Effect of Hydrothermal Ph Values on the Morphology of Special Microspheres of Lignin-Based Porous Carbon and the Mechanism of Co2 Adsorption

Abstract

The present study reports the economic and sustainable syntheses of lignin-based porous carbon (LPC) for CO2 capture applications. The pH values of hydrothermal solution affected the polymerization and aromatization stages of spheroidization, with morphological changes from blocky to microsphere. In addition, the reliable mechanisms of CO2 adsorption have been proposed by combining experiments with Gaussian 16 simulations based on DFT theory. The electrostatic attraction of oxygen-containing functional groups and the diffusivity resistance of CO2 in the pores are key factors in the adsorption of CO2. ​Carboxyl groups have the strongest electrostatic attraction to CO2. LPC-pH 1 has the highest carboxyl group content with a CO2 adsorption capacity of up to 3.59mmol/g at 25℃, 1bar. While CO2 diffusion resistance became a main factor as the adsorption temperature increased. Innovative combination of quantum chemical calculations and microscopic properties provides a viable method for future control of lignin-based carbon formation.

Keywords: Lignin, hydrothermal, carbon microspheres, CO2 adsorption mechanism, DFT