化学镀法制备多元金属催化剂及其在热化学循环制氢工艺中的应用研究

Hydrogen production by the the iodide-sulphur thermochemical water splitting cycle is widely conceived to be one of the most promising ways of massive,highly efficient and environment-friendly process for future development compared with other traditional processes using. The heterogeneous decomposition of hydeogen iodide is the key hydrogen-producing reaction involved in iodide-sulphur thermochemical water splitting cycle, both high activity and high stability of the catalyst are of great importance under such demanding conditions as the high temperature, the strong acidic corossion and the reducing ambience. Based on the initial research on the preapration and application of supported monometallic catalyst prepared by electroless plating, which exhibited comparatively better performance under the severe conditions during the process of hydrogen iodide decomposition, it is expected to conduct further studies on the preapration and the mechanism of the formation of the multimetalic catalyst with a view to increasing its acitvity, stability and economy of the catalyst for use in the hydrogen iodide decomposition process by the codeposition of the active components through electroless plating. And accordingly, the microscopic structure,the elemental composition, the distribution of the active components, the catalytic performance, and the related process parameters concerning the resultant multimetalic catalyst will be adjusted and optimized. And consequently, it is expected to present original and fundamental data for the application of the multimetalic catalyst in the iodide-sulphur thermochemical water splitting cycle and the preparation of other novel multimetalic catalysts associated with the codeposition of the active components by electroless plating.

与传统的以化石燃料为基础的制氢工艺相比较，通过碘-硫热化学循环分解水制氢是未来最有前景的高效和清洁的大规模制氢方式之一。碘化氢的分解反应是碘-硫热化学循环制氢工艺中关键的产氢步骤，在高温、强酸性和还原性气氛条件下进行非均相催化反应要求催化剂具有优异的活性和稳定性。本项目拟在前期探索研究利用化学镀的方法制备对于碘-硫热化学循环制氢工艺中的苛刻工艺条件具有良好适应性的负载型金属催化剂的基础上，以进一步提高催化剂的活性、稳定性和经济性为目标，通过化学共镀的方法制备多元金属催化剂并探索化学共镀过程中活性组分沉积的机理，进一步对多元金属催化剂的微观结构、组成、活性组分的分布、催化性能以及相关工艺参数调控和优化，为新型高效多元金属催化剂在热化学循环制氢工艺中的应用和化学共镀法制备负载型多元金属催化剂提供新的基础数据。

碘-硫热化学循环制氢工艺中关键的产氢步骤为碘化氢的分解反应，其反应特点是在高温、强酸性和还原性气氛条件下进行的受热力学限制的可逆反应。催化剂的活性和稳定性对于制氢效率具有重要的影响。本项目首先对铂、铱、钯、钌、铑和铼等金属的催化活性和稳定性进行了对比和分析，为后续的多元金属催化剂的组分筛选奠定基础。鉴于催化剂载体的性质对于负载型催化剂的使用性能并具有显著的影响，本项目进行了不同类型的碳材料的筛选以及改性研究，并开发出了低负载量和高活性的新型钯基催化剂，可有效地降低催化剂制备成本。为了进一步提高负载型金属催化剂的分散度和稳定性，在考察多种双金属催化剂的组成和负载量对于碘化氢分解性能的影响的基础上，通过化学镀法制备得到了具有核壳结构的铂钯铱三元合金催化剂。实验结果表明在反应条件下载体以及合金催化剂不同组分之间具有较好的协同效应是其具有良好活性和稳定性的主要原因。通过优化后得到的多元合金催化剂具有负载量低、活性高和和稳定性好的特点，在碘硫热化学循环制氢工艺中具有较好的应用前景。