(571e) Quantifying the Catalytic Effect of Calcium on Initiation during Cellulose Pyrolysis

Authors: 
Facas, G. G., University of Minnesota Twin Cities
Zhu, C., University of Minnesota Twin Cities
Neurock, M., University of Minnesota
Dauenhauer, P., University of Minnesota
During high temperature biomass pyrolysis, biopolymers undergo rapid decomposition to form hundreds of organic compounds which condense to form bio-oil and can be subsequently upgraded to fuel and chemicals. Inorganic metals naturally present in lignocellulosic biomass such as calcium and magnesium have been shown to catalyze pyrolysis chemistry[1]. However, little information is available that quantifies the catalytic behavior of these metals on pyrolysis chemistry. This work focuses on identifying the fundamental chemical mechanisms and kinetics involved in this catalytic chemistry. Using α-cyclodextrin as a cellulose surrogate[2] and a novel reactor system PHASR (Pulsed Heated Analysis of Solid Reactions)[3-4], time-resolved conversion data is obtained between 370 and 430 0C. To study the effect of calcium catalysis, varying concentrations of CaNO3 (0.4 to 2.0 wt%) were mixed with α-cyclodextrin to simulate calcium concentrations in lignocellulosic biomass[1]. Cellulose conversion exhibits first order like kinetic behavior among all temperatures and calcium concentrations. A catalyzed kinetic rate constant was extracted and exhibits similar energetics compared to a high-temperature non-catalyzed intra-chain scission regime determined in an earlier study[4].

References:

  1. Zhu, C.; Maduskar, S.; Paulsen A. D.; Dauenhauer, P. J., Alkaline-earth-metal-catalyzed thin film pyrolysis of cellulose. ChemCatChem, 2016, 8, 818-829.
  2. Mettler, M. S.; Mushrif, S. H.; Paulsen, A. D.; Javadekar, A. D.; Vlachos, D. G.; Dauenhauer, P. J., Revealing pyrolysis chemistry for biofuels production: Conversion of cellulose to furans and small oxygenates. Energy & Environmental Science 2012, 5, (1), 5414-5424.
  3. Krumm, C.; Pfaendtner, J.; Dauenhauer, P.J., Millisecond pulsed films unify the mechanisms of cellulose fragmentation. Chemistry of Materials 2016, 28, 3108-3114.
  4. Zhu, C.; Krumm, C.; Facas, G. G.; Neurock, M.; Dauenhauer, P.J., Energetics of cellulose glycosidic bond cleavage. Reaction Chemistry and Engineering 2017, 2, 201-214.