Simultaneous hydrodesulfurization of dibenzothiophene and substituted dibenzothiophenes over phosphorus modified CoMo/Al₂O₃ catalysts

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• 作者：Syed A. Ali^a ; Shakeel Ahmed^a ; ^{shakeel@kfupm.edu.sa} ; Khaja W. Ahmed^b ; Muhammad A. Al-Saleh^b
• 关键词：CoMo/Al2O3 ; Phosphorous addition ; Hydrodesulfurization ; DBT ; 4-MDBT ; 4 ; 6-DMDBT
• 刊名：Fuel Processing Technology
• 出版年：2012
• 期刊代码：36_03783820
• 类别：ce
• 出版时间：June, 2012
• 卷：98
• 期：Complete
• 页码：39-44
• 文件大小：1882 K

摘要

Phosphorous modified CoMo/纬-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_DBT/k_4,6-DMDBT ratio was about 6-7. Modification of CoMo/纬-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.