Evaluating the direct CO₂to diethyl carbonate (DEC) process: Rigorous simulation, techno-economical and environmental evaluation

In this work, the plant-wide process to produce diethyl carbonate (DEC) from the direct reaction of CO2 with ethanol, which uses 2-cyanopyridine (2-CP) as an in situ dehydrating agent, is proposed for the first time. Rigorous design, optimization, ability in carbon reduction, techno-economic and feasibility analyses are all performed in this work. The process consists of two sections. The first one is the main section, in which DEC is generated, along with the removal of water using 2-CP to form 2-picolinamide (2-PA). The second one is the regeneration section, where 2-CP is converted back from 2-PA and recycled. Using simulated annealing method, the optimized CO2 reduction rate in the main section is 0.237 (Ton CO2/Ton DEC generated) on an annual basis. We identify that when the regeneration section is operated with a molar ratio of mesitylene to 2-PA being less than 2.05, the overall process can be in net CO2 reduction. Under the constraint of 90 % regeneration of 2-CP as reported in available literature, the produced DEC can match the current market price range under 15 % internal rate of return (IRR), if 2-CP can be obtained with a price lower than 2.56 USD/kg (corresponding to DEC price of 1.10 USD/kg and ethanol price of 0.37 USD/kg) to 6.09 USD/kg (corresponding to DEC price of 1.90 USD/kg and ethanol price of 0.56 USD/kg).