123-72-8Relevant articles and documents
Supported homogeneous catalyst makes its own liquid phase
Kaftan, Andre,Sch?nweiz, Andreas,Nikiforidis, Ioannis,Hieringer, Wolfgang,Dyballa, Katrin M.,Franke, Robert,G?rling, Andreas,Libuda, J?rg,Wasserscheid, Peter,Laurin, Mathias,Haumann, Marco
, p. 32 - 38 (2015)
A catalyst designed for homogeneous catalysis is shown to generate its own liquid phase if deposited onto a support. In this way, a macroscopically heterogeneous catalyst generates a microscopically homogeneous catalytic environment by self-organization. 2,2′-((3,3′-di-tert-butyl-5,5′-dimethoxy-[1,1′-biphenyl]-2,2′-diyl)-bis(oxy))bis(4,4,5,5-tetraphenyl-1,3,2-dioxaphospholane) modified rhodium complexes molecularly adsorbed onto porous silica powder show surprisingly high activity and regioselectivity in the gas-phase hydroformylation of propene to butanal, with no sign of deactivation. Operando IR investigations combined with density functional theory calculations confirm a side reaction: the aldol condensation of the butanal products. These heavier by-products accumulate inside the pores of the catalytic material. IR and gas chromatography show a direct relation between formation of enones, products of the aldol condensation, performance, and stability of the catalytic system. This demonstrates that the aldol condensation products generated in situ act as a solvent providing an ideal environment to the impregnated homogeneous catalyst.
Effect of Sodium Cation Addition on the Hydroformylation of Propene over Silica-supported Group VIII Metal Catalysts
Naito, Shuichi,Tanimoto, Mitsutoshi
, p. 1403 - 1404 (1989)
Addition of a sodium cation to silica-supported Rh, Pd, Pt, and Ni catalysts markedly lowers the activation energy of the hydroformylation process without affecting the regioselectivity of the products and facilitates the CO insertion into propyl intermediates.
Kinetics and Mechanism of the Oxidation of Butane-2,3-Diol by Alkaline Hexacyanoferrate (III), Catalyzed by Ruthenium Trichloride
Balado, A. Mucientes,Jimenez, F. Santiago,Martin, F. J. Poblete,Castellanos, R. Varon
, p. 1 - 8 (1997)
The kinetics of oxidation of butane-2,3-diol by alkaline hexacyanoferrate (III), catalyzed by ruthenium trichloride has been studied spectrophotometrically.The reaction rate shows a zero-order dependence on oxidant, a first-order dependence on T, a Michaelis-Menten dependence on , and a variation complicated on ->.A reaction mechanism involving the existence of two active especies of catalyst, Ru(OH)2+ and Ru(OH)3, is proposed.Each one of the active species of catalyst forms an intermediate complex with the substrate, which disproportionates in the rate determining step.The complex disproportionation involves a hydrogen atom transfer from the α-C-H of alcohol to the oxygen of hydroxo ligand of ruthenium, to give Ru(II) and an intermediate radical which is then further oxidized.
Hydroformylation of propene heterogeneously catalyzed by HRh(CO)(PPh 3)3 encapsulated in to hexagonal mesoporous silica - Parametric variation and mass transfer study
Sudheesh,Parmar, Jaydeep N.,Shukla, Ram S.
, p. 124 - 131 (2012)
An in situ encapsulated HRh(CO)(PPh3)3 in to the pores of hexagonal mesoporous silica (HMS) acting as nanophase reactors, was investigated for the catalytic hydroformylation of propene. The encapsulated catalyst (Rh-HMS) was synthesized and characterized by PXRD, FT-IR, surface area measurements and TEM. The catalyst was effectively active with 99% conversion of propene and 100% selectivity to aldehydes. The effects of reaction parameters: temperature, partial pressure of CO and H2, amount of catalyst and HRh(CO)(PPh3)3 to TEOS ratio on conversion, selectivity and rates were investigated in detail. The rates determined in term of the formation of aldehydes were found to be first order with respect to hydrogen pressure. Catalyst showed first order dependence towards its lower amount. CO pressure variation showed positive order towards lower pressure and inhibition at higher pressures. The investigated mass transfer effects on the kinetics indicated that the reaction runs with negligible mass transfer limitations. The heterogenized Rh-HMS catalyst was effectively recycled for six times.
