scholarly journals High Dispersion of CeO2 on CeO2/MgO Prepared under Dry Conditions and Its Improved Redox Properties

Energies ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7922
Author(s):  
Kenji Taira ◽  
Reiko Murao
Keyword(s):  
Photoelectron Spectroscopy ◽  
Ambient Air ◽  
Ceo2 Nanoparticles ◽  
High Dispersion ◽  
Impregnation Method ◽  
X Ray ◽  
Temperature Programmed Oxidation ◽  
Dry Conditions ◽  
Common Technique ◽  
Temperature Programmed

Suppressing the usage of rare-earth elements is crucial for making the catalysts sustainable. Preparing CeO2 nanoparticles is a common technique to reduce CeO2 consumption, but such nanoparticles are prone to sinter or react with the supports when subjected to heat treatments. This study demonstrated that stable CeO2 nanoparticles were deposited on MgO by the simple impregnation method. When CeO2/MgO was prepared under the dry atmosphere, the CeO2 nanoparticles remained ~3 nm in diameter even after being heated at 800 °C, which is much smaller than ~5 nm of CeO2/MgO prepared under ambient air. Temperature-programmed reduction, temperature-programmed oxidation, X-ray photoelectron spectroscopy, and in situ X-ray diffraction studies showed that CeO2/MgO exhibited higher oxygen mobility when prepared under the dry atmosphere. Dry reforming reaction demonstrated that CeO2/MgO prepared under the dry atmosphere exhibited higher activity than that prepared under ambient air and pure CeO2.

scholarly journals Influence of Sulfur-Containing Sodium Salt Poisoned V2O5–WO3/TiO2 Catalysts on SO2–SO3 Conversion and NO Removal

Catalysts ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 541 ◽  
Author(s):  
Haiping Xiao ◽  
Chaozong Dou ◽  
Hao Shi ◽  
Jinlin Ge ◽  
Li Cai
Keyword(s):  
Photoelectron Spectroscopy ◽  
No Reduction ◽  
Catalytic Performance ◽  
Acid Sites ◽  
Impregnation Method ◽  
So2 Oxidation ◽  
Sodium Salts ◽  
X Ray ◽  
Temperature Programmed ◽  
Physical Features

A series of poisoned catalysts with various forms and contents of sodium salts (Na2SO4 and Na2S2O7) were prepared using the wet impregnation method. The influence of sodium salts poisoned catalysts on SO2 oxidation and NO reduction was investigated. The chemical and physical features of the catalysts were characterized via NH3-temperature programmed desorption (NH3-TPD), H2-temperature programmed reduction (H2-TPR), X-ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller (BET), X-ray diffraction (XRD), and Fourier Transform Infrared Spectroscopy (FT-IR). The results showed that sodium salts poisoned catalysts led to a decrease in the denitration efficiency. The 3.6% Na2SO4 poisoned catalyst was the most severely deactivated with denitration efficiency of only 50.97% at 350 °C. The introduction of SO42− and S2O72− created new Brønsted acid sites, which facilitated the adsorption of NH3 and NO reduction. The sodium salts poisoned catalysts significantly increased the conversion of SO2–SO3. 3.6%Na2S2O7 poisoned catalyst had the strongest effect on SO2 oxidation and the catalyst achieved a maximum SO2–SO3-conversion of 1.44% at 410 °C. Characterization results showed sodium salts poisoned catalysts consumed the active ingredient and lowered the V4+/V5+ ratio, which suppressed catalytic performance. However, they increased the content of chemically adsorbed oxygen and the strength of V5+=O bonds, which promoted SO2 oxidation.

scholarly journals Oxidized Palladium Supported on Ceria Nanorods for Catalytic Aerobic Oxidation of Benzyl Alcohol to Benzaldehyde in Protic Solvents

