CO Oxidation over Pd Catalysts Supported on Different Supports: A Consideration of Oxygen Storage Capacity of Catalyst

2011 ◽  
Vol 347-353 ◽  
pp. 3298-3301
Author(s):  
Ye Xu ◽  
Jin Qiang Ma ◽  
Yuan Feng Xu ◽  
Hui Li ◽  
He Xing Li ◽  
...  
Keyword(s):  
Co Oxidation ◽  
Storage Capacity ◽  
Oxygen Storage Capacity ◽  
Oxygen Storage ◽  
X Ray Diffraction ◽  
Pd Catalysts ◽  
Transmission Electron ◽  
Pulse Experiment ◽  
Temperature Programmed

A series of Pd catalysts supported on different materials (SiO2, γ-Al2O3, CeO2, TiO2) were synthesized through precipitation reduction of palladium ions with H2. They exhibited different activity during catalytic oxidation of CO to CO2. With the characterization of N2 physisorption experiment, X-ray diffraction, transmission electron microscopy, temperature-programmed reduction, and CO and O2 multi-pulse experiment, the correlation of catalytic activity and oxygen storage capacity (OSC) of catalyst has been investigated. It was found that the reactivity is largely controlled by the OSC of the catalysts, and thus Pd/CeO2 and Pd/TiO2 were more active than Pd/SiO2 and Pd/Al2O3 for CO oxidation.

Synthesis and Characterization of Ce0.5Zr0.5O2 Nanocomposite and its Supported Pd-Only Catalysis Activity

2014 ◽  
Vol 633 ◽  
pp. 77-81
Author(s):  
Dong Xia Yang ◽  
Ping Ning ◽  
Jie Li He ◽  
Jing Fang Zhu ◽  
Ting Ting Zheng ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Storage Capacity ◽  
Oxygen Storage Capacity ◽  
Oxygen Storage ◽  
X Ray Diffraction ◽  
Fractional Precipitation ◽  
Temperature Programmed ◽  
Co Precipitation ◽  
Redox Ability

The Ce0.5Zr0.5O2 nanocomposites (CZ) were prepared by co-precipitation(CP), fractional precipitation (FP) and fractional precipitation with hydrothermal treatment (FP-HT). The samples were characterized by X-ray diffraction (XRD), Brunauer-Emmet Teller method (BET), H2-temperature programmed reduction (H2-TPR), and thermogravimetric analysis (TG) under H2-N2. XRD results displayed that all samples formed a single solid solution-like ceria-zirconia phase. BET results revealed CZ prepared by FP-HT (CZ-FP-HT) had the highest surface area. H2-TPR and TG analysis under H2-N2 showed CZ-FP-HT exhibited the strongest redox ability and oxygen storage capacity. Moreover, three-way catalysts of Pd-Rh supported on CZ -FP-HT and commercial CZ with same composites were prepared, and their three-way catalytic activity were also studied by engine evaluation. Pd-Rh/CZ-FP-HT showed a bit of higher oxygen storage capacity, catalytic activity and better thermal stability than Pd-Rh/CZ-commercial.

Synthesis and Characterization of CeO2-ZrO2-Al2O3 with High Thermal Stability and Oxygen Storage Capacity from Pseudoboehmite Precursor

2012 ◽  
Vol 463-464 ◽  
pp. 160-164
Author(s):  
Dong Zhang
Keyword(s):  
Thermal Stability ◽  
Storage Capacity ◽  
Oxygen Storage Capacity ◽  
Oxygen Storage ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Alumina Oxide ◽  
Composite Solid

The surface and structural properties, thermal stability and oxygen storage capability are inverstigated in ceria-zirconia-alumina oxide with deposition coprecipitation method using the Pseudoboehmite precursor. X-ray diffraction (XRD), Brunauer-Emmet Teller method (BET), Transmission electron microscopy (TEM) and oxygen pulsing technique are used to character the prepared materials. The prepared ceria-zirconia-alumina oxides are highly dispersed composite solid solution. After calcination at 650 °C and 1000 °C respectively, these compounds can still keep the structural and textural stability and hold excellent oxygen storage capability.

scholarly journals CO oxidation over Pt-modified CuO catalysts in the presence of water vapour and SO2

2015 ◽  
Vol 18 (2) ◽  
pp. 187-196
Author(s):  
Tri Nguyen ◽  
Anh Cam Ha ◽  
Loc Cam Luu ◽  
Cuong Tien Hoang ◽  
Thi Thi Yen Trinh ◽  
...  
Keyword(s):  
Co Oxidation ◽  
Water Vapour ◽  
Co Adsorption ◽  
X Ray Diffraction ◽  
Active Centers ◽  
Highly Active ◽  
Transmission Electron ◽  
Physico Chemical ◽  
Adsorption Of Co ◽  
Temperature Programmed

The optimal Pt-modified CuO supported on γ-Al2O3 and γ-Al2O3 + CeO2 catalysts have been prepared. Physico-chemical characteristics of catalysts were investigated and determined by the methods of N2 adsorption (BET), X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), temperature-programmed reduction (TPR), and hydrogen pulse chemisorption (HPC). The characteristics of carbon monoxide (CO) adsorption on catalysts were defined by the method of infrared spectroscopy (IR) in the range of 4000 – 400 cm-1. The effect of the mixture of water vapour and SO2 on the activity of these catalysts for the CO oxidation was assessed. Reactions were conducted at 200oC and 350oC in the absence and presence of the mixture of water vapour (1.1 mol %) and SO2 (0.0625 mol %). Concentrations of O2 and CO in the gas mixture were 9.2 mol % and 0.5 mol %, respectively. The results showed that in the catalysts there exist highly active centers Cu1+ and Pt2+. On the catalysts the adsorption of CO on Cu2+, Pt2+, CeO2, and γ - Al2O3 centres was observed. Addition of CeO2 led to increase the reductivity, CO adsorption but decrease in specific surface area of catalyst. The result PtCu/CeAl catalyst shown higher active, but lower stability compared to PtCu/Al catalyst. The mixture of water vapour and SO2 showed the reversible poisoning toward the Pt-CuO catalysts at a temperature of 350oC, but irreversible at 200oC

scholarly journals Ce- and Y-Modified Double-Layered Hydroxides as Catalysts for Dry Reforming of Methane: On the Effect of Yttrium Promotion

