(147b) Reactant Conversion and Product Speciation of Carbohydrate Model-Compound Pyrolysis Using a Novel Flow Reactor

Reactant Conversion and Product Speciation of Carbohydrate Model-Compound Pyrolysis Using a Novel Flow Reactor

Patrick J. Fahey, Vikram Seshadri, Xinglian Geng, and Phillip R. Westmoreland*

North Carolina State University, Raleigh, NC 27695

The model compounds 1,2-propanediol, 1,3-propanediol, 1,2,3-propanetriol, hydroxypropanone, and acetaldehyde diethyl acetal were pyrolyzed neat and as methanol solutions in a pulse-injected tube-furnace reactor. Reaction products were analyzed directly by comprehensive, two-dimensional gas chromatography time-of-flight mass spectrometry (GCxGC-TOFMS). For example, pyrolysis of 1,3-propanediol at 500°C produced 90 identified peaks.

We experimented with molecules smaller than glucose to understand better the pyrolysis reaction networks of glucose-based carbohydrates. Cellulose has a complicated pyrolysis reaction network that researchers have tried to understand through experimenting with monosaccharide, disaccharide, and small-oligosaccharide pyrolyses.^1,2  Here, using molecules smaller than glucose provided two benefits not possible with using entire monomers or dimers. First, smaller molecules isolate specific sequences of functional groups, which reduces the number of possible side reactions and products. Thus, smaller molecules simplified the chemical analysis of the reaction-product mixture and the construction of reaction pathways.³ Second, smaller molecules allow computational-quantum-chemistry simulations to execute faster with the same level of theory. Thus, smaller molecules allow deeper analyses of the specific reaction mechanisms in their hypothesized pyrolysis reaction networks.⁴

References

1. Pushkaraj R. Patwardhhan, Justinus A. Satrio, Robert C. Brown, Brent H. Shanks, “Product distribution from fast pyrolysis of glucose-based carbohydrates,” Journal of Analytical and Applied Pyrolysis, 86 (2009) 323-330.
2. Edward B. Sanders, Alan I. Goldsmith, Jeffrey I. Seeman, “A model that distinguishes the pyrolysis of D-glucose, D-fructose, and sucrose from that of cellulose. Application to the understanding of cigarette smoke formation,” Journal of Analytical and Applied Pyrolysis 66 (2003) 29-50.
3. John B. Paine III, Yezdi B. Pithawalla, John D. Naworal, Charles E. Thomas Jr. “Carbohydrate pyrolysis mechanisms from isotopic labeling Part 1. The pyrolysis of glycerin: Discovery of competing fragmentation mechanisms affording acetaldehyde and formaldehyde and the implications for carbohydrate pyrolysis,” Journal of Analytical and Applied Pyrolysis 80 (2007) 297-311.
4. Vikram Seshadri and Phillip R. Westmoreland, “Concerted reactions and mechanism of glucose pyrolysis and implications for cellulose kinetics,” Journal of Physical Chemistry A, 116 (2012) 11997-12013.

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Contact Information

Patrick J. Fahey          

pjfahey@ncsu.edu

Department of Chemical & Biomolecular Engineering

North Carolina State University

Box 7905

Raleigh, NC 27695-7905

Vikram Seshadri         

vseshad@ncsu.edu

Department of Chemical & Biomolecular Engineering

North Carolina State University

Box 7905

Raleigh, NC 27695-7905

Xinglian Geng

xgeng@ncsu.edu

Department of Chemical & Biomolecular Engineering

North Carolina State University

Box 7905

Raleigh, NC 27695-7905

Phillip R. Westmoreland*       

prwestmo@ncsu.edu

Professor, Department of Chemical & Biomolecular Engineering

Executive Director, Institute for Computational Science and Engineering

North Carolina State University

Box 7905

Raleigh, NC 27695-7905

*To whom correspondence should be addressed.