A modified grain size distributed model for kinetic study of non‐catalytic gas‐solid reactions in presence of solid structural changes

Abstract

This study investigated the carbonation behaviour of a calcium-based sorbent in the calcium-looping CO 2 capture process as a non-catalytic gassolid reaction using a modified grain size distributed (GSD) model. In GSD model, the calcium-based particle consisted of numerous spherical grains with variable size distribution. The GSD model was modified by considering a variable diffusion coefficient of the gaseous reactant through the development of the product layer. The overall conversion over the reaction time was calculated by a mathematical modelling. The overall sorbent conversion obtained by using the modified GSD model showed better agreement with the experimental data with the average absolute deviation of 4.2 % than the results obtained using the grain model with the average absolute deviation 9.4 %. In the modified GSD model, the physical microstructure of the sorbent particle changes due to the molar volume expansion during the carbonation reaction. The model also predicted accurately the change of particle structural properties such as porosity, molar density, and specific surface area during the carbonation reaction.

Calcium looping carbon capture: Progress and prospects

“…Grain size distribution model (GSDM), reprinted with permission from Sedghkerdar and Mahinpey. [ 53 ] Copyright (2019) Wiley…”

Reactivity stabilization and capacity study of fabricated alumina and zirconia‐supported CaO‐based sorbents for high‐temperature CO2 capture in a fixed‐bed reactor

“…[6] The significant factor in controlling the reaction rate and ultimate conversion is the development of the solid carbonate product layer, which causes a significant CO 2 diffusion resistance in reaching reactant gas (CO 2 ) into the solid reactant surface (CaO). [7] Therefore, the carbonation reaction includes two regions: a kinetically controlled region, which takes minutes, followed by a diffusion-controlled region through the formed product layer. [6,8,9] The optimal temperature for CO 2 capture using a CaO-based sorbent is reported to be in the range of 650-700 C. However, the decay in the activity of CaO-based sorbents is a significant matter during cyclic operations.…”

Dynamic Desulfurization Process over Porous Zn–Cu-Based Materials in a Packed Column: Adsorption Kinetics and Breakthrough Modeling

“…Subsequently, new porous materials with high surface area and porosity were proposed to improve the reaction activity and final conversion of adsorbents for acid gases removal, including zeolites, , activated carbon, , alumina, , supported metal oxides, etc. Considering the influence of gas diffusion in porous particles on the reaction, some typical models such as random pore model (RPM), , grain model, , etc. are derived to describe the gas–solid dynamic process accurately .…”