Process Overview

Assessment of PET Depolymerization Processes for Circular Economy. 2. Process Design Options and Process Modeling Evaluation for Methanolysis, Glycolysis, and Hydrolysis

“…The target NaCl concentration we use for electrolysis is 24.6 wt % NaCl, which is consistent with an example membrane-type electrolysis mass balance demonstrated by O’Brien et al which we use as the basis for our electrolysis design. Brine concentrating processes commonly use a heat-integrated evaporation design that uses multiple evaporation stages where the pressure of the stages is set such that the condensing vapor of one stage can supply heat to another stage.…”

“…We assume that the concentration of the caustic feed is 32 wt %, which is a commonly produced concentration from membrane electrolysis. 28 We assume that the caustic rate is 110% of the stoichiometric rate to fully react PET. This provides approximately 0.5 kg of NaOH per kg of PET as indicated by Crippa and Morico.…”

“…We use the Handbook of Chlor-Alkali Technology as a reference to obtain typical operating conditions for state-of-the-art plants producing NaOH. 28 We describe this section in more detail in Section S5.3 of the Supporting Information. Importantly, the electricity requirement for the electrolyzer is ∼3326 kJ/kg of feed.…”

“…The conversion of NaCl to caustic and chlorine products is referred to as the chlor-alkali process and is well-known in industry. We use the Handbook of Chlor-Alkali Technology as a reference to obtain typical operating conditions for state-of-the-art plants producing NaOH . We describe this section in more detail in Section S5.3 of the Supporting Information.…”