Effect of promoter on study properties and catalytic activity of Ru/CeO2 catalyst for ammonia synthesis
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摘要: 以KF、KNO3、Ba(NO3)2、CsNO3为助剂前驱体,CeO2为载体采用氧化还原共沉淀法制备了一系列无氯负载型钌催化剂,考察了助剂种类和助剂含量及单双助剂对Ru/CeO2氨合成活性的影响,并采用N2物理吸附、CO脉冲吸附、XRD、XRF等表征手段,考察了助剂对Ru/CeO2催化剂比表面积、孔分布、钌分散度的影响。结果表明,F与碱金属、碱土金属一样可以促进Ru/CeO2催化剂的氨合成活性,四种单助剂中以CsNO3前驱体为助剂的促进效果最好,而对于双助剂Ba+Cs的促进效果最明显,在400℃,10 MPa,10 000 h-1反应条件下,出口氨浓度达到了13.3%。加入助剂后使各Ru/CeO2催化剂表面结构发生改变,但是催化剂的结构因素对氨合成活性的影响不明显,电子效应才是影响催化剂氨合成活性的主要因素。Abstract: A series of Ru based ammonia synthesis catalysts supported by ceria with different promoter precursors,such as KF、KNO3、Ba(NO3)2、CsNO3,were prepared.Not only studied the effect of single and double promoters for the catalytic activity but also studied the effect of promoters’ kinds and content.N2 physisorption,CO chemisorption and X-ray diffraction were carried out to investigate the effect of promoter on surface area,pore size distribution and ruthenium dispersion of catalysts.It has been found that the effectiveness of F ion just like the role of alkaline or alkaline-earth-promoter for ammonia synthesis.For the single-promoted Ru/CeO2 catalyst,cesium proved to be most effective in the studied four promoters.For the double-promoted one,the activity of the catalyst was affected remarkably by cesium and barium co-exists.Ammonia synthesis concentration of over 13.3% was obtained over Ba+Cs-Ru/CeO2 catalyst under 400℃,10 MPa and 10 000 h-1.The structure and the surface property of Ru/CeO2 catalyst were changed when promoters added.But the real factor to improving catalytic activity is electronic effect rather than structural factors.
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Key words:
- promoter /
- ruthenium /
- ammonia synthesis /
- ceria
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ENGVALL K, HOLMLID L, KOTARBA A, PETTERSSON J B C, MENON P G, SKAUGSET P. Potassium promoter in industrial ammonia synthesis catalyst: Studies by surface ionization[J]. Appl Catal A, 1996, 134(2): 239-246. HINRICHSEN O, ROSOWSKI F, MUHLER M, ERTL G. The microkinetics of ammonia synthesis catalyzed by cesium-promoted supported ruthenium[J]. Chem Eng Sci, 1996, 51(10): 1683-1690. KOWALCZYK Z, JODZIS S, RARG W, ZIELINSKI J, PIELASZEK J. Effect of potassium and barium on the stability of a carbon-supported ruthenium catalyst for the synthesis of ammonia[J]. Appl Catal A, 1998, 173(2): 153-160. RARG W, KOWALCZYK Z, SENTEK J, SKLADANOWSKI D, ZIELINSKI J. Effect of K, Cs and Ba on the kinetics of NH3 synthesis over carbon-based ruthenium catalysts[J]. Catal Lett, 2000, 68(3/4): 163-168. KOWALCZYK Z, KRUKOWSKI M, RARG-PILECKA W, SZMIGIEL D, ZIELINSKI J. Carbon-based ruthenium catalyst for ammonia synthesis: Role of the barium and caesium promoters and carbon support[J]. Appl Catal A, 2003, 248(1/2): 67-73. KADOWAKI Y, AIKA K-I. Promoter effect of Sm2O3on Ru/Al2O3 in ammonia synthesis[J]. J Catal, 1996, 161(1): 178-185. LIN B, WANG R, LIN J, NI J, WEI K. Sm-promoted alumina supported Ru catalysts for ammonia synthesis: Effect of the preparation method and Sm promoter[J]. Catal Commun, 2011, 12(6): 553-58. 郑晓玲 傅武俊, 俞裕斌, 张淑娟, 许交兴, 魏可镁. 助剂对Ru/C催化剂的表面性质及氨合成催化性能的影响[J]. 