Catalysts of 3D ordered macroporous ZrO2-supported core–shell Pt@CeO2−x nanoparticles: effect of the optimized Pt–CeO2 interface on improving the catalytic activity and stability of soot oxidation

2017 ◽  
Vol 7 (4) ◽  
pp. 968-981 ◽  
Author(s):  
Yazhao Li ◽  
Yuhao Du ◽  
Yuechang Wei ◽  
Zhen Zhao ◽  
Baofang Jin ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Soot Oxidation ◽  
Catalytic Performance ◽  
Core Shell ◽  
Ordered Macroporous ◽  
Better Than

The catalytic performance of 3D-OM Pt1.0@CeO2−x/ZrO2-1 is better than that of 3D-OM Pt1.0/ZrO2.

Three-dimensionally ordered macroporous spinel-type MCr2O4 (M = Co, Ni, Zn, Mn) catalysts with highly enhanced catalytic performance for soot combustion

2015 ◽  
Vol 5 (9) ◽  
pp. 4594-4601 ◽  
Author(s):  
Jinguo Wang ◽  
Gaoyang Yang ◽  
Li Cheng ◽  
Eun Woo Shin ◽  
Yong Men
Keyword(s):  
Catalytic Activity ◽  
Three Dimensional ◽  
Catalytic Performance ◽  
Soot Combustion ◽  
Spinel Type ◽  
Ordered Macroporous

MCr2O4 catalysts with three-dimensional ordered macroporous structures displayed superior catalytic activity for soot combustion to their bulk counterparts.

Facile synthesis of three-dimensional ordered macroporous Sr1−xKxTiO3 perovskites with enhanced catalytic activity for soot combustion

2018 ◽  
Vol 8 (21) ◽  
pp. 5462-5472 ◽  
Author(s):  
Peng Zhao ◽  
Nengjie Feng ◽  
Fan Fang ◽  
Geng Liu ◽  
Li Chen ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Three Dimensional ◽  
Catalytic Performance ◽  
Soot Combustion ◽  
Facile Synthesis ◽  
Ordered Macroporous

The appropriate incorporation of potassium into 3DOM SrTiO3 perovskites effectively improved the catalytic performance for soot combustion.

Design and Synthesis of 3D Ordered Macroporous CeO2-Supported Pt@CeO2-δCore-Shell Nanoparticle Materials for Enhanced Catalytic Activity of Soot Oxidation

Small ◽  
2013 ◽  
Vol 9 (23) ◽  
pp. 3957-3963 ◽  
Author(s):  
Yuechang Wei ◽  
Zhen Zhao ◽  
Jian Liu ◽  
Chunming Xu ◽  
Guiyuan Jiang ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Soot Oxidation ◽  
Design And Synthesis ◽  
Ordered Macroporous

scholarly journals Correlating the Structural Evolution of ZnO/Al2O3 to Spinel Zinc Aluminate with its Catalytic Performance in Propane Dehydrogenation

2021 ◽  
Author(s):  
Manouchehr Nadjafi ◽  
Agnieszka M. Kierzkowska ◽  
Andac Armutlulu ◽  
Rene Verel ◽  
Alexey Fedorov ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Spinel Phase ◽  
Structural Evolution ◽  
Atomic Layer ◽  
Catalytic Performance ◽  
Coke Deposition ◽  
Core Shell ◽  
Zinc Aluminate ◽  
Wurtzite Phase ◽  
X Ray

