INVESTIGATION OF MECHANICAL PROPERTIES OF ZEOLITE-Y AND ZSM-5 CATALYSTS SYNTHESIZED FROM LOCALLY AVAILABLE CLAYS
CHAPTER ONE
INTRODUCTION
1.1 Background to The Study
Zeolites are micro-porous alumina-silicate minerals used for numerous commercial and domestic applications. These include applications in petroleum and petrochemical industries as catalysts, adsorbents and ion exchangers, nuclear industries for nuclear reprocessing, heating and refrigeration, detergents, construction as material additives, medicine, agriculture as a soil treatment, gemstones, as ion-exchange beds in domestic and commercial water purification and softening. The term Zeolite was originally coined in 1756 by Swedish mineralogist Axel Fredrik Cronstedt, who observed that upon rapidly heating the material stilbite, it produced large amounts of steam from water that has been adsorbed by the material. Base on this, he called the material zeolite, from the Greekzep, meaning “to boil” And lithos meaning “stone” (Cejka et al, 2007). Today, Zeolite-Y is used commercially as catalyst in petroleum refinery because of its high concentration of active acid sites, its high thermal stability and high size selectivity. Zeolite-Y is a synthetic analog to the mineral faujasite and crystallizes with cubic symmetry. It has crystal sizes in the approximate range of 0.2-0.5µm and pore diameter of 7.4À. It thermally decomposes at 793oC (Htay et al, 2008).