Abstract
Even though dehydrocyclization is widely practiced in heterogeneous catalysis for the conversion of straight chain hydrocarbons into aromatic compounds, knowledge of the mechanism of this process remains limited, largely because it has not previously been possible to carry out the reaction under conditions amenable to detailed mechanistic study. We report here ultra-high vacuum studies of the dehydrocyclization of submonolayer coverages of 1-hexene to benzene on a Cu3Pt(111) single crystal surface. In these studies reflection-absorption infrared spectroscopy (RAIRS) and temperature-programmed reaction/desorption spectroscopy (TPR/D) have been used to investigate the mechanism of the reaction. The results obtained demonstrate that the mechanism involves two steps: dehydrogenation (T = 270 K) and additional dehydrogenation + cyclization (T = 405 K). The RAIRS and TPR/D results suggest that a planar intermediate with C6H8 stoichiometry (probably 1,3,5-hexatriene) exists on the surface between 270 and 405 K. For surface coverages of up to 12.5% of monolayer saturation the selectivity to benzene formation is 70% with the remaining 30% of the adsorbed 1-hexene dehydrogenating irreversibly to surface carbon and H2. For higher coverages, molecular desorption commences.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
F. Garin, S. Aeiyach, P. Legaire and M. Maire, J. Catal. 77 (1982) 323.
J.M. Muller and F.G. Gault, J. Catal. 24 (1972) 361.
F.M. Dautzenberg and J.C. Platteeuw, J. Catal 24 (1972) 364.
A.J. den Hartog, P.J.M. Rek and V. Ponec, J. Chem. Soc. Chem. Commun. (1988) 1470.
H.C. de Jongste, F.J. Kuijers and V. Ponec,Proc. 6h Int. Congr. on Catalysis Vol. 2, London 1976, eds. G.C. Bond, P.E. Wells and F.C. Tompkins (The Chemical Society, London, 1977) p. 915.
H.C. de Jongste, V. Ponec and F.G. Gault, J. Catal. 63 (1980) 395.
J.R.H. van Schaik, R.P. Dessing and V. Ponec, J. Catal. 38 (1975) 273.
A. O'Cinneide and F.G. Gault, J. Catal. 37 (1975) 311.
R.C. Yeates and G.A. Somorjai, J. Catal. 103 (1987) 208.
R.A. Saymeh, H.M. Asfour and S.S. Mahmoud, Indian J. Chem. 34B (1995) 546.
S.M. Davis, F. Zaera and G.A. Somorjai, J. Catal. 85 (1984) 206.
W.D. Gillespie, R.K. Herz, E.E. Petersen and G.A. Somorjai, J. Catal. 70 (1981) 147.
C.J. Jenks, B.E. Bent, N. Bernstein and F. Zaera, J. Am. Chem. Soc. 115 (1993) 308.
G.R. Castro, U. Schneider, H. Busse, T. Janssens and K. Wandelt, Surf. Sci. 269/270 (1992) 321.
U. Schneider, H. Busse, R. Linke, G.R. Castro and K. Wandelt, J. Vac. Sci. Technol. A 12 (1994) 2069;
R. Linke, U. Schneider, H. Busse, C. Becker, U. Schröder, G.R. Castro and K. Wandelt, Surf. Sci. 307 (1994) 407;
C. Becker, U. Schröder, G.R. Castro, U. Schneider, H. Busse, R. Linke and K. Wandelt, Surf. Sci. 307 (1994) 412;
Y.G. Shen, D.J. O'Connor, K. Wandelt and R.J. MacDonald, Surf. Sci. 328 (1995) 21;
Y.G. Shen, D.J. O'Connor, K. Wandelt and R.J. MacDonald, Surf. Sci. 331–333 (1995) 746.
M. Xi and B. Bent, J. Vac. Soc. Technol. B 10 (1992) 2440.
J.-L. Lin and B.E. Bent, J. Am. Chem. Soc. 115 (1993) 2849.
Z. Paál and P. Tétényi, J. Catal. 30 (1973) 350.
A. Papazov, Ch. Bonev, D. Shopov, G. Leitz, A. Sárkány and J. Völter, J. Catal. 103 (1987) 249.
B. Shi and B.H. Davis, in:Proc. 11th Int. Congr. on Catalysis, 40th Anniversary, Baltimore 1996, Studies in Surface Science and Catalysis, Vol. 101, Part B, eds. J.W. Hightower, W.N. Delgass, E. Iglesia and A.T. Bell (Elsevier, Amsterdam, 1996) p. 1145.
P.M. Hoffman, Surf. Sci. Rep. 3 (1983) 107.
Y.J. Chabal, Surf. Sci. Rep. 8 (1988) 211.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Teplyakov, A.V., Bent, B.E. Dehydrocyclization of 1-hexene to benzene on Cu3Pt(111). Catal Lett 42, 1–4 (1996). https://doi.org/10.1007/BF00814459
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00814459