Preparation and Catalytic Performance of Phosphotungstic Acid Active Sites Supported on Periodic Mesoporous Organosilica of SBA-15

2013 ◽  
Vol 33 (6) ◽  
pp. 1032-1040
Author(s):  
Cheng LIU ◽  
Rong TAN ◽  
Wenqing SUN ◽  
Donghong YIN
Keyword(s):  
Active Sites ◽  
Phosphotungstic Acid ◽  
Catalytic Performance ◽  
Periodic Mesoporous Organosilica ◽  
Mesoporous Organosilica

Synthesis of (E)-2-(1H-tetrazole-5-yl)-3-phenylacrylenenitrile Derivatives Under Green Conditions Catalyzed by New Thermally Stable Magnetic Periodic Mesoporous Ognosilica Embedded With ZnO Nanoparticles

2021 ◽  
Author(s):  
Sajedeh Safapoor ◽  
Mohammad G. Dekamin ◽  
Arezoo Akbari ◽  
M. Reza Naimi-Jamal
Keyword(s):  
Zno Nanoparticles ◽  
Active Sites ◽  
Significant Loss ◽  
Catalyst Loading ◽  
Thermally Stable ◽  
Green Solvents ◽  
Periodic Mesoporous Organosilica ◽  
Mesoporous Organosilica ◽  
Tetrazole Derivatives ◽  
Green Conditions

Abstract ZnO nanoparticles embedded on the surface of magnetic isocyanurate-based periodic mesoporous organosilica (Fe3O4@PMO-ICS–ZnO) was prepared through modified environmental-benign procedure for the first time and was properly characterized by appropriate spectroscopic and analytical methods or techniques used for mesoporous materials. The new thermally stable Fe3O4@PMO-ICS–ZnO materials with proper active sites, uniform particle size and surface area were investigated for the synthesis of medicinally important tetrazole derivatives through cascade condensation and concerted reactions as a representative of the Click Chemistry concept. The desired 5-substituted-1H-tetrazole derivatives were smoothly prepared in high to quantitative yields and good purity under green conditions. Low catalyst loading, very short reaction time and the use of green solvents such as EtOH and water instead of carcinogenic DMF as well as the possibility of easy separation and recyclability of the catalyst for at least five consecutive runs without significant loss of its activity are notable advantages of this new protocols compared to other recent introduced procedures.

scholarly journals Highly Active Benzotriazolium Ionic Liquid-modified Periodic Mesoporous Organosilica Supported Samarium/Lanthanum Nanoparticles for Sustainable Transformation of Carbon Dioxide to Cyclic Carbonates

2020 ◽  
Vol 64 (3) ◽  
Author(s):  
Hu Yu Lin ◽  
Bing Liu Xiao ◽  
Yang Liu
Keyword(s):  
Ionic Liquid ◽  
Cycloaddition Reaction ◽  
Catalytic Performance ◽  
Significant Loss ◽  
Cyclic Carbonates ◽  
Periodic Mesoporous Organosilica ◽  
Highly Active ◽  
Mesoporous Organosilica ◽  
High Yields ◽  
Lanthanum Acetate

Abstract. A novel type of multifunctional nanocatalysts (La-/Sm-PMO-ILCl) based on the immobilization of benzotriazolium ionic liquid and further incorporation of samarium acetate or lanthanum acetate onto periodic mesoporous organosilica were afforded for the cycloaddition of CO2 and epoxides to produce cyclic carbonates. In consequence of the intramolecular synergistic effect between samarium sites of periodic mesoporous organosilica and homogeneously dispersed basic sites of ionic liquid, the powerful catalyst Sm-PMO-ILCl offered superior catalytic performance with ultra high yields and selectivities in the cycloaddition reaction without the addition of any solvent and cocatalyst. Moreover, the catalyst Sm-PMO-ILCl could be easily recovered by filtration and reused for at least five runs without any significant loss of its catalytic activity. Resumen. Se prepararon nuevos nano catalizadores (La-(Sm-PMO-ILC1) por la vía de inmovilización del líquido iónico benzotriazolium y adición se acetato de samario o acetato de lantano en organosilice mesoporosa. Los catalizadores se evaluaron en la ciclo adición de CO2 y epóxidos para producir carbonatos cíclicos. El efecto sinérgico intramolecular entre los sitios de samario de la organosilice y los sitios básicos del líquido iónico homogéneamente distribuidos inducen una alta actividad catalítica en el catalizador Sm-PMO-ILC1. Así, con este catalizador se obtuvo alta conversión y selectividad en la reacción de ciclo adición, sin agregar solvente ni co-catalizador. Además, el catalizador Sm-PMO-ILC1 podría recuperarse fácilmente por filtración y reusado por al menos 5 corridas sin pérdida significativa de su actividad catalítica.

