Cobalt Loading Effects on the Physico-Chemical Properties and Performance of Co Promoted Alkalized MoS2/CNTs Catalysts for Higher Alcohols Synthesis

Document Type: Research Article

Authors

School of Chemistry, College of Science, University of Tehran, Tehran, I.R. IRAN

Abstract

An extensive study of Higher Alcohol Synthesis (HAS) from synthesis gas using cobalt (Co) promoted alkalized MoS2 catalysts supported on Carbon NanoTubes (CNTs) is reported. Up to  5wt.% of Co is added to the 15wt.% Mo-wt.%K/ CNTs by incipient wetness impregnation method. Most of the metal particles were homogeneously distributed inside the tubes and the rest on the outer surface of the CNTs. The catalysts are extensively characterized by different methods and    the activity and selectivity of the catalysts were assessed in a fixed bed micro-reactor. Temperature Programmed Reduction (TPR) tests showed that addition of cobalt decreased the second TPR peak temperature from 801 to 660oC. The diffraction peaks that represent the characteristic K-Mo-O phase (i.e. K2Mo2O7, K2MoO4, K2Mo7O20, KMo4O6, and K0.33MoO3; these species can enhances formation of higher alcohols) were observed in the X- Ray Diffraction (XRD) patterns of unpromoted Mo-K/CNTs and to a greater extent in the XRD patterns of Co-promoted Mo-K/CNTs catalysts.    Co addition to Mo-K/CNTs not only increased the number of surface sites, but also decreased      the average active metal particle sizes from 7.53 to 5.33 nm and increased the percentage dispersion from 51.1 to 68.2%. Among the catalysts with different Co loadings, catalyst with 5 wt.% Co showed the highest %CO conversion of  38.8%. The total alcohol selectivity reached a maximum of 59.7 wt.% on the catalyst promoted with 3 wt.% cobalt. The catalyst with 3 wt.% Co exhibited selectivity of 41.65 wt.% towards higher alcohols.  

