592-76-7Relevant academic research and scientific papers
Effect of reduction temperature on the characteristics and catalytic properties of TiO2 supported AuPd alloy particles prepared by one-step flame spray pyrolysis in the selective hydrogenation of 1-heptyne
Pongthawornsakun, Boontida,Mekasuwandumrong, Okorn,Prakash, Swamy,Ehret, Eric,Santos Aires, Francisco J. Cadete,Panpranot, Joongjai
, p. 278 - 287 (2015)
The bimetallic flame spray-synthesized AuPd/TiO2 catalysts (Au:Pd weight ratio 1:1) were reduced for 2 h under H2 at two different temperatures (40 °C and 500 °C) and tested in the liquid phase selective hydrogenation of 1-heptyne under mild conditions (30 °C and 4 bar H2). Based on TEM-EDX analysis of individual nanoparticles, reduction at 500 °C tends to homogenize the composition of the individual AuPd nanoparticles without significant changes of their average particle size and bulk composition. Higher reaction rate (245 μmol s-1 g cat.-1) was obtained on the AuPd/TiO2 R40 than on the AuPd/TiO2 R500 (223 μmol s-1 g cat.-1). Upon reduction at 500 °C, the bimetallic AuPd/TiO2 exhibited a similar degree of the strong-metal support interaction (SMSI) effect as the monometallic one. As revealed by XPS results, the ratios of Pd/Ti on both catalysts decreased by ca. 23%, due probably to the migration of TiOx species onto the metals. The highest yield of 1-heptene (～93%) was obtained over the bimetallic AuPd/TiO2 reduced at 40 °C in 20 min reaction time under the reaction conditions used. The high temperature reduction is unnecessary for the improvement of catalyst performances when using supported bimetallic AuPd catalysts.
n-Alkene and Dihydrogen Formation from n-Alkanes by Photocatalysis using Carbonyl(chloro)phosphine-Rhodium Complexes
Nomura, Kotohiro,Saito, Yasukazu
, p. 161 - 162 (1988)
n-Alkenes and dihydrogen were obtained from n-alkanes by photocatalysis using carbonyl(chloro)phosphine-rhodium complexes; the rate of alkane dehydrogenation was the same as that of propan-2-ol dehydrogenation under the same photocatalytic reaction condit
Characteristics and catalytic behavior of Pd catalysts supported on nanostructure titanate in liquid-phase hydrogenation
Putdee, Somjit,Mekasuwandumrong, Okorn,Soottitantawat, Apinan,Panpranot, Joongjai
, p. 3062 - 3067 (2013)
Titanate nanowire (TNW) and nanotube (TNT) structures were synthesized by the hydrothermal reaction using spherical shape anatase TiO2 nanoparticles (TNP) as the starting material and employed as Pd catalyst supports for the liquid-phase selective hydrogenation of 1-heptyne to 1-heptene. Pd dispersion was significantly improved as the specific surface area of the supports increased in the order: Pd/TNT > Pd/TNW > Pd/TNP. While the hydrogenation rate increased with increasing number of active Pd0 surface, the selectivity to 1-heptene depended largely on the degree of interaction between Pd and the supports. The catalysts prepared by impregnation method led to a stronger metal-support interaction than those prepared by colloidal route. The selectivity of 1-heptene at complete conversion of 1-heptyne was obtained in the order: I-Pd/TNT > I-Pd/TNP > Pd/TNT ≈ Pd/TNW > Pd/TNP. Copyright
ALKYLATION OF PENTAERYTHRITOL BY PHASE-TRANSFER CATALYSIS 2. Crucial Effect of the Aqueous Sodium Hydroxyde Solution
Nouguier, Robert,Mchich, Mohamed
, p. 2477 - 2482 (1988)
The mechanistic aspects of the alkylation of pentaerythritol (2-2'-bis(hydroxymethyl)-1,3-propanediol) (PE) by phase-transfer catalysis have been investigated.The dramatic effect of an excess and renewal of sodium hydroxide solutions on the one hand, and the solubility of the PT catalyst in the organic phase on the other, argue that the selectivity of this reaction appears to be controlled almost completely by the possible protonation of the sodium form of the alkoxide anion of PE (4).This protonation depends on the assumption that water molecules are present in the PT medium, and it based upon the observation that this PT medium is actually a three liquid-layer system.As the unusual layer (catalyst layer) may be readily hydrated, the concentrated sodium hydroxide solution can be no longer considered as an unquestionable desiccant.
