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Catalytic para ‐xylene maximization: III. Hydroisomerization of meta ‐xylene on H‐ZSM‐5 catalysts containing different platinum contents
Author(s) -
AboulGheit A K,
AbdelHamid S M,
Mohamed S Z,
ElDesouky D S
Publication year - 1999
Publication title -
journal of chemical technology and biotechnology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.64
H-Index - 117
eISSN - 1097-4660
pISSN - 0268-2575
DOI - 10.1002/(sici)1097-4660(199908)74:8<771::aid-jctb98>3.0.co;2-d
Subject(s) - catalysis , chemistry , isomerization , zsm 5 , platinum , desorption , xylene , zeolite , inorganic chemistry , hydrogen , ammonia , toluene , adsorption , organic chemistry
Hydroisomerization of meta ‐xylene was carried out using catalysts containing 0.15–0.60 wt% Pt on H‐ZSM‐5 zeolite, in a pulsed microreactor system connected to a gas chromatograph at a flow of hydrogen of 20 cm 3 min −1 and temperatures of 275–500 °C. Increasing temperature, increased isomerization with low rates. Increasing Pt content of the catalyst, decreased hydrodealkylation considerably via masking strong acid sites as revealed by temperature programmed desorption of ammonia measurements. Formation of trimethylbenzenes was inhibited by Pt incorporation in the H‐ZSM‐5 zeolite. The activation energies obtained for meta ‐xylene hydroisomerization were relatively low (24.4–61.6 kJ mol −1 ) on all catalysts under study. Para ‐xylene yields in the xylenes mixture of product relative to the corresponding thermodynamic equilibrium values amount to about 0.8–0.9 at temperatures of 400–500 °C but were lower at lower temperatures. © 1999 Society of Chemical Industry