Incorporating differential evolution (DE) optimization strategy to boost hydrogen and DME production rate through a membrane assisted single-step DME heat exchanger reactor

The present contribution aims to enhance dimethyl ether (DME) production rate as well as hydrogen as clean-burning fuels and versatile applications. In this regard, a thermally coupled membrane configuration (TCMDR), which is able to produce hydrogen and DME simultaneously, is proposed. Here, direct DME synthesis from syngas and cyclohexane dehydrogenation reaction are coupled and occur in the exothermic and endothermic compartments, respectively. The dehydrogenated product (hydrogen) is pushed through the wall of the third partition, which is a Pd/Ag membrane composite, in order to overcome the equilibrium constraints of dehydrogenation reaction. Moreover, the optimal operating conditions are sought by aid of differential evolution (DE) algorithm as a powerful optimization technique. During the optimization step, the sum of carbon monoxide and cyclohexane conversions along with the hydrogen mole fraction in the permeation side is considered as the objective function. Finally, the TCMDR behavior is examined based on the achievements during the optimization procedure and a one-dimensional steady-state heterogeneous model. The results show considerable DME enhancement in the TCMDR by 10.3% and 11.4% compared with the conventional direct DME synthesis reactor (CDR) and thermally coupled DME reactor (TCDR) arrangements and at the same time the amount of endothermic raw material drops about 120.3 kmol/h.

► Direct DME synthesis and cyclohexane dehydrogenation reaction are coupled.
► The hydrogen is pushed through the membrane to overcome the equilibrium.
► The optimal operating conditions are sought by aid of differential evolution algorithm.
► The objective function is sum of CO, H2 and cyclohexane conversions.
► The increase of production rate compared with the conventional and thermally coupled reactors are 10.3% and 11.4%.