Selection of mixed solvent for crude caprolactam extraction

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F61989100%3A27710%2F25%3A10259238" target="_blank" >RIV/61989100:27710/25:10259238 - isvavai.cz</a>

Výsledek na webu

<a href="https://www.sciencedirect.com/science/article/pii/S1383586625003600?via%3Dihub" target="_blank" >https://www.sciencedirect.com/science/article/pii/S1383586625003600?via%3Dihub</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1016/j.seppur.2025.131763" target="_blank" >10.1016/j.seppur.2025.131763</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Selection of mixed solvent for crude caprolactam extraction

Popis výsledku v původním jazyce

Most of the world&apos;s caprolactam production involves synthesizing caprolactam from cyclohexanone via the Beckmann rearrangement. Due to the presence of both polar and nonpolar impurities in crude caprolactam, purification traditionally includes forward extraction with a nonpolar solvent, such as trichloroethylene, followed by back-extraction with water and then multistage distillation. This study investigates mixed solvents containing 1-octanol or 1-heptanol combined with cyclohexane or n-heptane as safer, non-carcinogenic alternatives to trichloroethylene in caprolactam extraction. Cyclohexane and n-heptane were selected to adjust the solubility of the alcohols in the aqueous phase. Optimal alcohol concentrations in these mixed solvents were estimated through modeling based on Hansen solubility parameters and experimentally validated using a real crude caprolactam sample (70 wt% caprolactam in water). A 40 wt% 1-octanol in heptane mixture demonstrated a caprolactam distribution coefficient closely matching that of trichloroethylene. Liquid-liquid equilibrium data and key physical properties influencing mass transport (density, viscosity, and interfacial tension) for the chosen mixed solvents were experimentally determined and used to design Karr extraction columns for both forward and back-extraction processes. Literature correlations were applied to predict hydraulic characteristics, including Sauter drop diameter and dispersed phase hold-up. The model was further validated through performance trials with an actual extraction unit using trichloroethylene in caprolactam refining. A mixture of 60 wt% 1-octanol in cyclohexane was identified as optimal, offering a balance between column height, maximum caprolactam content in extract and mixed solvent consumption.

Název v anglickém jazyce

Selection of mixed solvent for crude caprolactam extraction

Popis výsledku anglicky

Most of the world&apos;s caprolactam production involves synthesizing caprolactam from cyclohexanone via the Beckmann rearrangement. Due to the presence of both polar and nonpolar impurities in crude caprolactam, purification traditionally includes forward extraction with a nonpolar solvent, such as trichloroethylene, followed by back-extraction with water and then multistage distillation. This study investigates mixed solvents containing 1-octanol or 1-heptanol combined with cyclohexane or n-heptane as safer, non-carcinogenic alternatives to trichloroethylene in caprolactam extraction. Cyclohexane and n-heptane were selected to adjust the solubility of the alcohols in the aqueous phase. Optimal alcohol concentrations in these mixed solvents were estimated through modeling based on Hansen solubility parameters and experimentally validated using a real crude caprolactam sample (70 wt% caprolactam in water). A 40 wt% 1-octanol in heptane mixture demonstrated a caprolactam distribution coefficient closely matching that of trichloroethylene. Liquid-liquid equilibrium data and key physical properties influencing mass transport (density, viscosity, and interfacial tension) for the chosen mixed solvents were experimentally determined and used to design Karr extraction columns for both forward and back-extraction processes. Literature correlations were applied to predict hydraulic characteristics, including Sauter drop diameter and dispersed phase hold-up. The model was further validated through performance trials with an actual extraction unit using trichloroethylene in caprolactam refining. A mixture of 60 wt% 1-octanol in cyclohexane was identified as optimal, offering a balance between column height, maximum caprolactam content in extract and mixed solvent consumption.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

20400 - Chemical engineering

Projekt

<a href="/cs/project/FV40040" target="_blank" >FV40040: Kontinuální rafinace kaprolaktamu</a><br>

Návaznosti

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Rok uplatnění

2025

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Separation and Purification Technology

ISSN

1383-5866

e-ISSN

1873-3794

Svazek periodika

362

Číslo periodika v rámci svazku

2

Stát vydavatele periodika

NL - Nizozemsko

Počet stran výsledku

10

Strana od-do

131763

Kód UT WoS článku

001420792200001

EID výsledku v databázi Scopus

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