Abstract Chemical Looping Combustion (CLC) is considered one of the low cost alternatives for CO2 capture for fossil fuels combustion and to reach negative emissions through biomass CLC. The cornerstone of the CLC process is the oxygen carrier performance that represents the main additional cost with respect to the conventional combustion. Manganese-based oxygen carriers are subjected to a growing interest because they are low cost, not toxic and environmentally friendly. In this work five impregnated oxygen carriers, with manganese oxide Mn3O4 or Mg6MnO8 as their active phase and three commercial supports based on zirconia and synthetic calcium aluminate, were prepared. Their behaviour for CLC was examined by TGA, batch fluidized bed reactor, TPR, SEM-EDX and XRD. After a preliminary screening two carriers (Mn-ZrM and Mn-ZrSG) were subjected to multiple redox cycles by TGA and batch fluidized bed reactor. Both showed high solids conversion by TGA under the tested conditions, appropriated resistance to fracture, rate indexes relatively high, although Mn-ZrM showed agglomeration and deactivation during batch fluidized bed tests. Reactivity in batch fluidized bed reactor of the Mn-ZrSG oxygen carrier with methane increases with temperature although suffered from significant deactivation. This was different to the results found during multiple redox cycles by TGA. There was not a clear reason for this decrease in the reactivity that likely could be due to the uncomplete oxidation in the batch fluidized bed reactor, although further investigations are needed. On the other hand, it presented high and constant reactivity with CO and H2 in all the range of temperatures tested, being suitable for iG-CLC processes of coal or biomass and syngas combustion. Agglomeration problems were not found and the attrition losses were small. Calculated lifetime was around 11,000 h, much higher than any other Mn-based material developed or tested for CLC.

中文翻译：

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锰基氧载体浸渍法制备，用于多种燃料化学循环燃烧

摘要 化学循环燃烧 (CLC) 被认为是用于化石燃料燃烧的 CO2 捕获和通过生物质 CLC 实现负排放的低成本替代方案之一。CLC 工艺的基石是氧载体性能，它代表了相对于传统燃烧的主要额外成本。锰基氧载体由于成本低、无毒且环境友好而受到越来越多的关注。在这项工作中，制备了五种浸渍氧载体，以氧化锰 Mn3O4 或 Mg6MnO8 为活性相，以及三种基于氧化锆和合成铝酸钙的商业载体。它们的 CLC 行为通过 TGA、间歇流化床反应器、TPR、SEM-EDX 和 XRD 进行了检查。在初步筛选后，两种载体（Mn-ZrM 和 Mn-ZrSG）通过 TGA 和间歇流化床反应器进行多次氧化还原循环。尽管 Mn-ZrM 在批量流化床试验中表现出团聚和失活，但两者在测试条件下都显示出 TGA 的高固体转化率、适当的抗断裂性、相对较高的速率指数。Mn-ZrSG 氧载体与甲烷在间歇流化床反应器中的反应性随温度升高而增加，尽管遭受了显着的失活。这与 TGA 在多次氧化还原循环中发现的结果不同。尽管需要进一步研究，但没有明确原因可能是由于间歇流化床反应器中的氧化不完全导致反应性降低。另一方面，它在测试的所有温度范围内都表现出与 CO 和 H2 的高且恒定的反应性，适用于煤或生物质和合成气燃烧的 iG-CLC 工艺。未发现团聚问题，磨损损失小。计算寿命约为 11,000 小时，远高于为 CLC 开发或测试的任何其他锰基材料。