scholarly journals Highly Active Hydrogenation Catalysts Based on Pd Nanoparticles Dispersed along Hierarchical Porous Silica Covered with Polydopamine as Interfacial Glue

Catalysts ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 449
Author(s):  
Miguel Ródenas ◽  
Jamal El Haskouri ◽  
José Vicente Ros-Lis ◽  
M. Dolores Marcos ◽  
Pedro Amorós ◽  
...  
Keyword(s):  
Porous Silica ◽  
Catalytic Efficiency ◽  
Pd Nanoparticles ◽  
Hydrogenation Catalysts ◽  
Highly Active ◽  
Hierarchical Porous ◽  
Similar Materials ◽  
Comprehensive Comparison ◽  
Palladium Content

New catalysts based on Pd(0) nanoparticles (Pd NPs) on a bimodal porous silica of the UVM-7/polydopamine (PDA) support have been synthesized following two preparative strategies based on the sequential or joint incorporation of two components of the composite (Pd and PDA). We analyzed the role played by the PDA as ‘interfacial glue’ between the silica scaffold and the Pd NPs. The catalysts were tested for the hydrogenation of 4-nitrophenol using (NEt4)BH4 as the hydrogenating agent. In addition to the palladium content, the characterization of the catalysts at the micro and nanoscale has highlighted the importance of different parameters, such as the size and dispersion of the Pd NPs, as well as their accessibility to the substrate (greater or lesser depending on their entrapment level in the PDA) on the catalytic efficiency. Staged sequential synthesis has led to better catalytic results. The most active Pd(0) centers seem to be Pd NPs of less than 1 nm on the PDA surface. The efficiency of the catalysts obtained is superior to that of similar materials without PDA. A comprehensive comparison has been made with other catalysts based on Pd NPs in a wide variety of supports. The TOF values achieved are among the best described in the literature.

Production and characterization of hierarchical porous silica made using natural rubber as template: Effects of the template removal methods, the pH of production, and the natural rubber sources

2016 ◽  
Vol 113 ◽  
pp. 273-283 ◽  
Author(s):  
Chayani Phattharachindanuwong ◽  
Nanthiya Hansupalak ◽  
Kanokwan Jantawatchai ◽  
Chompunuch Warakulwit ◽  
Johann Plank ◽  
...  
Keyword(s):  
Natural Rubber ◽  
Porous Silica ◽  
Template Removal ◽  
Hierarchical Porous

Preparation and characterization of highly active Pd nanoparticles supported Mn3O4 catalyst for low-temperature CO oxidation

2019 ◽  
Vol 113 ◽  
pp. 215-222 ◽  
Author(s):  
Abd El Rahman S. Khder ◽  
Hatem M. Altass ◽  
Mohamed I. Orif ◽  
Sheikha S. Ashour ◽  
Layla S. Almazroai
Keyword(s):  
Low Temperature ◽  
Co Oxidation ◽  
Pd Nanoparticles ◽  
Highly Active ◽  
Low Temperature Co Oxidation

Production and characterization of a novel hierarchical porous silica adsorbent for removal of methylene blue dye from wastewaters

2017 ◽  
Vol 204 (12) ◽  
pp. 1452-1465 ◽  
Author(s):  
Kanokwan Jantawatchai ◽  
Salinthip Jitpluem ◽  
Wanwisa Kerdlap ◽  
Phungphai Phanawadee ◽  
Chompunuch Warakulwit ◽  
...  
Keyword(s):  
Methylene Blue ◽  
Porous Silica ◽  
Blue Dye ◽  
Methylene Blue Dye ◽  
Hierarchical Porous ◽  
Silica Adsorbent

scholarly journals Rice Husk Derived Porous Silica as Support for Pd and CeO2 for Low Temperature Catalytic Methane Combustion

Catalysts ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 26 ◽  
Author(s):  
Dongjing Liu ◽  
Dominik Seeburg ◽  
Stefanie Kreft ◽  
René Bindig ◽  
Ingo Hartmann ◽  
...  
Keyword(s):  
Supported Catalysts ◽  
Nitrate Solution ◽  
Porous Silica ◽  
Methane Combustion ◽  
Pd Nanoparticles ◽  
Highly Active ◽  
Palladium Nitrate ◽  
The Cost ◽  
Supported Pd

The separation of Pd and CeO2 on the inner surface of controlled porous glass (CPG, obtained from phase-separated borosilicate glass after extraction) yields long-term stable and highly active methane combustion catalysts. However, the limited availability of the CPG makes such catalysts highly expensive and limits their applicability. In this work, porous silica obtained from acid leached rice husks after calcination (RHS) was used as a sustainable, cheap and broadly available substitute for the above mentioned CPG. RHS-supported Pd-CeO2 with separated CeO2 clusters and Pd nanoparticles was fabricated via subsequent impregnation/calcination of molten cerium nitrate and different amounts of palladium nitrate solution. The Pd/CeO2/RHS catalysts were employed for the catalytic methane combustion in the temperature range of 150–500 °C under methane lean conditions (1000 ppm) in a simulated off-gas consisting of 9.0 vol% O2, and 5.5 vol% CO2 balanced with N2. Additionally, tests with 10.5 vol% H2O as co-feed were carried out. The results revealed that the RHS-supported catalysts reached the performance of the cost intensive benchmark catalyst based on CPG. The incorporation of Pd-CeO2 into RHS additionally improved water-resistance compared to solely Pd/CeO2 lowering the required temperature for methane combustion in presence of 10.5 vol% H2O to values significantly below 500 °C (T90 = 425 °C).

scholarly journals An Electrochemical Approach to Follow and Evaluate the Kinetic Catalysis of Ricin on hsDNA

Life ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 405
Author(s):  
George Oliveira ◽  
José Maurício Schneedorf
Keyword(s):  
Catalytic Efficiency ◽  
Ricin Toxin ◽  
Wave Voltammetry ◽  
Progress Curve ◽  
Electrochemical Approach ◽  
Electro Oxidation ◽  
Castor Seeds ◽  
Identification And Characterization ◽  
Medical Countermeasures

International authorities classify the ricin toxin, present in castor seeds, as a potential agent for use in bioterrorism. Therefore, the detection, identification, and characterization of ricin are considered the first actions for its risk assessment during a suspected exposure, parallel to the development of therapeutic and medical countermeasures. In this study, we report the kinetic analysis of electro-oxidation of adenine released from hsDNA by the catalytic action of ricin by square wave voltammetry. The results suggest that ricin-mediated adenine release exhibited an unusual kinetic profile, with a progress curve controlled by the accumulation of the product and the values of the kinetic constants of 46.6 µM for Km and 2000 min−1 for kcat, leading to a catalytic efficiency of 7.1 × 105 s−1 M−1.

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.

Eco-fabrication of hierarchical porous silica monoliths by ice-templating of rice husk ash

2017 ◽  
Vol 19 (1) ◽  
pp. 188-195 ◽  
Author(s):  
Amin Bahrami ◽  
Ulla Simon ◽  
Niloofar Soltani ◽  
Sara Zavareh ◽  
Johannes Schmidt ◽  
...  
Keyword(s):  
Rice Husk ◽  
Rice Husk Ash ◽  
Porous Silica ◽  
Synthesis Process ◽  
Sustainable Chemistry ◽  
Silica Monoliths ◽  
Hierarchical Porous ◽  
Ice Templating

In this study, within a sustainable chemistry approach, a clean and eco-friendly synthesis process of silica monoliths compatible with environmental limitations is developed.

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