Catalytic distillation for one-step cyclohexyl acetate production and cyclohexene-cyclohexane separation via esterification of cyclohexene with acetic acid over microfibrous-structured Nafion-SiO2/SS-fiber packings

Abstract

Catalytic distillation (CD) has received inviting interests due to the green chemical process with a unique integration of catalytic reaction and distillative separation. This approach opens a promising way towards one-step cyclohexyl acetate production and cyclohexene-cyclohexane separation via esterification of cyclohexene (cyclohexene-cyclohexane mixture as feed) with acetic acid in a CD column, which can overcome many of the drawbacks encountered in the conventional reaction/separation processes. We present a microfibrous-structured Nafion-SiO2/SS-fiber solid acid catalyst as CD packings and demonstrate its high efficiency and effectiveness for synthesizing cyclohexyl acetate and separating cyclohexene/cyclohexane mixture in one-step. The Nafion-SiO2/SS-fiber catalytic packings achieved as-expected catalytic properties with respect to stability, adequate acidic sites and high mass/heat transfer, and therefore worked efficiently and effectively in the titled CD system. The operation parameters, including reboiler duty, molar ratio of acetic acid to cyclohexene, reflux ratio, and weight hourly space velocity (WHSV), were optimized with the aid of the factorial design based on response surface methodology (RSM). High actual yield of cyclohexyl acetate (78.1%) and high recovery of cyclohexane (93.0%) with 94.3% of cyclohexane purity were achievable, while such microfibrous-structured Nafion catalyst was stable for at least 200 h consecutive batch runs.