F:Flammable;
75-85-4Relevant articles and documents
In situ 13C DEPT-MRI as a tool to spatially resolve chemical conversion and selectivity of a heterogeneous catalytic reaction occurring in a fixed-bed reactor
Akpa, Belinda S.,Mantle, Michael D.,Sederman, Andrew J.,Gladden, Lynn F.
, p. 2741 - 2743 (2005)
The distortionless enhancement by polarisation transfer (DEPT) nuclear magnetic resonance (NMR) technique, combined with magnetic resonance imaging (MRI), has been used to provide the first in situ spatially-resolved and quantitative measurement of chemical conversion and selectivity within a fixed-bed reactor using natural abundance 13C NMR. The Royal Society of Chemistry 2005.
In situ X-ray absorption spectroscopic studies of magnetic Fe@FexOy/Pd nanoparticle catalysts for hydrogenation reactions
Yao, Yali,Rubino, Stefano,Gates, Byron D.,Scott, Robert W.J.,Hu, Yongfeng
, p. 180 - 186 (2017)
Core@shell Fe@FexOy nanoparticles (NPs) have attracted a great deal of interest as potential magnetic supports for catalytic metals via galvanic exchange reactions. In this study Fe@FexOy/Pd bimetallic NPs were synthesized through galvanic exchange reactions using 50:1, 20:1 and 5:1 molar ratios of Fe@FexOy NPs to Pd(NO3)2. The resulting Fe@FexOy/Pd NPs have Pd NPs on the Fe oxide surfaces, and still retain their response to external magnetic fields. The materials could be recovered after the reaction by an external magnetic field, and agitation of the solution via a magnetic field led to improvements of mass transfer of the substrates to the catalyst surface for hydrogenation reactions. The Fe@FexOy/Pd NPs derived from the 5:1 molar ratio of their respective salts (Fe:Pd) exhibited a higher catalytic activity than particles synthesized from 20:1 and 50:1 molar ratios for the hydrogenation of 2-methyl-3-buten-2-ol. The highest turnover frequency reached 3600?h?1 using ethanol as a solvent. In situ XANES spectra show that the Fe@FexOy NPs in the Fe@FexOy/Pd system are easily oxidized when dispersed in water, while they are very stable if ethanol is used as a solvent. This oxidative stability has important implications for the sustainable use of such particles in real world applications.
Reasons for the Inverse Dependence of the Turnover Frequency of Hydrogenation of Unsaturated Compounds on Palladium Catalyst Concentration
Skripov,Belykh,Sterenchuk,Levchenko,Schmidt
, p. 299 - 306 (2021/04/26)
Abstract: The hypotheses about reasons for the inverse dependence of the turnover frequency of hydrogenation of unsaturated compounds (alkyne, alkynol, olefin) on the catalyst concentration were discriminated by kinetic methods combined with electron microscopy. The reasons are: dissociation of polycrystalline Pd–P particles, equilibrium shift (stabilized cluster–cluster + stabilizer), and aggregation–disaggregation of Pd–P particles, the latter being the main reason for the concentration range 0.125–1 mmol/L. The effect of aggregation–disaggregation of Pd–P particles on the catalyst activity differs depending on the substrate. The proposed kinetic model was shown to be consistent with the experimental data for styrene hydrogenation used as an example. The rate constants of some stages were determined.
Novel nickel nanoparticles stabilized by imidazolium-amidinate ligands for selective hydrogenation of alkynes
López-Vinasco, Angela M.,Martínez-Prieto, Luis M.,Asensio, Juan M.,Lecante, Pierre,Chaudret, Bruno,Cámpora, Juan,Van Leeuwen, Piet W. N. M.
, p. 342 - 350 (2020/02/04)
The main challenge in the hydrogenation of alkynes into (E)- or (Z)-alkenes is to control the selective formation of the alkene, avoiding the over-reduction to the corresponding alkane. In addition, the preparation of recoverable and reusable catalysts is of high interest. In this work, we report novel nickel nanoparticles (Ni NPs) stabilized by three different imidazolium-amidinate ligands (ICy·(Ar)NCN; L1: Ar = p-tol, L2: Ar = p-anisyl and L3: Ar = p-ClC6H4). The as-prepared Ni NPs were fully characterized by (HR)-TEM, XRD, WASX, XPS and VSM. The nanocatalysts are active in the hydrogenation of various substrates. They present a remarkable selectivity in the hydrogenation of alkynes towards (Z)-alkenes, particularly in the hydrogenation of 3-hexyne into (Z)-3-hexene under mild reaction conditions (room temperature, 3% mol Ni and 1 bar H2). The catalytic behaviour of Ni NPs was influenced by the electron donor/acceptor groups (-Me, -OMe, -Cl) in the N-aryl substituents of the amidinate moiety of the ligands. Due to the magnetic character of the Ni NPs, recycling experiments were successfully performed after decantation in the presence of an external magnet, which allowed us to recover and reuse these catalysts at least 3 times preserving both activity and chemoselectivity.
Internal Surface Coating of a Capillary Microreactor for the Selective Hydrogenation of 2-Methyl-3-Butyn-2-Ol Using a PdZn/TiO2 Catalyst. The Effect of the Catalyst’s Activation Conditions on Its Catalytic Properties
Okhlopkova,Kerzhentsev,Ismagilov
, p. 347 - 356 (2018/06/12)
Finely divided polymer-stabilized PdZn bimetallic nanoclusters are prepared by the polyol method. TiO2 matrix-impregnated nanoclusters coated on the inner surface of a capillary microreactor are used as catalysts for the selective hydrogenation of 2-methyl-3-butyn-2-ol. The effect of the activation conditions (duration, temperature, and gas medium composition) on the physicochemical and catalytic properties of the coatings is studied. It is shown that their catalytic activities decrease and the reaction’s selectivity increases with an increase in the reaction time and the time of hydrogen reduction at 573 K. The highest selectivity (96.5% at a conversion rate of 99%) is reached on the coatings reduced with hydrogen for 6 h. The coatings remain highly active and stable for 1 month in the continuous flow mode of the reaction. Kinetic simulation showed that a high selectivity level is ensured by a decrease in the rate constants of hydrogenation of 2-methyl-3-buten-2-ol and the ratio of the alkene/alkyne adsorption constants after reductive treatment.