燃料化学学报, 2003, 31(1): 86-91. (ZHENG Xiao-lin, FU Wu-jun, YU Yu-bin, ZHANG Shu-juan, XU Jiao-xing, WEI Ke-mei. Effect of premoter on surface properties and catalytic activity of Ru/C catalyst for ammonia synthesis[J]. Journal of Fuel Chemistry and Technology, 2003, 31(1): 86-91.) KOWALCZYK Z, SENTEK J, JODZIS S, MIZERA E, GRALSKI J, PARYJCZAK T, DIDUSZKO R. An alkali-promoted ruthenium catalyst for the synthesis of ammonia, supported on thermally modified active carbon[J]. Catal Lett, 1997, 45(1/2): 65-72. FORNI L, MOLINARI D, ROSSETTI I, PERNICONE N. Carbon-supported promoted Ru catalyst for ammonia synthesis[J]. Appl Catal A, 1999, 185(2): 269-275. MURATA S, AIKA K. Preparation and characterization of chlorine-free ruthenium catalysts and the promoter effect in ammonia-synthesis: 2 A lanthanide oxide-promoted Ru/Al2O3 catalyst[J]. J Catal, 1992, 136(1): 118-125. AIKA K, TAKANO T, MURATA S. Preparation and characterization of chlorine-free ruthenium catalysts and the promoter effect in ammonia-synthesis: 3 A magnesia-supported ruthenium catalyst[J]. J Catal, 1992, 136(1): 126-140. 林敬东, 黄桂玉, 徐宗祥, 廖代伟. F离子对钌基氨合成催化剂活性的影响[J]. 化学学报, Acta Chimica Sinica, 2004, 62(18): 1717-1720. (LIN Jing-dong, HUANG Gui-yu, XU Zong-xiang, LIAO Dai-wei. Effect of fluoried on activities of Ru-based ammonia synthesis catalysts[J]. 2004, 62(18): 1717-1720.) NIWA Y, AIKA K. Ruthenium catalyst supported on CeO2 for ammonia synthesis[J]. Chem Lett, 1996, 25(1): 3-4. WANG X, NI J, LIN B, WANG R, LIN J, WEI K. Highly efficient Ru/MgO-CeO2 catalyst for ammonia synthesis[J]. Catal Commun, 2010, 12(4): 251-254. 罗小军 王榕, 林建新, 魏可镁. 沉淀方法对Ru/CeO2氨合成催化剂催化性能的影响[J]. 催化学报, 2009, 30(11): 1125-1130. (LUO Xiaojun, WANG Rong, LIN Jian-xin, WEI Kei-mei. Effect of precipitation methods on catalytic activity of Ru/CeO2 catalyst for ammonia synthesis[J]. Chinese Journal of Catalysis, 2009, 30(11): 1125-1130.) 罗小军, 王榕, 倪军, 林建新, 魏可镁. 沉淀剂种类对Ru/CeO2氨合成催化剂结构和性能的影响[J]. 化学学报, 2009, 67(22): 2573-2578. ( LUO Xiao-jun, WANG Rong, LIN Jian-xin, WEI Kei-mei. Effect of precipitants on structure and catalytic activity of Ru/CeO2 catalysts for ammonia synthesis[J]. Acta Chimica Sinica, 2009, 67(22): 2573-2578.) 王秀云, 王榕, 倪军, 林建新, 魏可镁. Ru 前驱体对 Ru/MgO-CeO2 氨合成催化剂性能的影响[J]. 催化学报, 2010, 31(12): 1452-1456. (WANG Xiu-yun, WANG Rong, NI Jun, LIN Jian-xin, WEI Kei-mei. Effect of precursors on catalytic activity of Ru/MgO-CeO2 catalyst for ammonia synthesis[J]. Chinese Journal of Catalysis, 2010, 31(12): 1452-1456.) RARG-PILECKA W, MISKIEWICZ E, JODZIS S, PETRYK J, LOMOT D, KASZKUR Z, KARPINSKI Z, KOWALCZYK Z. Carbon-supported ruthenium catalysts for NH3 synthesis doped with caesium nitrate: Activation process, working state of Cs-Ru/C[J]. J Catal, 2006, 239(2): 313-325. TRUSZKIEWICZ E, RAR PILECKA W, SCHMIDT-SZALOWSKI K, JODZIS S, WILCZKOWSKA E, LOMOT D, KASZKUR Z, KARPINSKI Z, KOWALCZYK Z. Barium-promoted Ru/carbon catalyst for ammonia synthesis: State of the system when operating[J]. J Catal, 2009, 265(2): 181-190. IZUMI Y, IWATA Y, AIKA K-I. Catalysis on ruthenium clusters supported on CeO2 or Ni-doped CeO2: Adsorption behavior of H2 and ammonia synthesis[J]. J Phys Chem, 1996, 100(22): 9421-9428. LIANG C, WEI Z, XIN Q, LI C. Ammonia synthesis over Ru/C catalysts with different carbon supports promoted by barium and potassium compounds[J]. Appl Catal A, 2001, 208(1/2): 193-201. ROSSETTI I, PERNICONE N, FORNI L. Promoters effect in Ru/C ammonia synthesis catalyst[J]. Appl Catal A, 2001, 208(1/2): 271-278. McCLAINE B C, DAVIS R J. Isotopic transient kinetic analysis of Cs-promoted Ru/MgO during ammonia synthesis[J]. J Catal, 2002, 210(2): 387-396.
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