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):  
Structural Evolution ◽  
Catalytic Performance ◽  
Propane Dehydrogenation ◽  
Zinc Aluminate

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>

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>

Enormous Passivation Effect of Surrounding Zeolitic Framework on Pt Clusters for Catalytic Propane Dehydrogenation

2021 ◽  
Author(s):  
Zhiyang Zhang ◽  
Wenlong Xu ◽  
Xiaomei Ye ◽  
Cunpu Qiu ◽  
Yonglan Xi ◽  
...  
Keyword(s):  
Metal Clusters ◽  
Catalytic Performance ◽  
Propane Dehydrogenation ◽  
Zeolitic Framework

Enclosing metal clusters into the inner of zeolite can enhance its catalytic performance due to the complex effects of the zeolitic environment surrounding them. Differently, here we report the enormous...

Synthesis of Pt-SnOx/TS-1@SBA-16 Composites and Their High Catalytic Performance for Propane Dehydrogenation

2019 ◽  
Vol 35 (5) ◽  
pp. 866-873
Author(s):  
Hongda Li ◽  
Zhen Zhao ◽  
Jiacheng Li ◽  
Jianmei Li ◽  
Linlin Zhao ◽  
...  
Keyword(s):  
Catalytic Performance ◽  
Propane Dehydrogenation

Size effect of TS-1 supports on the catalytic performance of PtSn/TS-1 catalysts for propane dehydrogenation

2017 ◽  
Vol 352 ◽  
pp. 361-370 ◽  
Author(s):  
Jiacheng Li ◽  
Jianmei Li ◽  
Zhen Zhao ◽  
Xiaoqiang Fan ◽  
Jian Liu ◽  
...  
Keyword(s):  
Size Effect ◽  
Catalytic Performance ◽  
Propane Dehydrogenation

scholarly journals Effect of ultrasonic irradiation on the catalytic performance of PtSnNa/ZSM-5 catalyst for propane dehydrogenation

2011 ◽  
Vol 18 (1) ◽  
pp. 19-22 ◽  
Author(s):  
Hui Liu ◽  
Shaobo Zhang ◽  
Yuming Zhou ◽  
Yiwei Zhang ◽  
Linyang Bai ◽  
...  
Keyword(s):  
Ultrasonic Irradiation ◽  
Catalytic Performance ◽  
Propane Dehydrogenation

Effect of K Addition on Catalytic Performance of PtSn/ZSM-5 Catalyst for Propane Dehydrogenation

2010 ◽  
Vol 135 (1-2) ◽  
pp. 76-82 ◽  
Author(s):  
Shaobo Zhang ◽  
Yuming Zhou ◽  
Yiwei Zhang ◽  
Li Huang
Keyword(s):  
Catalytic Performance ◽  
Propane Dehydrogenation
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