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  • 1 ADEQ and CIEQB, Instituto Superior de Engenharia de Lisboa, Rua Conselheiro Emídio Navarro, 1, 1959-007, Lisbon, Portugal
  • | 2 IBB, Instituto Superior Técnico, Av. Rovisco Pais, 1049-001, Lisbon, Portugal
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Abstract

The bifunctional transformation of n-hexane was carried out over Pt/MCM-22 based catalysts. MCM-22 was synthesized and submitted to ion exchange with rare earth nitrate solutions of La, Nd and Yb, followed by Pt introduction. Three different methods were used to introduce about 1 wt% of Pt in the zeolite: ion exchange, incipient wetness impregnation and mechanical mixture with Pt/Al2O3. The bifunctional catalysts were characterized by transmission electron microscopy and by the model reaction of toluene hydrogenation. These experiments showed that, in the ion exchanged sample, Pt is located both within the inner micropores and on the outer surface, whereas in the impregnated one, the metal is essentially located on the outer surface under the form of large particles. The presence of RE elements increases the hydrogenating activity of Pt/MCM-22 since the location of these species at the vicinity of metal particles causes modification on its electronic properties. Whatever the mode of Pt introduction, a fast initial decrease in conversion is observed for n-hexane transformation, followed by a plateau related to the occurrence of the catalytic transformations at the hemicages located at the outer surface of the crystals. The effect of rare earth elements on the hydrogenating function leads to a lower selectivity in dibranched isomers and increased amounts of light products.

  • 1.

    Directive 2003/17/EC of the European Parliament of the Council amending Directive 98/70/EC relating to the quality of petrol and diesel fuels, 3 Mar 2003.

    • Search Google Scholar
    • Export Citation
  • 2.

    Jensen RH (2002) In: Guisnet M, Gilson J-P (eds) Zeolites for cleaner technologies, vol 3. Imperial College Press, London, pp 75103.

  • 3.

    Alvarez, F, Ribeiro, FR, Perot, G, Thomazeau, C, Guisnet, M (1996) J Catal. 162:179189 .

  • 4.

    Vermeiren, W, Gilson, J-P (2009) Top Catal. 52:11311161 .

  • 5.

    Corma, A, Frontela, J, Lazaro, J, Perez, M (1991) Prep Am Chem Soc Div Pet Chem. 36:833840.

  • 6.

    Gillespie RD , Cohn MJ (2003) (UOP Llc, USA) WO2003020420.

  • 7.

    Martins, A, Silva, JM, Ribeiro, FR, Ribeiro, MF (2005) Stud Surf Sci Catal. 158:18751882 .

  • 8.

    Chica, A, Corma, A (1999) J Catal. 187:167176 .

  • 9.

    Calero, S, Schenk, M, Dubbeldam, D, Maesem, TLM, Smit, S (2004) J Catal. 228:121129 .

  • 10.

    Allain, JF, Magnoux, P, Schulz, Ph, Guisnet, M (1997) Appl Catal A Gen. 152:221235 .

  • 11.

    López-Gaona, A JA De losReyes Aguilar, J, Martín, N (2010) Reac Kinet Mech Catal. 99:177182.

  • 12.

    Rubin MK , Chu P (1990) US Patent 4,595,325.

  • 13.

    Leonowicz, ME, Lawton, SL, Partridge, RD, Chen, P, Rubin, MK (1994) Science. 264:19101913 .

  • 14.

    Beck JS , Dandekar AB, Degnan TF (2002) In: Guisnet M, Gilson J-P (eds) Zeolites for cleaner technologies, vol 3. Imperial College Press, London, pp 223237.

    • Search Google Scholar
    • Export Citation
  • 15.

    Corma, A, Martinez-Triguero, J (1997) J Catal. 16:102120 .

  • 16.

    Park, S-H, Rhee, H-K (2003) React Kin Catal Lett. 78:8189 .

  • 17.

    Ravishankar, R, Sivasanker, S (1996) Appl Catal A Gen. 142:4759 .

  • 18.

    Martins, A, Silva, JM, Ribeiro, FR, Guisnet, M, Ribeiro, MF (2008) Stud Surf Sci Catal. 174:11351138 .

  • 19.

    Martins, A, Silva, JM, Henriques, C, Ramôa Ribeiro, F, Ribeiro, MF (2005) Catal Today. 107–108:663670 .

  • 20.

    Hopkins, PD (1968) J. Catal. 12:325334 .

  • 21.

    Laforge, S, Martin, D, Guisnet, M (2004) Microp Mesop Mater. 67:235 .

  • 22.

    Matias, P, Lopes, JM, Laforge, S, Magnoux, P, Guisnet, M, Ramôa Ribeiro, F (2008) Appl Catal A Gen. 351:174183 .

  • 23.

    Corma, A, Corell, C, Pérez-Pariente, J (1995) Zeolites. 15:28 .

  • 24.

    Boudart, M (1985) J Mol Catal. 30:2738 .

  • 25.

    Chupin, J, Gnep, NS, Lacombe, S, Guisnet, M (2001) Appl Catal A Gen. 206:4356 .

  • 26.

    Zhang, Z, Cui, Z, Chen, KZ, Du, FL, Zhang, Z, Yu, DP (2000) Mater Charact. 44:371374 .

  • 27.

    Chen, J-K, Martin, AM, Kim, YG, John, VT (1998) Ind Eng Chem Res. 27:401409 .

  • 28.

    Roldán, R, Romero, FJ, Jimenez-Sachidrian, C, Marinas, JM, Goméz, JP (2005) Appl Catal A Gen. 288:104115 .