Light‐Assisted CO2 Hydrogenation over Pd3Cu@UiO‐66 Promoted by Active Sites in Close Proximity

2021 ◽  
Author(s):  
Li-Li Ling ◽  
Weijie Yang ◽  
Peng Yan ◽  
Min Wang ◽  
Hai-Long Jiang
Keyword(s):  
Active Sites ◽  
Co2 Hydrogenation ◽  
Close Proximity

scholarly journals Synergistic Effect of Alkali Na and K Promoter on Fe-Co-Cu-Al Catalysts for CO2 Hydrogenation to Light Hydrocarbons

Catalysts ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 735
Author(s):  
Yuhao Zheng ◽  
Chenghua Xu ◽  
Xia Zhang ◽  
Qiong Wu ◽  
Jie Liu
Keyword(s):  
Synergistic Effect ◽  
Active Sites ◽  
Intermediate Formation ◽  
Active Phase ◽  
Dissociative Adsorption ◽  
Co2 Hydrogenation ◽  
Chain Growth ◽  
Co2 Conversion ◽  
Light Hydrocarbons ◽  
Active Centers

Alkali metal K- and/or Na-promoted FeCoCuAl catalysts were synthesized by precipitation and impregnation, and their physicochemical and catalytic performance for CO2 hydrogenation to light hydrocarbons was also investigated in the present work. The results indicate that Na and/or K introduction leads to the formation of active phase metallic Fe and Fe-Co crystals in the order Na < K < K-Na. The simultaneous introduction of Na and K causes a synergistic effect on increasing the basicity and electron-rich property, promoting the formation of active sites Fe@Cu and Fe-Co@Cu with Cu0 as a crystal core. These effects are advantageous to H2 dissociative adsorption and CO2 activation, giving a high CO2 conversion with hydrogenation. Moreover, electron-rich Fe@Cu (110) and Fe-Co@Cu (200) provide active centers for further H2 dissociative adsorption and O-C-Fe intermediate formation after adsorption of CO produced by RWGS. It is beneficial for carbon chain growth in C2+ hydrocarbons, including olefins and alkanes. FeCoCuAl simultaneously modified by K-Na exhibits the highest CO2 conversion and C2+ selectivity of 52.87 mol% and 89.70 mol%, respectively.

scholarly journals Highly Selective Au/ZnO via Colloidal Deposition for CO2 Hydrogenation to Methanol: Evidence of AuZn Role

2021 ◽  
Vol 16 (1) ◽  
pp. 44-51
Author(s):  
Hasliza Bahruji ◽  
Mshaal Almalki ◽  
Norli Abdullah
Keyword(s):  
Active Sites ◽  
Au Nanoparticles ◽  
High Selectivity ◽  
Average Diameter ◽  
Co2 Hydrogenation ◽  
Impregnation Method ◽  
Co2 Conversion ◽  
Methanol Production ◽  
Surface Oxygen Vacancy ◽  
Colloidal Method

Gold, Au nanoparticles were deposited on ZnO, Al2O3, and Ga2O3 via colloidal method in order to investigate the role of support for CO2 hydrogenation to methanol. Au/ZnO was also produced using impregnation method to investigate the effect of colloidal method to improve methanol selectivity. Au/ZnO produced via sol immobilization showed high selectivity towards methanol meanwhile impregnation method produced Au/ZnO catalyst with high selectivity towards CO. The CO2 conversion was also influenced by the amount of Au weight loading. Au nanoparticles with average diameter of 3.5 nm exhibited 4% of CO2 conversion with 72% of methanol selectivity at 250 °C and 20 bar. The formation of AuZn alloy was identified as active sites for selective CO2 hydrogenation to methanol. Segregation of Zn from ZnO to form AuZn alloy increased the number of surface oxygen vacancy for CO2 adsorption to form formate intermediates. The formate was stabilized on AuZn alloy for further hydrogenation to form methanol.  The use of Al2O3 and Ga2O3 inhibited the formation of Au alloy, and therefore reduced methanol production. Au/Al2O3 showed 77% selectivity to methane, meanwhile Au/Ga2O3 produced 100% selectivity towards CO. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0). 

