Synthesis and Characterization of Ru/Al2O3 Nanocatalyst for Ammonia Synthesis

Document Type : Research Article

Authors

1 Department of Applied Chemistry, Faculty of Chemistry, Semnan University, Semnan, I.R. IRAN

2 Catalyst Research Group, Petrochemical Research and Technology Company, National Petrochemical Company, P.O. Box 14358–84711 Tehran, I.R. IRAN

Abstract

Ru/Al2O3 catalysts were prepared by conventional incipient wetness impregnation as well as colloid deposition of RuCl3 precursor via in situ reduction with ethylene glycol (polyol) method on alumina support. The samples were characterized by TEM, XRD and TPR techniques. The catalytic performance tests were carried out in a fixed-bed micro-reactor under different operating conditions. Ethylene glycol as the reducing agent in the polyol methodproduced well-dispersed and uniform ruthenium nanoparticles with an average diameter of 7 nm supported on Al2O3. In conventional method, however, reduction by hydrogen resulted in considerably larger particles with average size of 12 nm.The Ru/Al2O3 catalyst prepared by polyol method exhibited three-fold higher activity in ammonia synthesis compared to the catalyst prepared by conventional method. The turnover frequency ratio of ammonia synthesis of polyol to conventional catalyst was estimated to be 2.1 at 450°C implying the reaction is structure-sensitive over Ru-based catalysts.

