Zhu Qishuai, Wang Shunsheng, Kuai Long
Department of Chemical Engineering, Key Laboratory of Production and Conversion of Green Hydrogen, Anhui Polytechnic University, Wuhu 241000, China.
Inorg Chem. 2024 Oct 21;63(42):19864-19871. doi: 10.1021/acs.inorgchem.4c03275. Epub 2024 Oct 9.
Support modification is an important way to improve the activity of the Ru/MgO-based NH synthesis catalyst. This work synthesized 24 composite MgO-based supports of MO-MgO (M = La, Zn, etc.) via a microdrop-confined pyrolysis (MDCPy) method and then prepared the corresponding Cs-Ba-Ru/MO-MgO catalysts using the impregnation method. Under the same NH synthesis conditions, the activity of the Cs-Ba-Ru/MO-MgO catalysts composed of 17 elements such as Pr was significantly lower than that of Cs-Ba-Ru/MgO, while the activity of the Cs-Ba-Ru/MO-MgO catalysts composed of four elements such as Nd was comparable to that of Cs-Ba-Ru/MgO, and the activity of the Cs-Ba-Ru/MO-MgO catalysts composed of three elements such as La was significantly higher than that of Cs-Ba-Ru/MgO. Among them, it is clear that LaO-MgO composite supports have the most significant effect on the improvement of NH synthesis performance. Through the optimization of the La/Mg ratio and loading of Ru, the optimal activities achieved ∼7 mol/g/h with corresponding Ru loading of 0.25-0.5 wt % under mild conditions as follows: H/N ratio of 3:1, temperature of 400 °C, pressure of 3 MPa and a weight hourly space velocity (WHSV) of 96.0 L/g/h. In addition, the CsBa-Ru/LaO-MgO catalyst showed good stability.
载体改性是提高Ru/MgO基氨合成催化剂活性的重要途径。本工作通过微滴限域热解法（MDCPy）合成了24种MO-MgO（M = La、Zn等）复合MgO基载体，然后采用浸渍法制备了相应的Cs-Ba-Ru/MO-MgO催化剂。在相同的氨合成条件下，由Pr等17种元素组成的Cs-Ba-Ru/MO-MgO催化剂的活性明显低于Cs-Ba-Ru/MgO，而由Nd等四种元素组成的Cs-Ba-Ru/MO-MgO催化剂的活性与Cs-Ba-Ru/MgO相当，由La等三种元素组成的Cs-Ba-Ru/MO-MgO催化剂的活性明显高于Cs-Ba-Ru/MgO。其中，很明显LaO-MgO复合载体对氨合成性能的改善效果最为显著。通过优化La/Mg比和Ru负载量，在如下温和条件下：H₂/N₂比为3:1、温度为400℃、压力为3MPa、质量空速（WHSV）为96.0L/g/h，当Ru负载量为0.25 - 0.5wt%时，最佳活性达到约7mol/g/h。此外，CsBa-Ru/LaO-MgO催化剂表现出良好的稳定性。
