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1775293 
Journal Article 
Simultaneous hydrodesulfurization of dibenzothiophene and substituted dibenzothiophenes over phosphorus modified CoMo/Al2O3 catalysts 
Ali, SA; Ahmed, S; Ahmed, KW; Al-Saleh, MA 
2012 
Yes 
Fuel Processing Technology
ISSN: 0378-3820 
98 
39-44 
WOS:000303034000006 
Phosphorous modified CoMo/gamma-Al2O3 catalysts, containing
0.0 to 1.5 wt.% P2O5, were prepared by incipient wetness co-impregnation method. X-ray
diffraction results showed increase in MoO3 and CoMoO4 phases with the addition of phosphorous.
Pseudo-first order hydrodesulfurization (HDS) rates via direct desulfurization (DDS) and
hydrogenation (HYD) pathways were determined for simultaneous conversion of dibenzothiophene
(DBT) and 4-methyl DBT (4-MDBT) as well as DBT and 4,6-dimethyl DBT (4,6-DMDBT) in an autoclave
reactor at 6.2 MPa and 573-623 K. The k(DBT)/k(4-MDBT) ratio was 2-3, while the k(DBR)/k(4,6-
DMDBT) ratio was about 6-7. Modification of CoMo/gamma-Al2O3 catalysts by phosphorus addition
strongly increased the HDS activity and the maximum enhancement was achieved with 1.0 wt.% P2O5.
Results show that HDS of DBT and 4-MDBT proceed mainly via DDS pathway, whereas 4,6-DMDBT
exhibits preference towards HYD pathway. Due to competition for the DDS active sites, the DBT
conversion was lower in the presence of 4-MDBT than 4,6-DMDBT. Enhancement in HDS rates due to
1.0 wt.% P2O5 addition at 623 K was in the following order: 4,6-DMDBT (51%)>4-MDBT (38%) > DBT
(26%). Since 4,6-DMDBT is one of the most refractive sulfur compounds in the diesel fuel,
enhancement in its HDS rate by about 50% will substantially contribute in achieving the 10-15 ppm
sulfur level. (C) 2012 Elsevier B.V. All rights reserved. 
CoMo/Al2O3; Phosphorous addition; Hydrodesulfurization; DBT; 4-MDBT; 4,6-DMDBT