scholarly journals Controlling catalytic activity and selectivity for partial hydrogenation by tuning the environment around active sites in iridium complexes bonded to supports

2019 ◽  
Vol 10 (9) ◽  
pp. 2623-2632 ◽  
Author(s):  
Melike Babucci ◽  
Chia-Yu Fang ◽  
Jorge E. Perez-Aguilar ◽  
Adam S. Hoffman ◽  
Alexey Boubnov ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
Catalytic Activity ◽  
Active Sites ◽  
Catalytic Performance ◽  
Partial Hydrogenation ◽  
Iridium Complexes

Enveloping atomically dispersed supported iridium with the choice of ionic liquid molecular sheaths and supports controls the catalytic performance.

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.

Magnetic Nanoparticles Supported Acidic Ionic Liquid as a Highly Active and Reusable Catalyst for Esterification

2016 ◽  
Vol 852 ◽  
pp. 485-488 ◽  
Author(s):  
Qiang Zhang ◽  
Xin Zhao ◽  
Xue Hua Zhu ◽  
Ji Hang Li
Keyword(s):  
Ionic Liquid ◽  
Catalytic Activity ◽  
Magnetic Nanoparticles ◽  
Catalytic Performance ◽  
Significant Loss ◽  
Reusable Catalyst ◽  
Hydrogen Sulfate ◽  
External Magnet ◽  
Acidic Ionic Liquid ◽  
Highly Active

A magnetic nanoparticles supported dual acidic ionic liquid catalyst was prepared via anchoring 3-sulfobutyl-1-(3-propyltriethoxysilane) imidazolium hydrogen sulfate onto the surface of silica-coated Fe3O4 nanoparticles. And this novel supported acidic ionic liquid catalyst showed good catalytic performance in esterification. More importantly, the catalyst could be easily recovered by an external magnet and reused six times without significant loss of catalytic activity.

scholarly journals Effect of the oxygen coordination environment of Ca–Mn oxides on the catalytic performance of Pd supported catalysts for aerobic oxidation of 5-hydroxymethyl-2-furfural

2019 ◽  
Vol 9 (23) ◽  
pp. 6659-6668 ◽  
Author(s):  
Jie Yang ◽  
Haochen Yu ◽  
Yanbing Wang ◽  
Fuyuan Qi ◽  
Haodong Liu ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Charge Transfer ◽  
Active Sites ◽  
Supported Catalysts ◽  
Aerobic Oxidation ◽  
Oxygen Adsorption ◽  
Catalytic Performance ◽  
Coordination Environment ◽  
Oxygen Coordination ◽  
Mn Oxides

Pd/CaMn2O4 provides ideal active sites for oxygen adsorption and desorption, resulting in the promoted charge transfer ability and catalytic activity.

Carbon Dioxide Hydrogenation to Methanol over Cu/ZnO-SBA-15 Catalyst: Effect of Metal Loading

2017 ◽  
Vol 380 ◽  
pp. 151-160 ◽  
Author(s):  
Sara Faiz Hanna Tasfy ◽  
Noor Asmawati Mohd Zabidi ◽  
Maizatul Shima Shaharun ◽  
Duvvria Subbarao ◽  
Ahmed Elbagir
Keyword(s):  
Catalytic Activity ◽  
Carbon Source ◽  
Active Sites ◽  
Low Cost ◽  
Fixed Bed ◽  
Textural Properties ◽  
Catalytic Performance ◽  
Hydrogenation Reaction ◽  
Supported Metal Catalysts ◽  
Metal Loading

Utilization of CO2 as a carbon source to produce valuable chemicals is one of the important ways to reduce the global warming caused by increasing CO2 in the atmosphere. Supported metal catalysts are crucial to produce clean and renewable fuels and chemicals from the stable CO2 molecules. The catalytic conversion of CO2 into methanol is recently under increased scrutiny as an opportunity to be used as a low-cost carbon source. Therefore, a series of the bimetallic Cu/ZnO-based catalyst supported by SBA-15 were synthesized via an impregnation technique with different total metal loading and tested in the catalytic hydrogenation of CO2 to methanol. The morphological and textural properties of the synthesized catalysts were determined by transmission electron microscopy (TEM), temperature programmed desorption, reduction, oxidation and pulse chemisorption (TPDRO), and N2-adsorption. The CO2 hydrogenation reaction was performed in a microactivity fixed-bed system at 250oC, 2.25 MPa, and H2/CO2 ratio of 3. Experimental results showed that the catalytic structure and performance were strongly affected by the loading of the active site. Where, the catalytic activity, the methanol selectivity as well as the space-time yield increased with increasing the metal loading until it reaches the maximum values at a metal loading of 15 wt% while further addition of metal inhibits the catalytic performance. The higher catalytic activity of 14% and methanol selectivity of 92% was obtained over a Cu/ZnO-SBA-15 catalyst with a total bimetallic loading of 15 wt%. The excellent performance of 15 wt% Cu/ZnO-SBA-15 catalyst is attributed to the presence of well dispersed active sites with small particle size, higher Cu surface area, and lower catalytic reducibility.

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.

High-heat treatment enhanced catalytic activity of CuO/CeO2 catalysts with low CuO content for CO oxidation

2020 ◽  
Vol 10 (15) ◽  
pp. 5256-5266 ◽  
Author(s):  
Jihang Yu ◽  
Qiangsheng Guo ◽  
Xiuzhen Xiao ◽  
Haifang Mao ◽  
Dongsen Mao ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Catalytic Activity ◽  
Co Oxidation ◽  
Active Sites ◽  
High Heat ◽  
Catalytic Performance

CuO/CeO2 catalysts with low CuO content and calcined at 800 °C exhibited better catalytic performance than those calcined at 500 °C. The coordinatively unsaturated copper atoms were proved to be the main active sites in the CuO/CeO2 catalysts.

