scholarly journals Surface engineering of earth-abundant Fe catalysts for selective hydrodeoxygenation of phenolics in liquid phase

2020 ◽  
Vol 11 (23) ◽  
pp. 5874-5880 ◽  
Author(s):  
Jianghao Zhang ◽  
Junming Sun ◽  
Libor Kovarik ◽  
Mark H. Engelhard ◽  
Lei Du ◽  
...  
Keyword(s):  
Liquid Phase ◽  
Electronic Properties ◽  
Surface Engineering ◽  
Bond Cleavage ◽  
Earth Abundant ◽  
Fe Catalysts

Tailoring the graphene-covered Fe with Cs modifies the surface electronic properties of the catalysts such that selective C–O bond cleavage of phenol is achieved in liquid phase by inhibiting the facile tautomerization followed by ring saturation.

Room Temperature Alkali Metal Reduction of Carbon Dioxide

2020 ◽  
Author(s):  
Lucas A. Freeman ◽  
Akachukwu D. Obi ◽  
Haleigh R. Machost ◽  
Andrew Molino ◽  
Asa W. Nichols ◽  
...  
Keyword(s):  
Alkali Metal ◽  
Alkali Metals ◽  
Room Temperature ◽  
Chemical Reduction ◽  
Bond Cleavage ◽  
Open Shell ◽  
Metal Reduction ◽  
One Pot ◽  
Earth Abundant ◽  
Electron Reduction

The reduction of the relatively inert carbon–oxygen bonds of CO<sub>2</sub> to access useful CO<sub>2</sub>-derived organic products is one of the most important fundamental challenges in synthetic chemistry. Facilitating this bond-cleavage using earth-abundant, non-toxic main group elements (MGEs) is especially arduous because of the difficulty in achieving strong inner-sphere interactions between CO<sub>2</sub> and the MGE. Herein we report the first successful chemical reduction of CO<sub>2</sub> at room temperature by alkali metals, promoted by a cyclic(alkyl)(amino) carbene (CAAC). One-electron reduction of CAAC-CO<sub>2</sub> adduct (<b>1</b>) with lithium, sodium or potassium metal yields stable monoanionic radicals clusters [M(CAAC–CO<sub>2</sub>)]<sub>n</sub>(M = Li, Na, K, <b> 2</b>-<b>4</b>) and two-electron alkali metal reduction affords open-shell, dianionic clusters of the general formula [M<sub>2</sub>(CAAC–CO<sub>2</sub>)]<sub>n </sub>(<b>5</b>-<b>8</b>). It is notable that these crystalline clusters of reduced CO<sub>2</sub> may also be isolated via the “one-pot” reaction of free CO<sub>2</sub> with free CAAC followed by the addition of alkali metals – a reductive process which does not occur in the absence of carbene. Each of the products <b>2</b>-<b>8</b> were investigated using a combination of experimental and theoretical methods.<br>

Bimetallic Pt-Fe catalysts supported on mesoporous TS-1 microspheres for the liquid-phase selective hydrogenation of cinnamaldehyde

2021 ◽  
Vol 395 ◽  
pp. 375-386
Author(s):  
Wenbo Zhang ◽  
Huiyue Xin ◽  
Yaqiong Zhang ◽  
Xin Jin ◽  
Peng Wu ◽  
...  
Keyword(s):  
Liquid Phase ◽  
Selective Hydrogenation ◽  
Fe Catalysts

Structure and Electronic Properties of Grain Boundaries in Earth-Abundant Photovoltaic Absorber Cu2ZnSnSe4

ACS Nano ◽  
2011 ◽  
Vol 5 (11) ◽  
pp. 8613-8619 ◽  
Author(s):  
Junwen Li ◽  
David B. Mitzi ◽  
Vivek B. Shenoy
Keyword(s):  
Grain Boundaries ◽  
Electronic Properties ◽  
Earth Abundant

Radiolysis of methylcyclopentane. III. Liquid phase mechanism and comparison of cycloalkanes

1968 ◽  
Vol 46 (20) ◽  
pp. 3235-3240 ◽  
Author(s):  
Gordon R. Freeman ◽  
E. Diane Stover
Keyword(s):  
Liquid Phase ◽  
Gas Phase ◽  
Bond Cleavage ◽  
Open Chain ◽  
Methyl Substitution ◽  
Product Yields ◽  
Total Ionization ◽  
Gamma Radiolysis ◽  
G Value

