Modifying the Surface of γ-Al2O3with Y2Sn2O7Pyrochlore: Monolayer Dispersion Behaviour of Composite Oxides

ChemPhysChem ◽  
2017 ◽  
Vol 18 (12) ◽  
pp. 1533-1540 ◽  
Author(s):  
Xianglan Xu ◽  
Fang Liu ◽  
Jinshu Tian ◽  
Honggen Peng ◽  
Wenming Liu ◽  
...  
Keyword(s):  
Monolayer Dispersion ◽  
Composite Oxides

scholarly journals Interfaces in MOF-Derived CeO2–MnOX Composites as High-Activity Catalysts for Toluene Oxidation: Monolayer Dispersion Threshold

Catalysts ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 681
Author(s):  
Qian Zhang ◽  
Yiwen Jiang ◽  
Jingheng Gao ◽  
Mingli Fu ◽  
Sibei Zou ◽  
...  
Keyword(s):  
Metal Ion ◽  
Phase Changes ◽  
Toluene Oxidation ◽  
Monolayer Dispersion ◽  
Composite Oxides ◽  
Dispersion State ◽  
The Difference ◽  
State 1 ◽  
Monolayer Dispersion Threshold ◽  
Ce Content

A series of CeO2–MnOX catalysts with different Ce contents was prepared using Mn–BTC MOF as a sacrificial template for toluene oxidation. Interestingly, the performance of CeO2–MnOX increased rapidly only when the Ce content lower than 5%. The 1%-, 3%- and 10%-Ce-content samples exhibited the T90 value of 325 °C, 291 °C and 277 °C, respectively. XRD shows that the catalyst phase changes significantly before (Mn3O4 only) and after (Mn2O3, Mn3O4 and CeO2) 3% Ce loading. All other results indicated that the Ce–Mn interface properties of different Ce content composite oxides was quite distinguishable in terms of removal and energy efficiency. XRD and XPS results further showed that there a Ce monolayer dispersion threshold existed on the interface of MnOX (3.2 wt%, confirmed by XPS), which caused the difference in performance increment. The dispersed Ce could be divided into a monolayer dispersion state (1–3%) and a crystalline phase state (>3%), according to the existence form, which corresponded to the significant and minor enhancements of toluene conversion rate. Importantly, the Ce in monolayer dispersion state obviously improved the redox properties of catalysts interface, while the Ce in crystal state not. The interfaces with monolayer dispersion Ce result in more abundant metal ion states, oxygen vacancies, better electron transfer performance and catalytic activity.

Electron Donation by Low-Crystalline Ba-La-Ce Oxygen-Deficient Composite Oxide Accumulating on Ru Nanoparticles for Ammonia Synthesis under Mild Conditions

2019 ◽  
Author(s):  
Katsutoshi Sato ◽  
Shin-ichiro Miyahara ◽  
Yuta Ogura ◽  
Kotoko Tsujimaru ◽  
Yuichiro Wada ◽  
...  
Keyword(s):  
Ammonia Synthesis ◽  
Bond Cleavage ◽  
Synthesis Process ◽  
Strong Electron ◽  
Mild Conditions ◽  
Ru Nanoparticles ◽  
Rate Determining Step ◽  
Highly Active ◽  
Composite Oxides ◽  
Low Crystalline

<p>To mitigate global problems related to energy and global warming, it is helpful to develop an ammonia synthesis process using catalysts that are highly active under mild conditions. Here we show that the ammonia synthesis activity of Ru/Ba/LaCeO<i><sub>x</sub></i> pre-reduced at 700 °C is the highest reported among oxide-supported Ru catalysts. Our results indicate that low crystalline oxygen-deficient composite oxides, which include Ba<sup>2+</sup>, Ce<sup>3+</sup> and La<sup>3+</sup>, with strong electron-donating ability, accumulate on Ru particles and thus promote N≡N bond cleavage, which is the rate determining step for ammonia synthesis.</p>