Inverse relationship of dimensionality and catalytic activity in CO2transformation: a systematic investigation by comparing multidimensional metal–organic frameworks

2017 ◽  
Vol 5 (30) ◽  
pp. 15961-15969 ◽  
Author(s):  
Robin Babu ◽  
Roshith Roshan ◽  
Yeongrok Gim ◽  
Yun Hee Jang ◽  
Jintu Francis Kurisingal ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Active Sites ◽  
Inverse Relationship ◽  
Metal Organic Frameworks ◽  
Catalytic Performance ◽  
Systematic Investigation ◽  
Cycloaddition Reactions ◽  
Metal Organic ◽  
Relationship Of

The correlation between dimensionality and active sites on deciding the catalytic performance of an MOF catalyst in CO2–epoxide cycloaddition reactions has been studied.

Fe-Modified ZSM-5 and β Zeolites for Direct N2O Decomposition

2012 ◽  
Vol 610-613 ◽  
pp. 94-99 ◽  
Author(s):  
Quan Hui Guo ◽  
Juan Li ◽  
Ying Xia Li
Keyword(s):  
Catalytic Activity ◽  
Active Sites ◽  
Channel Wall ◽  
Decomposition Reaction ◽  
Catalytic Performance ◽  
Iron Ions ◽  
Exchange Method ◽  
Different Types ◽  
Charge Balancing ◽  
Better Than

Fe-modified ZSM-5 and β zeolites were prepared by adopting liquid ion-exchange method and their catalytic performance was studied in the N2O decomposition reaction. The state of Fe loaded on Fe-zeolites was investigated by means of UV-vis diffuse spectra, infrared spectroscopy, EPR and H2-TPR. The results of IR of hydroxyl stretching and UV-vis investigationSubscript texts indicated that part of the iron-ions was introduced into zeolites at the charge-balancing sites. The results of EPR and H2-TPR investigations showed that the same iron species were loaded on ZSM-5 and β zeolites. However, the results of IR of the perturbed anti-symmetric T-O-T vibrations of iron-ions indicated that different types of ZSM-5 and β zeolites resulted in different distributions of charge-balancing iron cations. The iron-ions could replace Brönsted acid protons at the straight channel wall (α sites), intersection of straight and sinusoidal channels (β sites), and sinusoidal channel wall (γ sites) within the ZSM-5 zeolite. In the case of Fe-β zeolites, iron-ions mainly located in the straight channels. We observed that the catalytic activity of the iron ions located on the α sites of ZSM-5 zeolites was better than those of iron ions located on β and γ sites in N2O direct decomposition, since the former was the most easily reduced from Fe3+to Fe2+in H2. Furthermore, it was found that Fe-β zeolite showed higher catalytic activity than Fe-ZSM-5 zeolite. This difference was attributed to the active sites located almost exclusively in the straight zeolite channels.

Freestanding CuS nanowalls: ionic liquid-assisted synthesis and prominent catalytic performance for the decomposition of ammonium perchlorate

CrystEngComm ◽  
2017 ◽  
Vol 19 (34) ◽  
pp. 5048-5057 ◽  
Author(s):  
Kaisheng Yao ◽  
Chenchen Zhao ◽  
Nannan Sun ◽  
Weiwei Lu ◽  
Yuan Zhang ◽  
...  
Keyword(s):  
Thermal Decomposition ◽  
Ionic Liquid ◽  
Catalytic Activity ◽  
Ammonium Perchlorate ◽  
Catalytic Performance ◽  
Liquid Interface

Freestanding CuS nanowalls, with excellent catalytic activity for AP thermal decomposition, were grown and assembled at the [C10mim]Br-modulated liquid–liquid interface.

scholarly journals Effect of Metal Loading in Unpromoted and Promoted CoMo/Al2O3–TiO2 Catalysts for the Hydrodeoxygenation of Phenol

Catalysts ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 550 ◽  
Author(s):  
J. Andrés Tavizón-Pozos ◽  
Carlos E. Santolalla-Vargas ◽  
Omar U. Valdés-Martínez ◽  
José Antonio de los Reyes Heredia
Keyword(s):  
Catalytic Activity ◽  
Active Sites ◽  
Mixed Oxides ◽  
Batch Reactor ◽  
Sol Gel ◽  
Active Phase ◽  
Catalytic Performance ◽  
Octahedral Coordination ◽  
Optimum Amount ◽  
Co Concentration

This paper reports the effects of changes in the supported active phase concentration over titania containing mixed oxides catalysts for hydrodeoxygenation (HDO). Mo and CoMo supported on sol–gel Al2O3–TiO2 (Al/Ti = 2) were synthetized and tested for the HDO of phenol in a batch reactor at 5.5 MPa, 593 K, and 100 ppm S. Characterization results showed that the increase in Mo loading led to an increase in the amount of oxide Mo species with octahedral coordination (MoOh), which produced more active sites and augmented the catalytic activity. The study of the change of Co concentration allowed prototypes of the oxide species and their relationship with the CoMo/AT2 activity to be described. Catalysts were tested at four different Co/(Co + Mo) ratios. The results presented a correlation between the available fraction of CoOh and the catalytic performance. At low CoOh fractions (Co/(Co + Mo) = 0.1), Co could not promote all MoS2 slabs and metallic sites from this latter phase performed the reaction. Also, at high Co/(Co + Mo) ratios (0.3 and 0.4), there was a loss of Co species. The Co/(Co + Mo) = 0.2 ratio presented an optimum amount of available CoOh and catalytic activity since the XPS results indicated a higher concentration of the CoMoS phase than at a higher ratio.

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