Dispersion State of Catalytic Metal Supported on Bio-Char Elucidated Using Energy Dispersive X-ray Spectroscopy: Effects of Catalyst Type and Heating Process

Abstract

Bio-chars loaded directly with catalytic metals such as K and Fe were gasified with CO2 at atmospheric pressure after being heated to 1023-1323 K under an Ar flow. The gasification rate constant (Kp) of K-loaded biochar was extremely higher than that of Fe-loaded bio-char. The structure such as surface and cross section of these bio-chars after (1) metal ions were supported on bio-char by the impregnation method (i.e. before heating) and (2) heating under an Ar flow (i.e. just before gasification) were observed using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Before heating, the K atoms were uniformly distributed with no crystal formation. Even after heating under an Ar flow, the distribution of K atoms on the surface and inside of bio-chars remained uniform, suggesting the efficient formation of active sites for CO 2 gasification, although the K content on the surface decreased because of releasing. In contrast, even before heating, the Fe atoms were