scholarly journals Ag Nanoparticles Stabilized on Cyclodextrin Polymer Decorated with Multi-Nitrogen Atom Containing Polymer: An Efficient Catalyst for the Synthesis of Xanthenes

Molecules ◽  
2020 ◽  
Vol 25 (2) ◽  
pp. 241 ◽  
Author(s):  
Samahe Sadjadi ◽  
Fatemeh Ghoreyshi Kahangi ◽  
Masoumeh Dorraj ◽  
Majid M. Heravi
Keyword(s):  
Catalytic Activity ◽  
Nitrogen Atom ◽  
Hybrid System ◽  
Ag Nanoparticles ◽  
Active Sites ◽  
Phase Transfer ◽  
High Catalytic Activity ◽  
Ag Nps ◽  
Efficient Catalyst ◽  
Cyclodextrin Polymer

In attempt to broaden the use of cyclodextrin polymer for catalytic purposes, a novel covalent hybrid system was prepared through growth of multi-nitrogen atom containing polymer (PMelamine) derived from reaction of ethylenediamine and 2,4,6-trichloro-1,3,5-triazine on the functionalized cyclodextrin polymer (CDNS). The resulting hybrid system was then utilized as a catalyst support for the immobilization of silver nanoparticles through using Cuscuta epithymum extract as a naturally-derived reducing agent. The catalytic activity of the catalyst, Ag@CDNS-N/PMelamine, for the synthesis of xanthenes through reaction of aldehydes and dimedone in aqueous media was examined. The results showed high catalytic activity and recyclability of the catalyst. It was believed that cyclodextrin in the backbone of the catalyst could act both as a capping agent for Ag nanoparticles and phase transfer agent to bring the hydrophobic substrates in the vicinity of the catalytic active sites and accelerate the reaction rate. Multi-nitrogen atoms on the polymer, on the other hand, could improve the Ag NPs anchoring and suppress their leaching.

scholarly journals CO Oxidation Efficiency and Hysteresis Behavior over Mesoporous Pd/SiO2 Catalyst

Catalysts ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 131 ◽  
Author(s):  
Rola Mohammad Al Soubaihi ◽  
Khaled Mohammad Saoud ◽  
Myo Tay Zar Myint ◽  
Mats A. Göthelid ◽  
Joydeep Dutta
Keyword(s):  
Carbon Monoxide ◽  
Catalytic Activity ◽  
Co Oxidation ◽  
Active Sites ◽  
Bond Activation ◽  
Dissociative Adsorption ◽  
High Catalytic Activity ◽  
Good Catalytic Activity ◽  
Pretreatment Conditions ◽  
Oxidation Efficiency

Carbon monoxide (CO) oxidation is considered an important reaction in heterogeneous industrial catalysis and has been extensively studied. Pd supported on SiO2 aerogel catalysts exhibit good catalytic activity toward this reaction owing to their CO bond activation capability and thermal stability. Pd/SiO2 catalysts were investigated using carbon monoxide (CO) oxidation as a model reaction. The catalyst becomes active, and the conversion increases after the temperature reaches the ignition temperature (Tig). A normal hysteresis in carbon monoxide (CO) oxidation has been observed, where the catalysts continue to exhibit high catalytic activity (CO conversion remains at 100%) during the extinction even at temperatures lower than Tig. The catalyst was characterized using BET, TEM, XPS, TGA-DSC, and FTIR. In this work, the influence of pretreatment conditions and stability of the active sites on the catalytic activity and hysteresis is presented. The CO oxidation on the Pd/SiO2 catalyst has been attributed to the dissociative adsorption of molecular oxygen and the activation of the C-O bond, followed by diffusion of adsorbates at Tig to form CO2. Whereas, the hysteresis has been explained by the enhanced stability of the active site caused by thermal effects, pretreatment conditions, Pd-SiO2 support interaction, and PdO formation and decomposition.

Role of microporous Janus silica nanosheets in the assembly of ultra-small Ag nanoparticles with high catalytic activity

2021 ◽  
Vol 50 (1) ◽  
pp. 208-216
Author(s):  
Mengnan Yang ◽  
Zhaoli Yan ◽  
Tiantian Li ◽  
Bing Liu ◽  
Qiangshan Jing ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Ag Nanoparticles ◽  
High Catalytic Activity ◽  
Charged Surface ◽  
Highly Efficient ◽  
Surface Hydroxyls

Negatively charged surface hydroxyls and micropores of Janus silica nanosheets play a particular role in the highly efficient and dispersed assembly of ultra-small Ag nanoparticles with high catalytic activity.

