Remarkable Activity of Nanoarchitectonics Mesoporous CuO/CeO2–TiO2 Prepared by Nanocasting and Deposition Precipitation Techniques

2020 ◽  
Vol 20 (5) ◽  
pp. 2791-2802
Author(s):  
Duangamol Ongmali ◽  
Sakollapath Pithakratanayothin ◽  
Sureerat Jampa ◽  
Apanee Luengnaruemitrchai ◽  
Thanyalak Chaisuwan ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Catalytic Activity ◽  
Co Oxidation ◽  
Crystallite Size ◽  
Oxygen Vacancies ◽  
Redox Properties ◽  
Oxygen Defect ◽  
Nitrate Salt ◽  
Hard Template ◽  
Different Levels

In this work, a ceria (CeO2) support was modified with titania (TiO2) by nanocasting using MCM-48 as a hard template and then loading Cu (as the nitrate salt) at different levels (3–9% by weight) by deposition-precipitation followed by calcination. The addition of TiO2 in MSP CeO2 revealed that the MSP CeO2 was significantly improved the oxygen vacancies of the catalyst by increasing the Ce3+ content from 38 to 75% and stabilizing the Ce3+ species by bonding with the oxygen as Ce(4f)-O(2p)-Ti(3d). Moreover, the bonding of MSP CeO2 with TiO2 generated the oxygen defect vacancies (s–Ti3+), allowing Cu2+ to occupy and be reduced to Cu+ during calcination. The smaller CeO2 crystallite size (2.7 nm) of 9Cu/CeO2–TiO2 increased the mass-specific CO-Oxidation, showing the best catalytic activity due to its highest redox properties, as determined by H2-TPR and also showing resistant property to water and carbon dioxide. Indeed, water was adsorbed on the Ce3+ sites, generating OHads which reacted with CO to form –COOH, resulting in CO2.

scholarly journals On the Effects of Doping on the Catalytic Performance of (La,Sr)CoO3. A DFT Study of CO Oxidation

Catalysts ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 312 ◽  
Author(s):  
Antonella Glisenti ◽  
Andrea Vittadini
Keyword(s):  
Catalytic Activity ◽  
Co Oxidation ◽  
Density Functional Calculations ◽  
Density Functional ◽  
Formation Energy ◽  
Oxygen Vacancies ◽  
Catalytic Performance ◽  
Energy Profiles ◽  
High Concentrations ◽  
3D Impurities

The effects of modifying the composition of LaCoO3 on the catalytic activity are predicted by density functional calculations. Partially replacing La by Sr ions has benefical effects, causing a lowering of the formation energy of O vacancies. In contrast to that, doping at the Co site is less effective, as only 3d impurities heavier than Co are able to stabilize vacancies at high concentrations. The comparison of the energy profiles for CO oxidation of undoped and of Ni-, Cu-m and Zn-doped (La,Sr)CoO3(100) surface shows that Cu is most effective. However, the effects are less spectacular than in the SrTiO3 case, due to the different energetics for the formation of oxygen vacancies in the two hosts.

Ba-Addition Induced Enhanced Surface Reducibility of SrTiO3: Implication on Catalytic Aspects

2019 ◽  
Author(s):  
Noopur Jain ◽  
ahin roy ◽  
Angana De
Keyword(s):  
Catalytic Activity ◽  
Co Oxidation ◽  
Oxygen Vacancies ◽  
Cation Substitution ◽  
Surface Oxygen ◽  
Chemical States ◽  
A Site ◽  
Adsorption Desorption ◽  
Enhanced Surface

This work compares the capacity of generating the surface oxygen vacancies over SrTiO<sub>3</sub>, BaTiO<sub>3</sub> and the mixed Sr<sub>0.5</sub>Ba<sub>0.5</sub>TiO<sub>3</sub>. This aspect is elucidated by significantly different chemical states of the elements on the surface of the three materials. Along with the fundamental materials aspect, CO oxidation studies complement the highest surface reducibility of the Sr<sub>0.5</sub>Ba<sub>0.5</sub>TiO<sub>3</sub> catalyst. With detailed adsorption-desorption studies, we report that the A-site cation substitution renders a better surface-reducibility induced catalytic activity for CO oxidation.

