A novel Pd precursor loaded γ-Al₂O₃ with excellent adsorbent performance for ultra-deep adsorptive desulfurization of benzene

Abstract

Fabricating highly water-soluble and chlorine-free precursors from Pd complexes remains challenging. Here, a novel Pd precursor (ammonium dinitrooxalato palladium(II) ((NH4)2[Pd(NO2)2(C2O4)]·2H2O)) is synthesized to address this challenge. Additionally, a Pd/Al2O3 adsorbent is prepared using γ-Al2O3 as a base material to host Pd. The ligand action of the Pd complex forms single Pd atoms and Pd sub-nano clusters on the surface of γ-Al2O3. Pd/Al2O3-4 as an adsorbent is evaluated using the benzene ultra-deep desulfurization procedure, wherein thiophene is used as a probe molecule. The sulfur adsorption capacity of Pd/Al2O3-4 is 1.76 mg g−1 for the ultra-deep adsorptive desulfurization of benzene at a sulfur concentration of 50 ppm. The sulfur adsorption capacity of the new Pd/Al2O3-4 adsorbent is 21.8% higher than that of a commercial Pd/Al2O3 adsorbent. In addition, the stability and durability of Pd/Al2O3-4 are investigated at a sulfur concentration of 1 ppm. The Pd/Al2O3-4 adsorbent achieves ≈100% thiophene removal after 434 h, which is 62 h more than the time required by the commercial Pd/Al2O3 adsorbent. The novel Pd precursor shows excellent potential for industrial applications, and the Pd/Al2O3-4 adsorbent can be produced on a mass scale of 500 kg per batch.