Enhancing ethylene epoxidation of a MWW-type titanosilicate/H2O2 catalytic system by fluorine implanting

2017 ◽  
Vol 7 (12) ◽  
pp. 2624-2631 ◽  
Author(s):  
Xinqing Lu ◽  
Wen-Juan Zhou ◽  
Yejun Guan ◽  
Armin Liebens ◽  
Peng Wu
Keyword(s):  
Hydrogen Bonding ◽  
Liquid Phase ◽  
Catalytic System ◽  
Catalytic Performance ◽  
Ethylene Epoxidation ◽  
Liquid Phase Epoxidation

SiO3/2F units in the framework of Ti-MWW generate stronger hydrogen-bonding between Hend in Ti–Oα–Oβ–Hend intermediates and the adjacent Si–F species, which effectively improves the catalytic performance of Ti-MWW for the liquid-phase epoxidation of ethylene.

Synthesis of Stainless-Steel-Net Supported TS-1 Catalyst and Its Catalytic Performance in Liquid-Phase Epoxidation Reactions

2011 ◽  
Vol 50 (16) ◽  
pp. 9587-9593 ◽  
Author(s):  
Yuting Zheng ◽  
Yingtian Zhang ◽  
Zhendong Wang ◽  
Yueming Liu ◽  
Mingyuan He ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Liquid Phase ◽  
Catalytic Performance ◽  
Liquid Phase Epoxidation

scholarly journals Deciphering the Role of π-Interactions in Polyelectrolyte Complexes Using Rationally Designed Peptides

Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2074
Author(s):  
Sara Tabandeh ◽  
Cristina Elisabeth Lemus ◽  
Lorraine Leon
Keyword(s):  
Hydrogen Bonding ◽  
Phase Separation ◽  
Liquid Phase ◽  
Charge Density ◽  
Secondary Structures ◽  
Liquid Phase Separation ◽  
Polyelectrolyte Complexes ◽  
Π Interactions ◽  
Liquid Liquid Phase Separation

Electrostatic interactions, and specifically π-interactions play a significant role in the liquid-liquid phase separation of proteins and formation of membraneless organelles/or biological condensates. Sequence patterning of peptides allows creating protein-like structures and controlling the chemistry and interactions of the mimetic molecules. A library of oppositely charged polypeptides was designed and synthesized to investigate the role of π-interactions on phase separation and secondary structures of polyelectrolyte complexes. Phenylalanine was chosen as the π-containing residue and was used together with lysine or glutamic acid in the design of positively or negatively charged sequences. The effect of charge density and also the substitution of fluorine on the phenylalanine ring, known to disrupt π-interactions, were investigated. Characterization analysis using MALDI-TOF mass spectroscopy, H NMR, and circular dichroism (CD) confirmed the molecular structure and chiral pattern of peptide sequences. Despite an alternating sequence of chirality previously shown to promote liquid-liquid phase separation, complexes appeared as solid precipitates, suggesting strong interactions between the sequence pairs. The secondary structures of sequence pairs showed the formation of hydrogen-bonded structures with a β-sheet signal in FTIR spectroscopy. The presence of fluorine decreased hydrogen bonding due to its inhibitory effect on π-interactions. π-interactions resulted in enhanced stability of complexes against salt, and higher critical salt concentrations for complexes with more π-containing amino acids. Furthermore, UV-vis spectroscopy showed that sequences containing π-interactions and increased charge density encapsulated a small charged molecule with π-bonds with high efficiency. These findings highlight the interplay between ionic, hydrophobic, hydrogen bonding, and π-interactions in polyelectrolyte complex formation and enhance our understanding of phase separation phenomena in protein-like structures.

scholarly journals Metal-Organic Frameworks in Oxidation Catalysis with Hydrogen Peroxide

Catalysts ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 283
Author(s):  
Oxana Kholdeeva ◽  
Nataliya Maksimchuk
Keyword(s):  
Hydrogen Peroxide ◽  
Liquid Phase ◽  
Selective Oxidation ◽  
Metal Organic Frameworks ◽  
Short Review ◽  
Catalytic Performance ◽  
Oxidation Catalysis ◽  
Catalyst Stability ◽  
Aqueous Hydrogen Peroxide ◽  
Metal Organic

In recent years, metal–organic frameworks (MOFs) have received increasing attention as selective oxidation catalysts and supports for their construction. In this short review paper, we survey recent findings concerning use of MOFs in heterogeneous liquid-phase selective oxidation catalysis with the green oxidant–aqueous hydrogen peroxide. MOFs having outstanding thermal and chemical stability, such as Cr(III)-based MIL-101, Ti(IV)-based MIL-125, Zr(IV)-based UiO-66(67), Zn(II)-based ZIF-8, and some others, will be in the main focus of this work. The effects of the metal nature and MOF structure on catalytic activity and oxidation selectivity are analyzed and the mechanisms of hydrogen peroxide activation are discussed. In some cases, we also make an attempt to analyze relationships between liquid-phase adsorption properties of MOFs and peculiarities of their catalytic performance. Attempts of using MOFs as supports for construction of single-site catalysts through their modification with heterometals will be also addressed in relation to the use of such catalysts for activation of H2O2. Special attention is given to the critical issues of catalyst stability and reusability. The scope and limitations of MOF catalysts in H2O2-based selective oxidation are discussed.

scholarly journals Continuous Liquid-Phase Epoxidation of Ethylene with Hydrogen Peroxide on a Titanium-Silicate Catalyst

2021 ◽  
Author(s):  
Matias Alvear ◽  
Michele Emanuele Fortunato ◽  
Vincenzo Russo ◽  
Kari Eränen ◽  
Martino Di Serio ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Liquid Phase ◽  
Titanium Silicate ◽  
Liquid Phase Epoxidation
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