CO₂-to-Carbonates via Reaction–Separation Coupling: Pilot Performance of Continuous DMC/DPC

This study develops and demonstrates integrated pilot plants for the continuous production of dimethyl carbonate (DMC) and diphenyl carbonate (DPC) as part of a carbon capture and utilization (CCU) strategy. DMC was synthesized from urea (derived from CO₂ + NH₃) and methanol over a zirconium-based catalyst. Across three campaigns totaling 211 h, the unit produced 570.5 kg of DMC, corresponding to an overall yield of 85.9% relative to the 663.9 kg theoretical maximum from 442.3 kg of urea. The product reached 99.93% purity, and electrolyte testing showed no statistically significant differences versus commercial battery-grade DMC. DPC was obtained via transesterification of phenol with DMC using a reactor–distillation configuration that enables in-situ removal of methanol. Over ~ 200 h of continuous operation, phenol conversion was ~ 100% and 65.8 kg of DPC were collected, equal to an overall yield of 32.1% versus the 204.98 kg theoretical limit. Yield shortfalls were attributed to hold-up of intermediates (e.g., phenyl methyl carbonate) and high-boiling residues within equipment. Both trains exhibited stable operability without catalyst bed plugging, and product specifications were consistently met. These results validate the technical feasibility of CCU-based carbonate ester production and identify clear levers—enhanced methanol removal, additional reaction stages, and tighter reaction–separation coupling—for yield intensification and scale-up.