Unraveling the role of OH groups over CeO2 derived from methanol modification for enhancing toluene oxidation: Experimental and theoretical studies

In catalytic oxidation reactions, the presence of environmental water poses challenges to the performance of Pt catalysts. This study aims to overcome this challenge by introducing hydroxyl groups onto the surface of Pt catalysts using the pyrolysis reduction method. Two silica supports were employed to investigate the impact of hydroxyl groups: SiO2–OH with hydroxyl groups and SiO2–C without hydroxyl groups. Structural characterization confirmed the presence of Pt–O x , Pt–OH x , and Pt0 species in the Pt/SiO2–OH catalysts, while only Pt–O x and Pt0 species were observed in the Pt/SiO2–C catalysts. Catalytic performance tests demonstrated the remarkable capacity of the 0.5 wt % Pt/SiO2–OH catalyst, achieving complete conversion of benzene at 160 °C under a high space velocity of 60,000 h–1. Notably, the catalytic oxidation capacity of the Pt/SiO2–OH catalyst remained largely unaffected even in the presence of 10 vol % water vapor. Moreover, the catalyst exhibited exceptional recyclability and stability, maintaining its performance over 16 repeated cycles and a continuous operation time of 70 h. Theoretical calculations revealed that the construction of Pt–OH x sites on the catalyst surface was beneficial for modulating the d-band structure, which in turn enhanced the adsorption and activation of reactants. This finding highlights the efficacy of decorating the Pt surface with hydroxyl groups as an effective strategy for improving the water resistance, catalytic activity, and long-term stability of Pt catalysts.

Section: Resultsmentioning

confidence: 93%

Section: Resultsmentioning

confidence: 99%

Hydroxyl-Decorated Pt as a Robust Water-Resistant Catalyst for Catalytic Benzene Oxidation

Zhou

Deng

et al. 2023

“…To better understand why the La 0.029 CoO x -based samples outperformed the original Co 3 O 4 -based samples in catalytic benzene oxidation, H 2 -TPR, O 2 -TPD, and XPS were conducted to evaluate their surface properties. As shown in Figure a, all of the tested catalysts exhibit two distinct reduction peaks, corresponding to the reduction of Co 3+ to Co 2+ (the first peak), and the reduction of Co 2+ to Co 0 (the second peak), respectively. , Additionally, some smaller reduction peaks were observed in the low-temperature range (50–150 °C), attributed to the reduction of surface-adsorbed hydroxyl species . Another noteworthy observation is that the reduction temperature for La 0.029 CoO x -based samples was slightly higher than that for Co 3 O 4 -based samples, which can be ascribed to the strong interaction between the La and Co species.…”

Section: Resultsmentioning

confidence: 99%

“…15,49 Additionally, some smaller reduction peaks were observed in the lowtemperature range (50−150 °C), attributed to the reduction of surface-adsorbed hydroxyl species. 50 Another noteworthy observation is that the reduction temperature for La 0.029 CoO x -based samples was slightly higher than that for Co 3 O 4 -based samples, which can be ascribed to the strong interaction between the La and Co species. With an increase in the calcination temperature, the maximum reduction peaks shifted to higher temperature ranges, indicating that the calcination temperature significantly influenced the catalyst's redox properties.…”

Section: Catalytic Performancesmentioning

confidence: 97%

Ultrathin La_yCoO_x Nanosheets with High Porosity Featuring Boosted Catalytic Oxidation of Benzene: Mechanism Elucidation via an Experiment–Theory Combined Paradigm

Li,

Deng,

Zhou

et al. 2024

Designing transition-metal oxides for catalytically removing the highly toxic benzene holds significance in addressing indoor/outdoor environmental pollution issues. Herein, we successfully synthesized ultrathin La y CoO x nanosheets (thickness of ∼1.8 nm) with high porosity, using a straightforward coprecipitation method. Comprehensive characterization techniques were employed to analyze the synthesized La y CoO x catalysts, revealing their low crystallinity, high surface area, and abundant porosity. Catalytic benzene oxidation tests demonstrated that the La 0.029 CoO x -300 nanosheet exhibited the most optimal performance. This catalyst enabled complete benzene degradation at a relatively low temperature of 220 °C, even under a high space velocity (SV) of 20,000 h −1 , and displayed remarkable durability throughout various catalytic assessments, including SV variations, exposure to water vapor, recycling, and long time-on-stream tests. Characterization analyses confirmed the enhanced interactions between Co and doped La, the presence of abundant adsorbed oxygen, and the extensive exposure of Co 3+ species in La 0.029 CoO x -300 nanosheets. Theoretical calculations further revealed that La doping was beneficial for the formation of oxygen vacancies and the adsorption of more hydroxyl groups. These features strongly promoted the adsorption and activation of oxygen, thereby accelerating the benzene oxidation processes. This work underscores the advantages of doping rare-earth elements into transition-metal oxides as a cost-effective yet efficient strategy for purifying industrial exhausts.

“…Volatile organic compounds (VOCs), as essential components for the formation of PM 2.5 and ozone (O 3 ) pollution, not only severely contribute to environmental hazards but also seriously harm human health. − Various technologies, such as photocatalytic degradation, adsorption, biological treatment, catalytic oxidation, and photothermal catalytic can be employed to control VOC emissions. − Among these, catalytic oxidation is considered one of the most effective VOC abatement technologies due to its higher purification efficiency, lower energy consumption, and minimal secondary pollution . The critical focus of catalytic oxidation technology lies in the research and development of highly active catalysts, which are currently categorized as noble metal-supported catalysts and metal oxide catalysts.…”

Section: Introductionmentioning

confidence: 99%

Tuning the Metal–Support Interaction by Modulating CeO₂ Oxygen Vacancies to Enhance the Toluene Oxidation Activity of Pt/CeO₂ Catalysts

Yan,

Li,

Zhong

et al. 2024

Self Cite

In this research, a range of Pt/CeO 2 catalysts featuring varying Pt−O−Ce bond contents were developed by modulating the oxygen vacancies of the CeO 2 support for toluene abatement. The Pt/CeO 2 −HA catalyst generated a maximum quantity of Pt−O−Ce bonds (possessed the strongest metal− support interaction), as evidenced by the visible Raman results, which demonstrated outstanding toluene catalytic performance. Additionally, the UV Raman results revealed that the strong metal− support interaction stimulated a substantial increase in oxygen vacancies, which could facilitate the activation of gaseous oxygen to generate abundant reactive oxygen species accumulated on the Pt/ CeO 2 −HA catalyst surface, a conclusion supported by the H 2 -TPR, XPS, and toluene-TPSR results. Furthermore, the results from quasi-in situ XPS, in situ DRIFTS, and DFT indicated that the Pt/ CeO 2 −HA catalyst with a strong metal−support interaction led to improved mobility of reactive oxygen species and lower oxygen activation energies, which could transfer a large number of activated reactive oxygen species to the reaction interface to participate in the toluene oxidation, resulting in the relatively superior catalytic performance. The approach of tuning the metal−support interaction of catalysts offers a promising avenue to develop highly active catalysts for toluene degradation.