CO2 gasification of Yangchangwan coal catalyzed by iron-based waste catalyst from indirect coal-liquefaction plant
Xinsha Zhang, Xudong Song, Jiaofei Wang, Weiguang Su, Yonghui Bai, Bing Zhou, Guangsuo Yu
Abstract
Coal char-CO 2 gasification is a strong endothermic reaction with high energy consumption, and a cheap catalyst use is one of the keys to save process costs. The iron-based waste catalyst (IWC) from indirect coal-liquefaction plant contains active component, but its effect on the gasification reactivity of coal char is seldom reported. Thus, CO 2 gasification of Yangchangwan coal (YCW) was conducted in thermogravimetric analyzer (TGA) with IWC as the catalyst. The change of functional group on coal char surface was measured by a Fourier transform infrared (FT-IR) spectroscopy. The morphology of coal char was characterized by focused ion beam scanning electron microscope (FIB-SEM). X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were employed to analyze phases and valences of iron. The results indicate that IWC was effective for YCW gasification. In the range of 1000–1200 °C, the optimal temperature of catalytic gasification was 1000 °C. The FT-IR spectra of YCW gasified char showed the changes of small molecule active groups, such as –OH, C–O, –CH 2 , –CH 3 , C=C and Fe–O in the process of catalytic gasification. The surface structure of coal char was rough and there were lots of tiny pores. The metallic Fe formed by IWC at 0 min was finally oxidized by gasification agent CO 2 to FeO and Fe 3 O 4 . The redox cycle between Fe 0 , Fe 2+ and Fe 3+ is the main reason for the catalytic YCW-CO 2 gasification reactivity in the presence of IWC.