Hierarchical-pore UiO-66 modified with Ag⁺ for π-complexation adsorption desulfurization

Area of Science:

• Materials Science
• Chemical Engineering
• Environmental Science

Background:

• Adsorption desulfurization is a key technology for removing thiophenic compounds from fuels.
• Metal-organic frameworks (MOFs), particularly UiO-66, are promising adsorbents due to their high surface areas.
• Pristine UiO-66 is effective for small thiophenic compounds, but larger molecules pose a challenge.

Purpose of the Study:

• To develop a hierarchical-pore UiO-66 (HP-UiO-66) with increased surface area and porosity for enhanced adsorption of larger thiophenic compounds.
• To synthesize and evaluate silver-ion exchanged hierarchical-pore UiO-66 (HP-UiO-66-SO3Ag) for improved adsorption desulfurization performance via π-complexation.
• To assess the stability and reusability of the developed adsorbent.

Main Methods:

• Hierarchical-pore UiO-66 was synthesized using MOF-5 as a template.
• Silver ions (Ag+) were exchanged into the hierarchical-pore UiO-66 via an ion-exchange method to create HP-UiO-66-SO3Ag.
• Material characterization included FTIR, XRD, SEM, TEM, and N2 adsorption-desorption isotherms.
• Static adsorption experiments were conducted to evaluate adsorption capacity and performance in the presence of toluene.
• Regeneration cycles were performed to assess reusability.

Main Results:

• The synthesized HP-UiO-66-SO3Ag exhibited significantly higher specific surface area, pore volume, and pore size compared to pristine UiO-66.
• HP-UiO-66-SO3Ag demonstrated high adsorption capacity for thiophene and benzothiophene.
• The adsorbent maintained high performance even in the presence of toluene, a common fuel component.
• Approximately 90% of the initial adsorption capacity was regenerated after four cycles, indicating good reusability.

Conclusions:

• Hierarchical-pore UiO-66 templated by MOF-5 effectively enhances porosity and surface area for improved adsorbate uptake.
• HP-UiO-66-SO3Ag is a highly efficient adsorbent for thiophenic compounds in fuels, outperforming pristine UiO-66.
• The developed material shows excellent stability, reusability, and performance in complex fuel matrices, making it a viable candidate for industrial desulfurization.