Catalysts ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 847 ◽  
Author(s):  
Seyed Moeini ◽  
Chiara Battocchio ◽  
Stefano Casciardi ◽  
Igor Luisetto ◽  
Paolo Lupattelli ◽  
...  
Keyword(s):  
Benzyl Alcohol ◽  
Surface Area ◽  
Photoelectron Spectroscopy ◽  
Aerobic Oxidation ◽  
Bet Surface Area ◽  
Impregnation Method ◽  
X Ray ◽  
Protic Solvents ◽  
Oxidation Of Benzyl Alcohol ◽  
Temperature Programmed

In the present study, the catalytic activity of palladium oxide (PdOx) supported on ceria nanorods (CeO2-NR) for aerobic selective oxidation of benzyl alcohol (BnOH) to benzaldehyde (PhCHO) was evaluated. The CeO2-NR was synthesized hydrothermally and the Pd(NO3)2 was deposited by a wet impregnation method, followed by calcination to acquire PdOx/CeO2-NR. The catalysts were characterized by X-ray diffraction (XRD), temperature programmed reduction (TPR), transmission electron microscopy (TEM), Brunauer–Emmet–Teller (BET) surface area analysis, and X-ray photoelectron spectroscopy (XPS). In addition, the TPR-reduced PdOx/CeO2-NR (PdOx/CeO2-NR-Red) was studied by XRD, BET, and XPS. Characterizations showed the formation of CeO2-NR with (111) exposed plane and relatively high BET surface area. PdOx (x > 1) was detected to be the major oxide species on the PdOx/CeO2-NR. The activities of the catalysts in BnOH oxidation were evaluated using air, as an environmentally friendly oxidant, and various solvents. Effects of temperature, solvent nature and palladium oxidation state were investigated. The PdOx/CeO2-NR showed remarkable activity when protic solvents were utilized. The best result was achieved using PdOx/CeO2-NR and boiling ethanol as solvent, leading to 93% BnOH conversion and 96% selectivity toward PhCHO. A mechanistic hypothesis for BnOH oxidation with PdOx/CeO2-NR in ethanol is presented.

scholarly journals High Active and Selective Ni/CeO2–Al2O3 and Pd–Ni/CeO2–Al2O3 Catalysts for Oxy-Steam Reforming of Methanol

Catalysts ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 380 ◽  
Author(s):  
Pawel Mierczynski ◽  
Agnieszka Mierczynska ◽  
Radoslaw Ciesielski ◽  
Magdalena Mosinska ◽  
Magdalena Nowosielska ◽  
...  
Keyword(s):  
Steam Reforming ◽  
Photoelectron Spectroscopy ◽  
Supported Catalysts ◽  
Energy Dispersive Spectrometer ◽  
Nickel Catalysts ◽  
Impregnation Method ◽  
Catalytic Systems ◽  
X Ray ◽  
Steam Reforming Of Methanol ◽  
Temperature Programmed

Herein, we report monometallic Ni and bimetallic Pd–Ni catalysts supported on CeO2–Al2O3 binary oxide which are highly active and selective in oxy-steam reforming of methanol (OSRM). Monometallic and bimetallic supported catalysts were prepared by an impregnation method. The physicochemical properties of the catalytic systems were investigated using a range of methods such as: Brunauer–Emmett–Teller (BET), X-ray Powder Diffraction (XRD), Temperature-programmed reduction (TPR–H2), Temperature-programmed desorption (TPD–NH3), X-ray photoelectron spectroscopy (XPS) and Scanning Electron Microscope equipped with an energy dispersive spectrometer (SEM–EDS). We demonstrate that the addition of palladium facilitates the reduction of nickel catalysts. The activity tests performed for all catalysts confirmed the promotion effect of palladium on the catalytic activity of nickel catalyst and their selectivity towards hydrogen production. Both nickel and bimetallic palladium–nickel supported catalysts showed excellent stability during the reaction. The reported catalytic systems are valuable to make advances in the field of fuel cell technology.

