Effect of hydrogen on the cracking mechanisms of cycloalkanes over zeolites

Pedro Castaño, José M. Arandes, Martin Olazar, Javier Bilbao, Bárbara Pawelec, Ulises Sedrán

Research output: Contribution to journalArticlepeer-review

15 Scopus citations

Abstract

Hydrocracking of secondary interest refinery streams (high aromatic content) can yield valuable products for transportation and petrochemical industry. In order to promote the hydrogenation and cracking steps, a bifunctional catalyst (metal + acid function) is required. We have studied the effect of the operating conditions on cycloalkane (product of aromatic hydrogenation) ring opening over a monofunctional HZSM-5 zeolite, by focusing on the effect of hydrogen in the cracking mechanisms. Methylcyclohexane has been selected as the test reactant and the conditions used corresponds to temperature, 250-450 °C; space velocity, 0.7-1.1 h-1; pressure, 2-80 bar; hydrogen/methylcyclohexane molar ratio, 1-79; conversion, 0-100% (integral reactor). At these conditions the zeolite catalyses hydrogenation as well as cracking (bifunctional capabilities), thus the cracking mechanisms are directly affected by hydrogen as products (alkenes) and intermediates (carbenium ions) are saturated. The overall effect of rising hydrogen partial pressure is an enhancement of (hydro)isomerization and monomolecular cracking, that is, an increase of the yield/selectivity of methane, ethane, penthane and isoalkanes. © 2009 Elsevier B.V. All rights reserved.
Original languageEnglish (US)
JournalCatalysis Today
Volume150
Issue number3-4
DOIs
StatePublished - Mar 30 2010
Externally publishedYes

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