1
54
G. Burnens et al. / Journal of Catalysis 282 (2011) 145–154
Table 3
Branchiness of hydrocracked products from pristane on Pt/US-Y catalyst.
Experimental condition
T (°C)
Hydrocracking yield
Mol/100 mol pristane cracked
Average branchiness of cracked products
%
Experimental
In absence of change of branchinessa
A
B
C
D
E
222
233
243
253
263
7.5
217
209
208
212
216
1.5
1.4
1.4
1.4
1.4
1.4
1.4
1.4
1.4
1.4
14.2
26.4
48.2
70.1
a
Assuming absence of changes of branchiness of pristane skeletal isomers undergoing.
to be suppressed [36,37]. Molecular modeling efforts will be
needed to evaluate the validity of such hypothesis.
[2] J.A.R. van Veen, J.K. Minderhoud, L.G. Huve, W.H.J. Stork, Hydrocracking and
Catalytic Dewaxing, Handbook of Heterogeneous Catalysis, 2008, p. 2778.
[
[
[
[
[
3] M. Stöcker, Angew. Chem. Int. Ed. 47 (2008) 9200.
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5] M. Höök, Int. J. Energy Res. 34 (2010) 848.
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7] A. de Klerk, Green Chem. 10 (2008) 1249.
4
. Conclusions
Pristane (2,6,10,14-tetramethylpentadecane) is a convenient
[8] N.H. Tran, J.R. Bartlett, Fuel 89 (2010) 265.
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[12] J. Weitkamp, Ind. Eng. Chem. Res. Dev. 21 (1982) 550.
13] J.A. Martens, P.A. Jacobs, in: J.B. Moffat (Ed.), Theoretical Aspects of
Heterogeneous Catalysis, Van Nostrand Reinhold, New York, 1990, p. 52.
14] J.A. Martens, P.A. Jacobs, J. Weitkamp, Appl. Catal. 20 (1986) 239.
[15] J.A. Martens, P.A. Jacobs, in: E.G. Derouane (Ed.), Zeolite Microporous Solids:
Synthesis, Structure, and Reactivity, Kluwer Academic, 1993, p. 511.
[
model molecule for investigating hydrocracking reaction pathways
of heavy multibranched alkanes with discarded methylbranched
contained in renewable hydrocarbon feedstocks. Analysis of the
reaction products from pristane skeletal isomerization and hydro-
cracking on silica–alumina and ultrastable Y zeolite catalyst re-
vealed a peculiar selectivity. Both catalysts caused methyl shifts
but did not alter the degree of branching of the tetrabranched pris-
tane molecule. The zeolite aselectively altered the position of the
four methyl groups along the main chain, while the silica–alumina
favored positional shifting of the two inner methyl groups. On both
catalysts at low hydrocracking conversion, one specific hydro-
cracking pathway leading to 2-methylpentane and 2,6-dimethyl-
undecane was strongly favored. This hydrocracking reaction can
be explained by type C (sec ? sec) b-scission of an alkylcarbenium
1
[
[
[
[
[
16] J.A. Martens, P.A. Jacobs, J. Catal. 124 (1990) 357.
17] J. Weitkamp, P.A. Jacobs, J.A. Martens, Appl. Catal. 8 (1983) 123.
[18] M. Steijns, G.F. Froment, P.A. Jacobs, J.B. Uytterhoeven, J. Weitkamp, Ind. Eng.
Chem. Prod. Res. Dev. 20 (1981) 654.
19] M. Steijns, G.F. Froment, Ind. Eng. Chem. Res. Dev. 20 (1981) 660.
20] M.A. Baltanas, H. Vansina, G. Froment, Ind. Eng. Chem. Prod. Res. Dev. 22
(1983) 532.
21] J.A. Martens, M. Tielen, PA. Jacobs, Catal. Today 1 (1987) 435.
22] J.A. Martens, P.A. Jacobs, J. Weitkamp, Appl. Catal. 20 (1986) 283.
23] M. Steijns, G.F. Froment, P.A. Jacobs, J.B. Uytterhoeven, J. Weitkamp, Erdol
Kohle Erdgas Petrochem. 31 (1978) 581.
24] J.A. Martens, M. Tielen, P.A. Jacobs, in: H.G. Karge, J. Weitkamp (Eds.), Zeolites
as Catalysts, Sorbents and Detergent Builders, Stud. Surf. Sci. Catal., Elsevier
Science Publishers B.V., Amsterdam, 1989, p. 51.
[25] J.W. Thybaut, I.R. Choudhury, J.F. Denayer, G.V. Baron, P.A. Jacobs, J.A. Martens,
Top. Catal. 52 (2009) 1251.
26] J. Avignan, M. Blumer, J. Lipid Res. 9 (1968) 350.
27] B. Valderrama, Stud. Surf. Sci. Catal. 151 (2004) 373.
28] R.J. Taylor, R.H. Petty, Appl. Catal. A: Gen. 119 (1994).
[
[
[
[
[
4
ion charged at C derived from the pristane molecule. Even at low
hydrocracking conversion, the primary 2,6-dimethylundecane
fragment underwent another cracking into n-pentane and 2-meth-
ylheptane. At higher conversions, the fingerprint of pristane in the
cracked products was less apparent because of skeletal isomeriza-
tion. On both catalysts, the hydrocracking occurred preferentially
at carbon–carbon bonds next to the inner methylbranchings lead-
ing to a monobranched and a dibranched fragment. This investiga-
tion revealed that kinetic models for hydrocracking of linear
alkanes in which scissions of alkylcarbenium ions of a same type
are considered to occur at a same rate will be inadequate for a
description of hydrocracking of heavy multibranched isomers. Pris-
tane can serve as a new paradigm for that type of catalytic
chemistry.
[
[
[
[
[29] K.P. de Jong, J. Ze cˇ evi c´ , H. Friedrich, P.E. de Jongh, M. Bulut, S. van Donk, R.
Kenmogne, A. Finiels, V. Hulea, F. Fajula, Angew. Chem. Int. Ed. 12 (2010)
10272.
[
30] E. Valery, D. Guillaume, K. Surla, P. Galtier, J. Verstraete, D. Schweich, Ind. Eng.
Chem. Res. 46 (2007) 4755.
31] M.C. Claude, J.A. Martens, J. Catal. 190 (2000) 39.
32] M.C. Claude, G. Vanbutsele, J.A. Martens, J. Catal. 203 (2001) 213.
33] G. Hastoy, E. Guillon, J.A. Martens, Stud. Surf. Sci. Catal. 158B (2005) 1359.
34] G.G. Martens, G.B. Marin, J.A. Martens, P.A. Jacobs, G.V. Baron, J. Catal. 195
[
[
[
[
(
2000) 253.
35] J.W. Thybaut, G.B. Marin, G.V. Baron, P.A. Jacobs, J.A. Martens, J. Catal. 202
2001) 324.
[36] C.S. Laxmi Narasimhan, J.W. Thybaut, G.B. Marin, P.A. Jacobs, J.A. Martens, J.F.
Denayer, G.V. Baron, J. Catal. 220 (2003) 399.
Acknowledgment
[
(
J.A.M. acknowledges the Flemish government for long-term
structural funding (Methusalem).
[
37] W. Souverijns, J.A. Martens, G.F. Froment, P.A. Jacobs, J. Catal. 174 (1998)
77.
1
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