ABSTRACT
Zeolites, Y, ZSM-11 and BETA, widely used in refineries and petrochemical processes, fine chemistry and environmental processes were subjected to an alkaline treatment of desilication, in order to generate mesoporosity in the structure. The process used consisted of treating samples with an aqueous solution of NaOH at 65 ° C for 30 minutes. An exchange with NH4Cl, to recover the acidity, followed by desorption in a N2 stream and subsequent calcination at 500 ° C was then performed.
The treated samples were evaluated by various techniques such as XRD, ICP, SEM, and surface area determination by BET method, specific external area, mesopore volume and distribution of pore size by the BJH method.
This treatment resulted in a mesoporous zeolitic materials phase hexagonal arrangement and defined pore size, coexisting with the remaining crystalline phase. The generation of mesopores would cause a decrease in the Si / Al ratio, accompanied by an increase of the surface area with respect to the starting material. The Si species are selectively extracted, although Al species are also removed. An increase in pore diameter and mesopore volume was also observed, with the microporous structure of the starting matrices being preserved.
Keywords
Zeolites; Mesoporosity; Characterization; Glycerol
