Evidence for the presence of a bimolecular pathway in the isomerization of xylene on some large-pore zeolites

Journal Article · Wed May 01 00:00:00 EDT 1991 · Journal of Catalysis; (USA)

DOI:https://doi.org/10.1016/0021-9517(91)90021-U· OSTI ID:5542929

Corma, A ^[1]; Sastre, E ^[2]

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1. Universidad Politecnica de Valencia (Spain)
2. Instituto de Catalisis y Petroleoquimica, Madrid (Spain)

Using deuterated para-xylene as a reactant, the authors have found that more than 20% of the meta- and ortho-xylenes, obtained when using a HY zeolite as catalyst, are formed via a bimolecular mechanism. This involves, as an intermediate complex, a molecule of trimethylbenzene and another of xylene. The bimolecular process is less important in the case of mordenite, and does not occur in Zeolite Beta at low levels of conversion. The relative proportion of uni- to bimolecular mechanism depends on: reaction conditions, zeolite composition, and zeolite structure. Some of the mechanistic conclusions, reached when using xylene isomerization and transalkylation as a test reaction on faujasite zeolites, should be revised in light of these results. Finally, transalkylation between trimethylbenzenes and xylenes is proposed as a test reaction for 12 membered-ring (MR) zeolites since structural differences can be better established than when the conventional xylene isomerization-transalkylation reaction is used.

• OSTI ID: 5542929
• Journal Information: Journal of Catalysis; (USA), Vol. 129:1; ISSN 0021-9517
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
XYLENE-PARA
ISOMERIZATION
ZEOLITES
CATALYTIC EFFECTS
ALKYLATION
CHEMICAL REACTION KINETICS
DEUTERIUM
FAUJASITE
LABELLED COMPOUNDS
MICROSTRUCTURE
MORDENITE
REACTION INTERMEDIATES
XYLENES
ALKYLATED AROMATICS
AROMATICS
CHEMICAL REACTIONS
CRYSTAL STRUCTURE
HYDROCARBONS
HYDROGEN ISOTOPES
INORGANIC ION EXCHANGERS
ION EXCHANGE MATERIALS
ISOTOPES
KINETICS
LIGHT NUCLEI
MATERIALS
MINERALS
NUCLEI
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
REACTION KINETICS
SILICATE MINERALS
STABLE ISOTOPES
020400* - Petroleum- Processing
400201 - Chemical & Physicochemical Properties