Equilibrium conversions for the direct condensation of MeOH and EtOH with CO2 to give dimethyl- and diethylcarbonate respectively have been calculated over a range of experimentally relevant conditions. The validity of these calculations has been verified in both batch and continuous flow experiments over a heterogeneous CeO2 catalyst. Operating under optimized conditions of 140°C and 200 bar CO2, record productivities of 235 mmol/L·h DMC and 241 mmol/L·h DEC have been achieved using neat alcohol dissolved in a continuous flow of supercritical CO2. Using our thermodynamic model, we show that to achieve maximum product yield both dialkylcarbonates and water should be continuously removed from the reactor instead of the conventionally used strategy of removing water alone which is much less efficient. Catalyst stability rather than activity emerges as the prime limiting factor and should thus become the focus of future catalyst development.
- continuous flow processing
- direct synthesis of dialkyl carbonates
- supercritical fluids
ASJC Scopus subject areas
- Environmental Chemistry
- Chemical Engineering(all)
- Renewable Energy, Sustainability and the Environment