Pyridinium Fluorochromate; A New and Efficient Oxidant for Organic Substrates
Bhattacharjee, Manabendra N.,Chaudhuri, Mihir K.,Dasgupta, Himadri S.,Roy, Nirmalendu,Khathing, Darlando T.
, p. 588 - 590 (1982)
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Two new fatty acid derivatives from the stem bark of alchornea laxiflora (euphorbiaceae)
Sandjo, Louis Pergaud,Poumale, Hervé M. Poumale,Siwe, Xavier Noudou,Ntede, Hippolyte Nga,Shiono, Yoshihito,Ngadjui, Bonaventure Tchaleu,Krause, Rui M. W.,Ndinteh, Derek Tantoh,Mbafor, Joseph Tanyi
, p. 1153 - 1159 (2011)
Euphorbiaceae is a family of plants used in traditional remedies in central Africa to treat selected diseases. Some of the phytochemical components in the stem bark of Alchornea laxiflora that have biochemical activity were identified. A number of novel compounds were isolated, including a new fatty acid ester, (1) a new ceramide, (2) some triterpenoids, (3-5), ellagic acid (6) and its derivatives (7, 8) were isolated. The structures of these compounds were determined on the basis of spectroscopic methods as well as HR-ESI-TOF-MS analysis, chemical transformation and by comparison of their physical and spectral data with those reported in the literature. The cytotoxicity of some isolated compounds was investigated against human promyelocytic leukaemia (HL60) cell line by using the MTT method. Compounds 1, 4 and 5 showed a cytotoxic activity with IC50 at 58.7, 6.6 and 6.8 μM, respectively.
Efficient strategy for interchangeable roles in a green and sustainable redox catalytic system: IL/PdII-decorated SBA-15 as a mesoporous nanocatalyst
Sadeghi, Samira,Karimi, Meghdad,Radfar, Iman,Gavinehroudi, Reza Ghahremani,Saberi, Dariush,Heydari, Akbar
, p. 6682 - 6692 (2021)
Time and again, SBA-15-based composites as mesoporous materials and the incorporation of transition metals in them have been attracting dramatic attention in the field of catalysis due to their remarkable features. In this paper, the activity of SBA-15 supported ionic liquid-Pd(ii) has been investigated in the catalytic transfer hydrogenation of nitroarenes with formic acid as a hydrogen donor at room temperature in water medium, and the oxidation of benzyl alcohols to benzaldehyde derivatives under atmospheric oxygen at high temperature. This novel nanocatalyst was characterized by FT-IR, SA-XRD, BET, BJH, TGA, FE-SEM, TEM, and ICP as the most commonplace techniques for analyzing its characteristics to be revealed as truth. Furthermore, the EDX analysis illustrates the grafting of the ionic liquid-Pd(ii) into SBA-15. The catalyst showed high stability under reaction conditions, and can be recovered and reused for at least 15 and 6 reaction runs in oxidation and reduction reactions, respectively.
Photosensitized oxidative deprotection of oximes to their corresponding carbonyl compounds by platinum(II) terpyridyl acetylide complex
Yang, Yue,Zhang, Dong,Wu, Li-Zhu,Chen, Bin,Zhang, Li-Ping,Tung, Chen-Ho
, p. 4788 - 4791 (2004)
Platinum(II) terpyridyl acetylide complex (1) photosensitizes the oxidation of aldoximes 2-4, aliphatic acyclic and cyclic ketoximes 5-7, and aromatic ketoximes 8-10 into their corresponding carbonyl compounds with good to excellent yields in acetonitrile solution. This deprotection of oximes proceeds via singlet oxygen (1O2) mechanism. The photosensitizer can be easily separated from the product and unreacted starting material by extraction with ethyl acetate and reused for photooxidation without loss of 1O2-generation capacity.
Compounds of chromium(VI): The pyridine-chromic anhydride complex, benzimidazolinium dichromate, and three 2-alkyl-1H-benzimidazolinium dichromates
Cameron, T. Stanley,Clyburne, Jason A.C.,Dubey, Pramod K.,Grossert, J. Stuart,Ramaiah,Ramanatham,Sereda, Sergei V.
