scholarly journals High Catalytic Activity of As-Synthesized, Ordered Porous Silicate–Quaternary Ammonium Composite for Knoevenagel Condensation

2000 ◽  
Vol 29 (9) ◽  
pp. 998-999 ◽  
Author(s):  
Yoshihiro Kubota ◽  
Yusuke Nishizaki ◽  
Yoshihiro Sugi
Keyword(s):  
Catalytic Activity ◽  
Quaternary Ammonium ◽  
Knoevenagel Condensation ◽  
High Catalytic Activity ◽  
Porous Silicate ◽  
Ordered Porous

An Efficient and Recyclable Imidazolium Salts-Functionalized Mesoporous Catalyst for Microwave-Promoted Knoevenagel Condensations in Solid Medium

2011 ◽  
Vol 347-353 ◽  
pp. 1944-1948
Author(s):  
Yu Long Xu ◽  
Chuan Shou Sun ◽  
Guo Hua Liu
Keyword(s):  
Catalytic Activity ◽  
Microwave Irradiation ◽  
Convenient Method ◽  
Solid Medium ◽  
Knoevenagel Condensation ◽  
Ethyl Cyanoacetate ◽  
High Catalytic Activity ◽  
Imidazolium Salts ◽  
Mesoporous Catalyst ◽  
Catalytic Activities

A convenient method for the preparation of imidazolium salts-functionalized mesoporous catalyst Me-Bmim-SBA-15 (2) by postgrafting [bmIm]OH on SBA-15 was developed. This catalyst presented excellent catalytic activities (more than 96% yields for all tested aldehydes) for Knoevenagel condensation of aldehydes and ethyl cyanoacetate under microwave irradiation in solid medium. Of particular note is that such a catalyst could be readily recovered and reused in the consecutively catalytic runs (up to 10 uses) while maintained high catalytic activity.

Construction of two Zn(ii)/Cd(ii) multifunctional coordination polymers with mixed ligands for catalytic and sensing properties

2018 ◽  
Vol 42 (17) ◽  
pp. 14203-14209 ◽  
Author(s):  
Li-Ping Xue ◽  
Zhao-Hao Li ◽  
Ting Zhang ◽  
Jia-Jia Cui ◽  
Yue Gao ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Coordination Polymers ◽  
Knoevenagel Condensation ◽  
Luminescence Quenching ◽  
High Catalytic Activity ◽  
Sensing Properties ◽  
Quenching Effect ◽  
Mixed Ligands

Two Zn(ii)/Cd(ii) coordination polymers with different networks were constructed with mixed ligands. The former compound shows high catalytic activity for Knoevenagel condensation, and the latter compound can selectively recognize l-cysteine through the luminescence quenching effect.

Preparation of hollow submicrospheres with ordered porous SiO 2 shell and multiple AuPt nanoalloy cores and their high catalytic activity

2016 ◽  
Vol 284 ◽  
pp. 351-356 ◽  
Author(s):  
Xinhong Qi ◽  
Xiangcun Li ◽  
Gaohong He ◽  
Yangzhi Zhu ◽  
Yurong Diao ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
High Catalytic Activity ◽  
Ordered Porous

Enhanced catalytic activity of low-Pt content nanocatalysts supported on hollow carbon spheres for the ORR in alkaline media

MRS Advances ◽  
2020 ◽  
Vol 5 (57-58) ◽  
pp. 2961-2972
Author(s):  
P.C. Meléndez-González ◽  
E. Garza-Duran ◽  
J.C. Martínez-Loyola ◽  
P. Quintana-Owen ◽  
I.L. Alonso-Lemus ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Anion Exchange ◽  
Average Particle Size ◽  
Synthesis Method ◽  
Alkaline Media ◽  
High Catalytic Activity ◽  
Average Particle ◽  
Carbon Spheres ◽  
Hollow Carbon ◽  
Hollow Carbon Spheres

In this work, low-Pt content nanocatalysts (≈ 5 wt. %) supported on Hollow Carbon Spheres (HCS) were synthesized by two routes: i) colloidal conventional polyol, and ii) surfactant-free Bromide Anion Exchange (BAE). The nanocatalysts were labelled as Pt/HCS-P and Pt/HCS-B for polyol and BAE, respectively. The physicochemical characterization of the nanocatalysts showed that by following both methods, a good control of chemical composition was achieved, obtaining in addition well dispersed nanoparticles of less than 3 nm TEM average particle size (d) on the HCS. Pt/HCS-B contained more Pt0 species than Pt/HCS-P, an effect of the synthesis method. In addition, the structure of the HCS remains more ordered after BAE synthesis, compared to polyol. Regarding the catalytic activity for the Oxygen Reduction Reaction (ORR) in 0.5 M KOH, Pt/HCS-P and Pt/HCS-B showed a similar performance in terms of current density (j) at 0.9 V vs. RHE than the benchmark commercial 20 wt. % Pt/C. However, Pt/HCS-P and Pt/HCS-B demonstrated a 6 and 5-fold increase in mass catalytic activity compared to Pt/C, respectively. A positive effect of the high specific surface area of the HCS and its interactions with metal nanoparticles and electrolyte, which promoted the mass transfer, increased the performance of Pt/HCS-P and Pt/HCS-B. The high catalytic activity showed by Pt/HCS-B and Pt/HCS-P for the ORR, even with a low-Pt content, make them promising cathode nanocatalysts for Anion Exchange Membrane Fuel Cells (AEMFC).

