Highly Selective Conversion of 1‐Butene to 1,3‐Butadiene under CO 2 Atmosphere over an Alumina‐supported Iron‐based Catalyst: The Role of Brønsted Acids and Lewis Acids

2020 ◽  
Vol 5 (36) ◽  
pp. 11237-11241 ◽  
Author(s):  
Bing Yan ◽  
Luyi Wang ◽  
Quanxin Chen ◽  
Hongxin Dou ◽  
Chunjing Liu ◽  
...  
Keyword(s):  
Lewis Acids ◽  
Bronsted Acids ◽  
Selective Conversion ◽  
Iron Based ◽  
Supported Iron

scholarly journals Theoretical Insight into the Reversal of Chemoselectivity in Diels-Alder Reactions of α,β-Unsaturated Aldehydes and Ketones Catalyzed by Brønsted and Lewis Acids

Organics ◽  
2021 ◽  
Vol 2 (1) ◽  
pp. 38-49
Author(s):  
Lakhdar Benhamed ◽  
Sidi Mohamed Mekelleche ◽  
Wafaa Benchouk
Keyword(s):  
Lewis Acids ◽  
Major Product ◽  
Diels Alder ◽  
Unsaturated Ketone ◽  
Unsaturated Aldehydes ◽  
Aldehydes And Ketones ◽  
Theoretical Insight ◽  
Insight Into ◽  
Good Agreement

Experimentally, a reversal of chemoselectivity has been observed in catalyzed Diels–Alder reactions of α,β-unsaturated aldehydes (e.g., (2E)-but-2-enal) and ketones (e.g., 2-hexen-4-one) with cyclopentadiene. Indeed, using the triflimidic Brønsted acid Tf2NH as catalyst, the reaction gave a Diels–Alder adduct derived from α,β-unsaturated ketone as a major product. On the other hand, the use of tris(pentafluorophenyl)borane B(C6F5)3 bulky Lewis acid as catalyst gave mainly the cycloadduct of α,β-unsaturated aldehyde as a major product. Our aim in the present work is to put in evidence the role of the catalyst in the reversal of the chemoselectivity of the catalyzed Diels–Alder reactions of (2E)-but-2-enal and 2-Hexen-4-one with cyclopentadiene. The calculations were performed at the ωB97XD/6-311G(d,p) level of theory and the solvent effects of dichloromethane were taken into account using the PCM solvation model. The obtained results are in good agreement with experimental outcomes.

Adsorption mechanism of NH3, NO, and O2 molecules over FexOy/AC catalyst surface: a DFT-D3 study

2021 ◽  
Author(s):  
Chaoyue Xie ◽  
Yunlan Sun ◽  
Baozhong Zhu ◽  
Weiyi Song ◽  
Minggao Xu
Keyword(s):  
Activated Carbon ◽  
Adsorption Mechanism ◽  
Catalyst Surface ◽  
Specific Adsorption ◽  
Adsorption Mechanisms ◽  
Iron Based ◽  
Iron Based Catalysts ◽  
Supported Iron ◽  
Denox Efficiency

Activated carbon-supported iron-based catalysts (FexOy/AC) show excellent deNOx efficiency. However, the specific adsorption mechanisms of NH3, NO, and O2 molecules on their surfaces are still unknown. In this study, the...

scholarly journals The Role of Chromium in Iron-based High-Temperature Water-Gas Shift Catalysts under Industrial Conditions

2021 ◽  
pp. 120465
Author(s):  
M.I. Ariëns ◽  
V. Chlan ◽  
P. Novák ◽  
L.G.A. van de Water ◽  
A.I. Dugulan ◽  
...  
Keyword(s):  
High Temperature ◽  
Water Gas Shift ◽  
High Temperature Water ◽  
Iron Based ◽  
Water Gas ◽  
Temperature Water

scholarly journals Recent Advances in Transition-Metal-Free (4+3)-Annulations

Synthesis ◽  
2021 ◽  
Author(s):  
Heather Lam ◽  
Mark Lautens ◽  
Xavier Abel-Snape ◽  
Martin F. Köllen
Keyword(s):  
Transition Metal ◽  
Boronic Acid ◽  
Lewis Acids ◽  
Acid Catalysis ◽  
Heterocyclic Carbenes ◽  
Bronsted Acids ◽  
Metal Free ◽  
Previous Review ◽  
Dual Activation ◽  
Metal Catalyzed

