Fabrication and CO2 capture performance of silicon carbide derived carbons from polysiloxane

Abstract

Microporous silicon carbide derived carbons (SiC-DCs) were obtained by chlorination with post treatment in ammonia (NH3) using a commercially available polymethyl(phenyl)siloxane resin. In this paper, attentions were focused on the compositional and structural evolutions as well as the CO2 capture performances of SiC-DCs as a function of chlorination temperature or affected by post-treatment. Microscopy analysis showed that the geometry and macrostructure, as well as the observed graphite ribbons were finely inherited from the as-received silicon carbide. Post-treatment under NH3 could introduce a few nitrogen-contained groups to SiC-DCs, and has an advantage on increasing the ultra-microporosity with little effect on the carbon crystallinity, both of which finally help increasing the CO2 adsorption capacity. Increasing etching temperature (900–1100°C) would lead to a tiny increase of carbon crystallinity and porosity (specific surface area and total pore volume). However, the ultra-micropore volume decreased instead, thus leading to a decrease of CO2 adsorption capacity. The final SiC-DCs samples exhibit excellent CO2 capture performances at 0°C under the ambient pressure, with a maximum value of 5.75mmol/g. Under the same condition, the N2 adsorption is as low as 0.46mmol/g, suggesting a potential selective adsorbent for CO2 and N2 separation.