Enhanced and environment-friendly chemical looping gasification of crop straw using red mud as a sinter-resistant oxygen carrier

• Published in: Waste management (Elmsford) Vol. 121; pp. 354 - 364
• Main Authors: Shen, Xuehua, Yan, Feng, Zhang, Zhen, Li, Chunyan, Zhao, Shiyin, Zhang, Zuotai
• Format: Journal Article
• Language: English
• Published: United States Elsevier Ltd 15.02.2021
• Subjects: Air pollutant mitigation; Biomass; Chemical looping gasification; Crop straw; Gases; Oxygen; Oxygen carrier; Red mud; Silicon Dioxide; Syngas production; Thermogravimetry; Oxygen carrier; Crop straw; Red mud; Syngas production; Chemical looping gasification; Air pollutant mitigation
• ISSN: 0956-053X; 1879-2456
• DOI: 10.1016/j.wasman.2020.12.028

[Display omitted] •Red mud was used as oxygen carrier for chemical looping gasification of crop straw.•Syngas yields was enhanced due to the sintering-resistant advantage of red mud.•Red mud effectively reduced the emission of air pollutants by alkaline components.•Red mud is an ideal oxygen carrier compared to traditional Fe-based oxygen carrier. Syngas production from biomass gasification is a promising technology, which is widely used in the chemical industry. Crop straw and red mud are typical agricultural and industrial wastes, respectively, which are cheap and widespread; however, they cause serious environmental pollution due to the open burning of straw and the toxicity and alkalinity of red mud. In the present work, we converted crop straw into syngas by chemical looping gasification using red mud as a sinter-resistant oxygen carrier. The reactivity of red mud, the syngas yields, and the air pollutant emissions under different conditions were systematically investigated through a thermo-gravimetric analyzer and mass spectrometer. Compared with pure Fe2O3, red mud can promote the syngas yields from crop straw gasification owing to the presence of inert Al2O3 and SiO2. Red mud can effectively reduce the emission of air pollutants owing to the presence of alkaline components such as CaO and Na2O. As the Fe2O3/fuel mass ratio increases, the syngas yield increases and the air pollutant emissions simultaneously reduce; whereas the syngas yield and the air pollutant emissions decrease with increasing heating rate. After calcination at high temperature, the structure of red mud remains stable with slight agglomeration, and can be easily regenerated. Therefore, the promising results provide a breakthrough for efficient utilization and disposal of both crop straw and red mud.