(320m) Production of 2,6-Dimethylnaphthalene Using a Simultaneous Isomerization and Adsorption Based Reactive Adsorption Technique

2,6-Dimethylnaphthalene (DMN) is a starting material for the synthesis of enhanced properties polyester, e.g. polyethylene naphthalate (PEN). Large scale production of 2,6-DMN is currently one of the limitations obstructing the widespread utilization of the polymer since the process employs a complex synthesis route with a thermodynamic limitation of the maximum 2,6-DMN yield in the final isomerization step from 1,5- to 2,6-DMN, entailing the high cost of both 2,6-DMN and PEN. Recently, it was found that the liquid phase isomerization in toluene media can be carried out at significant lower temperatures than that of the solvent-free system, and the adsorptive separation of 2,6-DMN using toluene as a desorbent appeared applicable in a rejective system. Therefore, an attempt to simultaneously carry out the isomerization and the adsorption based on the reactive adsorption technique was made in this study. Both isomerization and adsorption over a selected adsorbent were individually studied before the reactive adsorption experiments. The results show that the isomerization-adsorption over a physically mixed bed of H-beta (catalyst) to NaY (adsorbent) is a temperature dependent process. Performing the experiment at high temperatures can lead the reaction to reach its equilibrium, but diminishes the separation due to the very fast in reaction kinetics. On the other hand, conducting the experiment at low temperatures entails a low conversion of 1,5-DMN and little separation of 2,6-DMN. These results indicate a narrow operating window for the production of 2,6-DMN for the reactive adsorption approach. Interestingly, at a particular temperature, the isomerization is backwardly driven from 2,6- to 1,6- and 1,5-DMN when the reaction is simultaneously conducted with the rejective system of 2,6-DMN. The result is also substantiated by the study on the feed flow rate effect at a fixed temperature and the calculated equilibrium constants.