| 1. |
- Ahlford, Katrin, et al.
(författare)
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Amino acid-derived amides and hydroxamic acids as ligands for asymmetric transfer hydrogenation in aqueous media
- 2011
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Ingår i: Catalysis communications. - : Elsevier BV. - 1566-7367 .- 1873-3905. ; 12:12, s. 1118-1121
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Tidskriftsartikel (refereegranskat)abstract
- Amides and hydroxamic acids derived from α-amino acids were evaluated as ligands in combination with rhodium and iridium half-sandwich complexes in asymmetric transfer hydrogenation (ATH) of ketones. The reactions were performed in aqueous media using lithium formate as hydride source. The catalyst systems turned out to be highly efficient and ees up to 90% were obtained.
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| 2. |
- Gizinski, Damian, et al.
(författare)
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Chemoselective flow hydrogenation of alpha,beta - Unsaturated aldehyde with nano-nickel
- 2017
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Ingår i: Catalysis communications. - : ELSEVIER SCIENCE BV. - 1566-7367 .- 1873-3905. ; 98, s. 17-21
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Tidskriftsartikel (refereegranskat)abstract
- Herein, it is presented a novel catalytic system for the continuous flow chemoselective hydrogenation of a,alpha,beta- unsaturated aldehydes used in the production of high value cosmetics and pharmaceuticals precursors. The reaction was catalyzed by nano nickel particles grafted on polymeric support, synthesized via a simple, adaptable and green methodology. The system was highly active and very selective to C=C bond saturation.
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| 3. |
- Goszewska, Ilona, et al.
(författare)
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A novel nano-palladium catalyst for continuous-flow chemoselective hydrogenation reactions
- 2017
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Ingår i: Catalysis communications. - : Elsevier BV. - 1566-7367 .- 1873-3905. ; 94, s. 65-68
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Tidskriftsartikel (refereegranskat)abstract
- Herein, we report a catalyst composed of palladium nanoparticles immobilized on polymeric resin for chemoselective hydrogenation reactions under flow conditions. The catalyst exhibits high activity and selectivity towards hydrogenation of C=C double bond, as confirmed in the hydrogenation of 2-heptene and 6-methyl-5-hepten-2-one.
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| 4. |
- Lin, Junzhong, et al.
(författare)
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Hierarchical MFI zeolite synthesized via regulating the kinetic of dissolution-recrystallization and their catalytic properties
- 2018
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Ingår i: Catalysis communications. - : Elsevier BV. - 1566-7367 .- 1873-3905. ; 115, s. 82-86
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Tidskriftsartikel (refereegranskat)abstract
- Hierarchical MFI zeolites with open pores were synthesized by a temperature programmed dissolution-recrystallization post-treatment. By controlling the temperature of post-treatment using TPAOH, open macropores and mesopores were created by simply regulating the kinetics of dissolution and recrystallization. Benzyl alcohol self-etherification reaction, which only occurs in micropores, was tested on ZSM-5 to understand the effect of hierarchical pore system. The catalytic activity of hierarchical TS-1 was tested with cyclohexanone ammoximation. Hierarchical ZSM-5 and TS-1 zeolites with open pores showed higher catalytic activity compared with both hollow and conventional ones. The increased catalytic activities can be ascribed to the enhanced diffusion.
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| 5. |
- Liu, Haibin, et al.
(författare)
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Asymmetric oxidation of sulfides with hydrogen peroxide catalyzed by a vanadium complex of a new chiral NOO-ligand
- 2009
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Ingår i: Catalysis communications. - : Elsevier BV. - 1566-7367 .- 1873-3905. ; 11:4, s. 294-297
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Tidskriftsartikel (refereegranskat)abstract
- A new chiral NOO-tridentate ligand (8R)-2-(2-hydroxyphenyl)-4-methyl-5,6,7.8-tetrahydro-quinolin-8-ol (1) bearing a rigid tetrahydroquinoline framework was prepared and applied in the vanadium-catalyzed asymmetric oxidation of aryl methyl sulfides with H2O2 as oxidant. Less toxic acetone was found to be the proper solvent for the enantioselective oxidation of sulfides. Under the optimal condition, the asymmetric oxidation of aryl methyl sulfides in acetone catalyzed by VO(acac)(2)/1 at 0 degrees C gives good to high yields (80-95%) of sulfoxides with enantioselectivity up to 77% ee.
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| 6. |
- Lopez Nina, Luis Gagarin, et al.
