592-76-7Relevant articles and documents
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.
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
Vinogradov et al.
, (1976)
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.
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).