The design and catalytic performance of molybdenum active sites on an MCM-41 framework for the aerobic oxidation of 5-hydroxymethylfurfural to 2,5-diformylfuran

2019 ◽  
Vol 9 (3) ◽  
pp. 811-821 ◽  
Author(s):  
Zhao-Meng Wang ◽  
Li-Juan Liu ◽  
Bo Xiang ◽  
Yue Wang ◽  
Ya-Jing Lyu ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Active Sites ◽  
Aerobic Oxidation ◽  
Catalytic Performance ◽  
Mcm 41

The catalytic activity decreases as –(SiO)3Mo(OH)(O) > –(SiO)2Mo(O)2 > –(O)4–MoO.

Catalytic Resonance Theory: Parallel Reaction Pathway Control

2019 ◽  
Author(s):  
M. Alexander Ardagh ◽  
Manish Shetty ◽  
Anatoliy Kuznetsov ◽  
Qi Zhang ◽  
Phillip Christopher ◽  
...  
Keyword(s):  
Chemical Reactions ◽  
Active Site ◽  
Active Sites ◽  
Reaction Pathway ◽  
Control Strategies ◽  
Oscillation Amplitude ◽  
Catalytic Performance ◽  
Parallel Reaction ◽  
Resonance Theory ◽  
Static Conditions

Catalytic enhancement of chemical reactions via heterogeneous materials occurs through stabilization of transition states at designed active sites, but dramatically greater rate acceleration on that same active site is achieved when the surface intermediates oscillate in binding energy. The applied oscillation amplitude and frequency can accelerate reactions orders of magnitude above the catalytic rates of static systems, provided the active site dynamics are tuned to the natural frequencies of the surface chemistry. In this work, differences in the characteristics of parallel reactions are exploited via selective application of active site dynamics (0 < ΔU < 1.0 eV amplitude, 10<sup>-6</sup> < f < 10<sup>4</sup> Hz frequency) to control the extent of competing reactions occurring on the shared catalytic surface. Simulation of multiple parallel reaction systems with broad range of variation in chemical parameters revealed that parallel chemistries are highly tunable in selectivity between either pure product, even when specific products are not selectively produced under static conditions. Two mechanisms leading to dynamic selectivity control were identified: (i) surface thermodynamic control of one product species under strong binding conditions, or (ii) catalytic resonance of the kinetics of one reaction over the other. These dynamic parallel pathway control strategies applied to a host of chemical conditions indicate significant potential for improving the catalytic performance of many important industrial chemical reactions beyond their existing static performance.

Structural/Texture Evolution During Facile Substitution of Ni into ZSM-5 Nanostructure vs. its Impregnation Dispersion Used in Selective Transformation of Methanol to Ethylene and Propylene

2020 ◽  
Vol 23 ◽  
Author(s):  
Parisa Sadeghpour ◽  
Mohammad Haghighi ◽  
Mehrdad Esmaeili
Keyword(s):  
High Temperature ◽  
Physicochemical Properties ◽  
Active Sites ◽  
Catalytic Performance ◽  
Fixed Bed Reactor ◽  
Light Olefins ◽  
Isomorphous Substitution ◽  
Impregnation Method ◽  
Hydrothermal Temperature ◽  
X Ray

