Syngas produced from biomass is a clean energy source, which widely used in electricity, fuels and chemicals. Using chemical looping gasification (CLG) to produce syngas from biomass is a promising technology due to its higher gasification efficiency. In CLG process, oxygen carrier (like Fe2O3, CuO and NiO) plays a key role, whose oxygen supply capacity determines the yield and efficiency of syngas production. However, oxygen carrier is prone to sintering, aggregation and carbon deposition under high temperature conditions, resulting inactivation. In order to enhance the thermal stability of oxygen carrier and achieve better properties, using advanced technology to design oxygen carriers such as adding inert materials into oxygen carrier has become a development trend. However, the complexity and cost of oxygen carrier preparation technology must be greatly increased; therefore, a facile and cost-effective synthesis route for highly efficient and stable oxygen carriers is still a research priority. Here, we creatively using red mud, a typical alkaline industrial waste from aluminum industry, as sintering-resistant oxygen carrier to convert the crop straw into syngas through CLG process. The reactivity of red mud, the syngas yields and the air pollutants emission were detailed investigated under different conditions. Compared with pure Fe2O3, red mud could promote the syngas yields from on account of being supported by the inherent inert materials of Al2O3 and SiO2. Importantly, red mud could effectively reduce the emission of air pollutants due to the alkaline components such as CaO and Na2O. After calcination at high temperature, the structure of red mud was still stable with slight agglomeration, which could be easily regenerated. Therefore, the inspiring results provide a breakthrough for efficiently utilization and disposal of both red mud and crop straw, as well as producing the valuable syngas. This strategy innovatively used the industrial solid waste as oxygen carrier for the gasification of agricultural waste into syngas, which significantly reduced the design difficulty of oxygen carrier and the cost of syngas production. Therefore, the findings are of general significance for the utilization and disposal of industrial waste and agricultural waste into high value-added products.

Green chemical looping gasification of crop straw: The enhancement effect of red mud as a sinter-resistant oxygen carrier

ACS Spring Meeting 2021

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