Effect of lignin, cellulose and hemicellulose on calcium looping behavior of CaO-based sorbents derived from extrusion-spherization method

Abstract

Calcium looping process is well considered as one of the most promising technologies for trapping CO2 from flue gas. But the drastic decay of CO2 capture capacity and the severe attrition of the CaO-based sorbents are the two main obstacles for the calcium looping process. In order to enhance the CO2 capture capacity and the anti-attrition property of the CaO-based sorbents, an extrusion-spherization method was proposed by biomass templating method to manufacture spherical sorbents. In addition, the effects of three components of biomass, lignin, cellulose and hemicellulose in the spherical sorbents on the cyclic CO2 capture capacity were investigated in details. The CO2 capture performance of the sorbents and pyrolysis of three biomass components were test by a simultaneous thermal analyzer (STA), and the attrition resistance properties of the sorbents were examined by a friability tester (FT). The microstructure of the sorbents was measured by N2 adsorption/desorption measures, an X-ray diffraction apparatus (XRD) and a field emission scanning electron microscope apparatus (FESEM). Results showed that cellulose and hemicellulose templating processes were beneficial to the CO2 capture performance of the sorbents, whereas lignin was detrimental. The BET surface area of the molded sorbents increased drastically when templated with cellulose or hemicellulose. The binder effect of the three components on the modeled sorbents followed the order: lignin > cellulose > hemicellulose. Extrusion-spherization process is a promising technology to manufacture spherical tough sorbents. Considering the effect of CO2 capture capacity and the attrition resistance property, the optimal templating component of biomass is cellulose.