Amorphous molybdenum sulfide nanocatalysts simultaneously realizing efficient upgrading of residue and synergistic synthesis of 2D MoS2 nanosheets/carbon hierarchical structures†
Slurry-phase hydrocracking employing a dispersed catalyst is an efficient technology for the upgrading of residue to clean fuels. The green synthesis of 2D nanosheet hierarchical composites when carrying out some intrinsic functionalities is interesting for both scientific and technological applications. Herein, we present our effort in simultaneously enhancing the residue upgradation and synergistic fabrication of 2D MoS2 nanosheets/carbon hierarchical structures based on amorphous molybdenum sulfide nanocatalysts. The amorphous molybdenum sulfide nanocatalysts (MoSx-AM, x ≈ 2.79) are constructed in an inverse microemulsion system and are then either modified by oleic acid to synthesize oleophilic MoSx nanocatalysts (MoSx-OL) or annealed to obtain MoS2 nanocatalysts with the typical layered structure (denoted as MoSx-AN). Benefiting from the decomposition into 2D MoS2 nanosheets with a length less than 20 nm during the residue slurry-phase hydrocracking, MoSx-AM and MoSx-OL exhibit superior hydrogenation and anti-coke activity compared with MoSx-AN. X-ray photoelectron spectroscopy and density functional theory (DFT) calculation reveal that the residue macromolecules with a polycyclic aromatic structure and heteroatoms show strong interaction with 2D MoS2 nanosheets, which disturbs the formation of a layered-structure of MoS2 and results in isolated 2D MoS2 nanosheets. The generated 2D MoS2 nanosheets with abundant active sites lead to the superior performance in residue slurry-phase hydrocracking. These results demonstrate a dispersed nanocatalyst for slurry-phase hydrocracking and also provide a perspective for the anti-coke of petroleum refining. In particular, this process also enabled the dispersed 2D MoS2 nanosheet/carbon hierarchical structure formation synergistically.