Coupling exothermic and endothermic reactions—Application to combined aniline production/methyl-cyclohexane dehydrogenation

The scope of this study is to emphasize the possibility and benefits of direct coupling of exothermic and endothermic reactions. Simultaneous production of aniline by exothermic nitrobenzene hydrogenation and endothermic dehydrogenation of methyl-cyclohexane to toluene is investigated. Instead of multitubular reactor, the reaction is carried out in an adiabatic reactor eliminating the requirement of complex setup of the hydrogenation reactor. Additionally, large amount of hydrogen needed to avoid reaction runaway is no longer needed. Nonlinear analysis of reactor–separation–recycle shows difficulty in controlling integrated plants where unreacted reactant is recycled. Details of the plant design, obtained by Aspen Plus simulation, are given. The new integrated system is feasible with the benefits of simple reactor and reduce hydrogen requirement. Economic analysis shows that the total annual cost of coupled system is reduced by 20%. The results obtained here are also applicable to other chemical processes of practical relevance.