(författare)
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Effect of syngas conversion and catalyst reduction temperature in the synthesis of ethanol : concentration of water vapor in mesoporous Rh/MCM-41 catalyst
- 2015
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Ingår i: Catalysis communications. - : Elsevier. - 1566-7367 .- 1873-3905. ; 69, s. 183-187
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Tidskriftsartikel (refereegranskat)abstract
- Rh-based catalysts typically show low selectivity to CO2 in the synthesis of ethanol from syngas. However, a novel mesoporous Rh/MCM-41 catalyst shows high selectivity to CO2 in a large range of syngas conversions; 1% to 68%, regulated by adjusting the operation conditions (270-430 degrees C, 30-90 bar and 6000-40,000 ml(syngas)/gcat h). The same effect is obtained at different catalyst reduction temperatures (200 degrees C and 500 degrees C) as well as on the non-reduced catalyst. A high concentration of water vapor seems to occur in the pores of Rh/MCM-41 which may promote the water-gas-shift-reaction, producing extra CO2 and H-2. (C) 2015 Elsevier B.V. All rights reserved.
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| 7. |
- Paun, Cristina, et al.
(författare)
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p-Nitrophenol flow hydrogenation with nano-Cu2O grafted on polymeric resin
- 2017
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Ingår i: Catalysis communications. - : ELSEVIER SCIENCE BV. - 1566-7367 .- 1873-3905. ; 92, s. 61-64
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Tidskriftsartikel (refereegranskat)abstract
- Hydrogenation is the most widely used method to reduce organic compounds. There is a demand for the development of active heterogeneous catalysts based on 3d transition metals for economical and environmental reasons. Herein, we report the first continuous-flow hydrogenation of p-nitrophenol to p-aminophenol with molecular hydrogen and heterogeneous nano-Cu2O as reducing agent and Catalyst, respectively. This reaction converts a known pollutant into a high value product with only water as by-product, which is also the solvent. One-pot synthesis methodology was adapted to prepare the catalyst, which confers sufficient nominal size for direct usage in flow reactions, which are preferred from an engineering, industrial, and environmental perspective. Catalyst reactivity was linked to difference in density-of-states between surface and bulk sites, and nanoscale size of active material.
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| 8. |
- Rownaghi, Ali, et al.
(författare)
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Yield of gasoline-range hydrocarbons as a function of uniform ZSM-5 crystal size
- 2011
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Ingår i: Catalysis communications. - : Elsevier BV. - 1566-7367 .- 1873-3905. ; 14:1, s. 37-41
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Tidskriftsartikel (refereegranskat)abstract
- Uniform ZSM-5 nanocrystals were synthesized by a single-templating procedure. The samples were then characterized by a variety of physical techniques such as XRD, SEM, BET, ICP and TPD. The dehydration of methanol over synthesized ZSM-5 zeolite was studied in a fixed-bed continuous flow reactor at 370 °C and WHSV of 2.6 gg−1 h under ambient pressure. The effect of crystal size of zeolite catalysts on product distribution in methanol dehydration reaction was investigated. Good correlation was observed between catalytic performance, product distribution and size of ZSM-5 crystals. It was found that the decrease in crystal size significantly influences light olefins (ethylene and propylene) and paraffins (C1–C4) selectivity in methanol dehydration reaction. Furthermore, nanocrystal ZSM-5 showed long-term catalytic stability compared with conventional ZSM-5 provided that the reaction activity is strongly dependent on the crystal size in methanol dehydration process. The results indicated that crystal size significantly affects the catalyst lifetime and hydrocarbon distributions in product stream. Based on the obtained results, it is concluded that the use of uniform ZSM-5 nanocrystals improves the yield of propylene and alkyl aromatics in methanol conversion reaction at mild conditions.
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| 9. |
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| 10. |
- Solin, Niclas, et al.
(författare)
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An amphoteric mesoporous silica catalyzed aldol reaction
- 2009
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Ingår i: Catalysis communications. - : Elsevier BV. - 1566-7367 .- 1873-3905. ; 10:10, s. 1386-1389
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Tidskriftsartikel (refereegranskat)abstract
- A bi-functional mesoporous silica material, containing both carboxylic acid and amino groups, acts as a catalyst for the reaction between aldehydes and carbon nucleophiles. We demonstrate reaction conditions under which even aldehydes containing deactivating electron donating groups, or sterically demanding substituents, undergo the catalyzed reaction with acetone, affording primarily the condensation products. Moreover, we demonstrate that acetophenone and ethyl methyl ketone can replace acetone as nucleophile. The bi-functional mesoporous silica is a convenient catalyst, as it is simple to remove from the reaction media, thereby facilitating workup.
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