Deep desulfurization of fuel oil is essential for environmental protection and clean energy production. Herein, to overcome the limitations of commonly used adsorbents for adsorption desulfurization, the metal-organic framework material MFM-170 was investigated for removing typical thiophene compounds, i.e., dibenzothiophene, 4-methyldibenzothiophene, and 4,6-dimethyldibenzothiophene, from simulated oil. A systematic optimization of the adsorption conditions revealed that at 40 degrees C and an oil-to-adsorbent ratio of 300, the adsorption of the three thiophene compounds on MFM-170 reached equilibrium within 5 min, with saturation adsorption capacity values of 57, 44, and 37 mg S/g. MFM-170 demonstrated excellent reusability, retaining 93% of its initial adsorption capacity for dibenzothiophene after seven adsorption-desorption cycles. The adsorption data were well fitted by the Freundlich isotherm model and the pseudo-second-order kinetic equation, indicating a multilayer adsorption process dominated by chemisorption. Mechanistic analyses revealed that the open Cu(II) active sites rapidly adsorb thiophene compounds via coordination to the S atoms and pi-pi stacking interactions. This study demonstrates the promising application potential of MFM-170 in the deep desulfurization of fuel oil.
Effective water and heat management is essential for sustaining efficient electrochemical performance in proton exchange membrane fuel cells. Structural variations in the gas diffusion layer (GDL) markedly affect water removal and heat accumulation. Particularly, GDL multilayering has attracted increasing attention for optimizing local transport. However, the underlying microscopic mechanisms remain unclear. This work employs the lattice Boltzmann method to investigate microscopic coupling mechanisms by which GDL multilayering affects water removal and heat accumulation. The results indicate that increasing porosity in single-layer GDLs reduces capillary resistance, which broadens dominant water removal paths and intensifies localized heat accumulation, whereas excessive porosity weakens capillary effects, thus exacerbating water blockage. With GDL multilayering, an increasing porosity gradient along the through-plane direction establishes a capillary-pressure gradient, further enhancing water removal and heat accumulation until interlayer porosity differences become excessive. Unlike the single-layer case, heat accumulation is markedly mitigated beyond the turning point due to the combined effects of higher local water content and fiber fraction. A decoupled analysis was conducted to elucidate how water removal and heat accumulation affect the reaction rate through oxygen concentration and the rate constant, respectively. In single-layer GDLs, the determinant of reaction rate is the temperature-dependent rate constant, but shifts to oxygen concentration at excessive porosity. In multilayer GDLs, the determinant of reaction rate is the temperature-dependent rate constant when the porosity gradient decreases, whereas it shifts to oxygen concentration as the porosity gradient increases, but reverts to the temperature-dependent rate constant when interlayer porosity differences become excessive.
The sorption-enhanced biomass gasification with CaO-based materials exhibits considerable potential for simultaneous CO2 mitigation and hydrogen generation. However, activity attenuation of CaO-based materials over extended cyclic processes has limited their industrial applications. In this work, the improvement in cyclic stability of the materials is enhanced by Ni/Ce doping, and the sintering kinetics and tar cracking mechanisms are elucidated using combined density functional theory with experimental investigations. The results demonstrate that doping with Ni and Ce is found to reduce the band gap and introduce new states neighboring the Fermi level, which facilitate electron migration to stabilize reaction transition states. Therefore, the intrinsic kinetic barrier is reduced. The formation energies of the doped surfaces are significantly reduced, indicating enhanced intrinsic stability. Ca4O4 cluster adsorption is used to assess sintering resistance, which reveals that Ni aggravates sintering, while Ce stabilizes the lattice and suppresses Ni agglomeration. Cyclic CO2 capture tests indicate that Ni doping enhances initial activity, while Ce doping effectively suppresses high-temperature sintering, and high CO2 capture performance is obtained during 20 cycles. Toluene is physically adsorbed on the surfaces, and its adsorption energy is nearly doubled by doping. The ring-opening of toluene is calculated to be the rate-determining step on the CaO-based material surfaces, and the activation barrier is reduced by Ni and Ce doping. The synergistic incorporation of Ni and Ce balances catalytic reactivity and structural stability; thus, Ni/Ce-doped CaO exhibits promising potential to obtain high sintering resistance and tar cracking performance.
