Pyrene‐Thiol‐modified Pd Nanoparticles on Carbon Support: Kinetic Control by Steric Hinderance and Improved Stability by the Catalyst‐Support Interaction

ChemCatChem ◽  
2020 ◽  
Vol 12 (23) ◽  
pp. 5880-5887
Author(s):  
Takeharu Yoshii ◽  
Daiki Umemoto ◽  
Masanori Yamamoto ◽  
Yasutaka Kuwahara ◽  
Hirotomo Nishihara ◽  
...  
2021 ◽  
Author(s):  
Yannan Mao ◽  
Yongqing Shi ◽  
Yatao Su ◽  
Qi Shen ◽  
Yuangong Zhang ◽  
...  

The properties of catalyst support can greatly affect the catalytic performance. Therefore, it is very important to design and synthesize the catalyst support purposefully. Herein, a series of imidazolium-linked porous...


2019 ◽  
Vol 2 (6) ◽  
pp. 3385-3393 ◽  
Author(s):  
Yi Shi ◽  
Xiao-Kun Huang ◽  
Yang Wang ◽  
Yue Zhou ◽  
Dong-Rui Yang ◽  
...  

Nanomaterials ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 505
Author(s):  
Sofia Capelli ◽  
Davide Motta ◽  
Claudio Evangelisti ◽  
Nikolaos Dimitratos ◽  
Laura Prati ◽  
...  

The effect of support, stabilizing agent, and Pd nanoparticles (NPs) size was studied for sodium muconate and t,t-muconic acid hydrogenation to bio-adipic acid. Three different activated carbons (AC) were used (Norit, KB, and G60) and carbon morphology did not affect the substrate conversion, but it greatly influenced the adipic acid yield. 1% Pd/KB Darco catalyst, which has the highest surface area and Pd surface exposure, and the smallest NPs size displayed the highest activity. Furthermore, the effect of the amount of the protective agent was studied varying metal/protective agent weight ratios in the range of 1/0.00–1/1.20, using KB as the chosen support. For sodium muconate reduction 1% Pd/KB_1.2 catalyst gave the best results in terms of activity (0.73 s−1), conversion, and adipic acid yield (94.8%), while for t,t-muconic acid hydrogenation the best activity result (0.85 s−1) was obtained with 1% Pd/KB_0.0 catalyst. Correlating the results obtained from XPS and TEM analyses with catalytic results, we found that the amount of PVA (polyvinyl alcohol) influences mean Pd NPs size, Pd(0)/Pd(II) ratio, and Pd surface exposure. Pd(0)/Pd(II) ratio and Pd NPs size affected adipic acid yield and activity during sodium muconate hydrogenation, respectively, while adipic acid yield was related by exposed Pd amount during t,t-muconic acid hydrogenation. The synthesized catalysts showed higher activity than commercial 5% Pd/AC.


RSC Advances ◽  
2017 ◽  
Vol 7 (55) ◽  
pp. 34618-34623 ◽  
Author(s):  
Weichuan Xu ◽  
Litao Yan ◽  
Huiqiang Wang ◽  
Steven Liaw ◽  
Hongmei Luo

Pd nanoparticles anchored on Nb-doped TiO2 with functionalized carbon support (denoted as Pd/Nb–TiO2–C) is synthesized through a controllable hydrolysis and impregnation method.


2011 ◽  
Vol 115 (46) ◽  
pp. 23067-23073 ◽  
Author(s):  
Emma Rikkinen ◽  
Annukka Santasalo-Aarnio ◽  
Sanna Airaksinen ◽  
Maryam Borghei ◽  
Ville Viitanen ◽  
...  

2013 ◽  
Vol 11 (1) ◽  
Author(s):  
Denis Bona ◽  
Dennis E. Curtin ◽  
Francesco Pedrazzo ◽  
Elena Maria Tresso

Carbon black based electrodes are generally recognized as state of the art for PEM fuel cell technology due to the high performance achieved with a relatively low Pt content. However, the catalyst carbon support is prone to carbon oxidation. This leads to a loss of the catalyst area and overall performance, along with a higher mass transport loss due to an increased flooding tendency. This phenomenon is particularly severe when the fuel cell experiences repetitive start-stop cycles. Therefore, specific countermeasures against catalyst layer carbon oxidation are required, especially for automotive and backup power applications, where the startup/shutdown rate is considerably high. The authors evaluated a basic design that uses a stack shunt. A properly modified control protocol, which includes the stack shunt, is able to avoid high cathode potential peaks, which are known to accelerate catalyst carbon support corrosion and its negative effects. During two separate durability tests, one adopting the shunt design and another using nonprotected shutdown, a 24-cell stack was subjected to continuous starts and stops for several months and its performance constantly monitored. The results show that when the shunt is used, there is a 37% reduction in the voltage degradation rate for each startup/shutdown cycle and a two-fold increase in the number of startup/shutdown cycles before an individual cell reached the specified “end of life” voltage criteria. Furthermore, ex situ FE-SEM analysis revealed cathode catalyst layer thinning, which is an indication that the emerging degradation mechanism is the catalyst support carbon corrosion, as expected. This provides further support that the constant voltage degradation rate typically experienced in PEMFCs can be primarily attributed to the catalyst support carbon corrosion rate. The proposed shunt protocol is very cost effective and does not require any substantial changes in the system. For this reason, its adoption is recommended as a viable method to decrease the catalyst support carbon corrosion rate and extend the operating life of the PEMFC stack.


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