scholarly journals Styrene Oxidation by Copper(II) Complexes Salen-Type Encapsulated into Nay Zeolite

2013 ◽  
Vol 58 (4) ◽  
pp. 1291-1294
Author(s):  
I. Kuźniarska-Biernacka ◽  
M.A. Carvalho ◽  
I. Correia Neves ◽  
A. M. Fonseca ◽  
A. Lisińska-Czekaj ◽  
...  
Keyword(s):  
Schiff Base ◽  
Heterogeneous Catalysts ◽  
Moderate Activity ◽  
Nay Zeolite ◽  
Styrene Oxidation ◽  
Preparation Methods ◽  
Flexible Ligand ◽  
Complex Preparation ◽  
Optimized Conditions

Abstract The copper(II) complex with a Schiff-base salen-type ligand has been encapsulated in the nanopores of a NaY zeolite by using two different methodologies, the flexible ligand and in situ complex preparation methods. The encapsulated and non-encapsulated copper(II) complexes were screened as catalysts for styrene oxidation by using TBHP as the oxygen source in acetonitrile solvent. Under the optimized conditions, the catalysts exhibited moderate activity with higher selectivity to benzaldehyde. Both heterogeneous catalysts were found to be reusable after the catalytic cycle, but with some loss of activity

scholarly journals Styrene Epoxidation Over Heterogeneous Manganese(III) Complexes

2016 ◽  
Vol 61 (3) ◽  
pp. 1477-1482 ◽  
Author(s):  
I. Kuźniarska-Biernacka ◽  
A. Lisinska-Czekaj ◽  
D. Czekaj ◽  
M. José Alves ◽  
A. Mauricio Fonseca ◽  
...  
Keyword(s):  
High Selectivity ◽  
Moderate Activity ◽  
Styrene Epoxidation ◽  
Nay Zeolite ◽  
Styrene Oxidation ◽  
Flexible Ligand ◽  
Optimized Conditions

Abstract The manganes(III) complex functionalised with 2,3-dihydropyridazine has been encapsulated in the supercages of the NaY zeolite using two different procedures, flexible ligand and in situ complex. The parent zeolite and the encapsulated manganese(III) complexes were screened as catalysts for styrene oxidation by using t-BOOH as the oxygen source in acetonitrile. Under the optimized conditions, the catalysts exhibited moderate activity with high selectivity to benzaldehyde

scholarly journals Schiff base ligand derived from (±)trans-1,2-cyclohexanediamine and its Cu(II), Co(II), Zn(II) and Mn(II) complexes: Synthesis, characterization, styrene oxidation and hydrolysis study of the imine bond in Cu(II) Schiff base complex

2016 ◽  
Vol 81 (4) ◽  
pp. 369-382 ◽  
Author(s):  
Marzieh Sarkheil ◽  
Maryam Lashanizadegan
Keyword(s):  
Schiff Base ◽  
Coordination Sphere ◽  
Schiff Base Ligand ◽  
Heterogeneous Catalysts ◽  
Zeolite Y ◽  
Schiff Base Complex ◽  
Tridentate Ligand ◽  
Partial Hydrolysis ◽  
Hydrolytic Cleavage ◽  
Styrene Oxidation

A Schiff base ligand (H2L) derived from 2?-hydroxypropiophenone and (?)trans-1,2-cyclohexanediamine was synthesized. The reactions of MCl2.xH2O (M =Cu(II), Co(II), Zn(II) and Mn(II))with the di-Schiff base ligand (H2L) were studied. This ligand when stirred with 1 equivalent of CuCl2.2H2O in the solution of ethanol and chloroform undergoes partial hydrolysis of the imino bond and the resultant tridentate ligand (HL?)immediately forms complex[CuL?Cl]?3/2CHCl3(1)with N2O coordination sphere. Under the same condition, the reaction of H2L with MCl2.xH2O (M = Co(II) (3), Zn(II) (4) and Mn(II) (5)) gave complexes[ML]?1/2CHCl3?3/2H2O (3-5)with N2O2 coordination sphere and no hydrolytic cleavage was occurred. Also, the reaction of H2L with CuCl2.2H2O in THF gave the complex CuL (2)with N2O2 coordination sphere. The ligand and complexes were characterized by FTIR, UV-Vis, 1H NMRand elemental analysis. The homogeneous catalytic activity of the complexes1, 3 and 5wasevaluated for the oxidation of styrene using tert-butyl hydroperoxide (TBHP) as oxidant. Finally, the copper(II) complex(1)encapsulated in the nanopores of zeolite-Y by flexible ligand method (CuL?-Y)and its encapsulation was ensured by different studies. The catalytic performance of heterogeneous catalyst in the styrene oxidation with TBHP was investigated. The catalytic tests showed that the homogenous and heterogeneous catalysts were active in the oxidation of styrene.

scholarly journals Morphology Controlled Synthesis of γ-Al2O3 Nano-Crystallites in Al@Al2O3 Core–Shell Micro-Architectures by Interfacial Hydrothermal Reactions of Al Metal Substrates