, p. 612 - 619 (2003)
Pyridine, when allowed to react with chromic anhydride under strictly anhydrous conditions, gives the known, very air-sensitive, crystalline 2:1 Lewis acid-base complex 1. The crystal structure has now been successfully determined. When benzimidazole and three 2-alkyl-1H-benzimidazoles were treated with chromium trioxide in aqueous acetic acid, crystalline dichromate salts (2-5) were readily formed. These salts consist of dichromate anions linked to the cations by hydrogen bonds of the type N-H...O. The chromium atoms have distorted tetrahedral environments, with the Cr-O distances being typical for dichromate anions. In the cases of the 2-methyl and 2-ethyl salts, the anions are disordered about a centre of inversion. The hydrogen bonding arrangements are discussed and the structures are compared with other oxygenated chromium(VI) species. The dichromate salts are useful selective oxidants for a range of primary and secondary alcohols; examples of these reactions are reported.
Sandwich type tri-palladium substituted phosphotungstate, [Pd3(PW9O34)2]11?: Synthesis, structural characterization and catalytic evaluation
Patel, Anish,Patel, Anjali,Sadasivan, Rajesh
, (2021)
The present work showcases, first time, the synthesis of tri-palladium substituted sandwich type phosphotungstate, [Pd3(PW9O34)2]11?, from its individual salts in super acidic medium as well as the single crystal structure of the same. Further, various spectral analysis carried out to support the crystal data. A preliminary study for the hydrogenation of nitrobenzene has been carried out to evaluate the catalytic activity of the complex.
Cyclometalation of 1-Aza 1,3-Dienes in reactions with Ru3(CO)12 with formation of four- and five-membered azaruthenacycles
Mul, Wilhelmus P.,Elsevier, Cornelis J.,Polm, Louis H.,Vrieze, Kees,Zoutberg, Martin C.,Heijdenrijk, Dick,Stam, Casper H.
, p. 2247 - 2259 (1991)
The dinuclear compounds Ru2(CO)6[R1CH2CC(H)NR2] (2a-e) and Ru2(CO)6[R1C=C(H)CH2NR2] (3a,b,d) are the first isolable products during thermal reactions of Ru3(CO)12 with 1-aza 1,3-dienes R1C(H)=C-(H)C(H)=NR2(R1,R2-MAD; R1, R2 = CH3, i-Pr (1a), CH3, c-Hex (1b), CH3, t-Bu (1c), C6H5, i-Pr (1d), C6H5, T-Bu (1e)). Both primary products 2 and 3 contain an isomerized MAD ligand that is part of a four-(2) or five-membered (3) azaruthenacycle. The molecular structure of 3a has been solved by X-ray crystallography: space group P1?, with a = 22.511 (4) ?, b = 13.740 (3) ?, c = 12.443 (2) ?, α = 103.21 (1)?, β = 113.00 (1)?, γ = 77.71 (1)?, V = 851.3 ?, Z = 2, and R = 0.027 (Rw = 0.042), for 2540 observed reflections. Compound 3a contains a formally 6-electron donating enyl-amido ligand and is μ-N,-σ-Cβη2-C=C-coordinated to a sawhorse Ru2(CO)6 core. In solution both 2 and 3 are stereochemically nonrigid, due to windshield wiper motions of the asymmetrically bridged amido ligands. This process is more facile for 2 (ΔG? ≈ 35 kJ mol-1) than for 3 (ΔG? 62 kJ mol-1), and the ΔG? value for 3 was shown to be independent of the R1 and R2 substituents. In refluxing heptane 2 and 3 are converted into the linear 66-electron cluster Ru4(CO)10[R1C=C(H)C(H)=NR2] 2 (5a-e), albeit conversion of 2 into 5 proceeded very slowly and incompletely. Conversion of 3 into 5 proceeds via the intermediacy of (μ-H)Ru2(CO)5[R1C= C(H)C(H)=NR2] (4), which air-sensitive compound could be observed and isolated for R1, R2 = C6H5, i-Pr (4d). Reaction of 3a,b with CH,R2-MAD or crotonaldehyde in heptane at 90°C results in the formation Of Ru2(CO)6[CH2CC(H)C(H)=NR2] (6a,b). During this conversion the coordinated ligand is dehydrogenated whereas the added substrate acts as a hydrogen acceptor. For crotonaldehyde it was shown that the olefin moiety was hydrogenated chemoselectively. The formation of 2 and 3 out of Ru3(CO)12 and R1,R2-MAD and their conversion into 4-6 are discussed.
