Study of dibenzothiophene adsorption over carbon nanotube supported CoMo HDS catalysts

Thiophene, dibenzothiophene (DBT), and its alkyl derivatives are the most common sulfur containing organic molecules existing in the petroleum-derived feed-stocks. Adsorption properties of DBT on a carbon nanotube (CNT) support as well as on CoMoS/CNT and CoMoO/CNT catalysts were studied. There were no obvious differences in the XRD patterns between CoMoO/γ-Al2O3 and CoMoS/γ-Al2O3 indicating that all the active phases are smaller than 2 nm and could not be detected. Again, DBT diffractions were not detected, giving the evidence that the DBT is well dispersed on the γ-Al2O3 and on the supported catalyst. The adsorption amount of DBT on the CoMoO/CNT was smaller than on the CNT carrier alone, but the adsorption amount on the CoMoS/CNT was twice as great as on the CNT. The sulfide catalyst adsorbed much more DBT molecules than the corresponding oxide catalyst. Activated carbon (AC) had the strongest adsorption ability for DBT molecules among CNT, AC, and γ-Al2O3. Similarly, among the three oxide catalysts, the CoMo/AC has the highest adsorption ratio towards DBT.