The liquid-phase hydrogenation of cinnamaldehyde over a Pt/SiO₂ catalyst was investigated experimentally and theoretically. The experiments were conducted in a 300 cm³ stainless steel stirred batch reactor supplied with hydrogen gas and ethanol as a solvent. Five Langmuir–Hinshelwood kinetic models were investigated to fit the experimental data. The predictions from the bulk model were compared with predictions from the intraparticle diffusion model. Competitive and non-competitive mechanisms were applied to produce the main intermediate compound, cinnamyl alcohol. Reaction rate parameters for the different reaction steps were calculated by comparing between the experimental and mathematical models. All rate data utilized in the present study were obtained in the kinetic regime. The kinetic parameters were obtained by applying a nonlinear dynamic optimization algorithm. Nevertheless, the comparison between the methodology of the present model and these five models indicated that the non-competitive mechanism is more acceptable and identical with the single-site Langmuir–Hinshelwood kinetic model including mass transfer effects and it mimicked the reactant behavior better than the other models. In addition, the observed mean absolute error (MAE) for the non-competitive mechanism of the present model was 2.3022 mol/m³; however, the MAE for the competitive mechanism was 2.8233 mol/m³, which is an increase of approximately 18%. The prediction of the intraparticle diffusion model was found to be very close to that of the bulk model owing to the use of a catalyst with a very small particle size (<40 microns). Employing a commercial 5% Pt/SiO₂ catalyst showed a result consistent with previous research using different catalysts, with an activation energy of ≈24 kJ/mol.

中文翻译：

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Pt/SiO2 上的肉桂醛加氢反应动力学：体扩散模型和颗粒内扩散模型的比较

_{对肉桂醛在Pt/SiO 2}催化剂上的液相加氢反应进行了实验和理论研究。实验在 300 cm ³不锈钢搅拌间歇反应器，供应氢气和乙醇作为溶剂。研究了五个 Langmuir-Hinshelwood 动力学模型以拟合实验数据。将体模型的预测与颗粒内扩散模型的预测进行了比较。应用竞争和非竞争机制来生产主要的中间体化合物肉桂醇。通过比较实验模型和数学模型，计算出不同反应步骤的反应速率参数。本研究中使用的所有速率数据均在动力学状态下获得。通过应用非线性动态优化算法获得动力学参数。尽管如此，本模型的方法与这五个模型的比较表明，非竞争机制更容易接受，并且与包括传质效应的单中心 Langmuir-Hinshelwood 动力学模型相同，并且它比其他模型更好地模拟了反应物的行为. 此外，本模型非竞争机制的观测平均绝对误差 (MAE) 为 2.3022 mol/m³；然而，竞争机制的 MAE 为 2.8233 mol/m ³，增加了约 18%。由于使用了具有非常小粒径（<40 微米）的催化剂，发现颗粒内扩散模型的预测非常接近本体模型的预测。使用商业 5% Pt/SiO ₂催化剂的结果与之前使用不同催化剂的研究结果一致，活化能约为 24 kJ/mol。