Abstract
The pyrolysis of woody biomass, including the lignin component, is emerging as a potential technology for the production of renewable fuels and commodity chemicals. Here we describe the construction and implementation of an elementary chemical kinetic model for pyrolysis of the lignin model compound chroman and its reaction intermediate <em>ortho</em>-quinone methide (<em>o</em>-QM). The model is developed using both experimental and theoretical data, and represents a hybrid approach to kinetic modeling that has the potential to provide molecular level insight into reaction pathways and intermediates while accurately describing reaction rates and product formation. The kinetic model developed here can replicate all known aspects of chroman pyrolysis, and provides new information on elementary reaction steps. Chroman pyrolysis is found to proceed via an initial retro-Diels–Alder reaction to form <em>o</em>-QM + ethene (C<sub>2</sub>H<sub>4</sub>), followed by dissociation of <em>o</em>-QM to the C<sub>6</sub>H<sub>6</sub> isomers benzene and fulvene (+ CO). At temperatures of around 1000–1200 K and above fulvene rapidly isomerizes to benzene, where an activation energy of around 270 kJ mol<sup>-1</sup> is required to reproduce experimental observations. A new G3SX level energy surface for the isomerization of fulvene to benzene supports this result. Our modeling also suggests that thermal decomposition of fulvene may be important at around 950 K and above. This study demonstrates that theoretical protocols can provide a significant contribution to the development of kinetic models for biomass pyrolysis by elucidating reaction mechanisms, intermediates, and products, and also by supplying realistic rate coefficients and thermochemical properties.
Highlights
On the other hand in a coordination game, when hedging opportunities were more obvious, players recognized and used the hedging opportunity, but post-experiment surveys revealed that subjects adjusted their play in the coordination game because they thought others would recognize hedging opportunities. These results suggest that players may narrow bracket unless the benefits from broad bracketing are obvious to them, and that observing play consistent with narrow bracketing may be better explained by whether subjects are able to recognize that benefits of bracketing broadly exist, rather than that subjects’ mental costs of bracketing broadly are prohibitively high
Economic experiments often produce results not well explained by standard economic models
Such deviations in individual settings are in their own right interesting, but their relevance in games is not guaranteed until they are directly tested
Summary
A set of choices are bracketed together when the decision-maker takes into account the interaction of these choices, but ignores the effect of choices outside of this set (Read, Loewenstein and Rabin, 1999). Narrow bracketing is well documented in lottery choice experiments by Tversky and Kahneman (1981) and Rabin and Weizsacker (2009) Subjects in these experiments made paired lottery choices similar to that shown below: You face the following pair of concurrent decisions. If the representation effects in individual choice experiments of Tversky and Kahneman (1981) and Rabin and Weizsacker (2009) are relevant in strategic setting, playing multiple, payoff-relevant games at the same time may have different outcomes depending on whether individuals are able to integrate the lotteries induced by opponents’ strategies in the two games to fully understand the distribution of payoffs, and that presenting the “games” in Table 1 separately may result in treatment effects inconsistent with standard models of rationality used in economics. While the current experimental design does not vary the game form, one could hypothesize that there may be different representations of the Roommate’s Dilemma which either reduce or increase the cognitive cost of decision-making, potentially altering the results
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