BaO-Modified Pd-Based Catalyst for Methanol Oxidation

2012 ◽  
Vol 610-613 ◽  
pp. 577-580
Author(s):  
Xue Qiao Zhang ◽  
Ming Zhao ◽  
Zhi Xiang Ye ◽  
Sheng Yu Liu ◽  
Yao Qiang Chen
Keyword(s):  
Methanol Oxidation ◽  
Photoelectron Spectroscopy ◽  
Impregnation Method ◽  
Complete Conversion ◽  
X Ray ◽  
Support Interaction ◽  
Metal Support Interaction ◽  
Metal Support ◽  
Temperature Programmed ◽  
Conversion Temperature

Pd-based catalysts modified with BaO as a promoter was prepared by impregnation method. The catalyst was characterized by H2-temperature-programmed reduction (H2-TPR) and X-ray photoelectron spectroscopy (XPS). The catalytic activity towards methanol showed that the BaO modification promoted the conversion of methanol. The light-off temperature (T50), complete conversion temperature (T90) and ΔT (T90-T50) for methanol oxidation are 100°C, 125°C and 25°C, respectively. The H2-TPR results showed that the addition of BaO increased palladium highly dispersed and promoted the reductive ability. It also enhanced the metal-support interaction and increased the electronic surroundings of Pd and Ce sites, which maintained Pd in a higher oxidized state and Ce4+ in Ce3+ state, consequently increased the activity for methanol oxidation according to XPS measurements.

Synthesis, characterization, thermal stability and redox behavior of In3+2Ti4+1–xTm3+xO5–δ, (Tm = Fe3+ and Cr3+, 0.0 ≤ x ≤ 0.2) mixed-oxide catalysts

2007 ◽  
Vol 22 (7) ◽  
pp. 1787-1796 ◽  
Author(s):  
M.R. Pai ◽  
A.M. Banerjee ◽  
S.R. Bharadwaj ◽  
S.K. Kulshreshtha
Keyword(s):  
Thermal Stability ◽  
Photoelectron Spectroscopy ◽  
Oxide Catalysts ◽  
Maximum Temperature ◽  
Mixed Metal Oxide ◽  
Redox Behavior ◽  
X Ray ◽  
Temperature Programmed Oxidation ◽  
Mixed Oxide Catalysts ◽  
Temperature Programmed

Mixed metal oxide catalysts with nominal compositions of In2Ti1–xFexO5–δ, In2Ti1–xCrxO5–δ, where 0.0 ≤ x ≤ 0.2, have been synthesized by the ceramic route and characterized using the powder x-ray diffraction technique. The In2Ti1–xFexO5–δ samples were single-phase compositions, isomorphic with In2TiO5 phase. The particle size of the In2Ti1–xFexO5–δ samples was lower compared to the parent In2TiO5 oxide. Thermal stability (by thermogravimetry-differential thermal analysis) in varying atmospheres, and temperature-programmed reduction (TPR)/temperature-programmed oxidation cycles have been recorded to investigate their redox behavior as a function of the value of x in this study. The amount of H2 consumed under TPR curves was correlated with the nonstoichiometry generated in the In2Ti1–xFexO5–δ samples. Fe substitution induced ease in the reducibility (i.e., maximum temperature) of the substituted oxides compared to that in In2TiO5. X-ray photoelectron spectroscopy has been used to confirm the oxidation states of indium and other metal ions in fresh and reduced samples.

