Hydrogénation électrocatalytique sur des catalyseurs composites de nickel et hydroxyde d'aluminium en cellule dynamique

2002 ◽  
Vol 80 (4) ◽  
pp. 345-349 ◽  
Author(s):  
Patrick Dubé ◽  
Louis Brossard ◽  
Hugues Ménard
Keyword(s):  
Aluminum Oxide ◽  
Organic Compounds ◽  
Aluminum Hydroxide ◽  
Aqueous Media ◽  
Electrocatalytic Hydrogenation ◽  
Metallic Particles ◽  
Dynamic Cell ◽  
Physical Deposition ◽  
Adsorption Desorption

The electrocatalytic hydrogenation (ECH) of cyclohexanone into cyclohexanol has been studied in aqueous media with electrocatalysts on composites powders. These powders are formed of nanoaggregates of nickel obtained through a physical deposition under vacuum on particles of Al(OH)3, AlO(OH), and γ-Al2O3. The ECH reaction was done in a dynamic cell. Its yield is closely dependent on the nature of the non-metallic particles whose nature greatly influences the adsorption–desorption of the organic compounds involved in the reaction.Key words: electrocatalysis, aluminum oxide, aluminum hydroxide, hydrogenation, dynamic cell.[Traduit par la Rédaction]

scholarly journals Non-Enzymatic Desymmetrization Reactions in Aqueous Media

Symmetry ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 720
Author(s):  
Satomi Niwayama
Keyword(s):  
Natural Products ◽  
Total Synthesis ◽  
Functional Groups ◽  
Organic Compounds ◽  
Recent Progress ◽  
Aqueous Media ◽  
Building Blocks ◽  
Organic Reactions ◽  
Environmentally Benign ◽  
Enzymatic Desymmetrization

Symmetric organic compounds are generally obtained inexpensively, and therefore they can be attractive building blocks for the total synthesis of various pharmaceuticals and natural products. The drawback is that discriminating the identical functional groups in the symmetric compounds is difficult. Water is the most environmentally benign and inexpensive solvent. However, successful organic reactions in water are rather limited due to the hydrophobicity of organic compounds in general. Therefore, desymmetrization reactions in aqueous media are expected to offer versatile strategies for the synthesis of a variety of significant organic compounds. This review focuses on the recent progress of desymmetrization reactions of symmetric organic compounds in aqueous media without utilizing enzymes.

scholarly journals Extraction and Mass Spectrometric Characterization of Terpenes Recovered from Olive Leaves Using a New Adsorbent-Assisted Supercritical CO2 Process

Foods ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 1301
Author(s):  
Zully J. Suárez Montenegro ◽  
Gerardo Álvarez-Rivera ◽  
Jose A. Mendiola ◽  
Elena Ibáñez ◽  
Alejandro Cifuentes
Keyword(s):  
Aluminum Oxide ◽  
Silica Gel ◽  
Supercritical Co2 ◽  
Olive Leaves ◽  
Fractionation Process ◽  
Selective Enrichment ◽  
Adsorption Desorption ◽  
First Time ◽  
By Products

This work reports the use of GC-QTOF-MS to obtain a deep characterization of terpenoid compounds recovered from olive leaves, which is one of the largest by-products generated by the olive oil industry. This work includes an innovative supercritical CO2 fractionation process based on the online coupling of supercritical fluid extraction (SFE) and dynamic adsorption/desorption for the selective enrichment of terpenoids in the different olive leaves extracts. The selectivity of different commercial adsorbents such as silica gel, zeolite, and aluminum oxide was evaluated toward the different terpene families present in olive leaves. Operating at 30 MPa and 60 °C, an adsorbent-assisted fractionation was carried out every 20 min for a total time of 120 min. For the first time, GC-QTOF-MS allowed the identification of 40 terpenoids in olive leaves. The GC-QTOF-MS results indicate that silica gel is a suitable adsorbent to partially retain polyunsaturated C10 and C15 terpenes. In addition, aluminum oxide increases C20 recoveries, whereas crystalline zeolites favor C30 terpenes recoveries. The different healthy properties that have been described for terpenoids makes the current SFE-GC-QTOF-MS process especially interesting and suitable for their revalorization.