Selective Hydrogenation of Unsaturated Carbonyl Compounds over an Oxidized Gold-Zirconium Alloy
Shibata, M.,Kawata, N.,Masumoto, T.,Kimura, H.
, p. 154 - 156 (1988)
An oxidized amorphous Au-Zr alloy showed high selectivities for partial hydrogenation of unsaturated carbonyl compounds to unsaturated alcohols, contrasting with their low catalytic activity in the hydrogenation of unsaturated to saturated alcohols; the active sites of this catalyst are modified gold rather than impurities since the amounts of impurities present were too small (80 p.p.m.) to show hydrogenation activity.
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Scully Jr.,Davis
, p. 1467 (1978)
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In situ synthesis of gold nanoparticles inside the pores of MCM-48 in supercritical carbon dioxide and its catalytic application
Chatterjee,Ikushima,Hakuta,Kawanami
, p. 1580 - 1590 (2006)
Gold nanoparticles are deposited into the channels of MCM-48 through a simple H2-assisted reduction of HAuCl4 (aqueous solution) in supercritical carbon dioxide medium at 70 °C within 2-4 h. The nanoparticles were characterized by powder X-ray diffraction (PXRD), N 2 adsorption-desorption, transmission electron microscopy (TEM), and UV-Vis spectroscopy. The particle size of the synthesized material is tunable with the pressure (density) of the supercritical carbon dioxide medium. At the fixed temperature (70°C) and hydrogen pressure [P(H2) = 2 MPa], the Au particle size varies from ca. 25 nm to ca. 2 nm with the change in CO2 pressure from 7 MPa to 17 MPa. At the low solvent density conditions, larger particles of ～25 nm were obtained. On the contrary, a high solvent density of CO2 slows down particle aggregation, resulting in the small particle size within the range of 2-5 nm. This change in particle size with CO2 pressure and the interaction of the particles with the silica support were correlated well with long-range van der Waals interactions and consequently the Hamaker constant for the gold nanoparticle-CO2 (A131) and silica-gold core-CO 2 (A132), respectively. Supercritical carbon dioxide alone can provide a unique environment for stabilizing gold nanoparticles in the channels of the cubic mesoporous MCM-48 support and exquisite control of the particle size without perturbing the support structure. The synthesized material is highly stable, recyclable and no metal nanoparticle leaching was observed. The selective hydrogenation of crotonaldehyde with the synthesized material provides convincing evidence that the particles are inside the pores and available to the reactant molecules.
Kinetics and mechanism of catalytic oxidation of alcohols to carbonyl compounds with dioxygen in the Pd-containing aqua system
Potekhin
, p. 875 - 882 (2007)
The oxidation of lower aliphatic alcohols C1-C4 with dioxygen to form the corresponding carbonyl compounds in the presence of the PdII tetraaqua complexes and FeII-FeIII aqua ions in an aqueous medium was studie
Effect of reduction temperature on selective hydrogenation of crotonaldehyde over Ir/TiO2 catalysts
Chen, Ping,Lu, Ji-Qing,Xie, Guan-Qun,Hu, Geng-Shen,Zhu, Lin,Luo, Liang-Feng,Huang, Wei-Xin,Luo, Meng-Fei
, p. 236 - 242 (2012)
Vapor-phase selective hydrogenation of crotonaldehyde was conducted over Ir/TiO2 catalysts to investigate the effect of reduction temperature on the catalytic behaviors. The catalyst reduced at 100 °C contained large amount of strong Lewis acid
Rhodium Pyrrolylphosphine Complexes as Highly Active and Selective Catalysts for Propene Hydroformylation: The Effect of Water and Aldehyde on the Reaction Regioselectivity
Mieczyńska, Ewa,Grzybek, Ryzard,Trzeciak, Anna M.