Pd-Only Catalyst Modified by BaO with Co- Precipitation and Impregnation Methods towards the Methanol Fuel Emission Control

2012 ◽  
Vol 581-582 ◽  
pp. 313-316
Author(s):  
Xue Qiao Zhang ◽  
Zhi Xiang Ye ◽  
Cheng Hua Xu ◽  
Ming Zhao ◽  
Yao Qiang Chen
Keyword(s):  
Co Oxidation ◽  
Photoelectron Spectroscopy ◽  
Palladium Catalysts ◽  
Active Species ◽  
Precipitation Method ◽  
Impregnation Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Temperature Programmed ◽  
Co Precipitation

Barium oxide was introduced to modify Palladium catalysts supported on CeO2–ZrO2-La2O3-Al2O3 (CZLA) by impregnation and co-precipitation. methods. Various techniques, including X-ray diffraction (XRD), H2-temperature-programmed reduction (H2-TPR) and X-ray photoelectron spectroscopy (XPS), were employed to characterize the physicochemical properties of BaO-modified Pd-only catalyst. Catalytic activity for methanol, CO, C3H8 and NO conversions showed that BaO-modified catalyst prepared by impregnation method exhibited the best performance for methanol, C3H8 and NO removals, while the catalyst prepared by co-precipitation method was in favor of CO oxidation. Combined with the results of XRD, H2-TPR and XPS, it is concluded that the co-existence of PdO and Pd-O-Ce active species by impregnation played an important role in the methanol, C3H8 and NO removals, while the higher dispersion of palladium and improved reducibility were mostly favorable to the CO oxidation. The conversion of NO was co-effected by tow active species and the formation of Ba2AlLaO5 mixed oxide.

scholarly journals The Support Effects on the Direct Conversion of Syngas to Higher Alcohol Synthesis over Copper-Based Catalysts

Catalysts ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 199 ◽  
Author(s):  
Xiaoli Li ◽  
Junfeng Zhang ◽  
Min Zhang ◽  
Wei Zhang ◽  
Meng Zhang ◽  
...  
Keyword(s):  
Physicochemical Properties ◽  
Electronic Properties ◽  
Photoelectron Spectroscopy ◽  
Direct Synthesis ◽  
Higher Alcohols ◽  
Impregnation Method ◽  
Higher Alcohol Synthesis ◽  
Higher Alcohol ◽  
X Ray ◽  
Temperature Programmed

The types of supports employed profoundly influence the physicochemical properties and performances of as-prepared catalysts in almost all catalytic systems. Herein, Cu catalysts, with different supports (SiO2, Al2O3), were prepared by a facile impregnation method and used for the direct synthesis of higher alcohols from CO hydrogenation. The prepared catalysts were characterized using multiple techniques, such as X-ray diffraction (XRD), N2 sorption, H2-temperature-programmed reduction (H2-TPR), temperature-programmed desorption of ammonia (NH3-TPD), X-ray photoelectron spectroscopy (XPS) and in situ Fourier-transform infrared spectroscopy (FTIR), etc. Compared to the Cu/Al2O3 catalyst, the Cu/SiO2 catalyst easily promoted the formation of a higher amount of C1 oxygenate species on the surface, which is closely related to the formation of higher alcohols. Simultaneously, the Cu/Al2O3 and Cu/SiO2 catalysts showed obvious differences in the CO conversion, alcohol distribution, and CO2 selectivity, which were probably originated from differences in the structural and physicochemical properties, such as the types of copper species, the reduction behaviors, acidity, and electronic properties. Besides, it was also found that the gap in performances in two kinds of catalysts with the different supports could be narrowed by the addition of potassium because of its neutralization to surface acidy of Al2O3 and the creation of new basic sites, as well as the alteration of electronic properties.

scholarly journals Applicability of V2O5-WO3/TiO2 Catalysts for the SCR Denitrification of Alumina Calcining Flue Gas

Catalysts ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 220 ◽  
Author(s):  
Ruliang Ning ◽  
Li Chen ◽  
Erwei Li ◽  
Xiaolong Liu ◽  
Tingyu Zhu
Keyword(s):  
Flue Gas ◽  
Photoelectron Spectroscopy ◽  
Catalytic Performance ◽  
Inhibitory Effect ◽  
Impregnation Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
So2 Resistance ◽  
Temperature Programmed ◽  
Diffuse Reflectance Infrared

