High silica mordenite samples (Si/Al molar ratios 38 and 60) were synthesized hydrothermally at 433 K with the template route
method using o-phenylenediamine and characterized with several techniques including XRD, FT-IR, TG/DTA, pyridine-FTIR and
N2 adsorption. The effects of Na2O/SiO2 ratio, Si/Al ratio, temperature, crystallization time and various templates on mordenite
crystallization as well as crystallite size that was smaller than 50 nm, irrespective of varying the parameters were thoroughly investigated.
The effect of alkali cations such as Na+ and K+ on mordenite crystallization and on thermal stability of the produced mordenite
was also investigated. Pyridine adsorption suggests an increase in Lewis acid sites particularly following hydrothermal
treatment at 120 C where at 160 C both Lewis and Bro¨nsted acid sites in addition to oxidation products, which are indicative
of the existence of dual acid–base sites, were exposed. Surface texturing of the produced samples were correlated with their thermal
analyses data. |
