非均相反应中气体的热图
Thermal Maps of Gases in Heterogeneous Reactions
摘要：
超过85%的化学工业产品是使用催化剂制造的，其中绝大多数使用在气固界面起作用的多相催化剂。因此，优化催化反应器的设计吸引了大量的努力。这种优化依赖于与表面反应动力学耦合的传热和流体动力学建模。这些系统的复杂性需要许多近似，这只能用实验观测的数量，如温度，压力，浓度，流速等进行测试。一个重要的测量是整个催化剂床的温度的空间变化的地图。我们在这里提出的第一个非侵入性地图的气体温度在催化剂填充的反应器，包括高空间分辨率的地图，在微反应器使仲氢。热图揭示了能量通量模式，其长度尺度与催化剂填料相关。通过利用在弱磁场梯度下的运动平均，核磁共振（NMR）线宽与温度成反比。在填充有金属纳米颗粒和金属-有机骨架催化剂的反应器中测量丙烯加氢过程中的温度系数为~0.1 Hz/K，温度误差<4%。温度灵敏度随着梯度强度的增加而增加，从而可以调整精度。
英文摘要：
Over 85% of all chemical industry products are made using catalysts, with the overwhelming majority of these employing heterogeneous catalysts functioning at the gas-solid interface. Consequently, optimizing catalytic reactor design attracts much effort. Such optimization relies on heat transfer and fluid dynamics modeling coupled to surface reaction kinetics. The complexity of these systems demands many approximations, which can only be tested with experimental observations of quantities such as temperature, pressure, concentrations, flow rates, etc. One essential measurement is a map of the spatial variation in temperature throughout the catalyst bed. We present here the first non-invasive maps of gas temperatures in catalyst-filled reactors, including high spatial resolution maps in microreactors enabled by parahydrogen. The thermal maps reveal energy flux patterns whose length scale correlates with the catalyst packing. By exploiting the motional averaging under a weak applied magnetic-field gradient, the nuclear magnetic resonance (NMR) linewidths are inversely proportional to temperature. Measurements during the hydrogenation of propylene in reactors packed with metal nanoparticles and metal-organic framework catalysts yield temperature coefficients of ~0.1 Hz/K, and temperature error <4%. Temperature sensitivity increases with gradient strength, enabling tuning of precision.
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