Crystallization of Lithium Zeolites onto Foamed Geopolymers

Lithium-containing zeolites are receiving significant attention due to their intriguing properties in various industrial applications, mainly related to gas separation and catalyzed processes. This paper presents an in-depth exploration of a nucleation strategy aimed at producing porous ceramic monoliths enriched with lithium zeolites. The synthesis was obtained by means of a geopolymer gel conversion, carried out by submerging either sodium- or lithium-rich geopolymers in lithium hydroxide solutions and performing a hydrothermal treatment. A full factorial design of experiments (DoE) was adopted to investigate the effect of LiOH molarity, treatment temperature, and time on the zeolite content in the samples. The most abundant and recurring zeolites obtained were Li-ABW (ABW) and lithium edingtonite (EDI). Concerning the lithium/sodium-containing systems, the competing presence of sodium directed the nucleation towards faujasite as well, together with minor amounts of other zeolites. In contrast, in pure lithium treatment media, the samples showed just ABW and EDI as the only crystalline phases.