In Situ Amination of Lignin Waste for CO ₂ Capture

ABSTRACT Typically, SiO 2 , Al 2 O 3 , MOF, and polymers are used to prepare solid amine CO 2 adsorbents. In this manuscript, we explored abundant lignin waste to prepare a series of solid amine CO 2 adsorbents via in situ Mannich reactions with commercially available, cheap ethanolamine and polyethyleneimine. Upon optimization of amine loadings and reaction conditions, the novel ethanolamine modified adsorbents showed significantly improved CO 2 capture performance (6.83 mmol/g) compared to native lignin (2.57 mmol/g) under laboratory testing conditions (25 ° C, 1 bar, and 10 vol% CO 2 /Ar). Unfortunately, the captured CO 2 can be regenerated with a maximum limit of 50% under rather harsh conditions, implying likely utilization of the cheap adsorbents loaded with CO 2 as building fillers and adhesives. Elemental analysis, scanning electron microscopy, x‐ray photoelectron spectroscopy, thermogravimetric analyzer, CO 2 adsorption isotherm, and Fourier transform infrared spectrometer analysis were applied to characterize the texture properties and CO 2 capture mechanisms.