The kinetics of hydrogenation/reduction of uranium [U(VI)] has been investigated using a platinum catalyst loaded on silica substrates in a bubble column reactor at atmospheric pressure and room temperature. Effects of catalyst loading, hydrogen flow rate, and concentrations of nitric acid and hydrazine have been investigated. Several kinetic models are derived based on the Langmuir–Hinshelwood mechanism and each of them are evaluated. The experimental results indicate that the surface reaction between dissolved hydrogen and adsorbed reactants on the catalyst surface is the rate controlling step in the hydrogenation of uranyl ion. To test the applicability of the developed rate expression, the mass balance equations for uranium, nitric acid, and hydrogen around the bubble reactor have been solved numerically. The comparison of experimental and predicted results showed a reasonably good agreement.

中文翻译：

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气泡反应器在硝酸溶液中U（VI）催化加氢动力学的研究

在大气压力和室温下，使用负载在鼓泡塔反应器中的二氧化硅基质上的铂催化剂研究了铀[U（VI）]氢化/还原的动力学。研究了催化剂负载，氢气流速以及硝酸和肼浓度的影响。基于Langmuir-Hinshelwood机理推导了几个动力学模型，并对每个模型进行了评估。实验结果表明，催化剂表面溶解的氢与吸附的反应物之间的表面反应是铀酰离子加氢的速率控制步骤。为了测试所开发的速率表达式的适用性，已对气泡反应器周围的铀，硝酸和氢的质量平衡方程进行了数值求解。