Developing New MOF-Based Hybrid Materials for Efficient Adsorptive Desulfurization of a Refractory Sulfur Compound

To reduce threats to human health and the environment, enhance process safety and efficiency, and meet product standards, it is essential to remove organic sulfur compounds from liquid fuels. Activated carbon (AC) was successfully functionalized and incorporated into a chromium-based metal organic framework, namely, MIL-53(Cr), to further enhance its pore structure and surface properties. The synthesized materials were characterized using X-ray diffraction (XRD), N2 adsorption-desorption, Fourier transform infrared (FT-IR) spectroscopy, field-emission scanning wlectron microscopy (FE-SEM), and thermogravimetric analysis (TGA). The adsorption of a refractory sulfur compound, namely, dibenzothiophene (DBT), from model fuels with different initial sulfur concentrations, was investigated over the synthesized adsorbents. For the adsorption of DBT from n-octane over MIL-53(Cr) and AC@MIL-53(Cr) composites, the Temkin isotherm model and pseudo-second-order kinetic model provided the best fit to the experimental data. The composite of MIL-53(Cr) and activated carbon, particularly the one with an optimal AC loading of 2.5 wt %, demonstrated a notable adsorptive desulfurization efficiency. The results show that the adsorption capacities of adsorbents increase in the following order for ADS of DBT: activated carbon < MIL-53(Cr) < 10%AC@MIL-53(Cr) < 5%AC@MIL-53(Cr) < 2.5%AC@MIL-53(Cr). Adsorption capacities of 94.55%, 95.88%, and 91.85% were obtained for the adsorption of DBT from model fuels?with initial sulfur concentrations of 1000, 1500, and 2000 ppmw S?over 2.5%AC@MIL-53(Cr) composite. The surface chemistry and textural characteristics of the synthesized composites, including their surface area, average pore diameter, mesopore volume, and total pore volume were essential for the successful desulfurization.