The coupling separation process of ETBE production can be combined with the ethanol dehydration to save energy consumption. A new idea of introducing the dilute ethanol feedstock made from biomass material into the coupling separation process was proposed to enhance the sustainability of ETBE production. The ethanol concentrate is optimized in terms of minimizing the cost of energy consumption and maximizing the gross annual profit (GAP), respectively. The GAP is discussed at different prices of dilute ethanol feedstock and compared with those of conventional ETBE production process and process based on reactive distillation (RD). Meanwhile, the impact of ethanol-to-olefin ratio and conversion of isobutene on the optimal mass fraction is also explored. The result shows that the minimum feasible mass fraction of ethanol concentration is optimal when minimizing the energy consumption cost. The ethanol-to-olefin ratio and conversion of isobutene would affect the optimal mass fraction by affecting the minimum feasible mass fraction. Besides, to make the GAP maximum, the optimal mass fraction of ethanol concentration would take minimum or maximum feasible mass fraction at different prices of dilute ethanol feedstock. And the coupling separation process would have economic advantages compared to conventional ETBE process and RD-based process to some extent when the price of dilute ethanol feedstock is less than 7.372 €/t and the optimal mass fraction of ethanol concentration is 95 wt% in this case.
