Chemical looping gasification of biomass resources is an innovative technology to obtain high-quality syngas with less energy consumption and CO2 emission. In this work, to efficiently convert biomass wastes into syngas, red mud was tested as oxygen carrier for chemical looping gasification process. In order to enhance performance of this oxygen carrier, alkali and alkaline earth metal doping strategy was adopted and the mechanisms of this promotive effect were investigated in detail. Initially, red mud oxygen carriers modified by K2O and CaO were prepared via impregnation method, then the effects of element doping were examined. The results demonstrate that alkali and alkaline earth metals modification significantly enhanced gasification performance of red mud, particularly with K2O markedly improving CO selectivity to 84.79 % at maximum. In comparison, CaO-modified oxygen carrier exhibits a higher H2/CO ratio. The introduction of K2O and CaO generated a substantial amount of K-containing and Ca-containing ferrite compounds, enhancing oxygen release capacity of oxygen carriers and promoting gasification reactions. Moreover, BET analysis revealed that the specific surface area of the oxygen carriers decreased from 25.63 m2/g to 1.84–2.79 m2/g after modification. Co-modified oxygen carriers exhibited optimal gasification performance at K2O/CaO ratio of 4:1 and 20 % loading, increasing H2 yield 59 mmol/g, reaction time reduced to 38 min, and CO selectivity of 84 %. In conclusion, element doping strategy is proved to be feasible to achieve gasification reaction process control of for efficient conversion of biomass wastes.

中文翻译：

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利用 K/Ca 掺杂改性赤泥以增强其在生物质废弃物化学循环气化中的献氧性能

生物质资源的化学循环气化是一种创新技术，可以以更少的能耗和 CO2 排放获得高质量的合成气。在这项工作中，为了有效地将生物质废弃物转化为合成气，测试了赤泥作为化学回路气化过程的氧气载体。为了提高这种氧载体的性能，采用了碱和碱土金属掺杂策略，并详细研究了这种促进作用的机制。最初，通过浸渍法制备了由 K2O 和 CaO 改性的赤泥氧载体，然后检查了元素掺杂的影响。结果表明，碱和碱土金属改性显著提高了赤泥的气化性能，特别是 K2O 显著提高了 CO 选择性，最高可达 84.79 %。相比之下，CaO 修饰的氧载体表现出更高的 H2/CO 比率。K2O 和 CaO 的引入产生了大量的含 K 和含 Ca 的铁氧体化合物，增强了氧载体的释氧能力，促进了气化反应。此外，BET 分析显示，改性后氧载体的比表面积从 25.63 m2/g 下降到 1.84–2.79 m2/g。共改性氧载体在 K2O/CaO 比例为 4：1 和 20% 负载时表现出最佳的气化性能，H2 产率提高 59 mmol/g，反应时间缩短至 38 min，CO 选择性为 84 %。综上所述，元素掺杂策略被证明是实现生物质废弃物高效转化的气化反应过程控制的可行性。