Abstract Herein, we report on the effect of a high gravity field on metal-free catalytic reduction, taking the nitrobenzene (NB) reduction and methylene blue (MB) degradation as model reactions in a high-gravity rotating tube reactor packed with three-dimensional (3D) nitrogen-doped graphene foam (NGF) as a metal-free catalyst. The apparent rate constant (kapp) of the metal-free catalytic reduction of NB in the rotating tube reactor under a high gravity level of 6484g (g = 9.81 m·s−2) was six times greater than that in a conventional stirred reactor (STR) under gravity. Computational fluid dynamics (CFD) simulations indicated that the improvement of the catalytic efficiency was attributed to the much higher turbulent kinetic energy and faster surface renewal rate in the high-gravity tube reactor in comparison with those in a conventional STR. The structure of the 3D metal-free catalysts was stable during the reaction process under a high gravity field, as confirmed by X-ray photoelectron spectroscopy (XPS) and Raman spectra. In the other model reaction, the rate of MB degradation also increased as the high gravity level increased gradually, which aligns with the result for the NB catalytic reduction system. These results demonstrate the potential to use a high-gravity rotating packed tube reactor for the process intensification of metal-free catalytic reduction reactions.

中文翻译：

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氮掺杂石墨烯泡沫作为高重力场下还原反应的无金属催化剂

摘要 在此，我们报告了高重力场对无金属催化还原的影响，以硝基苯 (NB) 还原和亚甲蓝 (MB) 降解为模型反应，在装有 3 (3D) 氮掺杂石墨烯泡沫 (NGF) 作为无金属催化剂。在6484g（g = 9.81 m·s-2）的高重力水平下，在旋转管反应器中无金属催化还原NB的表观速率常数（kapp）是常规搅拌反应器的6倍（ STR）在重力下。计算流体动力学 (CFD) 模拟表明，与传统 STR 相比，高重力管式反应器中更高的湍流动能和更快的表面更新速率导致催化效率的提高。X射线光电子能谱（XPS）和拉曼光谱证实，3D无金属催化剂的结构在高重力场下的反应过程中是稳定的。在另一个模型反应中，随着高重力水平的逐渐增加，MB 降解率也增加，这与 NB 催化还原系统的结果一致。这些结果证明了使用高重力旋转填充管反应器进行无金属催化还原反应的过程强化的潜力。这与 NB 催化还原系统的结果一致。这些结果证明了使用高重力旋转填充管反应器进行无金属催化还原反应的过程强化的潜力。这与 NB 催化还原系统的结果一致。这些结果证明了使用高重力旋转填充管反应器进行无金属催化还原反应的过程强化的潜力。