Applied Catalysis A: General, Vol.231, No.1-2, 243-251, 2002
Aromatization of propene and n-butene over H-galloaluminosilicate (ZSM-5 type) zeolite
Aromatization of propene and n-butene (at 400 degreesC and atmospheric pressure) over H-GaAlMFI zeolite (bulk Si/Al = 37.5, bulk Si/Ga = 24.3, framework (FW) SUM = 40.3, FW Si/Ga = 49.9, non-FW Ga = 0.32mmol g(-1), crystal size = 5.5 +/- 1.5 muM) having high acidity (pyridine chemisorbed at 400degreesC = 0.46 mmol g(-1)) has been investigated at different space velocities (3100-58100cm(3) g(-1) h(-1)). The catalyst was found to have a high olefin aromatization activity and high aromatics selectivity, these are attributed to the presence of a large number of both non-framework Ga-species and protonic acid sites. The product selectivity and distribution were strongly influenced by the space velocity. The distributions of aromatics and xylene isomers are found to be similar for the aromatization of both propene and n-butene, but that of aliphatic hydrocarbons differed in the two cases. The propene and n-butene aromatization reactions involve both the protonic acid sites mediated hydride transfer reactions and the direct dehydrogenation reactions over non-framework Ga-species, probably in combination with the zeolitic protons. A reaction path for the propene/n-butene aromatization is proposed.
Keywords:aromatization of propene;aromatization of n-butene;H-galloaluminosilicate (ZSM-5 type) zeolite reaction path for olefin aromatization