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采用不同沉淀剂制备了MgO材料,以其为载体制备了Ba-Ru/MgO氨合成催化剂,考察了沉淀剂种类和BaO助剂对其氨合成性能的影响.通过X射线衍射(XRD)、N2物理吸附、X射线荧光光谱(XRF)、透射电镜(TEM)、H2程序升温还原(H2-TPR)、CO2程序升温脱附(CO2-TPD)、H2程序升温脱附(H2-TPD)和N2程序升温脱附(N2-TPD)表征手段,对不同沉淀剂影响Ba-Ru/MgO催化剂氨合成性能的原因进行了探索.结果表明:采用(NH4)2CO3作沉淀剂制备的Ba-Ru/MgO催化剂表面Ru物种易于在低温下还原,催化剂表面在低温区具有较多数量的弱碱性吸附位,在450℃、5.0 MPa和5 000 h-1条件下,由(NH4)2CO3做沉淀剂制备的Ba-Ru/MgO催化剂活性最高,出口氨浓度为3.74%.BaO助剂的加入大大减少了Ba-Ru/MgO催化剂表面吸附氢的数量,增大表面脱附氮的数量,从而易于N2解离吸附,提高氨合成反应速率.
MgO was prepared by using different precipitants and the Ba-Ru / MgO ammonia synthesis catalyst was prepared by the same method. The effects of precipitant and BaO additive on the ammonia synthesis were investigated. XRD, X-ray fluorescence (XRF), transmission electron microscopy (TEM), H2 temperature-programmed reduction (H2-TPR), CO2-TPD, H2-TPD and N2 (N2-TPD) characterization was used to explore the reasons why different precipitants affect the ammonia synthesis performance of Ba-Ru / MgO catalyst.The results show that the Ba-Ru / MgO catalyst prepared by using (NH4) 2CO3 as precipitant The Ru species on the catalyst surface is easily reduced at low temperature. The catalyst surface has a large number of weakly basic adsorption sites in the low temperature region and is prepared from (NH4) 2CO3 as precipitating agent at 450 ℃, 5.0 MPa and 5000 h-1 Of Ba-Ru / MgO catalyst has the highest activity and the outlet ammonia concentration is 3.74% .The addition of BaO additive greatly reduces the amount of hydrogen adsorbed on the surface of Ba-Ru / MgO catalyst and increases the amount of surface desorption nitrogen, Absorption, improve ammonia synthesis reaction rate.