Isosorbide, a bicyclic C6 diol, has received attention for its utility in the production of sustainable, bio-derived polymers. Large-scale production of isosorbide from sorbitol requires homogenous corrosive acid such as sulfuric or hydrochloric acid, which create harmful waste byproducts and complicate separation. A heterogenous acid catalyst capable of producing isosorbide from sorbitol in high yield under mild conditions is desirable. Neat, liquid-phase dehydration of sorbitol was investigated over sulfated zirconia (SZ) solid acid catalysts produced via sol-gel synthesis. The catalyst preparation methodology allows for precise particle morphology and tunable catalytic activity. The S/Zr ratio (0.1-2.0) and calcination temperature (425-625 °C) were varied to better understand their effect on morphology, acidity, and resulting reactivity. The SZ catalyst synthesized with S/Zr ratio of 0.5 and calcined at 625 °C achieved isosorbide isolated yield of 74% under mild conditions without the need for high pressure reactor or the need to recover solvent. A simple solid-liquid separation step leads to the isolation of highly pure isosorbide; furthermore, investigation of postreaction catalyst led to devising an effective catalyst recycling and regeneration methodology. A detailed kinetic analysis and modeling at several temperatures provided a plausible mechanism, its prevailing rate constants, and activation parameters. An insightful correlation between turnover frequency (TOF) and acid site density will be described and the role of tuning acidity in effectively suppressing side reactions that lead to the formation of oligomeric humins.

Kinetics, mechanism, and structure-activity relationship of sorbitol cyclodehydration to isosorbide catalyzed by sulfated zirconia

Where thousands of chemistry professionals meet to share ideas and advance scientific and technical knowledge. Spring 2023 abstracts, posters, and presentations will launch at the end of March.

ACS Spring 2023

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.