Catalytic Oxidation of Glycerol over Pt Supported on MOF-Derived Carbon Nanosheets

A series of nitrogen-doped porous carbon nanosheets (NPCNs) doped with transition-metal-supported Pt catalysts were prepared by colloidal deposition and evaluated for the selective oxidation of glycerol to glyceric acid (GLYA) under nonalkaline conditions. The transition metal contained in the catalyst was found to affect its performance and selectivity for GLYA, with the Pt/Zr@NPCN catalyst showing the highest catalytic activity and selectivity. These materials were characterized using Brunauer–Emmett–Teller surface area analysis, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and CO2 temperature-programmed desorption. The results showed that the small size of the Pt nanoparticles, the interaction between the Pt nanoparticles and the support, and the unique textural properties of the catalyst all promoted glycerol conversion and GLYA selectivity. A Zr concentration of 1.5 wt % and a support preparation temperature of 800 °C were found to provide a catalyst with the optimal performance that exhibited a glycerol conversion and selectivity for GLYA of 68.62 and 77.29%, respectively, at an initial O2 pressure of 10 bar and 60 °C after 6 h. Even after being recycled five times, this material provided a GLYA selectivity of approximately 75%, although the glycerol conversion decreased from 68 to 50%. The insights may provide new suggestions on the design of efficient support for the selective oxidation of polyols

MOFs-Derived Mn_<i>x</i>O_<i>y</i>C_<i>z</i> Supported Bimetallic Au–Pt Catalyst for the Catalytic Oxidation of Glycerol to Glyceric Acid

The specific structure of the support and the interactions between the catalyst components can lead to electron transfer, which in turn could affect the catalytic performance in heterogeneous catalytic reactions. In this paper, we have successfully prepared MnxOyCz composite materials from the calcination of the Mn-organic framework. Then bimetallic Au–Pt nanoparticles (NPs) were supported onto MnxOyCz via the colloidal-deposition method. These catalysts were tested in the selective oxidation of glycerol to glyceric acid under basic conditions. The results demonstrated that the catalytic activity of the bimetallic Au–Pt/MnxOyCz catalyst is considerably superior to those of the monometallic (Au and Pt) supported catalysts. Under the optimized conditions, 100% of glycerol can convert with 57.3% selectivity of glyceric acid. Multicharacterizations showed that the strong interaction between Au and Pt in the Au–Pt/MnxOyCz catalyst can enhance the dispersion of Au–Pt alloy NPs, promoting the electronic coupling effect on the metal surface. At the same time, the rich oxygen vacancies in this catalyst can facilitate the activation of oxygen, which causes the Au–Pt/MnxOyCz catalyst to show better catalytic activity. Specifically, the interaction between Au and Pt not only decreases the particle size of the Au–Pt alloy NPs but also promotes the reduction of Mn-based oxides and the mobility of oxygen. The absence of Au leads to a decrease in Pt 4f7/2 binding energy, resulting in an enrichment of electrons at the Pt active site and enhancing the oxidation ability of the primary hydroxyl group. In addition, the Au–Pt/MnxOyCz catalyst showed excellent stability without substantial loss of activity after being recycled five times. The insights and methodology may provide some new guidance for the reasonable design of bimetallic catalysts for the catalytic oxidation of biopolyols under mild conditions