Role of acid sites and selectivity correlation in solvent free liquid phase dehydration of sorbitol to isosorbide

Aasif A. Dabbawala, Dinesh K. Mishra, George W. Huber, Jin Soo Hwang

    Research output: Contribution to journalArticlepeer-review

    73 Scopus citations

    Abstract

    A number of Brönsted acids (methanesulfonic acid, p-toluene sulfonic acid, triflic acid, sulfamic acid, citric acid, NaHSO4, and boric acid) and Lewis acids (metal sulfate/triflates) were employed in solvent free dehydration of sorbitol and their influence on anhydroalcohols selectivity has been investigated. The outcome indicated that all the acid catalysts produced first mono-dehydrated product sorbitan followed by second dehydration of 1,4-sorbitan to isosorbide. However, the formation and yield isosorbide were found to depend on the nature of acid sites and their acidic strength. The Brönsted acids are more efficient to convert sorbitol to isosorbide than Lewis acids. The Brönsted acids having lower pKa value (i.e. strong acid) exhibited high catalytic activity as well as yield of isosorbide. In the case of Lewis acids, the catalytic activity and selectivity were radically depended on which metal used and their stability during the reaction. The water formed during reaction induced Brönsted acidity on Lewis acid metal site. The Lewis-assisted Brönsted acid site enabled high yield of isosorbide up to 70% at moderate temperature (160°C).

    Original languageBritish English
    Pages (from-to)252-261
    Number of pages10
    JournalApplied Catalysis A: General
    Volume492
    Issue number1
    DOIs
    StatePublished - 25 Feb 2015

    Keywords

    • Brönsted acid
    • Dehydration
    • Lewis acid
    • Selectivity
    • Sorbitol

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