Production of DMC from CO₂ via Indirect Route: Technical–Economical–Environmental Assessment and Analysis

Abstract

Interest in dimethyl carbonate (DMC), a saleable chemical destination of CO 2, has grown significantly. DMC is an oxygenated octane-booster and a safer and nontoxic substitute of well-established methylating-carbonylating hazardous chemicals like dimethyl sulfate and phosgene. Considering the CO 2 routes to DMC, the one commercially promising converts CO 2 with ethylene oxide (EO) to ethylene carbonate (EC), which then reacts with excess methanol (MeOH) to DMC and ethylene glycol (EG). This indirect route (IR) apparently exhibits green chemistry attributes. It converts greenhouse gases (GHG) to valuables, such as EG, EC, and DMC. Apparently, it is not energy intensive; it has 100% atom economy without wastes. However, there is a massive energetic obstacle occluded in the separation of the azeotropic pair DMC–MeOH yet to be considered. This work assesses the technical, economical, and environmental IR flowsheet for CO 2 conversion to DMC. Assessment of entrainers for extractive distillation of DMC–MeOH was accomplished for EG versus methyl–isobutyl–ketone. Process design, energy consumption, and GHG emissions were assessed and showed that both alternatives are profitable but gave negative chemical sequestration indexes. Their GHG emissions through energy consumption and purges overcome the chemical conversion of CO 2 to DMC. The process alternative using EG as the entrainer exhibits higher profitability and better sustainability indexes.