Synergistic effect of –COOH and Zr(IV) with a short distance in Zr-MOFs for promoting utilization of H2O2 in oxidative desulfurization

Abstract

The effectiveness of the catalytic oxidative desulfurization (CODS) process crucially depends on the catalytic activity of the catalyst and the utilization of oxidizing agent. Catalyst with multiple active sites is an effective method to improve the CODS effectiveness. The Zr(IV) and –COOH-containing metal–organic framework, UiO-66-(COOH)2, was synthesized and used as an active and recyclable catalyst for CODS. The UiO-66-(COOH)2 shows higher catalytic activity and H2O2 utilization in the CODS process than UiO-66/–COOH, UiO-66, and H2BDC. And the high catalytic performance is derived from the synergistic effect between the Zr(IV) open site and free –COOH functionality within the framework. Experimental analysis and DFT calculations results indicate that the synergistic effect, which changes the reaction path and protects the *O2– radical, is a very effective strategy to promote desulfurization efficiency and the utilization efficiency of H2O2. In addition, it is essential to highlight that the active-site distance also has a significant influence on the effectiveness of CODS. This research may provide a new avenue for improving the CODS performance.