Process Chemistry and Design Alternatives for Converting Dilute Acetic Acid to Esters in Reactive Distillation

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• 作者：Wan-Jen Hung ; I-Kuan Lai ; Yi-Wei Chen ; Shih-Bo Hung ; Hsiao-Ping Huang ; Ming-Jer Lee ; and Cheng-Ching Yu
• 刊名：Industrial & Engineering Chemistry Research
• 出版年：2006
• 出版时间：March 1, 2006
• 年：2006
• 卷：45
• 期：5
• 页码：1722 - 1733
• 全文大小：980K
• 年卷期：v.45,no.5(March 1, 2006)
• ISSN：1520-5045

文摘

This work explores the recovery of acetic acid aqueous solution with different acid concentrations. Instead ofseparating acid from water using azeotropic distillation, acetic acid is converted to acetate via esterification.Two questions then arise. First, what is a better choice of alcohol (e.g., ranging from methanol to pentanol,C₁-C₅) for the esterification? This is a solvent selection problem. Second, what is the more economicalprocess flowsheet (e.g., a stand-alone reactive distillation versus a pretreatment unit followed by a reactivedistillation)? For the solvent selection problem, an earlier study [Tang et al., AIChE J. 2005, 51, 1683-1699]has indicated that the esterifications using methanol or pentanol is much more economical as compared toother choices (e.g., ethanol, 2-propanol, or butanol). Quantitative analysis reveals that the production of methylacetate (from methanol and acetic acid) is not tolerant to acid concentration variation, and a very-high-purityacid feed is needed to achieve product specification. Thus, methanol is ruled out for esterification and pentanolis selected to convert acid to the ester. Next, a systematic design procedure is taken to design the processflowsheets and the total annual cost (TAC) is used to discriminate between different flowsheets, with andwithout pretreatment unit. A range of acetic acid concentration is explored, varying from 100 wt %, to 75 wt%, to 50 wt %, and then to 30 wt %. The TAC analysis shows that a stand-alone reactive distillation is moreeconomical than the flowsheet with a pretreatment unit.