Catalysts ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 56 ◽  
Author(s):  
Katarzyna Świrk ◽  
Magnus Rønning ◽  
Monika Motak ◽  
Patricia Beaunier ◽  
Patrick Da Costa ◽  
...  
Keyword(s):  
Textural Properties ◽  
Dry Reforming ◽  
Dry Reforming Of Methane ◽  
Side Reactions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Temperature Programmed ◽  
Nickel Species

Ce- and Y-promoted double-layered hydroxides were synthesized and tested in dry reforming of methane (CH4/CO2 = 1/1). The characterization of the catalysts was performed using X-ray fluorescence (XRF), X-ray diffraction (XRD), N2 sorption, temperature-programmed reduction in H2 (TPR-H2), temperature-programmed desorption of CO2 (TPD-CO2), H2 chemisorption, thermogravimetric analysis coupled by mass spectrometry (TGA/MS), Raman, and high-resolution transmission electron microscopy (HRTEM). The promotion with cerium influences textural properties, improves the Ni dispersion, decreases the number of total basic sites, and increases the reduction temperature of nickel species. After promotion with yttrium, the increase in basicity is not directly correlated with the increasing Y loading on the contrary of Ni dispersion. Dry reforming of methane (DRM) was performed as a function of temperature and in isothermal conditions at 700 °C for 5 h. For catalytic tests, a slight increase of the activity is observed for both Y and Ce doped catalysts. This improvement can of course be explained by Ni dispersion, which was found higher for both Y and Ce promoted catalysts. During DRM, the H2/CO ratio was found below unity, which can be explained by side reactions occurrence. These side reactions are linked with the increase of CO2 conversion and led to carbon deposition. By HRTEM, only multi-walled and helical-shaped carbon nanotubes were identified on Y and Ce promoted catalysts. Finally, from Raman spectroscopy, it was found that on Y and Ce promoted catalysts, the formed C is less graphitic as compared to only Ce-based catalyst.

A Study on Oxygen Storage Capacity of Zirconium-Cerium-Oxide Nanoparticles

2013 ◽  
Vol 685 ◽  
pp. 123-127 ◽  
Author(s):  
Ajin C. Sajeevan ◽  
V. Sajith
Keyword(s):  
Cerium Oxide ◽  
Storage Capacity ◽  
Oxygen Storage Capacity ◽  
Oxygen Storage ◽  
Precipitation Method ◽  
Xrd Pattern ◽  
Harmful Emissions ◽  
Uv Visible ◽  
Co Precipitation

One of the methods for the reduction of harmful emissions from diesel engines such as hydrocarbon, soot and NOx is the use of fuel born catalyst Cerium oxide. The oxygen storage capacity of Cerium oxide can be improved by coating it with metal such as Zirconium. Zr – Ce-O nanoparticles were synthesized by Co-precipitation method in the present work. Dynamic Light scattering, XRD pattern and UV-Visible spectroscopy were used for characterization of the prepared samples. Thermo gravimetric studies were conducted to investigate the thermal decomposition of Zr-Ce-O nanoparticles. The oxygen storage capacity of Zr-Ce-O nanoparticles was analyzed using TPR analysis.

scholarly journals Preparation and Characterization of Nanocrystalline Cerium (IV) Oxide and Doped Cerium (IV) Oxide, Ce1-x-yMgxZryO2-?

2015 ◽  
Vol 7 (1-2) ◽  
pp. 55-63 ◽  
Author(s):  
T. Debnath ◽  
L. Tashmim ◽  
C. H. Ruscher ◽  
A. Hussain
Keyword(s):  
Storage Capacity ◽  
Oxygen Storage Capacity ◽  
Oxygen Storage ◽  
Cubic Phase ◽  
Muffle Furnace ◽  
Crystallite Sizes ◽  
Edx Analyses ◽  
Scherrer Formula ◽  
Reported Data

Nanocrystalline cerium (IV) oxide is a technologically important material due to its high oxygen storage capacity, oxygen ionic conductivity and thermal stability. In this paper we report preparation of nanocrystalline CeO2 using glycerin nitrate method, where the precursor obtained from the mixture of cerium nitrate and glycerin were calcined at temperatures ranging from 200°C to 800°C in steps of 100°C in a muffle furnace. Attempts were also made to prepare nanocrystalline cerium (IV) oxide doped with both Mg and Zr using the same method. The calcined specimens were characterized using XRD, FTIR and SEM/EDX analyses. The influence of the calcination temperature on the cubic phase formation and its consequent effect on the crystallite size of the prepared CeO2 were studied and interpreted. The crystallite sizes calculated from XRD data using Scherrer formula reveal that the phases are nanocrystals, which was further supported by SEM photograph. The apparent activation energy for crystalline coarsening is found to be very low (26.8 kJmol-1) for this precursor compared to reported data. XRD data and also EDX analysis shows that both Mg and Zr could also be doped in CeO2 upto a certain composition,         Ce1-x-yMgxZryO2-?(x = 0.05, y = 0.05).

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