Structure and Impact of Spatiotemporal State on Catalytic Surfaces

自然界中存在各种各样的时空模式，具有广泛的复杂性，从简单而规则的结构到高度无序的结构。这些结构在复杂的非线性行为中显示出一定的秩序。众所周知，化学反应和传输过程的耦合，如扩散或流体动力对流，会导致活性化合物在空间上有组织的分布。到目前为止，对化学反应体系中的图样形成的分析和预测一直是针对均匀介质进行的，对于介质的不均质性是否会以何种方式扭曲存在于均匀介质中的图样缺乏了解。这与商业多相催化剂的性能直接相关，这些催化剂本质上是不均匀的。这一答案对评估时空模式对催化剂性能的影响具有重要意义。这项研究包括实验、数值和理论研究，包括催化表面空间和时空图案的形成、演化、表征和影响。这些实验将为几个测试反应提供关于具有简单和对称几何结构的催化剂上的图样在受控环境中的动态特征的定量数据，并将提供关于催化剂表面不均匀对观察到的图样的影响(或缺乏影响)的重要信息。实验信息将作为理论模型开发和修改的指南，并用于确定参数值。数值和理论研究将有助于指导和组织实验研究，指出可能感兴趣的实验区域和催化剂几何形状，并指导预测图案形成及其影响的原理的发展。这项研究应该深入了解时空模式对非均相催化剂性能的作用和影响。

A wide variety of spatiotemporal patterns exist in nature with a wide degree of complexity, from simple and regular to highly disordered structures. These structures show some order in the midst of complex nonlinear behavior. The coupling of chemical reactions and transport processes, such as diffusion or hydrodynamic convection, is known to lead to the formation of spatially organized distributions of reactive compounds. Analysis and prediction of pattern-formation in chemically reacting systems to date have been for homogeneous medium and there is lack of understanding if and in which way inhomogeneity of a medium will distort the patterns that exist in a uniform medium. This relates directly to the performance of commercial heterogeneous catalysts, which are inherently nonuniform. The answer has implications on the assessment of the impact of spatiotemporal patterns on the performance of catalysts. This research involves experimental, numerical and theoretical studies of the formation, evolution, characterization, and impact of spatial and spatiotemporal patterns on catalytic surfaces. The experiments will provide quantitative data about the dynamic features of the patterns on catalysts with simple and symmetric geometry in a well-controlled environment for several test reactions, and will provide important information on the impact (or lack of impact) of catalytic- surface inhomogeneity on the observed patterns. The experimental information will serve as a guide to theoretical- model development and modification and for determining parameter values. Numerical and theoretical studies will help direct and organize the experimental research and point out potentially interesting regions of experimentation and catalyst geometries, and guide the development of principles predicting pattern formation and its impact. The research should provide insight into the role and impact of spatiotemporal patterns on the performance of heterogeneous catalysts.