Nitrogen-enriched porous carbon supported Pd-nanoparticles as an efficient catalyst for the transfer hydrogenation of alkenes

2018 ◽  
Vol 42 (20) ◽  
pp. 16823-16828 ◽  
Author(s):  
Jie Li ◽  
Xin Zhou ◽  
Ning-Zhao Shang ◽  
Cheng Feng ◽  
Shu-Tao Gao ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Porous Carbon ◽  
Pd Nanoparticles ◽  
Transfer Hydrogenation ◽  
High Catalytic Activity ◽  
Efficient Catalyst ◽  
Supported Pd

Well-dispersed Pd nanoparticles supported on nitrogen-enriched porous carbon were prepared and this material displayed excellent catalytic activity for the transfer hydrogenation of alkenes. The Pd@NPC catalyst exhibited high catalytic activity and stability for the hydrogenation of alkenes.

scholarly journals New gold standard: weakly capped infant Au nanoclusters with record high catalytic activity for 4-nitrophenol reduction and hydrogen generation from an ammonia borane–sodium borohydride mixture

2020 ◽  
Vol 2 (11) ◽  
pp. 5384-5395
Author(s):  
Dinabandhu Patra ◽  
Srinivasa Rao Nalluri ◽  
Hui Ru Tan ◽  
Mohammad S. M. Saifullah ◽  
Ramakrishnan Ganesan ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Citric Acid ◽  
Solid State ◽  
Gold Standard ◽  
Active Sites ◽  
Hydrogen Generation ◽  
High Catalytic Activity ◽  
Au Nanoclusters ◽  
Nitrophenol Reduction ◽  
Rapid Dissolution

Active sites are preserved in the citric acid-capped Au nanoclusters prepared in solid state. In water, the rapid dissolution of citric acid allows the reactants to easily access the active sites of infant Au nanoclusters leading to faster catalysis.

Preparation, characterization and catalytic properties of yttrium-zirconium-pillared montmorillonite and their application in supported Ce catalysts

Clay Minerals ◽  
2015 ◽  
Vol 50 (2) ◽  
pp. 211-219 ◽  
Author(s):  
Bo Xue ◽  
Hongmei Guo ◽  
Lujie Liu ◽  
Min Chen
Keyword(s):  
Catalytic Activity ◽  
Ethyl Acetate ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Active Sites ◽  
Industrial Applications ◽  
High Catalytic Activity ◽  
Total Oxidation ◽  
Pillared Montmorillonite

AbstractA new yttrium-zirconium-pillared montmorillonite (Y-Zr-MMT), was synthesized, characterized and used as a Ce catalyst support. The Y-Zr-MMT is a good support for dispersing cerium active sites and it is responsible for the high activity in the total oxidation of acetone, toluene and ethyl acetate. The Y-Zr-MMT shows greater advantages than the conventional alumina/cordierite honeycomb supports such as large specific surface area, lower cost and easier preparation. Catalytic tests demonstrated that Ce/Y-Zr-MMT (Ce loading 8.0%) was the most active, with the total oxidation of acetone, toluene and ethyl acetate being achieved at 220, 300 and 220°C, respectively. The catalyst displayed better activity for the oxidation of acetone and ethyl acetate than a conventional, supported Pd-catalyst under similar conditions. The special structure of the yttrium-doped zirconium-pillared montmorillonite can strengthen the interaction between the CeO2 and Zr-MMT support and improve the dispersion of the Ce particles, which enhances the catalytic activity for the oxidation of VOCs. The new catalyst, 8.0%Ce/Y-Zr-MMT, could be promising for industrial applications due to its high catalytic activity and low cost. The support and the catalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and BET specific surface area measurements.

Morphological and physicochemical properties of Ag–Au binary nanocomposites prepared using different surfactant capped Ag nanoparticles

RSC Advances ◽  
2015 ◽  
Vol 5 (50) ◽  
pp. 39954-39963 ◽  
Author(s):  
Anila Monga ◽  
Bonamali Pal
Keyword(s):  
Catalytic Activity ◽  
Physicochemical Properties ◽  
Ag Nanoparticles ◽  
Ag Nps

The deposition of Au on Ag NPs passivated with PVP, CTAB and TX-100 surfactants resulted in the formation of hollow, solid and porous Ag–Au bimetallic NCs, respectively, exhibiting ∼2 times higher catalytic activity than the monometallic Ag NPs.