Nanomaterials ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 310
Author(s):  
Dohyeon Han ◽  
Doohwan Lee
Keyword(s):  
Electrostatic Interactions ◽  
Heterogeneous Catalysts ◽  
Metal Substrate ◽  
Inorganic Anions ◽  
Core Shell ◽  
Hydroxyl Groups ◽  
Hydrothermal Reactions ◽  
Fine Control ◽  
Reaction Processes

Fine control of morphology and exposed crystal facets of porous γ-Al2O3 is of significant importance in many application areas such as functional nanomaterials and heterogeneous catalysts. Herein, a morphology controlled in situ synthesis of Al@Al2O3 core–shell architecture consisting of an Al metal core and a porous γ-Al2O3 shell is explored based on interfacial hydrothermal reactions of an Al metal substrate in aqueous solutions of inorganic anions. It was found that the morphology and structure of boehmite (γ-AlOOH) nano-crystallites grown at the Al-metal/solution interface exhibit significant dependence on temperature, type of inorganic anions (Cl−, NO3−, and SO42−), and acid–base environment of the synthesis solution. Different extents of the electrostatic interactions between the protonated hydroxyl groups on (010) and (001) facets of γ-AlOOH and the inorganic anions (Cl−, NO3−, SO42−) appear to result in the preferential growth of γ-AlOOH toward specific crystallographic directions due to the selective capping of the facets by adsorption of the anions. It is hypothesized that the unique Al@Al2O3 core–shell architecture with controlled morphology and exposed crystal-facets of the γ-Al2O3 shell can provide significant intrinsic catalytic properties with enhanced heat and mass transport to heterogeneous catalysts for applications in many thermochemical reaction processes. The direct fabrication of γ-Al2O3 nano-crystallites from Al metal substrate with in-situ modulation of their morphologies and structures into 1D, 2D, and 3D nano-architectures explored in this work is unique and can offer significant opportunities over the conventional methods.

scholarly journals Structural Characterization of Heterodinuclear ZnII-LnIII Complexes (Ln = Pr, Nd) with a Ring-Contracted H2valdien-Derived Schiff Base Ligand

2021 ◽  
Author(s):  
Shabana Noor ◽  
Richard Goddard ◽  
Fehmeeda Khatoon ◽  
Sarvendra Kumar ◽  
Rüdiger W. Seidel
Keyword(s):  
Molecular Structure ◽  
Schiff Base ◽  
Structural Characterization ◽  
Schiff Base Ligand ◽  
Crystal And Molecular Structure ◽  
X Ray ◽  
X Ray Crystallography ◽  
Imidazoline Ring

AbstractSynthesis and structural characterization of two heterodinuclear ZnII-LnIII complexes with the formula [ZnLn(HL)(µ-OAc)(NO3)2(H2O)x(MeOH)1-x]NO3 · n H2O · n MeOH [Ln = Pr (1), Nd (2)] and the crystal and molecular structure of [ZnNd(HL)(µ-OAc)(NO3)2(H2O)] [ZnNd(HL)(OAc)(NO3)2(H2O)](NO3)2 · n H2O · n MeOH (3) are reported. The asymmetrical compartmental ligand (E)-2-(1-(2-((2-hydroxy-3-methoxybenzylidene)amino)-ethyl)imidazolidin-2-yl)-6-methoxyphenol (H2L) is formed from N1,N3-bis(3-methoxysalicylidene)diethylenetriamine (H2valdien) through intramolecular aminal formation, resulting in a peripheral imidazoline ring. The structures of 1–3 were revealed by X-ray crystallography. The smaller ZnII ion occupies the inner N2O2 compartment of the ligand, whereas the larger and more oxophilic LnIII ions are found in the outer O2O2’ site. Graphic Abstract Synthesis and structural characterization of two heterodinuclear ZnII-LnIII complexes (Ln = Pr, Nd) bearing an asymmetrical compartmental ligand formed in situ from N1,N3-bis(3-methoxysalicylidene)diethylenetriamine (H2valdien) through intramolecular aminal formation are reported.

scholarly journals Selective Styrene Oxidation to Benzaldehyde over Recently Developed Heterogeneous Catalysts

Molecules ◽  
2021 ◽  
Vol 26 (6) ◽  
pp. 1680
Author(s):  
Marta A. Andrade ◽  
Luísa M. D. R. S. Martins
Keyword(s):  
Heterogeneous Catalysts ◽  
Carbon Materials ◽  
Oxygen Species ◽  
Styrene Oxidation ◽  
Reaction Conditions ◽  
Reactive Metal ◽  
Catalytic Systems ◽  
Tert Butyl Hydroperoxide ◽  
Metal Organic ◽  
Important Intermediate

The selective oxidation of styrene under heterogeneous catalyzed conditions delivers environmentally friendly paths for the production of benzaldehyde, an important intermediate for the synthesis of several products. The present review explores heterogeneous catalysts for styrene oxidation using a variety of metal catalysts over the last decade. The use of several classes of supports is discussed, including metal–organic frameworks, zeolites, carbon materials and silicas, among others. The studied catalytic systems propose as most used oxidants tert-butyl hydroperoxide, and hydrogen peroxide and mild reaction conditions. The reaction mechanism proceeds through the generation of an intermediate reactive metal–oxygen species by catalyst-oxidant interactions. Overall, most of the studies highlight the synergetic effects among the metal and support for the activity and selectivity enhancement.

