Direct synthesis and catalytic activity of ordered large pore titanium-substituted spherical SBA-15 molecular sieves

2012 ◽  
Vol 106 (1) ◽  
pp. 245-256 ◽  
Author(s):  
Shengwen Chen ◽  
Changwen Ma ◽  
Minmin Qin ◽  
Haifeng Yang ◽  
Hongyong Xie ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Molecular Sieves ◽  
Direct Synthesis ◽  
Large Pore

Direct synthesis, characterization and catalytic activity of titanium-substituted SBA-15 mesoporous molecular sieves

2004 ◽  
Vol 273 (1-2) ◽  
pp. 185-191 ◽  
Author(s):  
Yangying Chen ◽  
Yanlei Huang ◽  
Jinghai Xiu ◽  
Xiuwen Han ◽  
Xinhe Bao
Keyword(s):  
Catalytic Activity ◽  
Molecular Sieves ◽  
Direct Synthesis ◽  
Mesoporous Molecular Sieves

Direct Synthesis and Catalytic Reactivity of Highly Ordered Large-Pore Methylaminopropyl-Functionalized SBA-15 Materials

2005 ◽  
Vol 58 (7) ◽  
pp. 507 ◽  
Author(s):  
Xueguang Wang ◽  
Soofin Cheng
Keyword(s):  
Catalytic Activity ◽  
Inorganic Salt ◽  
Direct Synthesis ◽  
Initial Mixture ◽  
Tetraethyl Orthosilicate ◽  
High Catalytic Activity ◽  
Amino Groups ◽  
Large Pore ◽  
Catalytic Reactivity ◽  
First Time

Highly ordered large-pore SBA-15 materials functionalized with a high loading of amino groups were synthesized for the first time by co-condensation of tetraethyl orthosilicate (TEOS) and [3-(methylamino)propyl]trimethoxysilane (MAPTMS) using an amphiphilic block copolymer. Addition of inorganic salt to the initial mixture greatly enhanced the mesostructure ordering and stability of the mesoporous materials. The materials thus obtained showed high catalytic activity and selectivity for the synthesis of flavanones by means of the Claisen–Schmidt condensation in the absence of solvent.

Functionalization of large-pore mesoporous silicas with organosilanes by direct synthesis

2004 ◽  
Vol 72 (1-3) ◽  
pp. 33-42 ◽  
Author(s):  
A.S Maria Chong ◽  
X.S Zhao ◽  
Angeline T Kustedjo ◽  
S.Z Qiao
Keyword(s):  
Direct Synthesis ◽  
Mesoporous Silicas ◽  
Large Pore

Direct Synthesis and Spectroscopic Evidence of Framework Co(II) ions in SBA-15 Mesoporous Molecular Sieves

2004 ◽  
Vol 33 (5) ◽  
pp. 588-589 ◽  
Author(s):  
Ajayan Vinu ◽  
Martin Hartmann
Keyword(s):  
Molecular Sieves ◽  
Direct Synthesis ◽  
Mesoporous Molecular Sieves ◽  
Spectroscopic Evidence

scholarly journals Gas phase synthesis of dimethyl carbonate from CO2 and CH3OH over Cu-Ni/AC. A kinetic study

2019 ◽  
pp. 88-99 ◽  
Author(s):  
Oscar Felipe Arbeláez-Pérez ◽  
Sara Dominguez Cardozo ◽  
Andrés Felipe Orrego-Romero ◽  
Aida Luz Villa Holguin ◽  
Felipe Bustamante Londoño
Keyword(s):  
Carbon Dioxide ◽  
Catalytic Activity ◽  
Activated Carbon ◽  
Gas Phase ◽  
Dimethyl Carbonate ◽  
Direct Synthesis ◽  
Dispersion Analysis ◽  
Molar Ratio ◽  
Rate Determining Step ◽  
Carbonate Formation

The catalytic activity for dimethyl carbonate formation from carbon dioxide and methanol over mono and bimetallic Cu:Ni supported on activated carbon is presented. Bimetallic catalysts exhibit higher catalytic activity than the monometallic samples, being Cu:Ni-2:1 (molar ratio) the best catalyst; X-Ray diffraction, transmission electron microscopy, and metal dispersion analysis provided insight into the improved activity. In situ FT-IR experiments were conducted to investigate the mechanism of formation of dimethyl carbonate from methanol and carbon dioxide over Cu-Ni:2-1. The kinetics of the direct synthesis of dimethyl carbonate in gas phase over Cu:Ni-2:1 supported on activated carbon catalyst was experimentally investigated at 12 bar and temperatures between 90 oC and 130 oC, varying the partial pressures of CO2 and methanol. Experimental kinetic data were consistent with a Langmuir–Hinshelwood model that included carbon dioxide and methanol adsorption on catalyst actives sites (Cu, Ni and Cu-Ni), and the reaction of adsorbed CO2 with methoxi species as the rate determining step. The estimated apparent activation energy was 94.2 kJ mol-1.