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[1] Herman R., “Studies in Surface and Catalyst’’, Chapter 7, Elsevier, Amsterdam, (1990).
[2] Johnston P., Hutchings G.J., Coville N.J., Finch K.P., Moss J.R., CO Hydrogenation Using Supported Iron Carbonyl Complexes, Appl. Catal. A: General, 186(1-2), p. 245 (1999).
[3] Smith K.J., Anderson R.B., A Chain Growth Scheme for the Higher Alcohols Synthesis, J. of Catalysis, 85, p. 428 (1984).
[4] Camposmartin J.M., Guerreroruiz A., Fierro J.L.G., Structural and Surface Properties of CuO-ZnO-Cr2O3 Catalysts and Their Relationship with Selectivity to Higher Alcohols Synthesis, J Catal, 156(2), p. 208 (1995).
[5] Boz I., Sahibzada M., Metcalfe I.S., Kinetics of the Higher Alcohol Synthesis over a K-Promoted Cuo/Zno/Al2o3 Catalyst, Ind Eng Chem Res, 33(9), p. 2021 (1994).
[6] Quarderer Q.J. et al., Catalytic Process for Producing Mixed Alcohols from Hydrogen and Carbon Monoxide, PCT Int. Pat. Publication No. WO84/03696 (1984).
[7] Kinkade N.E., Process for Producing Alcohols from Carbon Monoxide and Hydrogen Using an Alkali-Molybdenum Sulfide Catalyst, PCT Int. Pat. Publication No. WO 85/03073 (1985).
[8] Jackson G.R. et al., Method for Production of Mixed Alcohols from Synthesis Gas, U.S. Patent 6,248,796 (2001).
[9] Chaumette P., Courty P., Durand D., Grandvallet P., Travers C., Process for Synthesizing a Mixture of Primary Alcohols from a Synthesis Gas in the Presence of a Catalyst Containing Copper, Cobalt, Zinc, and Aluminum, GB Patent, 2,158,730 (1985).
[10] Woo H.C., Park K.Y., Mixed Alcohol Using Molybdenum Carbide Catalysts, Applied Catalysis, 75, p. 267 (1991).
[11] Jiang M., Bian G.-Z., Fu Y.-L., The Structure of Oxidic and Sulfided Mo Catalysts Supported on Activated Carbon was Studied by Means of X-Ray Diffraction, J. of Catalysis, 146, p. 144 (1994).
[12] Lee J.S., Kim S., Lee K.H., Nam I.-S., Chung J.S., Kim Y.G., Woo H.C., Effect of the K-Mo Interaction in K-MoO3/γ-Al2O3 Catalysts on the Properties for Alcohol Synthesis from Syngas, Applied Catalysis, 110, p. 11 (1994).
[13] Tatsumi T., Muramatsu A., Yokota K., Tominga H., Mechanistic Study on the Alcohol Synthesis over Molybdenum Catalysts: Addition of Probe Molecules to CO-H2, J. of Catalysis, 115, p. 388 (1989).
[14] Iranmahboob J., Toghiani H., Hill D.O., Dispersion of Alkali on the Surface of Co-MoS2/Clay Catalyst: a Comparison of K and Cs as a Promoter for Synthesis of Alcohol,  Applied Catalysis, 247, p. 207 (2003).
[15] Okamoto Y., Nakano H., Shimokawa T., Imanaka T., Teranishi S., Stabilization Effect of Co for Mo Phase in Co-Mo/Al2O3 hydrodesulfurization Catalysts Studied with X-Ray Photoelectron spectroscopy, J. of Catalysis, 50, p. 447 (1977).
[16] Murchison C., Conway M., Steven R., Quarderer G., Proceedings of the 9th International Congress on Catalyst, 2, p. 626 (1988).
[17] van Steen E., Prinsloo F.F., Comparison of Preparation Methods for Carbon Nanotubes Supported Iron Fischer-Tropsch Catalysts, Catalysis Today, 71, p. 327 (2002).
[18] Surisetty V.R., Tavasoli A., Dalai A.K., Synthesis of Higher Alcohols from Syngas over Alkali Promoted MoS2 Catalysts, Applied Catalysis, 365, p. 243 (2009).
[19] Surisetty V.R., Dalai A.K., Kozinski J., Intrinsic Reaction Kinetics of Higher Alcohol Synthesis from Synthesis Gas Over a Sulfide Alkali-Ppromoted Co-Rh-Mo Trimetallic Catalyst Supported on MWCNTs, Energy Fuels, 24, p. 4130 (2010).
[20] Surisetty V.R., Dalai A.K., Kozinski J., Influence of Porous Characteristics of the Carbon Support on Alkali-Modified Trimetallic Co-Rh-Mo Sulfided Catalysts for Higher Alcohols Synthesis from Synthesis gas, Applied Catalysis, 393, p. 50 (2011).
[21] Surisetty V.R., Dalai A.K., Kozinski J., Effect of Rh Promoter on MWCNT-Supported Alkali-Modified MoS2 Catalysts for Higher Alcohols Synthesis from CO Hydrogenation, Applied Catalysis, 381, p. 282 (2010).
[22] Surisetty V.R., Dalai A.K., Kozinski J., Synthesis of Higher Alcohols from Synthesis Gas Over Co-Promoted Alkali-Modified MoS2 Catalysts Supported on MWCNTs, Applied Catalysis, 358, p. 153 (2010).
[23] Tavasoli A., Karimi S., Nikookar H., Fadakar H., Molybdenum Loading Effects on the Physico-chemical Properties and Performance of Carbon Nanotubes Supported Alkalized MoS2 Catalysts for Higher Alcohols Synthesis, Iran. J. Chem. & Chem. Eng.(IJCCE), 32(1) p. 1 (2012).
[24] Sun M., Nelsona A.E., Adjaye J., On The Incorporation of Nickel and Cobalt Iinto MoS2-edge Structures, J. of Catalysis, 226, p. 32 (2004).
[25] Topsøe H., Clausen B.S., Massoth F.E., Hydrotreating Catalysis, Science and Technology, 11, p. 31 (1996).
[26] Tavasoli A., Sadaghiani K., Nakhaeipour A., Ahangari M.G., Cobalt Loading Effects on the Structure and Activity for Fischer-Tropsch and Water-Gas Shift Reactions of Co/Al2O3 Catalysts, Iran. J. Chem. & Chem. Eng.(IJCCE), 26(4), p. 9 (2007).