Novel eco-efficient process for dimethyl carbonate production by indirect alcoholysis of urea

Dimethyl carbonate (DMC) is a valuable eco-friendly compound which can be sustainable produced from CO2. Its rapid increase in demand is driven by the fast growth of its wide-ranging end-use industries (e.g. polycarbonates, solvent, pharmaceutical, and the lithium-ion battery industries). DMC can be produced in different ways, but the indirect alcoholysis of urea with ethylene- or propylene glycol is a very promising route. The trans-esterification of the ethylene- or propylene carbonate with methanol, leading to DMC, plays a key role in the energy efficiency of the process, being the main hurdle when it is performed using an excess of methanol due to the DMC-methanol azeotrope that requires expensive separation steps. This work proposes a new process in which the trans-esterification reaction takes place at an excess of propylene carbonate instead of methanol, such that the costly separation of DMC-methanol azeotrope is avoided and high purity DMC (>99.8% wt) can be produced. The newly proposed process is optimally designed. After heat integration, the energy requirement is only 2.64 kW h/kg DMC, which is about 35% lower than best reported figure for the classic process. The dynamics and control of the new process is also provided, and the stability of the process is proven for production changes of ±10% from the nominal rate of 32 ktpy DMC.