Efficient separation of cresol isomers using azeotropic coupling pressure-swing distillation: From separation mechanism to process integration

In this work, an azeotropic coupling pressure-swing distillation separation technology was proposed for the first time to achieve efficient separation of near-boiling complex separation systems in coal chemical wastewater, namely cresol isomers (m-cresol and p-cresol), and achieves process intensification by introducing heat-integration technology. Vapor-liquid equilibrium data and relative volatility analysis were used to screen suitable entrainer. Quinoline is considered to be the most potential entrainer. Quantum chemical calculations were performed to reveal the separation mechanism of the entrainer and the system to be separated at the molecular scale to demonstrate the feasibility of quinoline as an entrainer for the separation of cresol isomers. Based on the Aspen Plus V11 platform, two processes of APSDP and HI-APSDP were built. HI-APSDP can save 31.31% in TAC, reduce 39.50% in total energy consumption and gas emissions, and increase 26.01% in thermodynamic efficiency compared with APSDP. HI-APSDP process is an economical, energy-saving, and environmentally friendly production scheme superior to the APSDP process, which will have essential development prospects in coal chemical wastewater (cresol isomers) treatment.