c) Periodicity
In applied catalysis, the catalyst reusability is the most important
after the catalytic performance. The reusability of the tow employed
catalysts was studied at the previously optimized reaction conditions,viz., at 130oC, OA/TMP molar ratio of 3:1,
catalyst dosage 3wt. % and reaction time of 20h. At these optimized
circumstances, any change in the catalytic behavior will be easily
detectable. Figure 6 illustrates the observed results during six
consecutive runs where the recorded catalytic activity of each run is
slightly less than the previous one. The decrease in catalytic activity
most probably attributed to the slight leaching of acidic protons or the
adsorption of reactant molecules on the active sites (Li, 2012). In
general, the yield of TMPTO is maintained at the level of 83.40% and
65% for IL1/SBA and IL2/SBA-15
referring that the catalysts are relatively stable during the reaction.