Page 363 - Adsorbents - fundamentals and applications

348 SORBENTS FOR APPLICATIONS

9 1
8 2

7 3
S
6 4
5
Dibenzothiophene
Figure 10.50. Dibenzothiophene (DBT). Alkylated DBT with alkyl (e.g., methyl) groups at the 4-
and 6-positions, that is, 4-MDBT and 4,6-DMDBT, are the refractory sulfur compounds that are
most difficult to remove by HDS or sorbents aiming at bonding with S due to steric hindrance.

Gasoline
2-MT 3-MT
BT
T 2,4-DMT

2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38
2,3,7-TMBT
2,3-DMBT
Jet fuel (JP-8)
2,3,5-TMBT +
2,3,6-TMBT

2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38
2,3,5-TMBT + 4-MDBT 4,6-DMDBT
Diesel 2,3,6-TMBT 3,6-DMDBT
2-MDBT + 2,4,6-TMDBT
2,3,7-TMBT
3-MDBT 4-E,6-MDBT
1,4,6-TMDBT
DBT
2,3-DMBT

2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38
Retention time (min)
Figure 10.51. GC-FPD (flame photometric detector — for sulfur only) chromatograms for three
transportation fuels (Ma et al., 2001, with permission).

2,3,7-TMBT, 2,3-DMBT, and the minor species 2,3,5-TMBT and 2,3,6-TMBT.
The more detailed analyses of a diesel fuel by Ma et al. (1994) showed 61 sulfur
compounds. These were, again, almost exclusively alkyl benzothiophenes and
alkyl dibenzothiophenes. An example for the sulfur composition of gasoline is
given in Table 10.13.