Scalable production of wood carbon microspheres for high-efficiency carbon dioxide capture

Utilizing abundantly available biomass materials to prepare adsorbent substances is a simple and cost-effective method for CO 2 adsorption, which, however, is often hampered by low adsorption capacity. Here, we demonstrate near-spherical active carbon (C-DWP/Zn) with high CO 2 adsorption ability, employing delignification combination with ZnCl 2 activation of natural wood powder. Removing lignin from wood cell walls facilitates easy absorption of Zn ions by the cellulose nanofibers (CNFs), thereby promoting micro/nano pores formation. Moreover, rapid dehydration of cellulose molecular chains alters the morphology of activated carbon, resulting in a transition from a granular to a near-spherical shape. Consequently, C-DWP/Zn with high specific surface area of 1769 m 2 g −1 , shows a significantly higher microporous volume than that of a control sample without delignification. The CO 2 adsorption capacity of C-DWP/Zn, with values of 3.51 mmol g −1 and 5.12 mmol g −1 at 1 bar, 25 °C and 0 °C, respectively, is superior to that of commercial activated carbon. Attributable to its optimal micropore structure, C-DWP/Zn exhibits high CO 2 /N 2 selectivity. Furthermore, the high carbon dioxide adsorption efficiency of C-DWP/Zn was maintained and the substance could be reused at least 20 times. Near-spherical active carbon adsorbents prepared from low-value wood powders, all featuring high CO 2 adsorption performances, reasonable CO 2 /N 2 selectivity, good recoverability, suitable heat of adsorption, and fast adsorption kinetics, which are promising candidates for practical CO 2 adsorption.