The optimal operating conditions of a thermally double coupled, dual membrane reactor for simultaneous methanol synthesis, methanol dehydration and methyl cyclohexane dehydrogenation

• A thermally double coupled dual membrane reactor is proposed as an alternative configuration.
• Simultaneous methanol synthesis, methanol dehydration and methyl cyclohexane dehydrogenation occur in this configuration.
• The operating conditions are optimized via DE method.
• Methanol and DME production rate enhances about 10.9%, 19.5% respectively.
• Hydrogen and toluene are also produced in this configuration.

In this study, the concept of thermally double coupled reactor is proposed as an alternative configuration to mix the energy efficient concept of coupling two exothermic with one endothermic reaction. In this multi-tubular fixed bed reactor, methanol synthesis and methanol dehydration, as two exothermic reactions occur in the inner and outer tubes while the methyl cyclohexane dehydrogenation, as an endothermic reaction takes place in the middle tube. Two water permselective membranes are also applied in the inner and outer tubes to remove water from both exothermic sides. Extraction of water as one of the main byproducts in the DME (dimethyl ether) and methanol synthesis processes increases the production rate and the catalyst life time. In this configuration, the operating conditions are optimized using a differential evolution method in order to maximize the outlet methanol and DME mole fractions of the inner and outer exothermic sides respectively. Then the optimized results of the thermally double couple dual membrane reactor are compared with the optimized thermally double couple reactor and the ones in conventional methanol and DME synthesis reactors. This comparison shows the superiority of this configuration to the conventional ones owing to the enhancement of methanol and DME mole fractions (10.9% and 19.5% increase compared with conventional ones respectively). Hydrogen and toluene, as two valuable products, are also produced in a favorable mode.