Catalytic Synthesis of Diethyl Carbonate from Carbon Dioxide using Catalyst KI/EtONa with Propylene Oxide as Dehydration Agent and Process Optimization Based on Box-Behnken Design

Diethyl carbonate (DEC) was synthesized through catalytic conversion from carbon dioxide (CO₂) and ethanol. However, common challenges in synthesizing DEC from CO₂ have been high energy consumption, catalysts-dehydrating agent selection, and relatively complex reaction. In this study, propylene oxide (PO) was used as a dehydrating agent, and KI/Sodium ethoxide was employed as a catalyst, resulting in the highest yield of DEC. The synthesis was conducted in a stainless steel reactor under batch conditions, with an initial CO₂ pressure ranging from 20 to 40 bar, a reaction temperature between 130-190°C, and a reaction time of 1-5 hours. Product identification was conducted with gas chromatography analysis with FID detector. Besides kinetic study, optimizing the parameter process in DEC synthesis is necessary to find the highest yield of DEC because it is difficult to achieve optimum conditions using trial and error. So, this parameter process synthesis was also optimized with the Box-Bhenken Design (BBD) method to get optimal conditions and an equation to predict the yield of DEC. As confirmed with the BBD method, an initial pressure of CO₂ 40 bar, 190oC, and a 3-hour reaction were expected to perform optimized processing. By applying these optimized process parameters in experimental work, a DEC yield of up to 24.07% was obtained. This experimental result was relatively consistent with the findings of the simulation study, which achieved a yield of 24.3%.