Catalytic consequences of Ga promotion on Cu for CO2 hydrogenation to methanol

2017 ◽  
Vol 7 (15) ◽  
pp. 3375-3387 ◽  
Author(s):  
Juan C. Medina ◽  
Manuel Figueroa ◽  
Raydel Manrique ◽  
Jhonatan Rodríguez Pereira ◽  
Priya D. Srinivasan ◽  
...  
Keyword(s):  
Active Sites ◽  
Co2 Hydrogenation

The addition of Ga to Cu/SiO2 generates new active sites increasing selectivity to methanol. The mechanistic implications are studied by in situ DRIFTS and kinetic experiments.

Synergy between active sites of Cu-In-Zr-O catalyst in CO2 hydrogenation to methanol

2019 ◽  
Vol 372 ◽  
pp. 74-85 ◽  
Author(s):  
Libo Yao ◽  
Xiaochen Shen ◽  
Yanbo Pan ◽  
Zhenmeng Peng
Keyword(s):  
Active Sites ◽  
Co2 Hydrogenation

Boosting light olefin selectivity in CO2 hydrogenation by adding Co to Fe catalysts within close proximity

2020 ◽  
Author(s):  
Fei Yuan ◽  
Guanghui Zhang ◽  
Jie Zhu ◽  
Fanshu Ding ◽  
Anfeng Zhang ◽  
...  
Keyword(s):  
Co2 Hydrogenation ◽  
Light Olefin ◽  
Close Proximity ◽  
Fe Catalysts ◽  
Olefin Selectivity

Role of polyaniline morphology in Pd particles dispersion. Hydrogenation of alkynes in the presence of Pd-polyaniline catalysts

2013 ◽  
Vol 67 (8) ◽  
Author(s):  
Robert Kosydar ◽  
Monika Goral ◽  
Alicja Drelinkiewicz ◽  
Jaroslav Stejskal
Keyword(s):  
Palladium Catalysts ◽  
Active Sites ◽  
Pd Nanoparticles ◽  
Liquid Phase Hydrogenation ◽  
Close Proximity ◽  
Physicochemical Features ◽  
Molecular Masses ◽  
Palladium Particles ◽  
Pani Sample

AbstractTwo polyaniline (PANI) samples of various molecular masses were used for the preparation of palladium catalysts (with 2 mass % of Pd). The physicochemical features of starting polyanilines were found to substantially affect the size and extent of palladium nanoparticles aggregation. Strongly aggregated large palladium particles appeared in the PANI sample of more compact morphology (PANI-H), higher crystallinity and lower specific surface area. Pd nanoparticles of a definitively smaller size were formed in the more amorphous PANI sample of looser morphology (PANI-L) and the extent of particles aggregation was markedly lower. The catalytic properties of Pd/PANI samples were studied in a liquid phase hydrogenation of unsaturated triple bond (C≡C) in alkynes reactants, phenylacetylene, and cyclohexylacetylene. The 2 mass % Pd/PANI-L catalyst prepared using polymer of less compact texture exhibited much higher activity in both reactions. In the presence of the 2 mass % Pd/PANI-L catalyst, alkene products were formed with a high selectivity (approximately 90 %) attained at the almost complete conversion of alkynes. This highly selective hydrogenation of the C≡C to the C=C bond was related to the presence of an electroactive polymer, PANI, in close proximity with Pd active sites. Polyaniline could have a role in a steric effect as well as in a modification of adsorptive properties of Pd centres.

Grain boundaries modulating active sites in RhCo porous nanospheres for efficient CO2 hydrogenation

Nano Research ◽  
2018 ◽  
Vol 11 (5) ◽  
pp. 2357-2365 ◽  
Author(s):  
Xusheng Zheng ◽  
Yue Lin ◽  
Haibin Pan ◽  
Lihui Wu ◽  
Wei Zhang ◽  
...  
Keyword(s):  
Grain Boundaries ◽  
Active Sites ◽  
Co2 Hydrogenation

scholarly journals Sequential Immobilization of Ansa-Hafnocene Complexes for Propene Polymerization