In situ construction of phenanthroline-based cationic radical porous hybrid polymers for metal-free heterogeneous catalysis

2021 ◽  
Vol 9 (12) ◽  
pp. 7556-7565
Author(s):  
Guojian Chen ◽  
Yadong Zhang ◽  
Ke Liu ◽  
Xiaoqing Liu ◽  
Lei Wu ◽  
...  
Keyword(s):  
Heterogeneous Catalysis ◽  
Heterogeneous Catalysts ◽  
Hybrid Polymers ◽  
Metal Free ◽  
Oxidation Of Sulfides

Constructing phenanthroline-based cationic radical porous hybrid polymers as versatile metal-free heterogeneous catalysts for both oxidation of sulfides and CO2 conversion.

scholarly journals Sustainable M-MOF-74 (M = Cu, Co, Zn) prepared in methanol as heterogeneous catalysts in the synthesis of benzaldehyde from styrene oxidation

2021 ◽  
pp. 122151
Author(s):  
J. Gabriel Flores ◽  
Manuel Díaz-García ◽  
Ilich A. Ibarra ◽  
Julia Aguilar-Pliego ◽  
Manuel Sánchez-Sánchez
Keyword(s):  
Heterogeneous Catalysts ◽  
Styrene Oxidation

scholarly journals Ambient base-free glycerol oxidation over bimetallic PdFe/SiO2 by in situ generated active oxygen species

2021 ◽  
Author(s):  
Ricci Underhill ◽  
Mark Douthwaite ◽  
Richard J. Lewis ◽  
Peter J. Miedziak ◽  
Robert D. Armstrong ◽  
...  
Keyword(s):  
Heterogeneous Catalysts ◽  
Bimetallic Catalyst ◽  
Electron Paramagnetic Resonance Spectroscopy ◽  
Active Oxygen Species ◽  
Catalytic Performance ◽  
Resonance Spectroscopy ◽  
Oxygen Species ◽  
Paramagnetic Resonance ◽  
Temperature Oxidation

AbstractLow temperature oxidation of alcohols over heterogeneous catalysts is exceptionally challenging, particularly under neutral conditions. Herein, we report on an efficient, base-free method to oxidise glycerol over a 0.5%Pd-0.5%Fe/SiO2 catalyst at ambient temperature in the presence of gaseous H2 and O2. The exceptional catalytic performance was attributed to the in situ formation of highly reactive surface-bound oxygenated species, which promote the dehydrogenation on the alcohol. The PdFe bimetallic catalyst was determined to be significantly more active than corresponding monometallic analogues, highlighting the important role both metals have in this oxidative transformation. Fe leaching was confirmed to occur over the course of the reaction but sequestering experiments, involving the addition of bare carbon to the reactions, confirmed that the reaction was predominantly heterogeneous in nature. Investigations with electron paramagnetic resonance spectroscopy suggested that the reactivity in the early stages was mediated by surface-bound reactive oxygen species; no homogeneous radical species were observed in solution. This theory was further evidenced by a direct H2O2 synthesis study, which confirmed that the presence of Fe in the bimetallic catalyst neither improved the synthesis of H2O2 nor promoted its decomposition over the PdFe/SiO2 catalyst.

Optimization on Influencing Factors of Fracture Toughness of Corundum-Mullite Toughened by In Situ Synthesized Mullite Whiskers by Response Surface Methodology

2012 ◽  
Vol 581-582 ◽  
pp. 819-822 ◽  
Author(s):  
Bin Meng ◽  
Jin Hui Peng
Keyword(s):  
Fracture Toughness ◽  
Response Surface Methodology ◽  
Response Surface ◽  
Response Surface Method ◽  
Sintering Temperature ◽  
Surface Method ◽  
Mullite Whiskers ◽  
Optimized Conditions ◽  
Addition Amount

The corundum-mullite was toughened by in-situ synthesized mullite whiskers and the process parameters influencing the fracture toughness of corundum-mullite, such as sintering temperature, addition amount of AlF3 and V2O5, were optimized by means of response surface method. Corundum-mullite with fracture toughness of 9.44 MPa.m-1/2 could be obtained under the optimized conditions, i.e. sintering temperature of 1400°C, 4.8 wt.% of AlF3 and 5.8 wt.% of V2O5. The results showed that it was feasible to prepare corundum-mullite toughened by in-situ synthesized mullite whiskers by the optimized parameters. In addition, an accurate model based on response surface method was proposed to predict the experimental results.

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