Ordered Intermetallic Nanoparticles with High Catalytic Activity Prepared by an Electrochemically Induced Phase Transformation

2019 ◽  
Author(s):  
Du Sun ◽  
yunfei wang ◽  
Kenneth Livi ◽  
chuhong wang ◽  
ruichun luo ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Diffusion Mechanism ◽  
Reduction Reaction ◽  
Atomic Scale ◽  
High Catalytic Activity ◽  
Ambient Conditions ◽  
Magnetic Devices ◽  
Disordered Alloys ◽  
Ordered Intermetallic ◽  
Intermetallic Nanoparticles

<div> <p>The synthesis of alloys with long range atomic scale ordering (ordered intermetallics) is an emerging field of nanochemistry. Ordered intermetallic nanoparticles are useful for a wide variety of applications such as catalysis, superconductors, and magnetic devices. However, the preparation of nanostructured ordered intermetallics is challenging in comparison to disordered alloys, hindering progress in materials development. We report a process for converting colloidally synthesized ordered intermetallic PdBi<sub>2</sub> to ordered intermetallic Pd<sub>3</sub>Bi nanoparticles under ambient conditions by an electrochemically induced phase transition. The low melting point of PdBi<sub>2</sub> corresponds to low vacancy formation energies which enables the facile removal of the Bi from the surface, while simultaneously enabling interdiffusion of the constituent atoms via a vacancy diffusion mechanism under ambient conditions. The resulting phase-converted ordered intermetallic Pd<sub>3</sub>Bi exhibits 11x and 3.5x higher mass activty and high methanol tolerance for the oxygen reduction reaction compared to Pt/C and Pd/C, respectively,which is the highest reported for a Pd-based catalyst, to the best of our knowledge. These results establish a key development in the synthesis of noble metal rich ordered intermetallic phases with high catalytic activity, and sets forth guidelines for the design of ordered intermetallic compounds under ambient conditions.</p> </div>

Nickel (II) and oxovanadium (IV) complexes supported on MCM-41 mesoporous and their application in catalytic selective sulfide and thiol oxidation

2020 ◽  
Vol 23 ◽  
Author(s):  
Mohsen Nikoorazm ◽  
Maryam Khanmoradi ◽  
Masoumeh Sayadian
Keyword(s):  
Catalytic Activity ◽  
Room Temperature ◽  
Sol Gel ◽  
Reaction Times ◽  
Significant Loss ◽  
Spectral Studies ◽  
High Catalytic Activity ◽  
Catalytic Systems ◽  
Solvent Free Conditions ◽  
Mcm 41

Introduction:: MCM-41 was synthesized using the sol-gel method. Then two new transition metal complexes of Nickel (II) and Vanadium (IV), were synthesized by immobilization of adenine (6-aminopurine) into MCM-41 mesoporous. The compounds have been characterized by XRD, TGA, SEM, AAS and FT-IR spectral studies. Using these catalysts provided an efficient and enantioselective procedure for oxidation of sulfides to sulfoxides and oxidative coupling of thiols to their corresponding disulfides using hydrogen peroxide at room temperature. Materials and Methods:: To a solution of sulfide or thiol (1 mmol) and H2O2 (5 mmol), a determined amount of the catalyst was added. The reaction mixture was stirred at room temperature for the specific time under solvent free conditions. The progress of the reaction was monitored by TLC using n-hexane: acetone (8:2). Afterwards, the catalyst was removed from the reaction mixture by centrifugation and, then, washed with dichloromethane in order to give the pure products. Results:: All the products were obtained in excellent yields and short reaction times indicating the high activity of the synthesized catalysts. Besides, the catalysts can be recovered and reused for several runs without significant loss in their catalytic activity. Conclusion:: These catalytic systems furnish the products very quickly with excellent yields and VO-6AP-MCM-41 shows high catalytic activity compared to Ni-6AP-MCM-41.

Mechanisms of methane decomposition and carbon species oxidation on the Pr0.42Sr0.6Co0.2Fe0.7Nb0.1O3−σ electrode with high catalytic activity

2015 ◽  
Vol 3 (45) ◽  
pp. 22816-22823 ◽  
Author(s):  
Peng Zhang ◽  
Guoqing Guan ◽  
Deni S. Khaerudini ◽  
Xiaogang Hao ◽  
Chunfeng Xue ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Carbon Deposition ◽  
Methane Decomposition ◽  
High Catalytic Activity ◽  
Carbon Species

Carbon deposition characteristics on PSCFN and Ni–YSZ due to thermal CH4 decomposition are investigated by using TPR technique.

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