C. Kwak et al., Effect of phosphorus addition on the behavior of CoMoS/Al2O3 catalyst in hydrodesulfurization of dibenzothiophene and 4,6-dimethyl dibenzothiophene, APP CATAL A, 185(1), 1999, pp. 19-27
The hydrodesulfurization (HDS) activity of phosphorus-added CoMoS/Al2O3 cat
alysts has been examined using dibenzothiophene (DBT) and 4,6-dimethyldiben
zothiophene (4,6-DMDBT) as reactants. Phosphorus modifies catalytic behavio
r in two ways: increase of active sites by enhanced metal dispersion and in
crease of Bronsted acidity. These effects yield a different distribution of
products depending on the reactants. In thiophene HDS, phosphorus increase
s only the conversion. In DBT HDS, phosphorus increases the conversion and
produces more cyclohexylbenzene (CHB) than biphenyl (BP). In 4,6-DMDBT HDS,
the conversion also increases but more dimethylbiphenyl (DMBP) is produced
than methylcyclohexyltoluene (MCHT), the opposite trend from the one obser
ved in DBT HDS. This is due to enhanced acidity of the catalyst, which allo
ws migration of the methyl groups in 4,6-DMDBT. Maximum conversions are obt
ained when the phosphorus content is proper, 0.5 wt.% in this study. (C) 19
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