Analysis and Optimization of a Novel Coupling Process for Industrial Cresol Separation

Abstract

m-Cresol and p-cresol, important chemical intermediates, are widely used in medicine and pesticides. The mixture of m-cresol and p-cresol is easily produced in the industrial scale. However, it is very difficult to separate the mixture due to the boiling point. In this work, a new coupling process route combining complex crystallization and melt crystallization was proposed for the mixture separation. The key parameters in terms of crystallization temperature, solvent dosage, complexing agent dosage, initial purity of p-cresol, and crystallization time are investigated. The response surface methodology was employed to optimize the proposed process. The results show that the m-cresol and p-cresol mixture can be effectively separated, where the purity is >99% and the yields of m-cresol and p-cresol are over 63% and 55% respectively. In addition, recovery of solvents and complexing agents is achieved. The coupling route is proven to be a simple, environment-friendly, and sustainable process to separate industrial cresol. This study provided a reference for the isomerization separation process.

Online In Situ Real-Time Experimental Investigation of the Crystallization Characteristics and Kinetic Models during the Nucleation and Growth Process of Para-Xylene Suspension Crystallization

“…11 Since the three isomers of PX, m-xylene (MX), and o-xylene (OX) contained in mixed xylene have similar boiling points but vastly different melting points, the melting crystallization method that utilizes the melting point differences between different substances for crystallization separation has attracted people's attention. 12 For the preparation of high-purity organic matter, it takes multiple recrystallization operations to improve the crystal purity step by step, such as GTC company's CrystPX process, 13 BP company's BP process, 14 Sinopec's PX crystal separation process, 15 and so on. Nonetheless, the complexity of these multiple operations can lead to unstable product quality, limiting the widespread adoption of PX suspension crystallization devices and processes in industrial applications.…”

“…Para-xylene (PX) plays a vital role as a raw material in the polyester industry, and it serves as a vital connection between the chemical and refining sectors. − Currently, the primary method employed by the industry to obtain high-purity PX is to separate and purify PX from the mixed xylene raw material liquid . Since the three isomers of PX, m-xylene (MX), and o-xylene (OX) contained in mixed xylene have similar boiling points but vastly different melting points, the melting crystallization method that utilizes the melting point differences between different substances for crystallization separation has attracted people’s attention …”

Purification of p-Cresol, o-Cresol, m-Cresol, and 2,6-Xylenol from the Quaternary Mixture by Three-Phase Crystallization

“…The separation of 2,6-xylenol/cresol mixtures has been explored by adsorption using zeolites or ion-exchange resins, and crystallization using adductive agents . The separation of p-cresol/m-cresol mixtures has been studied by high-pressure crystallization, extractive crystallization using solvent, extractive distillation using reactive entrainer, alkylation using strong acid as catalyst, , adsorption using modified HZSM-pellets or zeolites, extraction using ionic liquid, − and cocrystallization through complex formation. − …”