Abstract
Analyses of a series of published n-hexane hydroisomerization product slates suggest that MAZ-type zeolites yield more dimethylbutane and less methylpentane than either FAU- or MOR-type zeolites. Molecular simulations do not corroborate the traditional view that these selectivity differences are specifically related to the MAZ-, FAU-, or MOR- type zeolite topology. A scrutiny of the literature indicates that reported variation in selectivity relates to a variation in the efficiency of the (de)hydrogenation function relative to the acid function. The FAU-type zeolite catalyst had the most efficient hydrogenation function. The efficiency of the hydrogenation function on the MAZ-type zeolite was low enough to significantly enhance the 2,3-dimethylbutane yield relative to the methylpentane yield, but not low enough to decrease the 2,2-dimethylbutane yield. The efficiency of the hydrogenation function on the MOR-type zeolite was low enough to do both. Only at a sufficiently high n-hexane hydroconversion does the catalyst with the most efficient hydrogenation function exhibit the highest dimethylbutane yield. This new perspective on the reported hexane hydroconversion selectivities suggests that a FAU-type zeolite catalyst with a highly efficient hydrogenation function is best suited for n-hexane hydroisomerization. The FAU topology has the highest porosity which should afford the highest activity without impairing selectivity.
Original language | English |
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Pages (from-to) | 121-129 |
Number of pages | 9 |
Journal | Journal of Catalysis |
Volume | 228 |
Issue number | 1 |
DOIs | |
Publication status | Published - 15 Nov 2004 |
Externally published | Yes |
Keywords
- FAU-type zeolite
- Kinetics
- MAZ-type zeolite
- MOR-type zeolite
- n-Hexane hydroconversion
- Shape selectivity