Search

Magnetic nanocomposites provide manifold perspectives for sustainable development. However, the cumbersome operation process and energy consumption after treatment limit its application in the practical industry. Herein, we present a simple and universal strategy to synthesize Fe3O4@PDA@shell nanoparticles via in-situ homogeneous hydrolysis reaction growth different nanomaterials on the PDA modified Fe3O4nanospheres, which can avoid multistep repetitive washing, redispersing, and drying. As an example, we introduced the synthesis process of Fe3O4@PDA@MoS2catalyst used for heavy oil hydrocracking in detail. The synthesis processes were significantly simplified and the dispersity and stability of the nanosized MoS2were improved due to the copious functional groups and strong adhesion properties of polydopamine. The as-prepared Fe3O4@PDA@MoS2nanoparticle catalysts showed high activity and excellent stability. The viscosity of residue was decreased by 99.8% and the recovery of the catalyst reached 90% under harsh conditions (405 ℃ at 13 MPa H2). We also demonstrate the versatility of this strategy for other shell materials, such as WS2, VS2, Pd, and Rh components, which is promising for designing multifunctional core−shell−shell materials for various applications.

Studies on the metal-support interaction have been a key step for deeply understanding the catalytic behavior of hydrodesulfurization (HDS) reactions. In particular, modification of the surface hydroxyl groups on alumina can determine its surface metal species and their dispersion degrees and thus influence the reactivity of catalysts. Herein, magnetic MoS2nanoparticles supported on thiol groups grafted alumina (Fe3O4@Al2O3-SH@MoS2) were synthesized, leading to excellent catalytic hydrodesulfurization performance in a slurry-phase reactor of 40% desulfurization efficiency and high stability of 105 h in the long-term evaluation. Density functional theory calculations and multiple catalyst characterizations demonstrated that the grafting of thiol groups not only significantly weakened the metal-support interaction by bridging the support and active phase but also inhibited the coke formation, improved the cycle performance of the catalyst. This work proves to be an effective method to adjust the metal-support interaction, leading to enhanced catalytic performance. Besides, the magnetic properties of the catalyst enable it to be separated from the reaction media quickly, which is promising to be used in slurry reactors that process heavy crude oil.

Exploring high-efficiency, robust and cost-effective catalysts for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) is greatly desirable. Herein, a series of transition-metal doped MoS2(M-MoS2, M = Mn, Fe, Co, Ni, Cu, Zn) with expanded interlayer spacing are fabricated by one-step solvothermal strategy. Notably, nickel doped molybdenum disulfide (Ni-MoS2) is found to exhibit prominent catalytic activity with an apparent rate constant (K) of 1.09 min-1and excellent stability over six continuous runs of recycling experiments. The results demonstrate that the expanded interlayer spacing (0.94 nm) can increase the active sites of reactant absorption, and Ni dopants can lower the energy level (d‐band center) to facilitate the desorption of H. Thus, the catalytic activity of Ni-MoS2is enhanced by synergistically structural and energy level modulation. This study offers an effective strategy to design transition metal sulfides with higher catalytic reactivity for the environment-related catalysis processes.