铜铝尖晶石缓释催化模型构建和衍变规律研究

Cu-Al spinel without pre-reduction can sustained release active copper during reaction, and the utilization of active copper is improved obviously. During the reaction, metallic copper atoms are sustained released from Cu-Al spinel, and tend to sintering for its thermal instability. At the same time, the high-density Cu-Al spinel converts to porous Al2O3, while the structure of the latter is not stable and rearranged to σ-Al2O3. In the reaction, the catalytic activity increases firstly and then decreases. For this complex transformation process, splitting and then fitting method would be adopted to study it. First, develop the models of copper release, sintering and structure transformation of catalyst. Then, fit these models and achieve the sustained-release model, and the catalyst transformation process can be deduced. .On basis of these results, prepare Cu-X-Al spinel catalyst by adding the second component X, and study the effect of X kind on the sustained-release model; optimize the second component X which can stabilize the porous Al2O3 structure and adjust the copper release and sintering rate in reaction. This research is benefit for understanding the catalytic model and transformation of Cu-Al spinel sustained-release active copper in reaction, and it can provide the theoretical foundation and basic data for the catalyst improvement and application.

铜铝尖晶石缓释铜催化，即不经过预还原处理，铜铝尖晶石缓慢释放活性铜催化反应，因而活性铜利用率得到大幅度提升。在缓释催化过程中，铜铝尖晶石不断地释放金属铜，而金属铜的热不稳定性又导致其持续地烧结；同时，致密的铜铝尖晶石释放金属铜后会形成多孔Al2O3，后者的结构不稳定会逐渐重排为σ-Al2O3；催化剂的活性则呈先增加后降低的趋势。针对这个复杂的变化过程，本项目拟采用先拆分后拟合的方法进行研究。首先，分别建立铜释放、烧结和催化剂结构变化模型，然后拟合获得缓释催化模型，并对催化剂衍变规律进行研究。在此基础上，制备第二组分X改性的Cu-X-Al混合尖晶石催化剂，通过考察第二组分X种类对缓释催化模型的影响，优选第二组分X，使其起到稳定多孔Al2O3及调节铜释放和烧结速率的作用。本项目研究有助于系统了解铜铝尖晶石缓释催化过程，及催化剂的衍变历程，为催化剂的进一步改进及应用提供理论依据和基础数据。

由于活性金属原子级分散在尖晶石结构中，尖晶石催化剂显示了较高的催化活性及稳定性。本项目优化了铜基尖晶石催化剂的合成方法，制备了Cu-Al-M混合尖晶石。以二氧化碳加氢反应为探针反应，对铜基尖晶石缓释过程中催化剂的组成、结构等参数的变化以及这些变化对催化剂活性及选择性的影响进行了研究。合成了不同尖晶石物种改性的有序介孔氧化铝MAl2O4-Al2O3（M=Co、Mn、Mg、Ni），考察了其在费托反应中的催化性能。以甲醇乙醇缩合为探针反应，以CuMgAlOx复合氧化物为催化剂考察了Cu含量、Mg/Al比等参数对催化剂性能及产物分布的影响。本项目的研究为铜基尖晶石缓释催化研究提供基础数据，并为尖晶石型催化剂的应用提供了可选择性的方向。