AUTHOR=Hilpmann Gerd , Kurzhals Pascal , Reuter Tom , Ayubi Mick Miro 

TITLE=Reaction Kinetics of One-Pot Xylan Conversion to Xylitol via Precious Metal Catalyst

JOURNAL=Frontiers in Chemical Engineering

VOLUME=Volume 2 - 2020

YEAR=2020

URL=https://www.frontiersin.org/journals/chemical-engineering/articles/10.3389/fceng.2020.600936

DOI=10.3389/fceng.2020.600936

ISSN=2673-2718

ABSTRACT=The hydrolytic hydrogenation of xylan to xylitol by a one-pot process was studied en detail in a batch reactor. The reaction was catalyzed by a combination of dilute sulfuric acid and precious metal Ru on carbon powder. Process parameters were varied between 120 – 150 °C, while maintaining constant hydrogen pressure at 20 bar and acid concentration equivalent of pH 2. The xylan solution consisted of 1 wt.-% beechwood powder (Carl Roth, > 90%) in deionized water. Sulfuric acid was added to the solution until pH 2 was reached, then the 0.3 wt.-% catalyst powder (5 % Ru on Act. C) was added and the solution was put into the batch reactor.
The first approach of kinetic modelling began with conventional 1st-order kinetics and compared this to a more complex model based on Langmuir-Hinshelwood kinetics. The xylan and xylitol data reached a good fit. However, the modelling results also showed that the rate-limiting step of xylose-formation was still not represented in a satisfactory manner. Therefore, the model was adapted and developed further. The advanced model finally showed a good fit the intermediate product xylose and the target product xylitol. The overall modelling methods and results are presented and discussed.