Deciphering the Adsorption Behavior of Volatile Organic Compounds with Electrospun Polyacrylonitrile/Molecular Sieve Nanocomposites

2019 ◽  
Vol 19 (11) ◽  
pp. 7315-7319 ◽  
Author(s):  
Yi-Xin Wang ◽  
Hong Tao ◽  
Min-Nan Chen ◽  
Ling-Shao ◽  
Guang-Feng Shang ◽  
...  
Keyword(s):  
Volatile Organic Compounds ◽  
Adsorption Capacity ◽  
Organic Compounds ◽  
Molecular Sieve ◽  
Fiber Surface ◽  
Polyacrylonitrile Fiber ◽  
Volatile Organic ◽  
New Type ◽  
Short Time ◽  
Adsorption Desorption

In this study, a new type of molecular sieve/polyacrylonitrile fiber (M-PAN) was prepared by electrospinning to adsorb atmospheric volatile organic compounds (VOCs). The suitable content of molecular sieve in nanocomposites was also determined for achieving maximum VOCs adsorption capacity. SEM, TEM and N2 adsorption/desorption analyzer were performed for characterization of the surface morphology, structural properties, surface area and pore size. A part of molecular sieve is exposed on the fiber surface where VOCs can be adsorbed efficiently in a short time. Acetone was used as a challenge pollutant to evaluate the adsorption of VOCs at different recycling times and types of electrospinning nanofibers. The adsorption capacity of 6M-PAN (60% weight of molecular sieve) nanofiber reached 58.2 μg g−1 and the reused nanofibers nearly had the same adsorption capacity as the newly prepared nanofibers after several times of recirculation.

scholarly journals BTX Removal from Open Aqueous Systems by Modified Cellulose Fibers and Evaluation of Competitive Evaporation Kinetics

Water ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 3154
Author(s):  
Antonio Tursi ◽  
Francesco Chidichimo ◽  
Rita Bagetta ◽  
Amerigo Beneduci
Keyword(s):  
Organic Compounds ◽  
Low Cost ◽  
Water System ◽  
Open Water ◽  
Cellulose Fibers ◽  
Petroleum Products ◽  
Pollutant Concentrations ◽  
Surface Modified ◽  
Adsorption Desorption ◽  
Modified Cellulose

BTX stands for Benzene, Toluene, and Xylenes, which are volatile organic compounds contained in petroleum products such as gasoline. They have negative health effects and are sadly known for soil, air, and water contamination. This paper provides an investigation on BTX removal from open water systems like those represented by natural water bodies. In such systems, the evaporation process takes place, stealing the pollutants from the aqueous matrix by transferring them into the air, resulting in a secondary pollution. To prevent this situation, adsorption of these organic compounds on cellulose fibers, extracted from Spanish Broom vegetable, was studied. Raw and surface modified cellulose fibers were used for this purpose. The second ones were hydrophobized by two different green and low-cost functionalization systems (no solvent urethane functionalization and low pressure plasma treatments). Batch experiments were performed in an open system where BTX underwent two competing removing mechanisms: volatilization, and adsorption/desorption on/from the fibers dispersed in the water system. A mathematical model was implemented for the interpretation of the observed time-varying pollutant concentrations and the estimation of the kinetic constants for adsorption, desorption, and evaporation. The developed model, provided with the aforementioned parameters calibrated for each type of fibers, was then used for the prediction of their adsorption capacities both into open and closed systems.

Evaluation of the adsorption and desorption properties of zeolitic imidazolate framework-7 for volatile organic compounds through thermal desorption-gas chromatography

2018 ◽  
Vol 10 (40) ◽  
pp. 4894-4901 ◽  
Author(s):  
Ya-Ting Zhao ◽  
Li-Qing Yu ◽  
Xin Xia ◽  
Xin-Yu Yang ◽  
Wei Hu ◽  
...  
Keyword(s):  
Gas Chromatography ◽  
Organic Compounds ◽  
Thermal Desorption ◽  
Hydrophobic Interaction ◽  
Molecular Size ◽  
Zeolitic Imidazolate Framework ◽  
Gate Opening ◽  
Volatile Organic ◽  
Stacking Effect ◽  
Adsorption Desorption

The adsorption/desorption properties of VOCs on ZIF-7 were evaluated by TD-GC. It was found that there are hydrophobic interaction, π–π stacking effect, molecular size effect and “gate-opening” effect between VOCs and ZIF-7.

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