IMPROVING TEXTURAL PROPERTIES OF EXPANDED PERLITE FROM NON-POROUS TO MICRO- AND MESOPOROUS MATERIALS

CORREGIDOR, PABLO; ACOSTA, DELICIA; DESTÉFANIS, HUGO

DF-Mexico

Congreso; XXII International Materials Research Congress IMCR 2013; 2013

Sociedad Mexicana de Materiales

ZSM-5 zeolite, a composite ZSM-5/MCM-41 material and Analcime molecular sieve were obtained by hydrothermal treatment of a non-porous Expanded Perlite. ZSM-5 has been prepared by a free-organic template synthesis, using a commercial ZSM-5 as crystallization seed. The crystallization field evaluated for the preparation was xSiO2/Al2O3/8Na2O/yH2O (x=20-40 and y=1000-1800). The presence of peaks corresponding to (101), (020), (501), (151) and (303) diffraction planes in the XRD patterns confirms the generation of MFI framework. FTIR reveals an asymmetric stretching due to D5R structure at 545 cm-1. An Analcime zeolite phase was obtained at high pH values during the synthesis of ZSM-5. A partial hydrolysis of the prepared zeolite with a 2.5 mol/L NaOH solution has been performed, followed by a second hydrothermal treatment where secondary units are assembly around cetyltrimethylammonium cations aggregates, used as templating agents. The XRD diffraction pattern shows three diffraction peaks at low angle diffraction range due to the (100), (110) and (200) crystal faces of micro-mesoporous ZSM-5/MCM-41 composite molecular sieves [1,2], respectively, while maintaining the characteristics peaks of ZSM-5 zeolite. Compared with ZSM-5 obtained from Perlite, the BET surface area and pore volume of ZSM-5/MCM-41 were both higher and there was vastly improved diffusion in the pores. SEM images confirm the change of a coffin-shaped well defined ZSM-5 molecular sieve to small sphere-like ZSM-5/MCM-41 nanoparticles. TEM images exhibit 2D-ordered hexagonal arrays of mesopores with average pore size of 4 nm which is similar to that previously reported [3]. These results indicate that porosity of low cost Expanded Perlite can be improve by controlling the synthesis, thus to improve the preparation of ZSM-5, an Analcime phase and a composite micro-mesoporous ZSM-5/MCM-41 molecular sieves.