Preparation of MoS2@GQDs for Slurry-Phase Hydrotreating of Waste Oil to Produce Biohydrogenated Diesel.

Graphene quantum dots (GQDs) were prepared by acid oxidation with deoiled asphalt (DOA) as the precursor. MoS2 was grown in situ on the surface of GQDs to obtain MoS2@GQDs utilized for slurry-phase hydrotreating of palm acid oil (PAO) to produce biohydrogenated diesel (BHD). The confinement effect of GQDs is attributed to the functional groups, which effectively restricts the agglomeration of MoS2 and contributes to its uniform distribution. There is a positive correlation between Mo loading and particle size of MoS2@GQDs. MoS2@GQDs with 10 wt % Mo loading (0.10MoS2@GQDs) exhibited suitable an average particle size of 121.11 nm, resulting in the lower extent of agglomeration. The degree of sulfurization (the proportion of Mo4+ in the Mo metal) increased with elevating temperature, reached a maximum of 63.77% at 350 °C, and subsequently decreased upon further temperature increase. 0.10MoS2@GQDs synthesized at 350 °C for 2 h exhibited the best catalytic performance. The BHD yield of 82.53 wt % and the PAO conversion of 102.38 wt % were obtained at a temperature of 380 °C, a residence time of 1 h, an initial H2 pressure of 6 MPa, and 1 wt % 0.10MoS2@GQDs.