The initial yields of the major products of the gamma radiolysis of liquid methylcyclopentane (MCP) at 25° are: G(H2) = 4.2, G(1-methylcyclopentene plus methylenecyclopentane) = 2.7, G(3- plus 4-methyl-cyclopentene) = 1.0, G(open chain hexene) = 1.0, and G(bimethylcyclopentyl) = 0.9. The effects of scavengers on the product yields are reported and the mechanism is discussed.The liquid phase radiolytic decompositions of cyclohexane (CH), methylcyclohexane (MCH), cyclopentane (CP), and MCP are compared. The net amount of C—C bond cleavage is much greater in the five-membered than in the six-membered rings. Methyl substitution on the ring reduces G(H2) by about one unit, mainly because of the formation of a type of ion (QH+) that does not yield hydrogen when neutralized by an electron. The QH+ type ions are formed in MCH and MCP, but not in CH and CP. In all the systems, another type of ion (N+) that does not yield hydrogen when neutralized by an electron is formed with a G value of about unity. The type of ion (PH+) that does yield hydrogen when neutralized by an electron has a G value of 3.4 in CH and CP, but only 2.0 in MCP. It is concluded that G(total ionization) is in the vicinity of 4.4 in the liquid compounds, virtually the same as the gas phase values.

scholarly journals Understanding Heteroatom-Mediated Metal–Support Interactions in Functionalized Carbons: A Perspective Review

2018 ◽  
Vol 8 (7) ◽  
pp. 1159 ◽  
Author(s):  
Sebastiano Campisi ◽  
Carine Chan-Thaw ◽  
Alberto Villa
Keyword(s):  
Liquid Phase ◽  
Metal Nanoparticles ◽  
Electronic Properties ◽  
Functional Groups ◽  
Theoretical Models ◽  
Alcohol Oxidation ◽  
Metal Interaction ◽  
Characterization Techniques ◽  
Metal Support ◽  
Metal Support Interactions

Carbon-based materials show unique chemicophysical properties, and they have been successfully used in many catalytic processes, including the production of chemicals and energy. The introduction of heteroatoms (N, B, P, S) alters the electronic properties, often increasing the reactivity of the surface of nanocarbons. The functional groups on the carbons have been reported to be effective for anchoring metal nanoparticles. Although the interaction between functional groups and metal has been studied by various characterization techniques, theoretical models, and catalytic results, the role and nature of heteroatoms is still an object of discussion. The aim of this review is to elucidate the metal–heteroatoms interaction, providing an overview of the main experimental and theoretical outcomes about heteroatom-mediated metal–support interactions. Selected studies showing the effect of heteroatom–metal interaction in the liquid-phase alcohol oxidation will be also presented.

Thermodynamics, kinetics and electronic properties of point defects in β-FeSi2

2019 ◽  
Vol 21 (20) ◽  
pp. 10497-10504 ◽  
Author(s):  
Jun Chai ◽  
Chen Ming ◽  
Xiaolong Du ◽  
Pengfei Qiu ◽  
Yi-Yang Sun ◽  
...  
Keyword(s):  
Band Gap ◽  
Electronic Properties ◽  
Point Defects ◽  
Systematic Study ◽  
Wide Temperature Range ◽  
Semiconductor Material ◽  
Temperature Range ◽  
Earth Abundant

β-FeSi2, a semiconductor material made of two of the most earth-abundant elements, has important applications in thermoelectrics, photovoltaics and optoelectronics owing to its attractive properties such as suitable band gap and air stability over a wide temperature range. In this paper, we present a systematic study on point defects in this material.

scholarly journals Selective Manganese-Catalyzed Dimerization and Cross-Coupling of Terminal Alkynes

2021 ◽  
Author(s):  
Stefan Weber ◽  
Luis F. Veiros ◽  
Karl Kirchner
Keyword(s):  
Dft Calculations ◽  
Precious Metal ◽  
Bond Cleavage ◽  
Cross Coupling ◽  
Metal Catalyst ◽  
Catalyst Loading ◽  
Terminal Alkynes ◽  
Migratory Insertion ◽  
Earth Abundant ◽  
First Time

<div>For the first time, an efficient manganese-catalyzed dimerization of terminal alkynes to afford 1,3-enynes is described. This reaction is atom economic, implementing an inexpensive, earth abundant non-precious metal catalyst. The pre-catalyst is the bench-stable alkyl bisphosphine Mn(I) complex fac-[Mn(dippe)(CO)3(CH2CH2CH3)]. The catalytic process is initiated by migratory insertion of a CO ligand into the Mn-alkyl bond to yield an acyl intermediate which undergoes rapid C-H bond cleavage of the alkyne forming an active Mn(I) acetylide catalyst [Mn(dippe)(CO)2(C≡CPh)(η2-HC≡CPh)] together with liberated butanal. A range of aromatic and aliphatic terminal alkynes were efficiently and selectively converted into head-to-head Z-1,3-enynes and head-to-tail gem-1,3-enynes, respectively, in good to excellent yields. Moreover, cross-coupling of aromatic and aliphatic alkynes yields selectively head-to-tail gem-1,3-enynes. In all cases, the reactions were performed at 70 °C with a catalyst loading of 1-2 mol %. A mechanism based on DFT calculations is presented.</div><div><br></div>

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