Energy-Efficient Direct Cyclohexene to Cyclohexanol Process by Heat Pump Assisted Reactive Distillation

Abstract

Abstract Cyclohexanol is regarded as an important raw material to produce many useful chemicals such as hexanedioic acid, hexamethylenediamine, and caprolactam. However, it’s production usually leads to high energy consumption. Traditional technologies include three routes: oxidation of cyclohexane, hydrogenation of phenol and direct hydration of cyclohexene. Avoiding the risk of explosion and a low price of raw material, the direct hydration of cyclohexene route is selected in this paper. To enhance the energy efficiency, a novel heat-pump-assisted reactive distillation process (HPRD) is proposed and simulated through AspenPlus. The discharge compressor pressure is optimized to be 3.2 bar to minimize the cost. For purposes of comparison, two conventional processes, aqueous-phase-refluxed reactive distillation with a stripper (ARDS) and organic-phase-refluxed reactive distillation with a stripper (ORDS), are also simulated and optimized through sensitivity analysis. All these three processes are evaluated through energy and economic analysis. The results show that the ORDS process saves the total energy and annualized cost by 15% and 12%, respectively, compared with the ARDS process, while the heat-pump-assisted process realizes a significant energy saving of 65% and achieves 33% reduction in total annualized cost, demonstrating a high economic feasibility.