Submitted to: Applied Catalysis A: General
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/24/2019
Publication Date: 3/25/2019
Citation: Jackson, M.A., Price, N.P., Blackburn, J.A., Peterson, S.C., Kenar, J.A., Haasch, R., Chen, C. 2019. Partial hydrodeoxygenation of corn cob hydrolysate over palladium catalysts to produce 1-hydroxy-2-pentanone. Applied Catalysis A: General. 577:52-61. https://doi.org/10.1016/j.apcata.2019.03.019.
DOI: https://doi.org/10.1016/j.apcata.2019.03.019

Interpretive Summary: Cobs are 15% of the weight of harvested corn so they represent a substantial potential resource stream for biorefineries and income stream for corn growers. ARS researchers in Peoria, Illinois have developed a method to produce a unique industrial chemical using corn cobs collected during harvest. The cobs are simply treated with dilute sulfuric acid and the resultant carbohydrate mixture converted to hydroxypentanone using a thermochemical catalytic process. This compound possesses unique chemical functionality and has many potential industrial uses including as a polymer precursor and biofuel additive. Hydroxypentanone is currently produced using expensive, petroleum-based chemistries, and developing methods to produce it from corn cobs affords an opportunity to augment biorefinery profitability with an alternative, high value, non-fuel revenue stream while increasing the value of the corn producers waste byproduct.

Technical Abstract: Milled corn cobs were hydrolyzed with 50 mM H2SO4 resulting in a hydrolysate rich in solubilized pentose sugars and particulate aromatic oligomers from the hemicellulose portion of the corn cobs. Following centrifugation to remove the solids, the acidic supernatant was treated under hydrodeoxygenation conditions of 3.5-7 MPa H2 at 160 °C with supported Rh, Pt, and Pd catalysts. Supports examined were alumina, silica-alumina, and the zeolites ZSM-5 and Beta. All three metals supported on the zeolites were more effective in producing 1-hydroxy-2-pentanone (HPO) than they were when supported on the mesoporous aluminas. Ultimately, 2 wt% Pd/Beta was chosen for further study and development. The selectivity to HPO was 90% and the yield was 10-14% of the starting mass of cob. With repeated use of the catalyst, the selectivity was unchanged but the yield fell as decreased activity allowed pentose dehydration to furfural to increase. It was found that addition of La to the support decreased the loss of activity substantially. The catalysts were characterized by gas sorption analysis, powder XRD, XPS, STEM-EDS, and H2-TPR. The reaction mechanism was probed using 13C-xylose as substrate.