Alginate versus Chitosan for Templating Growth and Shaping HKUST‐1 as Porous CO₂‐Adsorbent Beads

Abstract This study aims at elucidating the role of the polysaccharide skeleton (alginate versus chitosan) during the growth and shaping of HKUST‐1 as porous beads. Although the two biopolymers afford an open porous hydrogel network, the freeze‐drying step was crucial with water medium being inappropriate to preserve the crystalline framework of HKUST‐1. Alternatively, drying in ethanol circumvented this drawback by keeping intact the structure of HKUST‐1. However, a contrasting behavior was observed in the resulting polysaccharide@HKUST‐1 beads, as HKUST‐1 grown in alginate underwent a dramatic collapse, whereas self‐standing, open porous microspheres could be obtained using the chitosan templating route. The resulting chitosan@HKUST‐1 cryogel displays an enhanced CO 2 capture (2.67 mmol.g −1 ) compared to its analogs shaped by alginate, making consequently chitosan a better option for structuring MOF‐based adsorbents.