Zn-based Al<sub>2</sub>O<sub>3</sub>-suported materials have been proposed as inexpensive and environmentally friendly catalysts for the direct dehydrogenation of propane (PDH), however, our understanding of these catalysts’ structure and deactivation routes is still limited. Here, we correlate the catalytic activity for PDH of a series of Zn-based Al<sub>2</sub>O<sub>3</sub> catalysts with their structure and structural evolution. To this end, three model catalysts are investigated. (i) ZnO/Al<sub>2</sub>O<sub>3</sub> prepared by atomic layer deposition (ALD) of ZnO onto γ-Al<sub>2</sub>O<sub>3 </sub>followed by calcination at 700 °C, which yields a core-shell spinel zinc aluminate/γ-Al<sub>2</sub>O<sub>3</sub> structure. (ii) Zinc aluminate spinel nanoparticles (Zn<sub>x</sub>Al<sub>y</sub>O<sub>4</sub> NPs) prepared via a hydrothermal method. (iii) A reference core-shell ZnO/SiO<sub>2</sub> catalyst prepared by ALD of ZnO on SiO<sub>2</sub>. The catalysts are characterized in detail by synchrotron X-ray powder diffraction (XRD), Zn K-edge X-ray absorption spectroscopy (XAS), and <sup>27</sup>Al solid state nuclear magnetic resonance (ssNMR). These experiments allowed us to identify tetrahedral Zn sites in close proximity to Al sites of a zinc aluminate spinel phase (Zn<sub>IV</sub>–O–Al<sub>IV/VI</sub> linkages) as notably more active and selective in PDH relative to the supported ZnO wurtzite phase (Zn<sub>IV</sub>–O– Zn<sub>IV</sub> linkages) in ZnO/SiO<sub>2</sub>. The best performing catalyst, 50ZnO/Al<sub>2</sub>O<sub>3</sub> gives 77% selectivity to propene (gaseous products based) at 9 mmol C<sub>3</sub>H<sub>6</sub> gcat−1 h<sup>−1</sup> space time yield (STY) after 3 min of reaction at 600 °C. On the other hand, the core-shell ZnO/Al<sub>2</sub>O<sub>3</sub> catalyst shows an irreversible loss of activity over repeated PDH and air-regeneration cycles, explained by Zn depletion on the surface due to its diffusion into subsurface layers or the bulk. ZnxAlyO<sub>4</sub> NPs gave a comparable initial selectivity and catalytic activity as 50ZnO/Al<sub>2</sub>O<sub>3</sub>. With time on stream, Zn<sub>x</sub>Al<sub>y</sub>O<sub>4</sub> NPs deactivate due to the formation of coke at the catalyst surface, yet the extend of coke deposition is lower than for the ZnO/Al<sub>2</sub>O<sub>3</sub> catalysts, and the activity of Zn<sub>x</sub>Al<sub>y</sub>O<sub>4</sub> NPs can be regenerated almost fully using calcination in air.<br>

Electro-Catalytic Performance of Different Pt/Ag Ratio on H2O2 Electro-Reduction for Direct NaBH4-H2O2 Fuel Cell

2014 ◽  
Vol 986-987 ◽  
pp. 59-62
Author(s):  
Ting Fang Yang ◽  
Dan Zheng ◽  
Zao Xi Yu
Keyword(s):  
Cyclic Voltammetry ◽  
Catalytic Activity ◽  
Reduction Method ◽  
Catalytic Performance ◽  
Performance Tests ◽  
Peak Current Density ◽  
Acid Media ◽  
Electro Catalytic Activity ◽  
Xrd And Tem ◽  
Better Than

In this paper the different proportional Pt/Ag on XC-72 carbon are studied to serve as the electro-catalysts of H2O2in acid media. All catalysts are prepared by impregnation reduction method and characterized by XRD and TEM. The electrochemical performance tests are examined by cyclic voltammetry (CV) at 25°C and 30°C, respectively. The results suggest that the peak current density increases with increasing the Ag content in Pt-Ag/C. Attributed to the temperature factor, the electro-catalytic activity of all catalysts at 30°C is better than that of 25°C.

Fe-Modified ZSM-5 and β Zeolites for Direct N2O Decomposition

2012 ◽  
Vol 610-613 ◽  
pp. 94-99 ◽  
Author(s):  
Quan Hui Guo ◽  
Juan Li ◽  
Ying Xia Li
Keyword(s):  
Catalytic Activity ◽  
Active Sites ◽  
Channel Wall ◽  
Decomposition Reaction ◽  
Catalytic Performance ◽  
Iron Ions ◽  
Exchange Method ◽  
Different Types ◽  
Charge Balancing ◽  
Better Than