Abstract(4+3)-Annulations are incredibly versatile reactions which combine a 4-atom synthon and a 3-atom synthon to form both 7-membered carbocycles as well as heterocycles. We have previously reviewed transition-metal-catalyzed (4+3)-annulations. In this review, we will cover examples involving bases, NHCs, phosphines, Lewis and Brønsted acids as well as some rare examples of boronic acid catalysis and photocatalysis. In analogy to our previous review, we exclude annulations involving cyclic dienes like furan, pyrrole, cyclohexadiene or cyclopentadiene, as Chiu, Harmata, Fernándes and others have recently published reviews encompassing such substrates. We will however discuss the recent additions (2010–2020) to the literature on (4+3)-annulations involving other types of 4-atom-synthons.1 Introduction2 Bases3 Annulations Using N-Heterocyclic Carbenes3.1 N-Heterocyclic Carbenes (NHCs)3.2 N-Heterocyclic Carbenes and Base Dual-Activation4 Phosphines5 Acids5.1 Lewis Acids5.2 Brønsted Acids6 Boronic Acid Catalysis and Photocatalysis7 Conclusion

scholarly journals Role of molybdenum in corrosion of iron-based alloys in contact with hydrogen sulfide containing solution

2016 ◽  
Vol 68 (6) ◽  
pp. 595-603 ◽  
Author(s):  
G. Genchev ◽  
C. Bosch ◽  
E. Wanzenberg ◽  
A. Erbe
Keyword(s):  
Hydrogen Sulfide ◽  
Iron Based ◽  
Corrosion Of Iron

The role of Lewis acids in promoting the electrocatalytic four-electron reduction of dioxygen

1987 ◽  
pp. 1537 ◽  
Author(s):  
James P. Collman ◽  
Neil H. Hendricks ◽  
Kimoon Kim ◽  
C. Susana Bencosme
Keyword(s):  
Lewis Acids ◽  
Electron Reduction

The role of chemical composition in the synthesis of Ca/K-1144 iron based superconductors

2021 ◽  
pp. 159202
Author(s):  
Andrea Masi ◽  
Achille Angrisani Armenio ◽  
Giuseppe Celentano ◽  
Aurelio La Barbera ◽  
Alessandro Rufoloni ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Iron Based Superconductors ◽  
Iron Based

scholarly journals The role of a chemical loop in removal of hazardous contaminants from coke oven wastewater during its treatment

2019 ◽  
Vol 17 (1) ◽  
pp. 1288-1300
Author(s):  
Anna Kwiecińska-Mydlak ◽  
Marcin Sajdak ◽  
Katarzyna Rychlewska ◽  
Jan Figa
Keyword(s):  
Chemical Treatment ◽  
Treatment Process ◽  
Oxygen Demand ◽  
Coke Oven ◽  
Main Role ◽  
Biological Processes ◽  
Coal Processing ◽  
Wastewater Treatment Process ◽  
Iron Based

AbstractCoke oven liquor is one of the most contaminated liquid streams generated by the coal processing industry, thus its proper treatment and utilization is crucial for sustainable and environmentally neutral plant operation. The conventional wastewater treatment process comprises of chemical and biological processes. Within the current research the detailed role of chemical treatment is described. Commercially available iron-based coagulants (PIX100, PIX100COP, PIX113, PIX116) were tested to understand their removal efficiency and impact on the stream parameters. The influence of iron dose in the range of 300-500 mgFe/L on the process performance was also examined.It was found that the main role of chemical treatment was to bind toxicants harmful to activated sludge microorganisms, i.e. free and complex cyanides and sulphides. Among the tested iron-based conventional coagulants ferrous salts were more efficient than ferric salts. It was also observed that efficiency of the process strongly depended on wastewater properties (especially in regard to pH, which should be in the range of 9-10) and the coagulant selection needed to be done individually for a given wastewater type. The removal rates of particular contaminants were diversified and for free cyanides, complex cyanides and sulphides they were in the range of 23-91%, -156-77% and -357-98%, respectively. The expected, simultaneous removal of chemical oxygen demand (COD) during the treatment was not observed and even the parameter value increased after the process due to probable formation of compounds less vulnerable to oxidation.

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