A novel boron nitride supported Pt catalyst for VOC incineration

Low-crystalline hexagonal boron nitride (h-BN) and γ-alumina supported Pt catalysts were employed to investigate the catalytic destruction of volatile organic compounds (VOC). The 0.3wt.% Pt catalysts were prepared via incipient wetness method using H₂PtCl₆ as precursor. The oxidation of volatile gasoline was performed in a concentration of 2500ppmv with volume hour space velocity (VHSV) near 20000h^-1 from 100 to 500°C. Instead of deactivation, the activity of Pt/h-BN increased significantly in the second run of the oxidation reaction. The light-off temperature (50% conversion) decreased from 210 to 160-170°C in the second run of oxidation. Furthermore, 95% conversion was achieved at less than 200°C. Meanwhile, the Pt/γ-Al₂O₃ became deactivated in the second run of oxidation. The activity of Pt/h-BN was maintained for three temperature cycles. Long-term oxidation proved that Pt/h-BN activity did not decline over up to 80h. The positive binding energy shift from XPS revealed that a few boron oxide impurities contaminated on the h-BN surface, these provided the anchorage for the Pt clusters. Metallic Pt surface was oxidized to PtO during the initial oxidation, thus enhancing the oxidation activity. Based on irreversible H₂ chemisorption, the platinum dispersion of Pt/h-BN were near 20% and did not change after oxidation at 500°C. Metal sintering was minimal, owing to the high thermal conductivity of h-BN, which prevented any hot spots of oxidation on Pt sites. In sum, experimental results demonstrated that Pt/h-BN was a promising catalyst for VOC destruction.