(695h) Hydrodeoxygenation of Sorbitol to Monofunctional Fuel Precursors over Co/TiO2
Sorbitol APHDO of Co/TiO2 produced a 56% yield (on a carbon basis) to MFs at a moderate WHSV of 0.70 h-1. This is the highest yield reported from sorbitol in the literature. We estimate the Co catalyst is 50 to 1,000 times cheaper than previously reported precious metal catalysts. Increasing space time leads to excessive deoxygenation and therefore selectivity toward alkanes and COx while decreasing space time leads to higher oxygenates, including diols, oxygenated heterocycles, unidentified O3+ species. The MFs produced are mostly primary alcohols (37% at 0.70 h-1), secondary alcohols (32%), and heterocycles (23%). Ketones (7%) and aldehydes (<1%) are produced in much lower yields. 67% of the MFs are C5+ and would therefore be suitable for coupling. FTICR-MS shows that sorbitol/anhydrosorbitol species can oligomerize at lower contact times to form C9-C18 species which appear to break down to some degree at longer contact times to eventually form MFs. Overall, the product distribution vs. WHSV suggests that about one third of the fed carbon reacts through the retro-aldol route and overall 20% of the carbon is lost to C1 gases such as CO2 and methane. The need to suppress retro-aldol condensation and decarbonylation in sorbitol APHDO is a clear limitation for the production of C5+ MFs. In the present study, Co/TiO2 catalyst shows irreversible deactivation with TOS due to sintering and leaching of the Co. Overall, this work shows that Co/TiO2 can be used to produce monofunctional fuel precursors from sorbitol at high yields, but suffers from irreversible leaching and sintering due to chelation from highly-oxygenated species.
- ExxonMobil, 2017 Outlook for energy: A view to 2040. ExxonMobil: Irving, 2017.
- Kunkes, E. L.; Simonetti, D. A.; West, R. M.; Serrano-Ruiz, J. C.; Gärtner, C. A.; Dumesic, J. A., Catalytic conversion of biomass to monofunctional hydrocarbons and targeted liquid-fuel classes. Science 2008, 322 (5900), 417-421.
- Vilcocq, L.; Cabiac, A.; Especel, C.; Guillon, E.; Duprez, D., Transformation of sorbitol to biofuels by heterogeneous catalysis: Chemical and industrial considerations. Oil & Gas Science and TechnologyâRevue dâIFP Energies nouvelles 2013, 68 (5), 841-860.
- Li, N.; Huber, G. W., Aqueous-phase hydrodeoxygenation of sorbitol with Pt/SiO2âAl2O3: Identification of reaction intermediates. Journal of Catalysis 2010, 270 (1), 48-59.
- Lee, J.; Burt, S. P.; Carrero, C. A.; Alba-Rubio, A. C.; Ro, I.; OâNeill, B. J.; Kim, H. J.; Jackson, D. H.; Kuech, T. F.; Hermans, I.; Dumesic, J. A.; Huber, G. W., Stabilizing cobalt catalysts for aqueous-phase reactions by strong metal-support interaction. Journal of Catalysis 2015, 330, 19-27.
- Eagan, N. M.; Chada, J. P.; Wittrig, A. M.; Buchanan, J. S.; Dumesic, J. A.; Huber, G. W., Hydrodeoxygenation of Sorbitol to Monofunctional Fuel Precursors over Co/TiO2. Joule 2017, 1 (1), 178-199.