Pore Structure Modified CaO-Based Sorbents with Different Sized Templates for CO2 Capture

Abstract

Porous structure is critical for CO2 capture performance of CaO-based sorbents in Ca-Looping. The sacrificial template method is an easy and effective way to alter the texture structure of sorbent pellets. In order to explore the optimal pore size distribution for CO2 sorption, two micron templates - starch (ST) and cotton fiber (CF), and two nano templates - carbon nanotubes (CNT) and carbon nanofibers (CNF) were used to modify pore structure on different scales for the first time. The CO2 capture capacity of Ca-CNT in the 15th carbonation under severe calcination conditions was 86% more than the sorbent without templates. The enhanced CO2 capture performance was attributed to the uniform small mesopores (2-10 nm) produced by nano-sized templates. In this case, a large specific surface area is provided for carbonation. Micron templates would produce additional pores ranging from 10 nm to 100 nm and even large pores (>400 nm). The analysis results suggested that the pore volume (ranging from 2nm to 10 nm)...