Structure and Impact of Spatiotemporal Catalytic Systems

摘要-LUSS-9529393许多工业化学反应都是使用多相催化剂进行的。多相催化反应中也存在着双稳态、振荡运动和兴奋性等现象，这些现象在均相液相反应中引起了大量的时空运动。最近的实验结果表明，在放热反应过程中，催化小球上可以发现周期性的温度模式，如旋转脉冲。该项目的目标是探索和利用这种振荡热现象，以提高所需产品的产率和选择性。PI计划进行一项实验与理论相结合的研究，目的是找到并分类保存在连续搅拌釜式反应器(CSTR)和径向流动填充床反应器中的全圆柱形或中空圆柱形催化颗粒可能存在的所有可能的温度模式。在单粒实验中，将用红外热像仪测量催化剂表面和侧面的温度分布。测试反应将是氢气在镍-氧化铝催化剂上的氧化和一氧化碳在铂-氧化铝催化剂上的氧化。这项研究将确定导致不同图案演变的条件；粒内和粒间传输限制的影响；图案对催化剂性能的影响；以及固有的催化活性不均匀对图案的影响。将确定每个动作的主要动态特征，如特征长度、周期、速度和形状。这些周期性的温度波动可能会刺激人们试图从中受益，特别是当它们导致催化剂活性发生相应的周期性变化时。

Abstract - Luss - 9529393 Many industrial chemical reactions are carried out using heterogeneous catalysts. The phenomena of bistability, oscillatory motion and excitability, which induce a plethora of spatiotemporal motions in homogeneous liquid-phase reactions, exist also in heterogeneous catalytic reactions. Recent experimental results indicate that periodic temperature patterns, such as rotating pulses, may be found on catalytic pellets during exothermic reactions. The goal of this project is to explore and exploit such oscillatory thermal phenomena to enhance the yield and selectivity of desired products. The PI plans to conduct a combined experimental-theoretical study with the goal of finding and classifying all the possible temperature patterns that may exist on either full or hollow cylindrical catalytic pellets kept in a continuously stirred tank reactor (CSTR) and in a radial-flow packed-bed reactor. In the single-pellet experiments, the temperature patterns on the surface and sides of the catalysts will be measured by an infrared thermal imager. The test reactions will be the oxidation of hydrogen on a nickel-on-alumina catalyst and the oxidation of carbon monoxide on a platinum-on-alumina catalyst. The study will determine the conditions leading to the evolution of different patterns; the influence of intra- and interparticle transport limitations; the impact of the patterns on the performance of the catalyst; and the influence of inherent nonuniform catalytic activity on the patterns. The main dynamic features of each motion, such as characteristic length, period, velocity, and shape, will be determined. These periodic temperature motions are likely to stimulate attempts to benefit from them, especially when they induce corresponding periodic changes in the catalyst activity.