Process intensification in the continuous dehydrogenation of methylcyclohexane to toluene

Abstract

The toluene/methylcyclohexane cycle is a safe and practical Liquid Organic Hydrogen Carrier (LOHC) for the storage of hydrogen. Nevertheless, the dehydrogenation reaction of methylcyclohexane (MCH) should be improved to assure a total selectivity to toluene (TOL), avoiding the subproducts formation. In this research, a millireactor with channel internal diameter in the range of milimeters has been tested and evaluated in the dehydrogenation of MCH to TOL. The millireactor configuration confers it some features and advantages compared to fixed-bed reactors, e.g., better mass and energy transfer and increased performance (10–20 %). To verify these advantages, a comparison between conventional fixed bed (9 mm i.d.) and millireactor is carried out. Thanks to its configuration, the millireactor could control effectively the heat generated by the reactions to avoid hot-spot formation and the sintering of the catalyst. The results obtained demonstrate that the catalysts activity in the reaction is improved with the application of the millireactor respect the fixed-bed ones and neither catalyst sintering, nor pressure drop was appreciated during the catalytic tests. At the best reaction conditions, Tecnalia´s millireactor converses continuously up to 99 % of MCH to TOL with 100 % selectivity at atmospheric pressure, showing the huge potential of the millireactor concept.