Vapor–liquid behavior of phenol and cumene in ternary and quaternary mixtures

BACKGROUND: Although phenol is a key intermediate in the plastics and polycarbonate industry, it is also a toxic component that requires removal from dilute aqueous streams, potentially by liquid–liquid extraction (LLX). For LLX, cumene is suggested as a solvent as it is already present in processes in the polycarbonate industry. For the recovery of cumene from phenol by distillation, knowledge on vapor–liquid equilibrium (VLE) behavior is important, in combination with how this is affected by other components possibly present as an impurity or explicitly added as a solvent. This was investigated in this work. RESULTS: The binary cumene–phenol system shows a tangent pinch in the binary VLE diagram. Addition of a range of impurities and solvents showed that hydrogen bond accepting compounds strongly improve the relative volatility of the mixture, whereas dodecane, not capable of forming hydrogen bonds, has a negative effect on the relative volatility. CONCLUSION: Addition of polar components with hydrogen bonding abilities, i.e. ketones or ethers, affected the relative volatility of cumene over phenol the most positively. Combining two types of components results in similar effects, and clear synergistic effects could not be shown based on current VLE measurements. Addition of an apolar component in combination with polar components with hydrogen abilities had only a minor effect on the relative volatility.