Total Oxidation of Light Alkane over Phosphate-Modified Pt/CeO₂ Catalysts

Abstract

Developing efficient catalysts for the total oxidation of light alkane at low temperatures is challenging. In this study, superior catalytic performance in the total oxidation of light alkane was achieved by modulating the acidity and redox property of a Pt/CeO2 catalyst through phosphorus modification. Surface modification with phosphorus resulted in electron withdrawal from Pt, leading to platinum species with high valency and the generation of Brönsted acid sites, leading to increased acidity of the Pt/CeO2 catalyst. Consequently, the ability of the Pt/CeO2 catalyst to activate the C–H bond increased with increasing P content in the catalyst owing to the synergistic effect of Ptδ+–(CeO2-PO x )δ− dipolar catalytic sites. In contrast, the redox property of the Pt/CeO2 catalyst weakened at first; subsequently, it was partially restored owing to the recovery of a part of the bare ceria surface with increasing P content. The turnover frequency in propane oxidation over the phosphate-modified Pt/CeO2 catalyst with a P/Ce atomic ratio of 0.06 was 10-fold higher than that over the unmodified Pt/CeO2 catalyst at 220 °C. This comprehensive study not only sheds light on the mechanism underlying the surface modification process but also offers a strategy for realizing higher catalytic activity in the total oxidation of light alkanes.

Highly Efficient Oxidation of Propane at Low Temperature over a Pt-Based Catalyst by Optimization Support

“…After loading the noble metal, slight electron transfer from the noble metal to O atoms occurs, and the noble metal supported on Nb 2 O 5 tends to exist in a metallic state. , Similar results have been reported in which Pd on metal oxide supports (TiO 2 and Nb 2 O 5 ) with high Δ f H M‑O θ was barely oxidized, resulting in stable metallic Pd particles . Furthermore, Pt catalysts on niobium oxide possess superior performance in the dehydrogenation of propane, which may result in different reaction routines for propane oxidation on supported Pt catalysts. , Therefore, niobium oxides are more promising for constructing metallic Pt active sites for C 3 H 8 oxidation.…”

“…The result showed that the peaks at 71.4 and 74.7 eV were related to the Pt 0 species, the peaks at 72.5 and 75.8 eV were correlated with the Pt 2+ species, and the peaks at 74.4 and 77.8 eV were attributed to the Pt 4+ species (Figure A). , Furthermore, the relative concentrations of different Pt species on the catalyst surface are summarized in Table S4. The Pt 4+ and Pt 2+ species were predominant on the surface of the Pt/SnO 2 and Pt/CeO 2 catalysts, respectively, which was consistent with the results reported in the literature. , In contrast, both the Pt 2+ and Pt 0 species dominated for the Pt/Nb 2 O 5 and Pt/ZrO 2 catalysts. These results demonstrated that the support significantly affected the oxidation state of Pt, although the Pt particle sizes were similar for all catalysts.…”

“…The Pt 4+ and Pt 2+ species were predominant on the surface of the Pt/ SnO 2 and Pt/CeO 2 catalysts, respectively, which was consistent with the results reported in the literature. 11,14 In contrast, both the Pt 2+ and Pt 0 species dominated for the Pt/ Nb 2 O 5 and Pt/ZrO 2 catalysts. These results demonstrated that the support significantly affected the oxidation state of Pt, although the Pt particle sizes were similar for all catalysts.…”

“…The XRD patterns of the Pt/MO x catalysts are shown in Figure S11. The patterns of Nb 2 O 5 , SnO 2 , ZrO 2 , and CeO 2 were indexed to orthorhombic, 22 tetragonal, 14 monoclinic, 13 and cubic structures, 11 respectively. The XRD patterns of all Pt/MO x catalysts were similar to those of the corresponding supports (Figure S11).…”

“…20 Furthermore, Pt catalysts on niobium oxide possess superior performance in the dehydrogenation of propane, 21 which may result in different reaction routines for propane oxidation on supported Pt catalysts. 11,13 Therefore, niobium oxides are more promising for constructing metallic Pt active sites for C 3 H 8 oxidation.…”