, p. 305 - 310 (2018)
The hydroformylation of propene catalyzed by Rh(acac)(CO)2 (acac=acetylacetonate) with a 13-fold excess of N-pyrrolylphosphine ligands PPyr3, PPh2Pyr, or PPh(Pyr)2 (Pyr=NC4H4) was investigated under a pressure of 15 bar (propene/H2/CO=5:5:5) at 80 °C. The N-pyrrolylphosphine ligands facilitated an excellent regioselectivity towards n-butanal aldehyde, significantly better than PPh3 and PCy3 under the same conditions. In the presence of the strongest π-acceptor, PPyr3, the linear-to-branched aldehyde (l/b) ratio was 8.6, which increased to 27.1 if water was added to the system. The application of a pure aldehyde as a solvent instead of toluene caused a significant increase in the aldehyde yield but with a decreased l/b ratio (2.9–7.6). The regioselectivity parameter l/b increased to 19.3 after the introduction of water as a cosolvent.
Preparation of SiO2-encapsulated SnPt nanoparticle catalysts for selective hydrogenation of unsaturated aldehyde
Taniya, Keita,Yu, Chih Hao,Tsang, Shik Chi,Ichihashi, Yuichi,Nishiyama, Satoru
, p. 6 - 9 (2011)
The SiO2-encapsulated SnPt catalysts having the core-shell structures were prepared by using the polyol process. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) results indicated the SnPt alloy nanoparticles were covered with a thin silica layer with the porous structures. The SiO2-encapsulated SnPt catalysts showed the higher selectivity of crotyl alcohol for selective hydrogenation of crotonaldehyde in comparison with the Sn-Pt/SiO2 catalysts prepared by a conventional co-impregnation. It was considered that the formation of uniform SnPt alloy phases and the pore structures in the silica layers with the steric hindrance would enhance the chemo-selective hydrogenation of crotonaldehyde.
Dibal-H reduction of methyl butyrate into butyraldehyde using microreactors
Ducry, Laurent,Roberge, Dominique M.
, p. 163 - 167 (2008)
The reduction of methyl butyrate into butyraldehyde with Dibal-H in inicroreactors is described. Running the reaction continuously in a microreactor afforded results similar to those of batch experiments, but very low temperatures are not necessary and the reaction may be scaled-up without selectivity decrease. Different microreaetors were used, and their mixing performances were compared. Increasing the reaction concentration and thus the throughput showed that even when working with microreactors, heat management should not be underestimated. Multi-injection was tested as a way to better control the temperature at the mixing point(s).
Identification of an unexpected peroxide formed by successive isomerization reactions of the n-butoxy radical in oxygen
Jorand, Francois,Heiss, Adolphe,Sahetchian, Krikor,Kerhoas, Lucien,Einhorn, Jacques
, p. 4167 - 4171 (1996)
A previously unreported peroxide, C4H8O3 (5), has been identified and its mechanism of formation proposed. It is generated by two successive isomerization reactions of n-C4H9O radicals in O2. These radicals are produced by di-n-C4H9O-OC4H9 pyrolysis at 480 K in a wall-passivated quartz vessel. The peroxide is collected, among other end-products, on a liquid-nitrogen trap and recovered in liquid acetonitrile. Analysis was carried out by GC-MS, GC-MS-MS [electron impact (EI) and NH3 (or ND3)-chemical ionization (CI) conditions] and GC-FTIR. After micropreparative GC separation of the titled peroxide, 1H NMR and high-resolution EIMS were also obtained. The compound was identified as 3α-hydroxy-1,2-dioxane. The hydroperoxybutyraldehyde OHC-(CH2)2-CH2O2H is proposed to be initially formed in the gas phase and to be in equilibrium with its cyclic form (six-membered ring peroxide), by far predominant in the liquid phase at room temperature. The implications of this hydroperoxybutyraldehyde in atmospheric pollution (due to the peroxide producing capability of radicals) and in combustion are discussed.