Electron Donation by Low-Crystalline Ba-La-Ce Oxygen-Deficient Composite Oxide Accumulating on Ru Nanoparticles for Ammonia Synthesis under Mild Conditions

2019 ◽  
Author(s):  
Katsutoshi Sato ◽  
Shin-ichiro Miyahara ◽  
Yuta Ogura ◽  
Kotoko Tsujimaru ◽  
Yuichiro Wada ◽  
...  
Keyword(s):  
Ammonia Synthesis ◽  
Bond Cleavage ◽  
Synthesis Process ◽  
Strong Electron ◽  
Mild Conditions ◽  
Ru Nanoparticles ◽  
Rate Determining Step ◽  
Highly Active ◽  
Composite Oxides ◽  
Low Crystalline

<p>To mitigate global problems related to energy and global warming, it is helpful to develop an ammonia synthesis process using catalysts that are highly active under mild conditions. Here we show that the ammonia synthesis activity of Ru/Ba/LaCeO<i><sub>x</sub></i> pre-reduced at 700 °C is the highest reported among oxide-supported Ru catalysts. Our results indicate that low crystalline oxygen-deficient composite oxides, which include Ba<sup>2+</sup>, Ce<sup>3+</sup> and La<sup>3+</sup>, with strong electron-donating ability, accumulate on Ru particles and thus promote N≡N bond cleavage, which is the rate determining step for ammonia synthesis.</p>

Characterization and catalytic application of homogeneous nano-composite oxides ZrO2–Al2O3

2004 ◽  
Vol 93-95 ◽  
pp. 595-601 ◽  
Author(s):  
Guoran Li ◽  
Wei Li ◽  
Minghui Zhang ◽  
Keyi Tao
Keyword(s):  
Nano Composite ◽  
Catalytic Application ◽  
Composite Oxides

Co3O4/CeO2 composite oxides for methane emissions abatement: Relationship between Co3O4–CeO2 interaction and catalytic activity

2006 ◽  
Vol 66 (3-4) ◽  
pp. 217-227 ◽  
Author(s):  
L.F. Liotta ◽  
G. Di Carlo ◽  
G. Pantaleo ◽  
A.M. Venezia ◽  
G. Deganello
Keyword(s):  
Catalytic Activity ◽  
Methane Emissions ◽  
Composite Oxides

scholarly journals Prepare a catalyst consist of rare earth minerals to denitrate via NH3-SCR

2020 ◽  
Vol 9 (1) ◽  
pp. 191-202
Author(s):  
Jian Wang ◽  
Chao Zhu ◽  
Baowei Li ◽  
Zhijun Gong ◽  
Zhaolei Meng ◽  
...  
Keyword(s):  
Rare Earth ◽  
Active Sites ◽  
Nh3 Scr ◽  
Composite Oxides ◽  
Rare Earth Minerals ◽  
Denitrification Activity ◽  
Denitrification Reactor ◽  
Surface Active ◽  
Rare Earth Tailings ◽  
Treatment Step

AbstractTo research the roles of rare earth minerals in denitrification via the NH3-SCR, a mixture was made by certain ratio of rare earth concentrates and rare earth tailings, then treated by microwave roasting, and acids and bases to form a denitrification catalyst. The mineral phase structure and surface morphology of the catalyst were characterized by XRD, BET, SEM and EDS. The surface properties of the catalyst were tested by TPD and XPS methods, and the denitrification activity of the catalyst was evaluated in a denitrification reactor. The results showed that the denitrification efficiency increased up to 82% with complete processing. XRD, BET, SEM, and EDS spectrum analysis stated that the treated minerals contained cerium oxides and Fe−Ce composite oxides. The surface of the modified minerals became rough and porous, the surface area increased, and the surface-active sites were exposed. The results of NH3-TPD and NO-TPD showed that the catalyst surface could gradually adsorb more NH3 and NO after each step. XPS analysis indicated that there were more Ce3+, Fe2+, and lattice oxygen in rare earth minerals catalyst after each treatment step.

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