High Catalytic Activity of Pd Nanoparticles Synthesized from Green Alga Chlorella vulgaris in Buchwald-hartwig Synthesis of N-Aryl Piperazines

2019 ◽  
Vol 7 (1) ◽  
pp. 23-33
Author(s):  
Vaibhav Mishra ◽  
Anju Arya ◽  
Tejpal Singh Chundawat
Keyword(s):  
Catalytic Activity ◽  
Green Alga ◽  
Chlorella Vulgaris ◽  
Direct Synthesis ◽  
Coupling Reaction ◽  
Pd Nanoparticles ◽  
High Catalytic Activity ◽  
Pd Nanoparticle ◽  
Green Algal ◽  
Green Alga Chlorella

Background: The N-aryl piperazines are an important component of many drug products used for the treatment of malaria, depression, anxiety and Parkinson diseases. Buchwald-Hartwig amination is the latest and well-known reaction for Pd catalyzed direct synthesis of N-aryl piperazine from aryl halides. Although several Pd-ligand systems have already been discovered for this conversion, Pd nanoparticles are recently being used for this useful coupling reaction due to their recyclability and durability. Metal nanoparticles show enhanced catalytic activity compared to their bulk counterparts due to increased surface area at the edges and corners. The use of green algal extract in place of chemical ligands makes this process more environment-friendly and cost-effective. In this research, Pd nanoparticles synthesized using green alga C. Vulgaris were utilized as an alternative approach for the coupling reaction during the preparation of N-aryl piperazines. Methods: Synthesized Pd nanoparticles from C. Vulgaris were characterized by FTIR, SEM and XRD techniques. The catalytic activity of the synthesized nanoparticles was monitored for the synthesis of N-aryl piperazines by Buchwald-Hartwig reaction. The synthesized N-aryl piperazines were characterized by NMR, FTIR and mass analysis. Results: A very good catalytic activity of the synthesized Pd nanoparticles from green alga Chlorella vulgaris extract was observed. The green alga not only reduces the size of the Pd metal to nanoparticles but also acts as a green ligand for reduction of Pd(II) to Pd(0) during nanoparticle synthesis. Using this Pd nanoparticles-green ligand system, several N-aryl piperazines were synthesized in good to excellent yields. Reaction conditions for better conversion were optimized. The comparative advantage of the catalytic system with recently published works on Buchwald-Hartwig C-N coupling reaction is given. Recyclability and durability of the catalyst were explored and the results were found to be promising. A plausible mechanism of Pd nanoparticle catalyzed reaction is also proposed. Conclusion: Catalytic activity of the Pd nanoparticle synthesized from Chlorella vulagris in the synthesis of N-aryl piperazines by Buchwald-Hartwig reaction is reported first time to the best of our knowledge and understanding. The green approach of Pd catalyst to facilitate the reaction and its environmental impact is the main characteristic of the process.

Synthesis, characterization and catalytic activity of actinide Th-MCM-41 and U-MCM-41 hexagonal packed mesoporous molecular sieves

2001 ◽  
Vol 171 (1-2) ◽  
pp. 229-241 ◽  
Author(s):  
Rodica Tismaneanu ◽  
Biswajit Ray ◽  
Rafael Khalfin ◽  
Rafi Semiat ◽  
Moris S. Eisen
Keyword(s):  
Catalytic Activity ◽  
Molecular Sieves ◽  
Mesoporous Molecular Sieves ◽  
Mcm 41

Synthesis of Al-free Sn-containing molecular sieves of MFI, MEL and MTWtypes and their catalytic activity in oxidation reactions

1995 ◽  
pp. 317-324 ◽  
Author(s):  
Nawal Kishor Mal ◽  
Asim Bhaumik ◽  
Veda Ramaswamy ◽  
Anagha A. Belhekar ◽  
Arumugamangalam V. Ramaswamy
Keyword(s):  
Catalytic Activity ◽  
Molecular Sieves ◽  
Oxidation Reactions
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