Insights into the CeO2 facet-depended performance of propane oxidation over Pt-CeO2 catalysts

Tuning the Interaction between Platinum Single Atoms and Ceria by Zirconia Doping for Efficient Catalytic Ammonia Oxidation

Aiming at the development of an efficient NH3 oxidation catalyst to eliminate the harmful NH3 slip from the stationary flue gas denitrification system and diesel exhaust aftertreatment system, a facile ZrO2 doping strategy was proposed to construct Pt1/CexZr1-xO2 catalysts with a tunable Pt-CeO2 interaction strength and Pt-O-Ce coordination environment. According to the results of systematic characterizations, Pt species supported on CexZr1-xO2 were mainly in the form of single atoms when x ≥ 0.7, and the strength of the Pt-CeO2 interaction and the coordination number of Pt-O-Ce bond (CNPt-O-Ce) on Pt1/CexZr1-xO2 showed a volcanic change as a function of the ZrO2 doping amount. It was proposed that the balance between the reasonable concentration of oxygen defects and limited surface Zr-Ox species well accounted for the strongest Pt-CeO2 interaction and the highest CNPt-O-Ce on Pt/Ce0.9Zr0.1O2. It was observed that the Pt/Ce0.9Zr0.1O2 catalyst exhibited much higher NH3 oxidation activity than other Pt/CexZr1-xO2 catalysts. The mechanism study revealed that the Pt1 species with the stronger Pt-CeO2 interaction and higher CNPt-O-Ce within Pt/Ce0.9Zr0.1O2 could better activate NH3 adsorbed on Lewis acid sites to react with O2 thus resulting in superior NH3 oxidation activity. This work provides a new approach for designing highly efficient Pt/CeO2 based catalysts for low-temperature NH3 oxidation.

Preformed Pt Nanoparticles Supported on Nanoshaped CeO2 for Total Propane Oxidation

Pt-based catalysts have been widely used for the removal of short-chain volatile organic compounds (VOCs), such as propane. In this study, we synthesized Pt nanoparticles with a size of ca. 2.4 nm and loaded them on various fine-shaped CeO2 with different facets to investigate the effect of CeO2 morphology on the complete oxidation of propane. The Pt/CeO2-o catalyst with {111} facets exhibited superior catalytic activity compared to the Pt/CeO2-r catalyst with {110} and {100} facets. Specifically, the turnover frequency (TOF) value of Pt/CeO2-o was 1.8 times higher than that of Pt/CeO2-r. Moreover, Pt/CeO2-o showed outstanding long-term stability during 50 h. X-ray photoelectron spectroscopy (XPS) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) revealed that the excellent performance of Pt/CeO2-o is due to the prevalence of metallic Pt species, which promotes C-C bond cleavage and facilitates the rapid removal of surface formate species. In contrast, a stronger metal-support interaction in Pt/CeO2-r leads to easier oxidation of Pt species and the accumulation of intermediates, which is detrimental to the catalytic activity. Our work provides insight into the oxidation of propane on different nanoshaped Pt/CeO2 catalysts.

Catalytic Oxidation of n-Decane, n-Hexane, and Propane over Pt/CeO2 Catalysts

Pt species with different chemical states and structures were supported on CeO₂ by solution reduction (Pt/CeO₂-SR) and wet impregnation (Pt/CeO₂-WI) and investigated in catalytic oxidation of n-decane (C₁₀H₂₂), n-hexane (C₆H₁₄), and propane (C₃H₈). Characterization by X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, H₂-temperature programming reduction, and oxygen temperature-programmed desorption showed that Pt⁰ and Pt²⁺ existed on Pt nanoparticles of the Pt/CeO₂-SR sample, which promoted redox, oxygen adsorption, and activation. On Pt/CeO₂-WI, Pt species were highly dispersed on CeO₂ as the Pt-O-Ce structure, in which surface oxygen decreased significantly. The Pt/CeO₂-SR catalyst presents high activity in oxidation of C₁₀H₂₂ with a rate of 0.164 μmol min^-1 m^-2 at 150 °C. The rate increased with oxygen concentration. Moreover, Pt/CeO₂-SR presents high stability on feed stream containing 1000 ppm C₁₀H₂₂ at gas hour space velocity = 30,000 h^-1 as low as 150 °C for 1800 min. The low activity and stability of Pt/CeO₂-WI were probably related to its low availability of surface oxygen. In situ Fourier transform infrared results showed that the adsorption of alkane occurred through the interaction with Ce-OH. The adsorption of C₆H₁₄ and C₃H₈ was much weaker than that of C₁₀H₂₂, which resulted in the decrease in activity for C₆H₁₄ and C₃H₈ oxidation of Pt/CeO₂ catalysts.

Influence of reduction temperature on Pt–ZrO2 interfaces for the gas-phase hydrogenation of acetone to isopropanol

Pt/ZrO2 reduced at 200 °C offers higher Ov and Pt0 contents, thus leading to excellent acetone hydrogenation activity.

The Emergence of the Ubiquity of Cerium in Heterogeneous Oxidation Catalysis Science and Technology

Research into the incorporation of cerium into a diverse range of catalyst systems for a wide spectrum of process chemistries has expanded rapidly. This has been evidenced since about 1980 in the increasing number of both scientific research journals and patent publications that address the application of cerium as a component of a multi-metal oxide system and as a support material for metal catalysts. This review chronicles both the applied and fundamental research into cerium-containing oxide catalysts where cerium’s redox activity confers enhanced and new catalytic functionality. Application areas of cerium-containing catalysts include selective oxidation, combustion, NOx remediation, and the production of sustainable chemicals and materials via bio-based feedstocks, among others. The newfound interest in cerium-containing catalysts stems from the benefits achieved by cerium’s inclusion, which include selectivity, activity, and stability. These benefits arise because of cerium’s unique combination of chemical and thermal stability, its redox active properties, its ability to stabilize defect structures in multicomponent oxides, and its propensity to stabilize catalytically optimal oxidation states of other multivalent elements. This review surveys the origins and some of the current directions in the research and application of cerium oxide-based catalysts.