Synthesis of a highly efficient Li4SiO4 ceramic modified with a gluconic acid-based carbon coating for high-temperature CO2 capture

Abstract

A unique gluconic acid treatment coupled with a carbon coating process was used to synthesize Li4SiO4 ceramics (GAC-Li4SiO4) with superior performance for high-temperature CO2 capture. The effects of different synthetic methods, carbonization temperatures, acid sources and acid contents on the performance of the sorbent were studied and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), nitrogen absorption and thermogravimetric analyses. After the gluconic acid treatment and carbon coating, the GAC-Li4SiO4 had a small crystal size, hollow morphology and enhanced pore features. Significant improvements in CO2 sorption performance (i.e., low absorption temperature, fast absorption rate, and high capacity) were thus obtained. Moreover, the carbonization temperature, acid content and acid type greatly affected the morphology and chemisorption properties of the Li4SiO4 sorbents. Under the optimized synthetic conditions, the maximum CO2 absorption capacity was 34.7% after isothermal absorption at 665°C for 10min. This sorbent also maintained good cyclic properties.