Ba-Addition Induced Enhanced Surface Reducibility of SrTiO3: Implication on Catalytic Aspects

2019 ◽  
Author(s):  
Noopur Jain ◽  
ahin roy ◽  
Angana De
Keyword(s):  
Catalytic Activity ◽  
Co Oxidation ◽  
Oxygen Vacancies ◽  
Cation Substitution ◽  
Surface Oxygen ◽  
Chemical States ◽  
A Site ◽  
Adsorption Desorption ◽  
Enhanced Surface

This work compares the capacity of generating the surface oxygen vacancies over SrTiO<sub>3</sub>, BaTiO<sub>3</sub> and the mixed Sr<sub>0.5</sub>Ba<sub>0.5</sub>TiO<sub>3</sub>. This aspect is elucidated by significantly different chemical states of the elements on the surface of the three materials. Along with the fundamental materials aspect, CO oxidation studies complement the highest surface reducibility of the Sr<sub>0.5</sub>Ba<sub>0.5</sub>TiO<sub>3</sub> catalyst. With detailed adsorption-desorption studies, we report that the A-site cation substitution renders a better surface-reducibility induced catalytic activity for CO oxidation.

Metal-organic framework-derived porous CeO2 loading Au as efficient nanocatalysts for CO oxidation and 4-nitrophenol reduction

2018 ◽  
Vol 11 (03) ◽  
pp. 1850048 ◽  
Author(s):  
Xue-Zhi Song ◽  
Xiao-Lei Chen ◽  
Xi Chen ◽  
Xiao-Feng Wang ◽  
Teng Huang ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Synergistic Effect ◽  
Co Oxidation ◽  
Oxygen Vacancies ◽  
Metal Organic Framework ◽  
High Surface ◽  
High Surface Area ◽  
Catalytic Systems ◽  
Nitrophenol Reduction ◽  
Metal Organic

In this paper, two Au/CeO2 catalytic systems have been fabricated through the synthesis of porous CeO2 from Ce-BTC MOFs nanorod and nanobundle precursors by thermal annealing, and the subsequent Au loading. Significantly, the catalytic activity of Au/CeO2 nanorods is higher than that of bare CeO2 and even Au/CeO2 nanobundles for both CO oxidation and 4-nitrophenol reduction. The remarkably enhanced performance of Au/CeO2 nanorods can be attributed to the unique porous structure, high surface area, abundant oxygen vacancies on the surface of CeO2, and the synergistic effect between gold and ceria.

scholarly journals Physical and Chemical Synthesis of Au/CeO2 Nanoparticle Catalysts for Room Temperature CO Oxidation: A Comparative Study

Catalysts ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1351
Author(s):  
Khaled Mohammad Saoud ◽  
Mohamed Samy El-Shall
Keyword(s):  
Catalytic Activity ◽  
Low Temperature ◽  
Co Oxidation ◽  
Room Temperature ◽  
Au Nanoparticles ◽  
Redox Properties ◽  
Preparation Methods ◽  
Nanoparticle Catalysts ◽  
Low Temperature Co Oxidation ◽  
Physical And Chemical

In many heterogeneous catalytic reactions, such as low-temperature CO oxidation, the preparation conditions, and the role of the CeO2 support (oxygen vacancies and redox properties) in the dispersion and the chemical state of Au, are considered critical factors for obtaining gold nanoparticle catalysts with high catalytic performance. In this work, the physical and chemical preparation methods were compared, aiming at understanding how the preparation method influences the catalytic activity. The Au/CeO2 nanoparticle catalysts with 5% Au loading were prepared via the Physical Laser Vaporization Controlled Condensation method (LVCC), and the chemical Deposition-Precipitation method (DP) was used to investigate the effect of synthesis methods on the structure and the catalytic activity toward the CO oxidation. In this manuscript, we compare the activity of nanostructured Au/CeO2 catalysts. The structure and the redox properties of the catalysts were investigated by the XRD, SEM, TEM, TPR, and XPS. The catalytic activity for low-temperature CO oxidation was studied using a custom-built quartz tube flow reactor coupled with an infrared detector system at atmospheric pressure. The study reveals that the prepared CeO2-supported Au nanoparticles’ catalytic activity was highly dependent on the preparation methods. It showed that the sample prepared by the DP method exhibits higher catalytic efficiency toward CO oxidation when compared with the sample prepared by the LVCC method. The high catalytic activity could be attributed to the small particle size and shape, slightly higher Au concentration at the surface, surface-active Au species such as Au1+, along with the large interface between Au and CeO2. This study suggests that the stability, dispersion of Au nanoparticles on CeO2, and strong interaction between Au and CeO2 lead to strong oxidation ability even below room temperature. Considering the universal character of different physical and chemical methods for Au/CeO2 preparation, this study may also provide a base for supported Au-based catalysts for many oxidation reactions in energy and environmental applications.