Highly selective semi-hydrogenation of alkynes with a Pd nanocatalyst modified with sulfide-based solid-phase ligands
Huang, Lingqi,Hu, Kecheng,Ye, Ganggang,Ye, Zhibin
, (2021/03/30)
Soluble small molecular/polymeric ligands are often used in Pd-catalyzed semi-hydrogenation of alkynes as an efficient strategy to improve the selectivity of targeted alkene products. The use of soluble ligands requires their thorough removal from the reaction products, which adds significant extra costs. In the paper, commercially available, inexpensive, metallic sulfide-based solid-phase ligands (SPL8-4 and SPL8-6) are demonstrated as simple yet high-performance insoluble ligands for a heterogeneous Pd nanocatalyst (Pd@CaCO3) toward the semi-hydrogenation of alkynes. Based on the reactions with a range of terminal and internal alkyne substrates, the use of the solid-phase ligands has been shown to markedly enhance the selectivity of the desired alkene products by efficiently suppressing over-hydrogenation and isomerization side reactions, even during the long extension of the reactions following full substrate conversion. A proper increase in the dosage or a reduction in the average size of the solid-phase ligands enhances such effects. With their insoluble nature, the solid-phase ligands have the distinct advantage in their simple, convenient recycling and reuse while without contaminating the products. A ten-cycle reusability test with the SPL8-4/Pd@CaCO3 catalyst system confirms its well-maintained activity and selectivity over repeated uses. A mechanistic study with x-ray photoelectron spectroscopy indicates that the solid-phase ligands have electronic interactions with Pd in the supported catalyst, contributing to inhibit the binding and further reaction of the alkene products. This is the first demonstration of solid-phase ligands for highly selective semi-hydrogenation of alkynes, which show strong promise for commercial applications.
Directing the Rate-Enhancement for Hydronium Ion Catalyzed Dehydration via Organization of Alkanols in Nanoscopic Confinements
Shetty, Manish,Wang, Huamin,Chen, Feng,Jaegers, Nicholas,Liu, Yue,Camaioni, Donald M.,Gutiérrez, Oliver Y.,Lercher, Johannes A.
supporting information, p. 2304 - 2311 (2020/12/01)
Alkanol dehydration rates catalyzed by hydronium ions are enhanced by the dimensions of steric confinements of zeolite pores as well as by intraporous intermolecular interactions with other alkanols. The higher rates with zeolite MFI having pores smaller than those of zeolite BEA for dehydration of secondary alkanols, 3-heptanol and 2-methyl-3-hexanol, is caused by the lower activation enthalpy in the tighter confinements of MFI that offsets a less positive activation entropy. The higher activity in BEA than in MFI for dehydration of a tertiary alkanol, 2-methyl-2-hexanol, is primarily attributed to the reduction of the activation enthalpy by stabilizing intraporous interactions of the Cβ-H transition state with surrounding alcohol molecules. Overall, we show that the positive impact of zeolite confinements results from the stabilization of transition state provided by the confinement and intermolecular interaction of alkanols with the transition state, which is impacted by both the size of confinements and the structure of alkanols in the E1 pathway of dehydration.
