Highly Dispersed HKUST-1 on Milimeter-Sized Mesoporous γ-Al2O3 Beads for Highly Effective Adsorptive Desulfurization

HKUST-1 was impregnated effectively on millimeter-sized mesoporous gamma-Al2O3 beads under hydrothermal conditions, resulting in formation of a composite material HKUST-1@gamma-Al2O3 that features high specific surface area, remarkable enhanced mechanical strength, chemical and thermal stability, and low cost. The composite material exhibited excellent performance with the adsorptive desulfurization capacity of 59.7 mg S/g MOF (versus 49.1 mg S/g MOF for bare HKUST-1) for a model oil composed of dibenzothiophene (with the initial S-content being 1000 ppmwS) and n-octane. Experimental results also revealed that HKUST-1@gamma-Al2O3 could reduce 35 ppmwS sulfur content of the model oil lower than 9.6 ppmwS at a ratio of HKUST-1@gamma-Al2O3 to oil over 30 wt %, indicating effectiveness for deep adsorptive desulfurization. The Gibbs free energy for DBT adsorption by HKUST-1@gamma-Al2O3 was found smaller than that by HKUST-1 due to efficient utilization of active centers, shorter diffusion channels and larger specific surface area of nanosized HKUST-1 particles formed under confined environment of gamma-Al2O3 channels/pores. Remarkably, the used HKUST-1@gamma-Al2O3 beads can easily be regenerated by acetone washing and the adsorptive desulfurization capacity just slightly decreased after experiencing five recycles. The results indicate that the as-synthesized HKUST-1@gamma-Al2O3 beads have great potential as an adsorbent for adsorptive desulfurization in practical applications.