Aim and Objective: Effect of two different modification methods for introducing Ni into ZSM-5 framework was investigated under high temperature synthesis conditions. The nickel successfully introduced into the MFI structures at different crystallization conditions to enhance the physicochemical properties and catalytic performance. Materials and Methods: A series of impregnated Ni/ZSM-5 and isomorphous substituted NiZSM-5 nanostructure catalysts were prepared hydrothermally at different high temperatures and within short times. X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), Energy dispersive X-ray (EDX), Brunner, Emmett and Teller-Barrett, Joyner and Halenda (BET-BJH), Fourier transform infrared (FTIR) and Temperature-programmed desorption of ammonia (TPDNH3) were applied to investigate the physicochemical properties. Results: Although all the catalysts showed pure silica MFI–type nanosheets and coffin-like morphology, using the isomorphous substitution for Ni incorporation into the ZSM-5 framework led to the formation of materials with lower crystallinity, higher pore volume and stronger acidity compared to using impregnation method. Moreover, it was found that raising the hydrothermal temperature increased the crystallinity and enhanced more uniform incorporation of Ni atoms in the crystalline structure of catalysts. TPD-NH3 analysis demonstrated that high crystallization temperature and short crystallization time of NiZSM-5(350-0.5) resulted in fewer weak acid sites and medium acid strength. The MTO catalytic performance was tested in a fixed bed reactor at 460ºC and GHSV=10500 cm3 /gcat.h. A slightly different reaction pathway was proposed for the production of light olefins over impregnated Ni/ZSM-5 catalysts based on the role of NiO species. The enhanced methanol conversion for isomorphous substituted NiZSM-5 catalysts could be related to the most accessible active sites located inside the pores. Conclusion: The impregnated Ni/ZSM-5 catalyst prepared at low hydrothermal temperature showed the best catalytic performance, while the isomorphous substituted NiZSM-5 prepared at high temperature was found to be the active molecular sieve regarding the stability performance.

Efficient Production of Biodiesel Catalyzed by Acidic Nanoporous Carbon Materials：A Review

2020 ◽  
Vol 16 ◽  
Author(s):  
Anping Wang ◽  
Heng Zhang ◽  
Hu Li ◽  
Song Yang
Keyword(s):  
Pore Structure ◽  
Active Sites ◽  
Catalytic Performance ◽  
Nanoporous Carbon ◽  
Biodiesel Production ◽  
Efficient Production ◽  
Fossil Energy ◽  
Catalytic Materials ◽  
High Acid ◽  
Carbon Based

Background: With the gradual decrease of fossil energy, the development of alternatives to fossil energy has attracted more and more attention. Biodiesel is considered to be the most potent alternative to fossil energy, mainly due to its green, renewable and biodegradable advantages. The stable, efficient and reusable catalysts are undoubtedly the most critical in the preparation of biodiesel. Among them, nanoporous carbon-based acidic materials are very important biodiesel catalysts. Objective: The latest advances of acidic nanoporous carbon catalysts in biodiesel production was reviewed. Methods: Biodiesel is mainly synthesized by esterification and transesterification. Due to the important role of nanoporous carbon-based acidic materials in the catalytic preparation of biodiesel, we focused on the synthesis, physical and chemical properties, catalytic performance and reusability. Results: Acidic catalytic materials have a good catalytic performance for high acid value feedstocks. However, the preparation of biodiesel with acid catalyst requires relatively strict reaction conditions. The application of nanoporous acidic carbon-based materials, due to the support of carbon-based framework, makes the catalyst have good stability and unique pore structure, accelerates the reaction mass transfer speed and accelerates the reaction. Conclusion: Nanoporous carbon-based acidic catalysts have the advantages of suitable pore structure, high active sites, and high stability. In order to make these catalytic processes more efficient, environmentally friendly and low cost, it is an important research direction for the future biodiesel catalysts to develop new catalytic materials with high specific surface area, suitable pore size, high acid density, and excellent performance.

Light-harvesting photocatalysis for H2 evolution by methylacridone-bridged periodic mesoporous organosilica

2021 ◽  
Vol 287 ◽  
pp. 119965
Author(s):  
Yasutomo Goto ◽  
Ken-ichi Yamanaka ◽  
Masataka Ohashi ◽  
Yoshifumi Maegawa ◽  
Shinji Inagaki
Keyword(s):  
Light Harvesting ◽  
H2 Evolution ◽  
Periodic Mesoporous Organosilica ◽  
Mesoporous Organosilica
Sign in / Sign up

Export Citation Format

Share Document