b) Effect of OA:TMP molar ratio
For reversible reactions, an excess of a reactant drives the foreword reaction generating more products to restore a new equilibrium point. In the case of catalytic reversible reactions, where the reactants must collide the catalyst active site on the same time, this concept is limited to a certain excess reactant concentration. The increase of a reactant concentration will dilute the other reactant and diminish the probability to meet each other on the catalyst surface. This research may confirm this concept where the catalytic performance was investigated over the molar ratio of OA: TMP range from 3:1 to 5:1 at fixed: temperature of 130oC, reaction time of 20h and catalyst dosage of 3 wt.%. Figure 5, shows the increase of total conversion with increase of OA/TMP molar ratio up to 4.5:1 to begin dramatically decrease with further increase of OA/TMP molar ratio. The same result was reported by Li et al (Li, 2012). It is noticeable that the increase of OA/TMP has a significant effect on the increase of the total conversion at the beginning and diminishes gradually till reaches the minimal increase at 4.5:1. This result runs in harmony with the previous concept.