Achieving ultra-deep hydrodesulfurization means enabling removal of the last fractions of sulfur, contained in refractory molecules, from oil. Improving the state-of-the-art Co-promoted MoS₂ (CoMoS) catalyst or the development of novel catalysts is crucial for this. Improving CoMoS requires more insight in the way sulfur containing molecules interact with it. Herein, we model the adsorption of sulfur containing molecules on the S-edge, M-edge, corner and basal plane of CoMoS using density functional theory. The obtained adsorption configurations and energies point to a preference towards physisorption at the S-edge and chemisorption in vacancies at the M-edge and corner. Smaller molecules, such as thiophene and methylthiol, were found to prefer vacancies when adsorbing while larger, sterically hindered molecules as 4,6-dimethyldibenzothiophene prefer physisorption on the brim of the edges or the basal plane through van der Waals interactions. Hydrogenation generally leads to a preference towards adsorption at vacancies for thiophene and dibenzothiophene while for 4,6-dimethyldibenzothiophene hydrogenation leads to preferential adsorption on the S-edge brim, possibly explaining why 4,6-dimethyldibenzothiophene does not get desulfurized directly but follows a hydrogenation route. Thiolate formation energies were also calculated for the different molecules and used to predict which sites are most likely to be involved in breaking carbon-sulfur bonds. The thiolate formation energies show the inert nature of the basal plane towards breaking carbon-sulfur and sulfur-hydrogen bonds. Additionally, activation energies for thiophene and dibenzothiophene carbon-sulfur bond scission indicate that both molecules follow the direct desulfurization route on under-coordinated sites or vacancies.

实现超深度加氢脱硫意味着能够从油中去除耐火分子中所含的最后一部分硫。改进最新的共同推广MoS ₂（CoMoS）催化剂或新型催化剂的开发对此至关重要。改善CoMoS需要对含硫分子与之相互作用的方式有更多的了解。在本文中，我们使用密度泛函理论模拟了含硫分子在CoMoS的S边缘，M边缘，拐角和基面上的吸附。所获得的吸附构型和能量指向在S边缘的物理吸附和在M边缘和角落的空位的化学吸附的偏爱。发现较小的分子（例如噻吩和甲基硫醇）在吸附时更喜欢空位，而较大的，空间受阻的分子（例如4,6-二甲基二苯并噻吩）更喜欢通过范德华相互作用在边缘或基面边缘上进行物理吸附。氢化通常导致噻吩和二苯并噻吩更倾向于在空位处吸附，而4,6-二甲基二苯并噻吩的氢化导致S边沿上发生优先吸附，这可能解释了为什么4,6-二甲基二苯并噻吩不会直接脱硫而是在氢化后发生路线。还计算出了不同分子的硫醇盐形成能，并用来预测哪些位置最有可能参与破坏碳硫键。硫醇盐的形成能显示出基面对打破碳-硫键和硫-氢键的惰性性质。此外，噻吩和二苯并噻吩碳-硫键断裂的活化能表明，这两个分子在配位不足的位点或空位上都遵循直接脱硫的路线。