Thermodynamics and kinetics of CO2 splitting with the redox system Ce3+/Ce4+ at high temperatures

氧化还原系统Ce3/Ce4在高温下CO2分解的热力学和动力学

• 批准号: 433306682
• 负责人: Professor Dr.-Ing. Günter Borchardt
• 金额: --
• 依托单位: Deutsches Zentrum für Luft- und Raumfahrt (DLR)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2019
• 资助国家: 德国
• 起止时间: 2018-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/433306682?language=en
• 关键词: Thermodynamics; kinetics; CO2; splitting; redox

For the reduction of CO2 to CO, (solar) thermal cycles based on the Ce+3/Ce4+ redox system are well suited. The information on the thermodynamics of pure cerium oxide (CeO2) and, especially, on the thermodynamics of solid solutions with homovalent (Zr) oxides or oxides with lower cation valences (Gd, Sm, Y, Ca, Mg, ...), albeit extensive, is partially incomplete and contradictory and comprises primarily only the dependency of the oxygen stoichiometry on temperature, oxygen partial pressure and dopants. With respect to the kinetics of the surface exchange of oxygen in the global CO2 splitting reaction at the CeO2 surface, as well as for the oxygen transport in the (doped/undoped) CeO2 matrix information is even more scarce. Therefore, the aim of the concerted action is to provide reliable thermodynamic information on the solid solutions with potential technological relevance, and to experimentally quantify the dependency of the surface exchange coefficient K, the diffusion coefficient D and the equilibrium exchange rate of oxygen, R°, on the process variables (temperature, oxygen potential or CO2/CO ratio, kind and concentration of dopants) of the CO2 splitting process, and to present a consistent model. To this purpose, a model published recently by the applicants shall be expanded. This model quantitatively describes the relation between K, D and R°.In order to gain the necessary experimental data two complementary experimental approaches are combined in this concerted action, if possible on the same samples. The first method is the exchange of rare stable isotopes (13C, 18O) in combination with SIMS depth profiling. The second method comprises the time dependent gravimetric and dilatometric thermal analysis in order to detect the relaxation kinetics of bulk samples after an oxygen potential change.The data gained from these complementary experiments will be checked for consistency with the above mentioned model. They will yield K, D and the equilibrium exchange rate of oxygen, R°, at the respective surface. The envisaged concerted action will enable the gathering of the information needed to understand and apply CO2 splitting with the redox system Ce+3 /Ce4+ in technologically relevant solid solutions. Thus, it will simultaneously supply the scientific basis for a technological realization. This implies that the results can be principally transferred to other material systems. Further, the present state of the phenomenological kinetic model developed by the applicants supports the expectation that the model will also enable to quantitatively describe other reaction systems where a fluid and a solid phase exchange a common component.

对于将CO2降低到CO，基于CE+ 3/CE4+氧化还原系统的（太阳能）热循环非常适合。有关纯含氧纯铜（CEO2）热力学的信息，尤其是关于具有较低阳离子率（GD，SM，SM，Y，CA，MG，...）的固体溶液的热力学（Zr）或氧化物的一部分，尽管很广泛，但仍是部分不完整的和矛盾的氧气和依赖性的氧化含量。掺杂剂。关于在CEO2表面的全局CO2分裂反应中氧表面交换的动力学，以及（掺杂/未掺杂的）CEO2矩阵信息中的氧气传输更加稀缺。 Therefore, the aim of the concerted action is to provide reliable thermodynamic information on the solid solutions with potential technical relevance, and to experimentally quantify the dependency of the surface exchange Corefficient K, the diffusion coefficient D and the equivalent exchange rate of oxygen, R°, on the process variables (temperature, oxygen potential or CO2/CO ratio, kind and concentration of dopants) of the CO2 splitting process, and to present a consistent 模型。为此，应扩大申请人最近发布的模型。该模型定量地描述了K，d和r°之间的关系。在获得必要的实验数据中，如果可能的话，将两种完整的实验方法组合在同一样品上。第一种方法是交换稀有稳定同位素（13c，18o）与SIMS深度分析的结合。第二种方法包括依赖时间的粒度和扩张测量热分析，以检测氧气电位变化后的散装样品的松弛动力学。将从这些互补实验中获得的数据与上述模型一起检查是否一致性。它们将在相关表面产生K，D和氧的等效汇率。设想的协同行动将使我们能够在技术相关的实心解决方案中收集使用Redox System CE+ 3 /CE4+来理解和应用CO2分裂所需的信息。这就是为了实现技术实现的科学基础。这意味着结果主要可以转移到其他材料系统上。此外，应用程序开发的现象学动力学模型的当前状态支持了这样一种预期，即该模型还可以定量描述流体和固相交换的其他反应系统。