Experimental study on the structure and reactivity of palm kernel shell chars duing CO₂ gasification

The palm kernel shell(PKS) chars of different conversions were prepared in a tube furnace by using CO₂ as gasification agent, and the gasification reactivity of PKS chars were tested by thermogravimetry analyzer. The pore structure, degree of carbon structure ordering, mineral element content and distribution of PKS chars of different conversions were characterized by surface area measurement, Raman spectra, X-ray flourimeter(XRF), scanning electron microscopy and energy dispersive X-ray spectroscopy(SEM-EDX), respectively. The results show that the fixed carbon content of PKS chars reduces gradually, and the proportion of ordered carbon stabilizes at 0.30~0.33 during CO₂ gasification. The ash content increases gradually along with the increasing of conversion, but the gasification reaction index R_s of PKS chars increases after a decreased stage. At the early stage of pore size expansion (conversion x< 23%), the change tendency of R_s of PKS chars is in accordance with the surface area. As the gasification reaction continues (23%< x< 31%), R_s has few changes. The surface area of PKS chars has a linear correlation with the conversion from 31% to 68%, and R_s increases with the increasing surface area and the catalysis of mineral elements as x> 56%. When x> 68%, the R_s of PKS chars is mainly controlled by catalysis of minerals.