Structured sorbents for Direct Air Capture: The impact of materials and chemicals on performance

Abstract

Structured sorbents can efficiently process large air volumes required for Direct Air Capture (DAC), but their broad implementation is limited by challenges in producing reproducible and homogeneous materials. This work presents a robust procedure to graft amines onto monolithic sorbents and systematically investigates how capture performance is influenced by three fundamental material building blocks: substrate type (mullite vs. cordierite), alumina loading, and amine type (APTMS vs. TRI). X‐ray Computed Tomography and gravimetric analyses confirm uniform amine distribution, with adsorption capacity scaling linearly with alumina mass. From a process perspective, lower density substrates achieve higher specific uptake, thus reducing the energy demand for regeneration. Breakthrough experiments demonstrate that humidity significantly enhances adsorption thermodynamics and kinetics: uptake increases by 30% for APTMS and 70% for TRI, and adsorption kinetics are accelerated. This study provides quantitative material performance relationships necessary for process design and contactor optimization.