Improvement in Ammonia, Hydrogen, and Methyl Formate Synthesis Process by Employing Multiobjective Optimization of a Novel Multifunctional Membrane Reactor

Abstract

This investigation analyzes the simultaneous production of hydrogen and ammonia as carbon-free energy carriers and methyl formate (MF) as a widely used chemical intermediate in a multifunctional membrane reactor (MFMR). The MFMR, based on Le Chatelier’s principle, has the advantage of changing the thermodynamic equilibrium by direct thermal coupling between ammonia synthesis and MF production and shifting the chemical equilibrium with the use of the Pd–Ag membrane. In the innovative configuration, the nitrogen conversion rate has been increased from 38.2 to 41.2% and the methanol conversion from 16.3 to 99.1%. Other benefits of the MFMR include providing the required energy for an endothermic reaction and eliminating a furnace and cooler in methanol dehydrogenation and ammonia synthesis reactors. Furthermore, it has been demonstrated that if the ammonia synthesis reaction is positioned at the center side of the MFMR, the nitrogen and methanol conversion are, respectively, 1.32 and 7.34% higher than when the reaction is located at the outer side of the MFMR. Likewise, the effect of operational process parameters such as inlet flow rates, inlet temperatures, and membrane thickness on the performance of each reaction has been studied. Utilizing multiobjective optimization (MOO), it has been observed that ammonia and MF production yields can reach 20.3 and 24.1%, respectively.