A Novel Process Using Ion Exchange Resins for the Coproduction of Ethyl and Butyl Acetates

Before proposing an innovative process for the coproduction of ethyl and butyl acetates, the individual syntheses of ethyl acetate and butyl acetate by two different routes were first studied. These syntheses involved the reaction of ethanol or n-butanol with acetic acid or acetic anhydride in the presence of ion exchange resins: Amberlyst 15, Amberlyst 16, Amberlyst 36 and Dowex 50WX8. Kinetic and thermodynamic studies were performed with all resins. The lowest activation energy (Ea) value was obtained with Dowex 50WX8, which was identified as the best-performing resin, able to be reused at least in four runs without regeneration. The presence of water-azeotropes during the synthesis of ethyl acetate makes its purification difficult. A new strategy was adopted here, involving the use of ethanol and acetic anhydride as the starting material. In order to minimize acetic acid as co-product of this reaction, a novel two-step process for the coproduction of ethyl and butyl acetates was developed. The first step involves the production of ethyl acetate and its purification. Butyl acetate was produced in the second step: n-butanol was added to the mixture of acetic acid and the resin remaining after the first-step distillation. This process yields ethyl acetate and butyl acetate at high purity and shows an environmental benefit over the independent syntheses by green metrics calculation and life cycle assessment.

Alternative technology for the recovery of butyl acetate with low concentration:high capacity adsorbent and high efficiency adsorption

Industrial pharmaceutical wastewater usually contains butyl acetate(BA)with a concentration of 1 wt%-7 wt%,and the traditional method for BA recovery is distillation with high energy consumption.Adsorption method is developed to recover BA with low concentration for the high efficiency and low energy consumption.Medium polar polyacrylate resins with macroporous structure of 233.1 nm and average particle size of about 526.5μm are successfully synthesized by suspension polymerization and used for the BA adsorption and desorption.The maximum adsorption capacity reaches 171.1 mg g^(-1)with relative standard deviation(RSD)value of 0.2%,which is more than twice the results in the literature.The BA desorption rate is 97.0%at 100℃with RSD value of 0.4%,and the resins are beneficial to the reuse in the adsorption-desorption cycle.The adsorption thermodynamics and kinetics are investigated,and the BA adsorption is a spontaneous and endothermic process with the increase of disorder degree.This process is mainly contributed by physical absorption and agree well with Freundlich model and pseudo-first-order adsorption kinetic model.The adsorption method avoids boiling a large amount of wastewater and hopefully provides a novel alternative technology for the BA recovery.