic properties of MEL zeolite. Relationships are demonstrated between the MEL synthesis conditions and the catalytic properties of these zeolites in alkylation and disproportionation of aromatic compounds, oligomerization of lower olefins, oxidation of glycerol, amination of isobutylene, and conversion of lower alcohols.