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[1] Schlogl R., Ammonia Synthesis in: "Handbook of Heterogeneous Catalysis", Department of Inorganic Chemistry, Fritz-Haber-Institute of the MPG, Germany (1991).
[2] Kojima R, Aika K., Cobalt Molybdenum Bimetallic Nitride Catalysts for Ammonia Synthesis Part 1. Preparation and Characterization, Appl. Catal. A: General, 215(1-2): 149-160 (2001).
[3] Nielsen S.E., "Ammonia Synthesis: Catalyst and Technologies", Haldor Topsoe A/SNymoelleves 55, DK-2800 Lyngby, Denmark (2008).
[4] Jafari A., Saadatjou N., Yazdani rad R., Sahebdelfar S., The Effect of Sulfur Content and Cooling Rate on Fused Iron Catalyst for Ammonia Synthesis, "Proc. of the 16th Iranian Chemistry Congress", Yazd, Iran, 404 (2013).
[7] Tavasoli A., Karimi A., Khodadadi A.A., Mortazavi Y., Mousavian M.A., Accelerated Deactivation and Activity Recovery Studies of Ruthenium and Rhenium Promoted Cobalt Catalysts in Fischer-Tropsch Synthesis, Iran. J. Chem. Chem. Eng. (IJCCE), 24(4): 25-36 (2005).
[9] Yang Z., Guo W., Lin J., Liao D., Supported Catalysts with Ru–M (M = Fe, Co, Ni, Mo) Bimetallic Active Centers for Ammonia Synthesis, Chin. J. Catal., 27(5): 378-380 (2006).
[10] Ozaki A., Development of Alkali-Promoted Ruthenium as a Novel Catalyst for Ammonia Synthesis, Acc. Chem. Res., 14(1): 16-21 (1981).
[11] Dahl S., "N2 Activation and NH3 Synthesis over Ru, Fe and Fe/Ru Model Catalysts", Ph.D. Thesis, Technical University of Denmark, Lyngby, Denmark, (1999).
[13] Gharibi M., Tahriri Zangeneh F., Yaripour F., Sahebdelfar S., Nanocatalysts for Conversion of Natural Gas to Liquid Fuels and Petrochemical Feedstocks, Appl. Catal. A: General, 443-444(7): 8-26 (2012).
[14] Dahl S., Tornqvist E., Chorkendorff I., Dissociative Adsorption of N2 on Ru(0001): A Surface Reaction Totally Dominated by Steps, J. Catal., 192(2): 381-390 (2000).
[15] Jacobsen C.J.H., Dahl S., Hansen P.L., Tornqvist E., Jensen L., Topsoe H., Prip, D.V., Moenshaug, P.B., Chorkendorff, I., Structure Sensitivity of Supported Ruthenium Catalysts for Ammonia Synthesis, J. Mol. Catal.: A Chem., 163(1-2): 19-26 (2000).
[16] Kurihara L.K., Chow G.M., Schoen P.E., Nanocrystalline Metallic Powders and Films Produced by the Polyol Method, Nanostruct. Mater., 5(6): 607-613 (1995).
[17] Lin B., Wei K., Carbon-Supported Ru Catalyst with Lithium Promoter for Ammonia Synthesis, Catal. Commun., 41: 110-114 (2013).
[18] Ji Z., Liang S., Jiang Y., Li H., Liu Z. Zhao T., Synthesis and Characterization of Ruthenium-Containing Ordered Mesoporous Carbon with High Specific Surface Area, Carbon, 47(9): 2194-2199 (2009).
[19] Iwamoto J., Itoh M., Kajita Y., Saito M., Machida K., Ammonia Synthesis on Magnesia Supported Ruthenium Catalysts with Mesoporous Structure, Catal. Commun., 8(6): 941-944(2007).
[20] Kadowaki Y., Aika K., Promoter Effect of Sm2O3 on Ru/Al2O3 in Ammonia Synthesis, J. Catal., 161(1): 178-185 (1996).
[21] 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, Catal. Commun., 12(6): 553-558 (2011).
[22] Davis R.J., New Perspectives on Basic Zeolites as Catalysts and Catalyst Supports, J. Catal., 216(1-2): 396-405 (2003).
[23] Laricheva Y., Moroza B., Bukhtiyarova V., Electronic State of Ruthenium Deposited onto Oxide Supports: An XPS Study Taking into Account the Final State Effects, Appl. Sur. Sci., 258(4): 1541-1550 (2011).
[24] Okal J., Kepineski L., Sintering of Colloidal Ru/γ-Al2O3 Catalyst in Hydrogen, Catal. Lett., 128(3-4): 331-336 (2009).
[25] Bartholomew C.H., Farrauto R.J., "Fundamentals of Industrial Catalytic Processes", 2nd ed., Wiley, New Jersey, (2006).
[26] Aika K., Shimazaki K., Hattori Y., Ohya A., Ohshima S., Shirota K., Ozaki A., Support and Promoter Effect of Ruthenium Catalyst I. Characterization of Alkali-Promoted Ruthenium/Alumina Catalysts for Ammonia Synthesis, J. Catal., 92(2): 296-304 (1985).
[27] Liang C., Wei Z., Luo M., Ying P., Xin Q., Li C., Hydrogen Spillover Effect in the Reduction of Barium Nitrate of Ru-Ba(NO3)2/AC Catalysts for Ammonia Synthesis, Stud. Surf. Sci. Catal., 138: 283-290 (2001).
[28] Rosowski F., Hornung A., Hinrichsen O., Herein D., Muhler M., Ertl G., Ruthenium Catalysts for Ammonia Synthesis at High Pressures: Preparation, Characterization, and Power-Law Kinetics, Appl. Catal. A: Gen., 151(2): 443-460 (1997).
[29] Lin B., Wang R., Lin J., Ni J., Wei K., Effect of Chlorine on the Chemisorptive Properties and Ammonia Synthesis Activity of Alumina-Supported Ru Catalysts, Catal. Lett., 141(10): 1557-1568 (2011).
[30] Seetharamulu P., Kumar V.S., Padmasri A.H., Raju B.D., Rao K.S.R., A Highly Active Nano-Ru Catalyst Supported on Novel Mg–Al Hydrotalcite Precursor for the Synthesis of Ammonia, J. Mol. Catal.: A Chem., 263(1-2): 253-258 (2007).
[31] Vasiliadou E.S., Heracleous E., Vasalos I.A., Lemonidou A.A., Ru-based Catalysts for Glycerol Hydrogenolysis Effect of Support and Metal Precursor, Appl. Catal. B, 92(1-2): 90-99 (2009).
[33] Hinrichsen O., Rosowski F., Hornung A., Muhler M., Ertl, G., The Kinetics of Ammonia Synthesis over Ru-based Catalysts Part 1: Dissociative Chemisorptions and Associative Desorption of N2, J. Catal., 165(1): 33-44 (1997).