Promoted chemoselective crotonaldehyde hydrogenation on zirconia-doped SiO2 supported Ag catalysts: Interfacial catalysis over ternary Ag–ZrO2–SiO2 interfaces
Lin, Haiqiang,Qu, Hongyan,Chen, Weikun,Xu, Kang,Zheng, Jianwei,Duan, Xinping,Zhai, Hesheng,Yuan, Youzhu
, p. 19 - 32 (2019)
In gas-phase chemoselective hydrogenation of crotonaldehyde on Ag-based catalysts, zirconia doping on silica supports was found to improve catalytic performance in terms of unsaturated alcohol selectivity, hydrogenation activity, and stability. The surface modification of silica by zirconia doping favors the fine dispersion of Ag species due to the enhanced quantity and strength of surface acid sites, which enable construction of abundant catalytic sites effective for C[dbnd]O bond hydrogenation. High crotyl alcohol selectivity, exceeding 80%, and significant inhibition of monohydrogenation on the C[dbnd]C bond were observed on the optimal Ag/Zr–SiO2 catalyst. Dynamic O2 chemisorption measurement revealed that the pure Ag powders did not chemisorb O2 irreversibly under 323 K, but SiO2 or Zr–SiO2 supported Ag catalysts did. The amounts of Ag active for O2 chemisorption, which are at least one order of magnitude lower than that of surface Ag derived from TEM and XRD characterizations, match well with the perimeter interface Ag of hemispherical particles. A strong correlation between hydrogenation activity and O2 uptake on those Ag/SiO2 and Ag/Zr–SiO2 catalysts with different Ag dispersions and deactivation degrees was observed, implying that the effective catalytic sites for crotonaldehyde chemoselective hydrogenation may originate from accessible interface sites with unique redox properties. Catalyst induction and deactivation were observed on both Ag/SiO2 and Ag/Zr–SiO2 catalysts in real catalytic operation. Changes in metal stable interface structure, rather than metal aggregation and coagulation, are assumed to be the main cause of irreversible catalyst deactivation, because the apparent Ag particle sizes changed slightly, but the oxygen chemisorption ability deteriorated considerably. Electropositive Ag sites interacting with neighboring oxygen from oxide supports at the ternary Ag–ZrO2–SiO2 interface are proposed to account for highly selective C[dbnd]O bond hydrogenation to produce the desired unsaturated alcohol.
Highly efficient and chemoselective hydrogenation of α,β-unsaturated carbonyls over Pd/N-doped hierarchically porous carbon
Wei, Zhongzhe,Gong, Yutong,Xiong, Tianyi,Zhang, Pengfei,Li, Haoran,Wang, Yong
, p. 397 - 404 (2015)
Palladium nanoparticles supported on N-doped hierarchically porous carbon, Pd/CNx, has been developed as a highly efficient, reusable and environmentally benign heterogeneous catalyst for the selective hydrogenation of various α,β-unsaturated carbonyls to their corresponding saturated carbonyls under mild conditions (303 K, 1 bar H2). Complete conversion of a series of α,β-unsaturated carbonyls was achieved with excellent selectivity (>99%) within 4 h. Moreover, the catalyst can be easily recovered by centrifugation and withstands recycling up to 8 times without apparent loss of activity and selectivity. The considerable catalytic performance is attributed to the hierarchically porous network and incorporation of nitrogen atoms. This catalytic system opens up an efficient, selective, recyclable and sustainable method for selective hydrogenation.
