Effects of calcination temperature on the structure and CO2 sorption properties of Li4SiO4 sorbents from rice husk ash

Abstract

Highly efficient Li4SiO4-based sorbents for CO2 capture at high temperature, were developed using waste rice husk ash (RHA). Two different RHAS resulted from different calcination temperature as raw materials for preparing the Li4SiO4-based sorbents. These raw ashes and their resulting Li4SiO4-based sorbents were characterized by X-ray diffraction, thermogravimetry (dynamic and isothermically), and nitrogen adsorption. CO2 sorption stability was investigated in a dual fixed-bed reactor. The characteristic results showed that high calcination temperature could lead to crystalline silica, which may produce the lower crystalline size, higher porosity and larger surface area as compared with the case of low temperature. This favourable structure appeared to be the main reason for increasing in CO2 capture performance and kinetic behavior as illustrated by the thermogravimetric analyses. This pretreatment Li4SiO4-based sorbent also maintained a higher capacity during the multiple cycles. It was concluded that the synthesis of Li4SiO4-based sorbents obtained from biomass ash is a promising approach for CO2 capture at high temperature.