Hydrothermal Stability Of Catalysts Research Articles

Facile synthesis of Pt–Ce0.63Zr0·37O2–Y catalysts and the application in catalytic oxidation of toluene

In this work, a series of Pt–Ce0.63Zr0·37O2–Y catalysts were prepared by unique simple mechanical mixing method. The catalytic activity of these catalysts for toluene oxidation was investigated. The physicochemical properties of the catalysts were characterized by XRD, ICP-MS, SEM, TEM, XPS and N2 sorption. Pore size distribution was analyzed according nitrogen adsorption and desorption isotherms. The catalytic results showed that using NaY as support for Pt–Ce0.63Zr0·37O2–Y could enhance the conversion of toluene during the oxidation process in comparison with HY. Further mixing cerium zirconium solid solution with Pt–NaY can improve the oxidation catalytic property of these catalysts. The conversion of toluene over Pt–Ce0.63Zr0·37O2–NaY reached more than 90% at 200 °C. High catalytic stability was obtained for toluene oxidation over Pt–Ce0.63Zr0·37O2–NaY. Platinum, cerium and zirconium can be uniformly dispersed on Y zeolite with small particle size by simple mechanical synthesis. The effect of drying methods on catalytic activity and hydrothermal stability of catalysts were also investigated in this research.

Improved Selectivity of Long-Chain Products from Aqueous Acetone–Butanol–Ethanol Mixture over High Water Resistant Catalyst Based on Hydrophobic SBA-16

Water resistance and/or hydrothermal stability of catalysts are key concerns during the obtention of biofuels from fermentation products, which always involve considerable amounts of water. Herein,...

Catalysis: An Integrated Textbook

Pd/Al2O3 catalysts modified by different metal oxides (Mn, Fe, La, Mg and Ni oxides) were prepared and tested for fuel-lean methane/air catalytic combustion. It was found that the support material influenced the combustion performance significantly. The addition of NiO or MgO effectively improved the activity and hydrothermal stability of catalysts. X-ray diffraction (XRD) results showed the presence of spinel phase in the Pd/Al2O3–NiO and Pd/Al2O3–MgO catalysts. Temperature-programmed desorption of ammonia (NH3-TPD) measurements indicated that the supports became weakly acidic because of the formation of NiAl2O4 or MgAl2O4 spinel. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images showed the well dispersion of Pd particles on the Al2O3–NiO and Al2O3–MgO supports. It was concluded that the formation of the NiAl2O4 or MgAl2O4 spinel phase during preparation would be beneficial for the methane catalytic performance of Pd catalysts.

Influence of metal oxides on the performance of Pd/Al2O3 catalysts for methane combustion under lean-fuel conditions

Pd/Al2O3 catalysts modified by different metal oxides (Mn, Fe, La, Mg and Ni oxides) were prepared and tested for fuel-lean methane/air catalytic combustion. It was found that the support material influenced the combustion performance significantly. The addition of NiO or MgO effectively improved the activity and hydrothermal stability of catalysts. X-ray diffraction (XRD) results showed the presence of spinel phase in the Pd/Al2O3–NiO and Pd/Al2O3–MgO catalysts. Temperature-programmed desorption of ammonia (NH3-TPD) measurements indicated that the supports became weakly acidic because of the formation of NiAl2O4 or MgAl2O4 spinel. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images showed the well dispersion of Pd particles on the Al2O3–NiO and Al2O3–MgO supports. It was concluded that the formation of the NiAl2O4 or MgAl2O4 spinel phase during preparation would be beneficial for the methane catalytic performance of Pd catalysts.

Catalytic degradation of aqueous Fischer–Tropsch effluents to fuel gas over oxide‐supported Ru catalysts and hydrothermal stability of catalysts

AbstractBACKGROUND: The catalytic degradation of aqueous Fischer–Tropsch (FT) effluents to fuel gas over Ru/AC has been investigated. In order to understand the catalytic performance and stability of oxide‐supported Ru catalysts, several oxide supports (titania, zirconia, γ‐alumina and silica) were selected for study, with a focus on the hydrothermal stability of catalysts.RESULTS: The catalytic efficiency for transforming the oxygenates in aqueous FT effluents to C1–C6 alkanes decreased in the order: Ru/ZrO2∼ Ru/TiO2 > Ru/SiO2 > Ru/Al2O3. The conversion of alcohols was greatly suppressed over Ru/γ‐Al2O3. The former two catalysts (Ru/ZrO2 and Ru/TiO2) exhibited enhanced efficiency and long‐term stability (400 h) relative to Ru/SiO2 and Ru/Al2O3. N2‐physisorption, XRD and SEM showed that titania and zirconia exhibited high structural stability in an aqueous environment. However, the structures of γ‐alumina and silica were unstable due to significant drop in surface area and adverse changes in surface morphology. Especially for the case of the Ru/γ‐Al2O3 catalyst, the γ‐alumina was transformed into boehmite structure after reaction, and metal leaching and carbon deposition were extensive.CONCLUSION: Ru/ZrO2 or Ru/TiO2 may be a promising alternative for degrading aqueous FT effluents due to their long‐term stability. Copyright © 2012 Society of Chemical Industry

Irreversible Deactivation of Zeolite Fluid Cracking Catalyst. 2. Hydrothermal Stability of Catalysts Containing NH4Y and Rare Earth Y

Irreversible Deactivation of Zeolite Fluid Cracking Catalyst. 2. Hydrothermal Stability of Catalysts Containing NH₄Y and Rare Earth Y