A pore-structure dependent kinetic adsorption model for consideration in char conversion – Adsorption kinetics of CO2 on biomass chars. (15th February 2021) - Wedler, Carsten
Highlights: Kinetic adsorption model as a function of time, temperature, and pressure. Time-resolved mass transfer coefficients and effective diffusion coefficients. Derivative with regard to time leads to adsorption flow rates. Model considers pore size distribution from NLDFT calculations. Abstract: This study presents a pore-structure dependent kinetic adsorption (PSK) model to describe experimentally observed adsorption processes. The model describes loadings and adsorption kinetics as a function of time, pressure and temperature, considering pore size distributions derived from non-local density functional theory (NLDFT) calculations. Time-resolved mass transfer coefficients, effective diffusion coefficients and adsorption flow rates can be derived from the model. For the integration of mass transfer or effective diffusion coefficients into carbon conversion models, the time-resolved description is more meaningful than an averaged coefficient from the established linear driving force model or the Fickian diffusion models. Using the PSK model, adsorption effects for different pore regimes can be calculated separately, which helps to understand the occurring diffusion phenomena. The PSK model has been validated with data for CO2 adsorption on two different biomass chars at temperatures from (298.15 to 398.15 K) and pressures from (46 to 540) kPa.