Fe-modified ZSM-5 and β zeolites were prepared by adopting liquid ion-exchange method and their catalytic performance was studied in the N2O decomposition reaction. The state of Fe loaded on Fe-zeolites was investigated by means of UV-vis diffuse spectra, infrared spectroscopy, EPR and H2-TPR. The results of IR of hydroxyl stretching and UV-vis investigationSubscript texts indicated that part of the iron-ions was introduced into zeolites at the charge-balancing sites. The results of EPR and H2-TPR investigations showed that the same iron species were loaded on ZSM-5 and β zeolites. However, the results of IR of the perturbed anti-symmetric T-O-T vibrations of iron-ions indicated that different types of ZSM-5 and β zeolites resulted in different distributions of charge-balancing iron cations. The iron-ions could replace Brönsted acid protons at the straight channel wall (α sites), intersection of straight and sinusoidal channels (β sites), and sinusoidal channel wall (γ sites) within the ZSM-5 zeolite. In the case of Fe-β zeolites, iron-ions mainly located in the straight channels. We observed that the catalytic activity of the iron ions located on the α sites of ZSM-5 zeolites was better than those of iron ions located on β and γ sites in N2O direct decomposition, since the former was the most easily reduced from Fe3+to Fe2+in H2. Furthermore, it was found that Fe-β zeolite showed higher catalytic activity than Fe-ZSM-5 zeolite. This difference was attributed to the active sites located almost exclusively in the straight zeolite channels.

scholarly journals Correlating the Structural Evolution of ZnO/Al2O3 to Spinel Zinc Aluminate with its Catalytic Performance in Propane Dehydrogenation

2021 ◽  
Author(s):  
Manouchehr Nadjafi ◽  
Agnieszka M. Kierzkowska ◽  
Andac Armutlulu ◽  
Rene Verel ◽  
Alexey Fedorov ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Spinel Phase ◽  
Structural Evolution ◽  
Atomic Layer ◽  
Catalytic Performance ◽  
Coke Deposition ◽  
Core Shell ◽  
Zinc Aluminate ◽  
Wurtzite Phase ◽  
X Ray

Zn-based Al<sub>2</sub>O<sub>3</sub>-suported materials have been proposed as inexpensive and environmentally friendly catalysts for the direct dehydrogenation of propane (PDH), however, our understanding of these catalysts’ structure and deactivation routes is still limited. Here, we correlate the catalytic activity for PDH of a series of Zn-based Al<sub>2</sub>O<sub>3</sub> catalysts with their structure and structural evolution. To this end, three model catalysts are investigated. (i) ZnO/Al<sub>2</sub>O<sub>3</sub> prepared by atomic layer deposition (ALD) of ZnO onto γ-Al<sub>2</sub>O<sub>3 </sub>followed by calcination at 700 °C, which yields a core-shell spinel zinc aluminate/γ-Al<sub>2</sub>O<sub>3</sub> structure. (ii) Zinc aluminate spinel nanoparticles (Zn<sub>x</sub>Al<sub>y</sub>O<sub>4</sub> NPs) prepared via a hydrothermal method. (iii) A reference core-shell ZnO/SiO<sub>2</sub> catalyst prepared by ALD of ZnO on SiO<sub>2</sub>. The catalysts are characterized in detail by synchrotron X-ray powder diffraction (XRD), Zn K-edge X-ray absorption spectroscopy (XAS), and <sup>27</sup>Al solid state nuclear magnetic resonance (ssNMR). These experiments allowed us to identify tetrahedral Zn sites in close proximity to Al sites of a zinc aluminate spinel phase (Zn<sub>IV</sub>–O–Al<sub>IV/VI</sub> linkages) as notably more active and selective in PDH relative to the supported ZnO wurtzite phase (Zn<sub>IV</sub>–O– Zn<sub>IV</sub> linkages) in ZnO/SiO<sub>2</sub>. The best performing catalyst, 50ZnO/Al<sub>2</sub>O<sub>3</sub> gives 77% selectivity to propene (gaseous products based) at 9 mmol C<sub>3</sub>H<sub>6</sub> gcat−1 h<sup>−1</sup> space time yield (STY) after 3 min of reaction at 600 °C. On the other hand, the core-shell ZnO/Al<sub>2</sub>O<sub>3</sub> catalyst shows an irreversible loss of activity over repeated PDH and air-regeneration cycles, explained by Zn depletion on the surface due to its diffusion into subsurface layers or the bulk. ZnxAlyO<sub>4</sub> NPs gave a comparable initial selectivity and catalytic activity as 50ZnO/Al<sub>2</sub>O<sub>3</sub>. With time on stream, Zn<sub>x</sub>Al<sub>y</sub>O<sub>4</sub> NPs deactivate due to the formation of coke at the catalyst surface, yet the extend of coke deposition is lower than for the ZnO/Al<sub>2</sub>O<sub>3</sub> catalysts, and the activity of Zn<sub>x</sub>Al<sub>y</sub>O<sub>4</sub> NPs can be regenerated almost fully using calcination in air.<br>

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