title: Recovery of acetic acid from dilute aqueous solutions using catalytic dehydrative esterification with ethanol.
abstract: We have developed a direct esterification of aqueous acetic acid with ethanol (molar ratio=1:1) catalyzed by polystyrene-supported or homogeneous sulfonic acids toward the recovery of acetic acid from wastewater in chemical plants. The equilibrium yield was significantly increased by the addition of toluene, which had a high ability to extract ethyl acetate from the aqueous phase. It was shown that low-loading and alkylated polystyrene-supported sulfonic acid efficiently accelerated the reaction. These results suggest that the construction of hydrophobic reaction environments in water was critical in improving the chemical yield. Addition of inorganic salts was also effective for the reaction under not only biphasic conditions (toluene-water) but also toluene-free conditions, because the mutual solubility of ethyl acetate and water was suppressed by the salting-out effect. Among the tested salts, CaCl(2) was found to be the most suitable for this reaction system.
authors.affiliation: SHOWA DENKO K.K., 1-13-9, ShibaDaimon, Tokyo 105-8518, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Yagyu
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Ohishi
authors.forename: Takeshi
authors.initials: T
authors.lastname: Igarashi
authors.forename: Yoshikuni
authors.initials: Y
authors.lastname: Okumura
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Nakajo
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Mori
authors.forename: Shū
authors.initials: S
authors.lastname: Kobayashi
mesh_terms: D019342:Acetic Acid / Q000032:analysis / Q000737:chemistry*; D002384:Catalysis; D004951:Esterification; D000431:Ethanol / Q000737:chemistry*; D014865:Waste Disposal, Fluid / Q000379:methods; D062065:Wastewater / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000737:chemistry*
chemical_list: D019342:Acetic Acid; D000431:Ethanol; D062065:Wastewater; D014874:Water Pollutants, Chemical