Piperazine-promoted gold-catalyzed hydrogenation: The influence of capping ligands
Barbosa, Eduardo C. M.,Camargo, Pedro H. C.,Fiorio, Jhonatan L.,Hashmi, A. Stephen K.,Kikuchi, Danielle K.,Rossi, Liane M.,Rudolph, Matthias
, p. 1996 - 2003 (2020/04/22)
Gold nanoparticles (NPs) combined with Lewis bases, such as piperazine, were found to perform selective hydrogenation reactions via the heterolytic cleavage of H2. Since gold nanoparticles can be prepared by many different methodologies and using different capping ligands, in this study, we investigated the influence of capping ligands adsorbed on gold surfaces on the formation of the gold-ligand interface. Citrate (Citr), poly(vinyl alcohol) (PVA), polyvinylpyrrolidone (PVP), and oleylamine (Oley)-stabilized Au NPs were not activated by piperazine for the hydrogenation of alkynes, but the catalytic activity was greatly enhanced after removing the capping ligands from the gold surface by calcination at 400 °C and the subsequent adsorption of piperazine. Therefore, the capping ligand can limit the catalytic activity if not carefully removed, demonstrating the need of a cleaner surface for a ligand-metal cooperative effect in the activation of H2 for selective semihydrogenation of various alkynes under mild reaction conditions.
A Method for preparing alpha-olefins from Biomass-derived fat and oil
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Paragraph 0191-0202, (2020/09/22)
The present invention relates to a method for preparing alpha-olefins from biomass-derived fats and oils. According to the preparation method, all of the various saturated or unsaturated fatty acids in the biomass-derived fats and oils can be prepared into alpha-olefins, and a conventional problem that the saturated fatty acids do not participate in a reaction or a mixture is generated due to polyunsaturated fatty acids can be solved. Thus, the present invention can be advantageously used to prepare alpha-olefins from biomass.
Kolbe Electrolysis of Biomass-Derived Fatty Acids Over Pt Nanocrystals in an Electrochemical Cell
Yuan, Gang,Wu, Chan,Zeng, Guorong,Niu, Xiaopo,Shen, Guoqiang,Wang, Li,Zhang, Xiangwen,Luque, Rafael,Wang, Qingfa
, p. 642 - 648 (2019/12/24)
Electrochemical valorization of non-food biomass-derived carboxylates into fuels is promising for the conversion, storage, and distribution of renewable electricity. Herein, we demonstrate that biofuels, hydrogen, and bicarbonate can be simultaneously produced in an electrochemical cell by one-step electrolysis of free fatty acids under ambient conditions on 3D self-supported ultralow Pt loading (2 wt %) electrode. The three valuable products can naturally separate from each other during the electrolysis in the alkaline aqueous solution. The experimental suggests that Pt(100) and Pt(110) are favorable for the production of non-Kolbe and Kolbe hydrocarbons, respectively. DFT calculation further clarifies the adsorption and stabilization of the reaction intermediates on Pt(100) and Pt(110).
Hydrogenation of hydrophobic substrates catalyzed by gold nanoparticles embedded in Tetronic/cyclodextrin-based hydrogels
Chevry,Menuel,Léger,No?l,Monflier,Hapiot
, p. 9865 - 9872 (2019/07/04)
Hydrogenation of alkenes, alkynes and aldehydes was investigated under biphasic conditions using Au nanoparticles (AuNP) embedded into combinations of α-cyclodextrin (α-CD) and a poloxamine (Tetronic90R4). Thermo-responsive AuNP-containing α-CD/Tetronic90R4 hydrogels are formed under well-defined conditions of concentration. The AuNP displayed an average size of ca. 7 nm and a narrow distribution, as determined by TEM. The AuNP/α-CD/Tetronic90R4 system proved to be stable over time. Upon heating above the gel-to-sol transition temperature, the studied catalytic system allowed hydrogenation of a wide range of substrates such as alkenes, alkynes and aldehydes under biphasic conditions. Upon repeated heating/cooling cycles, the Au NP/α-CD/Tetronic90R4 catalytic system could be recycled several times without a significant decline in catalytic activity.
