Operating parameters and sorbent properties affecting ca (OH) 2 carbonation for direct air capture (DAC) applications

[Geoengineering News]

https://www.sciencedirect.com/science/article/pii/S1385894726071056

Authors: Yolanda A Criado, Carlos Bajo, Loreto Suarez, Roberto García

Abstract

Direct Air Capture (DAC) based on Ca(OH) 2 carbonation has emerged as a promising route for atmospheric CO 2 removal. However, the maximum attainable carbonation conversion (X Max ), a key parameter governing sorbent utilization and process performance, is strongly influenced by operating conditions and sorbent properties. In this work, X Max was investigated over a wide range of CO 2 concentrations (500–120,000 ppm), relative humidity (10–95%), and temperatures (30–80 °C), using both commercial standard and high-surface-area Ca(OH) 2 materials. The results show that X Max exhibits a sigmoidal dependence on relative humidity and is strongly affected by sorbent surface area. Higher CO 2 concentrations increase initial carbonation rates but may reduce the maximum attainable conversion, while temperature has a comparatively smaller influence on X Max within the investigated range. Based on the experimental dataset, an empirical correlation was developed to calculate X Max as a function of CO 2 concentration, relative humidity, temperature, and sorbent specific surface area. The proposed correlation provides a simple tool for estimating X Max within the range of conditions investigated and may facilitate material screening, operating-condition assessment, and preliminary evaluation of Ca(OH) 2 -based DAC systems.

Source: ScienceDirect