Upcycling of Municipal Glass and Aluminum Wastes for Synthesis of Hierarchical ZSM‐5

Abstract

AbstractThe synthesis of MFI zeolite is explored through use of recycled aluminum (soda can tabs and aluminum foil) and silicon (crushed bottle glass) wastes, giving rise to highly crystalline ZSM‐5. The effects of impurities from the wastes on crystallinity, particle morphology, surface area, and porosity are studied (electron microscopy, X‐ray diffraction, N2 isotherms at 77 K), and highly crystalline microporousmesoporous MFI structure resulted. t‐plot and mesopore hysteresis trends showed that magnesium or chromium impurities in soda can tabs induce the formation of intracrystalline 2 nm sized supermicropores. Recycled aluminum transformed into pure aluminum hydroxide polymorphs (bayerite and gibbsite) for use with the synthesis gel. Glycerol is used as a green alternative to mineral base solutions to depolymerize powdered glass bottles to form the gel precursor to crystallization. The hydrothermal treatment of this gel with the aluminum foil dissolution, using tetra‐propylammonium bromide (TPABr) as directing agent, formed a hierarchical ZSM‐5 zeolite, in which ZSM‐5 zeolite nanocrystals are supported on an amorphous silico‐aluminate mesoporous material with a pore diameter centered at 4 nm. The upcycling of scrap Al and municipal glass to catalytic‐grade ZSM‐5 can potentially compete with existing processes and imparts positive social and environmental impacts.