柠檬酸络合法制备Ba促进ZrO2负载Ru催化剂上氨合成反应性能

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5.0MPa,10000h-1,425℃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29.77mmol/(g·h).这主要归因于载体的强电子传导性能和碱性提高.%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 BaZiO3 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 mmoV(g·h), respectively, at 425℃, 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.