2019 ◽  
Author(s):  
Marius Arz ◽  
Tim Kratky ◽  
Sebastian Günther ◽  
Katia Rodewald ◽  
Thomas Burger ◽  
...  
Keyword(s):  
Active Sites ◽  
Poor Performance ◽  
Reaction Conditions ◽  
Continuous Polymerization ◽  
Propene Polymerization ◽  
Close Proximity ◽  
Catalytically Active

We report the immobilization of the ultrarigid <i>ansa</i>-hafnocene complexes [Me<sub>2</sub>Si(Ind*)<sub>2</sub>HfCl<sub>2</sub>] (Ind* = 7,(3',5'-Di-<i>tert</i>-butylphenyl)-4-methoxy-2-methylindenyl) on silica as heteregeneous catalysts for propene polymerization. A sequential three-step synthesis on the siliceous surface led to pre-catalysts of the generalized structure SiO<sub>2</sub>-Si(Ind*)<sub>2</sub>HfCl<sub>2</sub>, which possess the silylene bridge of the substituted bis(indenyl) ligand directly attached to the surface. The immobilized pre-catalysts show very poor performance in the polymerization of propene, independent on the reaction conditions and the employed silica. Based on the results, we suggest that the close proximity of the catalyst to the surface combined with the steric congestion provoked by the ligand prevents a continuous polymerization, most likely due to a blockage of the catalytically active sites with growing polymer.<br>

Dependence of copper particles size and interface on the methanol and CO formation in CO2 hydrogenation over Cu@ZnO catalysts

2021 ◽  
Author(s):  
Feng Jiang ◽  
Yu Yang ◽  
Li Wang ◽  
Yufeng Li ◽  
Zhihao Fang ◽  
...  
Keyword(s):  
Methanol Synthesis ◽  
Active Sites ◽  
Co2 Hydrogenation ◽  
Copper Particles

Although Cu-based catalysts have been intensively investigated on methanol synthesis from CO2 hydrogenation, there still exists debate on the active sites for methanol and CO formation. In this work, the...

scholarly journals CO2 Hydrogenation to Methanol over Ce and Zr Containing UiO-66 and Cu/UiO-66

Catalysts ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 39 ◽  
Author(s):  
Michalina Stawowy ◽  
Radosław Ciesielski ◽  
Tomasz Maniecki ◽  
Krzysztof Matus ◽  
Rafał Łużny ◽  
...  
Keyword(s):  
Active Sites ◽  
Fossil Fuels ◽  
Co2 Hydrogenation ◽  
Structure Stability ◽  
New Class ◽  
Developed Surface ◽  
Metal Organic ◽  
Direct Hydrogenation ◽  
The Impact ◽  
First Time

Direct hydrogenation of CO2 to methanol is an interesting method to recycle CO2 emitted e.g., during combustion of fossil fuels. However, it is a challenging process because both the selectivity to methanol and its production are low. The metal-organic frameworks are relatively new class of materials with a potential to be used as catalysts or catalysts supports, also in the reaction of MeOH production. Among many interesting structures, the UiO-66 draws significant attention owing to its chemical and thermal stability, developed surface area, and the possibility of tuning its properties e.g., by exchanging the zirconium in the nodes to other metal cations. In this work we discuss—for the first time—the performance of Cu supported on UiO-66(Ce/Zr) in CO2 hydrogenation to MeOH. We show the impact of the composition of UiO-66-based catalysts, and the character of Cu-Zr and Cu-Ce interactions on MeOH production and MeOH selectivity during test carried out for 25 h at T = 200 °C and p = 1.8 MPa. Significant increase of selectivity to MeOH was noticed after exchanging half of Zr4+ cations with Ce4+; however, no change in MeOH production occurred. It was found that the Cu-Ce coexistence in the UiO-66-based catalytic system reduced the selectivity to MeOH when compared to Cu/UiO-66(Zr), which was ascribed to lower concentration of Cu0 active sites in Cu/UiO-66(Ce/Zr), and this was caused by oxygen spill-over between Cu0 and Ce4+, and thus, the oxidation of the former. The impact of reaction conditions on the structure stability of tested catalyst was also determined.

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