Selectable Microporous Carbons Derived from Poplar Wood by Three Preparation Routes for CO2Capture

Abstract

Biomass-derived porous carbons are one kind of sustainable, extensive, and flexible carbon material for CO2 capture. Here, we prepared several microporous carbons from poplar wood by three preparation routes. Especially, the residues of the poplar wood after the bioethanol process were explored as precursors to prepare activated carbon by KOH and ZnCl2 activation. By the adjustment of the preparation routes and the optimization of the activation conditions, these porous carbons exhibited diversified morphology (sponge, nanosheets, and honeycomb structure), tunable porosity (specific surface areas: 511-2153 m2/g), and narrow micropore distribution (0.55-1.2 nm). These carbons had a high CO2 uptake of up to 217 mg/g at 273 K and 1 bar, which was comparable with those of many N-doped porous carbons, and possessed moderate isosteric heat of CO2 adsorption (21.1-43.2 kJ/mol), good cyclic ability, and high CO2/N2 selectivity (Henry's law: 44.0). The results indicated that CO2 uptake of these carbons was mainly decided by their micropore volume (d < 1.0 nm) at 273 K and 1 bar. This work provides an important reference for preparing promising CO2 adsorbents with tunable structures from similar biomass resources.