scholarly journals CO Oxidation Efficiency and Hysteresis Behavior over Mesoporous Pd/SiO2 Catalyst

Catalysts ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 131 ◽  
Author(s):  
Rola Mohammad Al Soubaihi ◽  
Khaled Mohammad Saoud ◽  
Myo Tay Zar Myint ◽  
Mats A. Göthelid ◽  
Joydeep Dutta
Keyword(s):  
Carbon Monoxide ◽  
Catalytic Activity ◽  
Co Oxidation ◽  
Active Sites ◽  
Bond Activation ◽  
Dissociative Adsorption ◽  
High Catalytic Activity ◽  
Good Catalytic Activity ◽  
Pretreatment Conditions ◽  
Oxidation Efficiency

Carbon monoxide (CO) oxidation is considered an important reaction in heterogeneous industrial catalysis and has been extensively studied. Pd supported on SiO2 aerogel catalysts exhibit good catalytic activity toward this reaction owing to their CO bond activation capability and thermal stability. Pd/SiO2 catalysts were investigated using carbon monoxide (CO) oxidation as a model reaction. The catalyst becomes active, and the conversion increases after the temperature reaches the ignition temperature (Tig). A normal hysteresis in carbon monoxide (CO) oxidation has been observed, where the catalysts continue to exhibit high catalytic activity (CO conversion remains at 100%) during the extinction even at temperatures lower than Tig. The catalyst was characterized using BET, TEM, XPS, TGA-DSC, and FTIR. In this work, the influence of pretreatment conditions and stability of the active sites on the catalytic activity and hysteresis is presented. The CO oxidation on the Pd/SiO2 catalyst has been attributed to the dissociative adsorption of molecular oxygen and the activation of the C-O bond, followed by diffusion of adsorbates at Tig to form CO2. Whereas, the hysteresis has been explained by the enhanced stability of the active site caused by thermal effects, pretreatment conditions, Pd-SiO2 support interaction, and PdO formation and decomposition.

scholarly journals Highly Dispersed Pd Species Supported on CeO2 Catalyst for Lean Methane Combustion: The Effect of the Occurrence State of Surface Pd Species on the Catalytic Activity

Catalysts ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 772
Author(s):  
Yanxiong Liu ◽  
Changhua Hu ◽  
Longchun Bian
Keyword(s):  
Catalytic Activity ◽  
Oxygen Vacancies ◽  
Methane Combustion ◽  
Pd Nanoparticles ◽  
High Concentration ◽  
Ch4 Combustion ◽  
Highly Active ◽  
Δ Phase ◽  
Occurrence State ◽  
Comprehensive Characterization

The correlation between the occurrence state of surface Pd species of Pd/CeO2 for lean CH4 combustion is investigated. Herein, by using a reduction-deposition method, we have synthesized a highly active 0.5% PdO/CeO2-RE catalyst, in which the Pd nanoparticles are evenly dispersed on the CeO2 nanorods CeO2-R. Based on comprehensive characterization, we have revealed that the uniformly dispersed Pd nanoparticles with a particle size distribution of 2.3 ± 0.6 nm are responsible for the generation of PdO and PdxCe1−xO2−δ phase with –Pd2+–O2−–Ce4+– linkage, which can easily provide oxygen vacancies and facilitate the transfer of reactive oxygen species between the CeO2-R and Pd species. As a consequence, the remarkable catalytic activity of 0.5% Pd/CeO2-RE is related to the high concentration of PdO species on the surface of the catalyst and the synergistic interaction between the Pd species and the CeO2 nanorod.

Effects of rare earth metal doping on Au/ReZrO2 catalysts for efficient hydrogen generation from formic acid

2021 ◽  
Vol 45 (12) ◽  
pp. 5704-5711
Author(s):  
Luming Wu ◽  
Yu Hao ◽  
Shaohua Chen ◽  
Rui Chen ◽  
Pingchuan Sun ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Rare Earth ◽  
Rare Earth Metal ◽  
Oxygen Vacancies ◽  
Hydrogen Generation ◽  
Earth Metal ◽  
Support Interaction ◽  
Metal Support Interaction ◽  
Metal Support ◽  
Metal Doped

Rare earth metal doped ZrO2 can promote the formation of oxygen vacancies in zirconia, which enhances the metal–support interaction, finally promoting catalytic activity of FA dehydrogenation.

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