Interfacial Catalysis in Biphasic Carboxylic Acid Esterification with a Nickel-Based Metallosurfactant

Andreas Toth, Silke Schnedl, Daniela Painer, Matthäus Siebenhofer, Susanne Lux

Research output: Contribution to journalArticlepeer-review

Abstract

A metallosurfactant catalyst was developed to address the requirements for the utilization of low-molecular-weight carboxylic acids from dilute effluents. The catalyst Ni(DBSA)2 combines transition-metal catalysis of nickel ions and surfactant catalysis of 4-dodecylbenzenesulfonic acid (4-DBSA). Requirements for the metallosurfactant catalyst are low water solubility, high catalytic activity in biphasic esterification, and self-assembling properties at the interface. Ni(DBSA)2 was tested for applicability in the interfacial catalysis of esterification of dilute acetic acid with the solvent 1-octanol and resulted in an octyl acetate yield of 31.3%. Under identical reaction conditions, Ni(DBSA)2 performed better than sulfuric acid with a yield of 1.7%. The limited catalytic performance of sulfuric acid is caused by the presence of sulfuric acid mainly in the aqueous phase. In contrast, Ni(DBSA)2 is dissolved in the solvent and assembles at the aqueous/solvent interface where the reaction takes place. Additionally, the metallosurfactant lowers the interfacial tension between 1-octanol and deionized water by up to 75%, thus enhancing mass transfer. Compared to catalysis with 4-DBSA in emulsion, the catalytic performance of Ni(DBSA)2 dropped by 62%, but this drawback is compensated by the complete suppression of emulsification. With Ni(DBSA)2, the development of a catalyst was achieved, which self-enhances its catalytic performance in the interfacial catalysis through increased mass transfer area due to its surfactant properties.
Original languageEnglish
Pages (from-to)18547-18553
JournalACS Sustainable Chemistry & Engineering
Volume7
Issue number22
DOIs
Publication statusPublished - 12 Oct 2019

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