Stability of amine-functionalized CO ₂ adsorbents: a multifaceted puzzle

Abstract

All sources of thermal, hydrothermal and chemical stability, or lack thereof, for amine-functionalized CO ₂ adsorbents were critically reviewed.

Abstract

This review focuses on important stability issues facing amine-functionalized CO ₂ adsorbents, including amine-grafted and amine-impregnated silicas, zeolites, metal–organic frameworks and carbons. During the past couple of decades, major advances were achieved in understanding and improving the performance of such materials, particularly in terms of CO ₂ adsorptive properties such as adsorption capacity, selectivity and kinetics. Nonetheless, to pave the way toward commercialization of adsorption-based CO ₂ capture technologies, in addition to other attributes, adsorbent materials should be stable over many thousands of adsorption–desorption cycles. Adsorbent stability, which is of utmost importance as it determines adsorbent lifetime and operational costs of CO ₂ capture, is a multifaceted issue involving thermal, hydrothermal, and chemical stability. Here we discuss the impact of the adsorbent physical and chemical properties, the feed gas composition and characteristics, and the adsorption–desorption operational parameters on the long-term stability of amine-functionalized CO ₂ adsorbents. We also review important insights associated with the underlying deactivation pathways of the adsorbents upon exposure to high temperature, oxygen, dry CO ₂, sulfur-containing compounds, nitrogen oxides, oxygen and steam. Finally, specific recommendations are provided to address outstanding stability issues.