Ammonia Synthesis over Ruthenium Catalysts Using Barium-Doped Zirconia as Supports Prepared by Citric Acid Method

Barium-promoted zirconia (Ba-ZrO2) was synthesized by the citric acid method and used as supports for Ru/Ba-ZrO2 catalysts, which were prepared by incipient wetness impregnation with K2RuO4 as precursor. The obtained Ba-ZrO2 and catalysts were characterized by X-ray diffraction and CO2 temperature-programmed desorption. The effect of Ba content on the structure and catalytic activity of K-Ru/Ba-ZrO2 catalysts is discussed. The formation of BaZrO3 can improve significantly the catalytic activity of Ru/Ba-ZrO2 for ammonia synthesis. The ammonia concentration and rate of ammonia synthesis of the K-Ru/Ba-ZrO2 catalyst (molar ratio of Ba: Zr is 1:1) were 9.24% and 29.77 mmol/(g·h), respectively, at 425°C, 5.0 MPa, and 10000 h−1. Improvements in electron conductivity and the basic nature of the catalyst may be the main reasons for such high catalytic activity in ammonia synthesis.

摘要采用柠檬酸络合法制备了一系列不同含量 Ba 掺杂的 ZrO2, 再用浸渍法制备了 K-Ru/Ba-ZrO2 催化剂并将其用于氨合成反应. 采用 X 射线衍射和 CO2 程序升温脱附技术考察了 Ba 含量对催化剂结构与性能的影响. 结果表明, Ba 掺入 ZrO2 后形成的 BaZrO3 有助于其负载的 Ru 催化剂氨合成活性的显著提高. 在 5.0 MPa, 10000 h–1, 425 °C 时, Ru/Ba-ZrO2 (Ba:Zr 摩尔比为 1:1) 催化剂活性最高, 出口氨浓度和反应速率分别达 9.24% 和 29.77 mmol/(g·h). 这主要归因于载体的强电子传导性能和碱性提高. 

Ru/Ba-ZrO2 was an excellent catalyst for ammonia synthesis especially under mild conditions. This was attributed to the presence of BaZrO3 with high basicity and ability to conduct electrons.Figure optionsDownload as PowerPoint slide