Pseudo-catalytic kinetics induced by electron withdrawal of Na ions for cellulose activation: A theoretical multiscale study

Abstract

Understanding the thermodynamic role of alkali ions in cellulose is important for the utilization of biomass as an energy source. However, the behavior of low-period alkali ions is insufficiently discussed in traditional catalyst models as they do not contain lone pairs and high-angular momentum electrons in their valence shells. In this study, the theoretical principles of pseudo catalytic behavior owing to the interaction between alkali ions and cellulose are explored in silico. By integrating reactive molecular dynamics and first-principles calculations, the proposed multiscale simulations indicate, for the first time, unconventional thermodynamics-based catalytic behavior owing to electron withdrawal. In cellulose pyrolysis in the presence of Na ionic bonds, the ions respond to the reaction kinetics solely through the modulation of molecular vibrational properties without utilizing electron and proton transfer. The thermodynamic properties resulting from such electron withdrawal were found to activate the low-temperature fuelization pathway of cellulose, accounting for the temperature-dependent regulation of its conversion to fuel. Our findings comprehensively reveal the role of Na ions, from the atomic Hamiltonian-level interactions between the ion cores and glucose to the overall pyrolysis process of cellulose.