Sorbitol is a sugar alcohol derived from the cellulose portion of lignocellulosic biomass, and is commonly used as a sugar substitute. Sorbitol can be chemically upgraded into value added platform chemicals such as 1,2-hexanediol, 1,4-hexanediol and 1,6-hexanediol via a simultaneous hydrodeoxygenation (S-HDO). The hexanediols are 40-7,750 times more valuable than the initial cost of Sorbitol on a per mass basis. The S-HDO removes two vicinal hydroxyl groups by undergoing a deoxydehydration (DODH) to form a double bond which is then hydrogenated to a single bond1,2. The ReOx-Pd/CeO2 catalyst was determined to be the best catalyst for the S-HDO of sugar alcohols in the literature1. Sorbitol S-HDO was previously reported in literature at 160°C and 80bar H2 with a 72-hour reaction time while utilizing a 2wt% ReOx-Pd/CeO2 catalyst1. However, the temperature, pressure, and catalyst loading effects on conversion and selectivity of sorbitol S-HDO are unknown. To investigate these factor effects and explore milder conditions, a Taguchi design and a Box-Behnken response surface design of experiments were implemented. The designs tested temperatures ranging from 150-170°C, pressures of 5-10bar H2, and Re loadings of 2-4 Re wt%. The Taguchi design offers a significant reduction in the necessary experimental runs but only gives linear correlations3. The Box-Behnken response surface uses higher order terms to model the design space and gives insight into cofactor interactions but requires more experimental runs. The two designs were compared to see if the complexity of the design selected led to differing conclusions, and to elucidate optimal reaction conditions within the design space. The Box-Behnken model fit the data better than the Taguchi model, but both models suggested similar factor importance for the responses of conversion and selectivity to hexanediols. The models also predicted similar optimal conditions for sorbitol S-HDO.

Reaction condition optimization of sorbitol hydrodeoxygenation over a ReOx-Pd/CeO2 catalyst via design of experiments

ACS Fall 2021

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