Synthesis, characterization, electrochemical, catalytic and antimicrobial activity studies of hydrazone Schiff base ruthenium(II) complexes
Thilagavathi,Manimaran,Priya, N. Padma,Sathya,Jayabalakrishnan
, p. 301 - 307 (2010)
Four tridentate O, N, O donor Schiff base ligands were prepared by the reaction of substituted benzhydrazide and appropriate salicylaldehyde. Thecomplexesof these ligandswere synthesizedby refluxingtheligands with ruthenium(II) starting complexes of the formula [RuHCl(CO)(EPh3) 2B] in benzene, where E = P or As; B = PPh3 or AsPh 3 or pyridine. The newly synthesized complexes were characterized by elemental, spectral (FT-IR, UV and NMR) and electrochemical data. On the basis of the above studies, an octahedral structure has been proposed for all the complexes. The catalytic efficiency of the complexes in aryl-aryl couplings and oxidation of alcohols was examined and their inhibition activity against the growth of themicro-organisms was also examined. Copyright
Fluid phase equilibria of the reaction mixture during the selective hydrogenation of 2-butenal in dense carbon dioxide
Musko, Nikolai E.,Jensen, Anker Degn,Baiker, Alfons,Kontogeorgis, Georgios M.,Grunwaldt, Jan-Dierk
, p. 67 - 75 (2012)
Knowledge of the phase behaviour and composition is of paramount importance for understanding multiphase reactions. We have investigated the effect of the phase behaviour in the palladium-catalysed selective hydrogenation of 2-butenal to saturated butanal in dense carbon dioxide. The reactions were performed using a 5 wt% Pd on activated carbon in custom-designed high pressure autoclaves at 323 K. The Cubic-Plus-Association (CPA) equation of state was employed to model the phase behaviour of the experimentally studied systems. CPA binary interaction parameters were estimated based on the experimental vapour-liquid or liquid-liquid equilibria data available in the literature. No experimental data for the CO2-2-butenal binary system were available in the literature; therefore, the bubble points of this mixture of varying composition at three different temperatures were measured in a high-pressure view cell. The results of the catalytic experiments showed that small amounts of carbon dioxide added to the system significantly decrease the conversion, whereas at higher loadings of CO2 the reaction rate gradually increases reaching a maximum. The CPA calculations revealed that this maximum is achieved in the so-called "expanded liquid" region, which is located near the critical point of the reacting mixture. It was also found that in this point the hydrogen concentration achieved its maximum in the CO2-expanded phase. Furthermore, the pressure - temperature regions where the multicomponent reaction system exists in one single phase and in multiphase were calculated.
Ru-Ti intermetallic catalysts for the selective hydrogenation of crotonaldehyde
Ruiz-Martinez,Fukui,Komatsu,Sepulveda-Escribano
, p. 150 - 156 (2008)
Titanium-doped ruthenium catalysts were prepared, characterized, and studied in the vapor-phase selective hydrogenation of crotonaldehyde. The catalysts were prepared by co-impregnation and by the chemical vapor deposition (CVD) method. XPS results indicate that titanium was well dispersed on the support for the catalyst prepared by CVD. Ruthenium dispersion was diminished by titanium addition, and a strong interaction of ruthenium with titanium was deduced from CO adsorption microcalorimetry. Results obtained in the vapor-phase hydrogenation of crotonaldehyde showed that the monometallic Ru catalyst had no selectivity toward crotyl alcohol, whereas the RuTi catalyst prepared by the CVD method gave the highest selectivity.
ALDEHYDE GENERATION VIA ALKENE HYDROFORMYLATION
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Paragraph 0083; 0084, (2021/09/26)
Aldehyde generation includes providing a first input stream, a second input, and an alkene substrate to a reactor system. The first input stream includes a catalyst, a ligand, and an organic solvent. The second input stream includes a mixture of carbon monoxide (CO) and hydrogen gas (H2). The alkene substrate is in either gaseous form or liquid form, the liquid form of the alkene substrate being provided with the first input stream, the gaseous form of the alkene substrate being provided with the second input stream. The reactor system includes a first reactor and a second reactor, where the second reactor is gas permeable and positioned within the first reactor.
Designing of Highly Active and Sustainable Encapsulated Stabilized Palladium Nanoclusters as well as Real Exploitation for Catalytic Hydrogenation in Water
Patel, Anish,Patel, Anjali
, p. 803 - 820 (2020/08/12)
Abstract: Encapsulated nanoclusters based on palladium, 12-tunstophosphoric acid and silica was designed by simple wet impregnation methodology. The catalyst was found to be very efficient towards cyclohexene hydrogenation up to five catalytic runs with substrate/catalyst ratio of 4377/1 at 50?°C as well as for alkene, aldehyde, nitro and halogen compounds. Graphic Abstract: Silica encapsulated Pd nanoclusters stabilized by 12-tungstophosphoric acid is proved to be sustainable and excellent for water mediated hydrogenation reaction with very high catalyst to substrate ratio as well as TON.[Figure not available: see fulltext.]