Silica Gel Supported Dual Acidic Ionic Liquid as a Recyclable and Efficient Catalyst for Esterification and Acetalization Reactions

2011 ◽  
Vol 233-235 ◽  
pp. 1336-1339 ◽  
Author(s):  
Qiang Zhang ◽  
Hong Su ◽  
Jun Luo
Keyword(s):  
Ionic Liquid ◽  
Catalytic Activity ◽  
Silica Gel ◽  
Covalent Bond ◽  
High Catalytic Activity ◽  
The Novel ◽  
Hydrogen Sulfate ◽  
Efficient Catalyst ◽  
Acidic Ionic Liquid

A supported dual acidic ionic liquid was prepared via anchoring 3-sulfobutyl-1-(3-propyltriethoxysilane) imidazolium hydrogen sulfate onto common silica gel by covalent bond. The novel immobilized acidic ionic liquid illustrated high catalytic activity in esterification and acetalization reactions. The products could be separated by simple decantation and the recovered catalyst could be recycled without remarkable loss of catalytic activity even after eight runs for esterification and six runs for acetalization.

scholarly journals Biodiesel Production over Niobium-Containing Catalysts: A Review

Energies ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 5506
Author(s):  
Daniel Carreira Batalha ◽  
Márcio José da Silva
Keyword(s):  
Catalytic Activity ◽  
Active Sites ◽  
Heterogeneous Catalysts ◽  
Raw Materials ◽  
Catalytic Performance ◽  
High Specific Surface Area ◽  
Biodiesel Production ◽  
Molar Ratio ◽  
Main Reaction ◽  
High Catalytic Activity

Nowadays, the synthesis of biofuels from renewable raw materials is very popular. Among the various challenges involved in improving these processes, environmentally benign catalysts compatible with an inexpensive feedstock have become more important. Herein, we report the recent advances achieved in the development of Niobium-containing heterogeneous catalysts as well as their use in routes to produce biodiesel. The efficiency of different Niobium catalysts in esterification and transesterification reactions of lipids and oleaginous raw materials was evaluated, considering the effect of main reaction parameters such as temperature, time, catalyst load, and oil:alcohol molar ratio on the biodiesel yield. The catalytic performance of Niobium compounds was discussed considering the characterization data obtained by different techniques, including NH3-TPD, BET, and Pyr-FT-IR analysis. The high catalytic activity is attributed to its inherent properties, such as the active sites distribution over a high specific surface area, strength of acidity, nature, amount of acidic sites, and inherent mesoporosity. On top of this, recycling experiments have proven that most Niobium catalysts are stable and can be repeatedly used with consistent catalytic activity.

scholarly journals Pd On Thermo-Responsive Composite of Silica-Coated Carbon Nanotube And 1-Vinyl-3-Butylimidazolium-Based Ionic Liquid Copolymers As An Efficient Catalyst For Hydrogenation of Nitro Compounds

2021 ◽  
Author(s):  
Samahe Sadjadi ◽  
Neda Abedian-Dehaghani ◽  
Majid M. Heravi
Keyword(s):  
Ionic Liquid ◽  
Catalytic Activity ◽  
Aqueous Media ◽  
Nitro Compounds ◽  
Solution Temperature ◽  
High Catalytic Activity ◽  
Impregnation Method ◽  
Efficient Catalyst ◽  
Wet Impregnation ◽  
Coated Carbon

Abstract In this work, an ionic liquid-containing thermo-responsive heterogeneous catalyst with utility for promoting hydrogenation of nitro-compounds in aqueous media is developed. To prepare the catalyst, silica-coated carbon nanotubes were synthesized and vinyl-functionalized. The resulted compound was then polymerized with 1-viny-3-butylimidazolium bromide and N-isopropylacrylamide. The obtained ionic liquid-containing thermo-responsive composite was palladated via wet-impregnation method to give the final catalyst. Study of the performance of the catalyst confirmed high catalytic activity of the catalyst at temperature above the lower critical solution temperature. Furthermore, the catalyst was highly recyclable and showed negligible Pd leaching upon recycling. Broad substrate scope and selectivity of the catalyst towards reduction of nitro functionality were also confirmed. Furthermore, hot filtration test implied the heterogeneous nature of the catalysis. The comparison of the activity of Pd/CNT-P with some control catalysts approved the importance of hybridization of P and CNT and the presence of ionic liquid for the catalytic activity.

Sign in / Sign up

Export Citation Format

Share Document