V2O5-WO3/TiO2 catalysts with different V2O5 and WO3 loadings were prepared by the impregnation method. H2O and SO2 resistance of the catalysts under high H2O concentration (30 vol.%) was studied. Influence of various basic metal oxides, such as Al2O3, CaO, Na2O, and K2O on the catalytic performance was studied and compared. It is revealed that the inhibitory effect is in the sequence of K > Na > Ca > Al, which is consistent with their alkalinity. X-ray diffraction (XRD), N2 physisorption (BET), temperature-programmed desorption of NH3 (NH3-TPD), H2-temperature programmed reduction (H2-TPR), X-ray photoelectron spectroscopy (XPS) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) were carried out, and the results were well-correlated with the catalytic studies.

Effect of La Addition on Ru/Al2O3 Catalyst for Selective CO Oxidation

2011 ◽  
Vol 347-353 ◽  
pp. 3616-3620 ◽  
Author(s):  
Xi Rong Chen ◽  
Zao Ming Chen ◽  
Wei Ming Lin
Keyword(s):  
Co Oxidation ◽  
Photoelectron Spectroscopy ◽  
Impregnation Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Selective Co Oxidation ◽  
La Addition ◽  
Temperature Programmed ◽  
And Performance ◽  
Ru Species

Ru/Al2O3 catalysts with various La2O3 contents were synthesized by impregnation method. The catalysts were tested for selective CO oxidation and characterized by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy with energy-dispersive spectroscopy, and H2 temperature-programmed reduction. The effects of La addition into Ru/Al2O3 catalysts on structure and performance were investigated. Results show that higher CO conversions (>99%) and CO2 selectivity are obtained at 110–170 °C on RuLa/Al2O3. La doping promotes the dispersion of Ru species, thereby enhancing catalytic activity. The analysis reveals that the modification of La2O3 is favorable for the formation of active Ru species with good dispersion and enhanced selective CO oxidation.

scholarly journals Zeolite Beta Doped with La, Fe, and Pd as a Hydrocarbon Trap

Catalysts ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 173
Author(s):  
Rasmus Jonsson ◽  
Jungwon Woo ◽  
Magnus Skoglundh ◽  
Louise Olsson
Keyword(s):  
Photoelectron Spectroscopy ◽  
Inductively Coupled Plasma ◽  
Zeolite Beta ◽  
Substantial Part ◽  
Catalyst Characterization ◽  
Incipient Wetness Impregnation ◽  
X Ray ◽  
Temperature Programmed Oxidation ◽  
Temperature Programmed

Hydrocarbon trapping is a technique of great relevance, since a substantial part of hydrocarbon emissions from engines are released from engines before the catalyst has reached the temperature for efficient conversion of the hydrocarbons. In this work, the influence of doping zeolite beta (BEA) with Fe, Pd, and La on the storage and release of propene and toluene is studied. Five monolith samples were prepared; Fe/BEA, La/BEA, Pd/BEA, Pd/Fe/BEA, and Pd/La/BEA using incipient wetness impregnation, and the corresponding powder samples were used for catalyst characterization by Inductively coupled plasma sector field mass spectrometry (ICP-SFMS), Temperature-programmed oxidation (TPO), X-ray photoelectron spectroscopy (XPS) and Scanning transmission electron microscopy with Energy dispersive X-ray analysis (STEM-EDX). The hydrocarbon trapping ability of the samples was quantified using Temperature-programmed desorption (TPD) of propene and toluene, and in situ Diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). The results from the TPD experiments show that the addition of Pd and La to the zeolite affected the release patterns of the stored hydrocarbons on the trapping material in a positive way. The in situ DRIFTS results indicate that these elements provide H-BEA with additional sites for the storage of hydrocarbons. Furthermore, EDX-mapping showed that the La and Pd are located in close connection.

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