稀土掺杂对纳米钡-氧化镁载体及其负载钌基氨合成催化剂性能的影响  

Effects of Rare Earth Doping on the Performance of Nano-Ba-Magnesia Supports and Ru-Based Catalysts for Ammonia Synthesis

作　　者：霍超[1] 夏庆华[1] 杨霞珍[1] 骆燕[1] 刘化章[1] 

机构地区：[1]浙江工业大学化学工程与材料学院,浙江杭州310032

出　　处：《催化学报》2009年第3期218-222,共5页

基　　金：国家自然科学基金(20203016);浙江省自然科学基金(Y406294)

摘　　要：利用超声-共沉淀技术制备了一系列稀土与钡共掺杂的纳米氧化镁载体(RE-Ba-MgO,RE=La,Sm和Ce)及其负载的钌基氨合成催化剂(Ru/RE-Ba-MgO).通过氮气物理吸附、X射线衍射、场发射扫描电镜、热重分析仪及H2程序升温还原等方法对载体和催化剂进行了表征.结果表明,Ba在载体中的掺杂形式分为低温分解型BaCO3和高温分解型BaCO3.稀土的掺杂可明显改变载体的表面形态及表面结构,使载体化学与结构性能发生变化,从而导致低温分解型BaCO3的相对含量发生变化,进而改变催化剂的低温活性.在10MPa,400oC,10000h-1的测试条件下,Ru/La-Ba-MgO催化剂的出口氨浓度达到65.49mmol/(g·h),比Ru/Ba-MgO催化剂活性提高了66.3%.A series of RE-Ba-MgO supports were prepared by coprecipitating rare earth （La, Sm, and Ce） and barium under ultrasonic irradiation, and the corresponding ruthenium catalysts for ammonia synthesis were prepared by the impregnation method. The physical and chemical properties of the supports and catalysts were characterized by nitrogen physical adsorption, X-ray diffraction, field emission scanning electron microscopy, thermogravimetry combined with mass spectrometry, and H2 temperature-programmed reduction. The results showed that the Ba doped in the supports exhibited two barium carbonate phases, low-temperature barium carbonate and high-temperature barium carbonate. The introduction of rare earth not only changed the chemical and textural properties of nano-Ba-MgO support but also controlled the formation state of barium. The Ru/La-Ba-MgO catalyst showed the highest catalytic activity for the ammonia synthesis with a reaction rate of 65.49 mmol/（g.h） （10 MPa, 400 ℃ 10 000 h^-1）, which is 66.3% higher than that with Ru/Ba-MgO.

关 键 词：稀土 掺钡纳米氧化镁 钌基催化剂 氨合成 超声制备 

分 类 号：TQ113.24[化学工程—无机化工]