Aqueous Catalyst Phase Research Articles

Surface acidity and reactivity of β-FeOOH/Al2O3 for pharmaceuticals degradation with ozone: In situ ATR-FTIR studies

The surface acidity and reactive activity of β-FeOOH, mesoporous alumina (MA), β-FeOOH/MA were investigated in catalytic ozonation of pharmaceutically active compounds (PhACs) aqueous solution. β-FeOOH/MA showed high efficiency for the degradation and mineralization of ibuprofen and ciprofloxacin. Its surface Lewis acid sites on β-FeOOH/MA were more greatly enhanced compared with those on MA and β-FeOOH. In situ attenuated total reflection FTIR (ATR-FTIR) spectroscopy was used to investigate the interaction of D2O and O3 with the catalysts in aqueous phase under various conditions. The dissociative chemisorptions of D2O occurred at the surface Lewis acid sites of the catalyst. Furthermore, O3 interacted with the surface hydrogen-bonded –O–D and D2O to initiate reactive oxygen species (ROS). The stronger Lewis acid sites of β-FeOOH/MA caused the more chemisorbed water enhancing the interaction with ozone, resulting in higher catalytic reactivity. The observations verified that the Lewis acid sites were reactive centers for the catalytic ozonation of PhACs in water.

Selective oxidation of aromatic primary alcohols to aldehydes using molybdenum acetylide oxo-peroxo complex as catalyst

Selective oxidation of various aromatic alcohols to aldehydes has been carried out with very high conversion (90%) and selectivity (90%) for aldehydes using cyclopentadienyl molybdenum acetylide complex, CpMo(CO) 3(C CPh) ( 1) as catalyst and hydrogen peroxide as environmentally benign oxidant. Water-soluble Mo acetylide oxo-peroxo species is formed in situ after reaction of 1 with aqueous hydrogen peroxide during the course of reaction as catalytically active species. Interestingly even though the catalyst is homogeneous it could be recycled very easily by separating the products in organic phase and catalyst in aqueous phase using separating funnel. Even after five recycles no appreciable loss in alcohol conversion and aldehyde selectivity was observed.

Anticipating catalytic oxidation reactions on gold at high pressure (including liquid phase) from ultrahigh vacuum studies

Evidence for the mechanistic link between low pressure studies and the high pressure, aqueous phase, catalytic partial oxidation reactions of ethanol on gold is provided. The oxidation of ethanol on gold (111) leads to the formation of ethyl acetate and acetic acid, as was also reported for this reaction over supported gold catalysts in aqueous phase. This reaction follows a pattern previously observed in ultrahigh vacuum on both silver and gold single crystals. The formation of both acetic acid and ethyl acetate in solution can be anticipated from prior experiments on single-crystal surfaces in ultrahigh vacuum, showing a strong parallel between the oxidation behavior of gold under these extremely different conditions. This parallel suggests that other oxidation reactions on gold may be anticipated from previous studies at low pressure and may serve as a guide for their prediction even in the liquid phase.

Characterization of the micellar ring opening metathesis polymerization in water of a norbornene derivative initiated by Hoveyda‐Grubbs' catalyst

AbstractSolubilization of the hydrophobic Hoveyda‐Grubbs' catalyst in micellar aqueous phase has been achieved using dodecyl and cetyl ammonium chloride as surfactants. The domain of solubilization has been estimated before carrying out ring‐opening metathesis polymerization in these micellar solutions with a hydrophilic monomer. Kinetics orders have been determined relative to monomer, initiator, and surfactant. A good control of the molecular weight has been obtained for ratios [micelles]/[initiator] over 1. The better control of the polymerization obtained in micellar solution has been explained by a difference of reactivity leading to a more efficient initiation step in the presence of the micelles. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2833–2844, 2008

Aqueous biphasic catalytic hydroformylation of higher olefins: Promotion effect of cationic gemini and trimeric surfactants

Abstract Six cationic gemini and trimeric surfactants: N,N′-didodecyl-N,N′-dimethyl piperazinium iodide (2), the monooxlate of N,N′-didodecylpiperazine (3), the hydrochloride of N,N′-didodecylpiperazine (4), the 1,3,5-trimethyl-1,3,5-tridodecylhexahydro-1,3,5-trazinium iodide (5), the monooxlate of 1,3,5-tridodecylhexahydro-1,3,5-triazine (6) and the hydrochloride of 1,3,5-tridodecylhexahydro-1,3,5-triazine (7) were prepared using the regular methods. These cationic surfactants and a double-chained surfactant, didodecyldimethylammonium bromide (1), were successfully applied as catalysis promotion agents in aqueous biphasic hydroformylation of higher olefins. The aqueous catalysts used in present study were RhCl(CO)(TPPTS)2–TPPTS [TPPTS: P(m-C6H4SO3Na)3]. The experimental results showed that while all these cationic surfactants could accelerate the hydroformylation reaction, surfactants 1, 2, 6, 7 exhibited more significant promotion effects. The influences of the surfactant anions on the reaction were also discussed. Of the three gemini surfactants 2, 3, and 4, which were derived from N,N′-didodecylpiperazine, surfactant 2 with iodide as anion exhibited substantially higher promotion effect than surfactants 3 with monooxalate and 4 with chloride as anion, respectively. On the other hand, among the three trimeric surfactants 5, 6, 7, which were derived from 1,3,5-tridodecylhexahydro-1,3,5-triazine, surfactants 6 with monooxalate and 7 with hydrochloride as anion displayed better acceleration effect than surfactant 5 with iodide as anion. Compared with the double-chained and single headed surfactant 1, surfactant 2 containing two alkyl chains and cationic heads and surfactant 6 with three alkyl chains and cationic heads were superior additives to accelerate the hydroformylation reactions. When they were used as catalysis promotion additives, less water-soluble phosphine (TPPTS) was required to immobilize the rhodium catalyst in aqueous phase, and the hydroformylation reaction proceeded more regioselectively toward the valuable linear aldehyde under lower syngas pressure.

Catalyst Regenerator for Partial Oxidation of Benzene in Reaction-extraction System

The liquid-phase oxidation of benzene to phenol was investigated in the biphasic benzene-water system using VCl3 and molecular oxygen as the catalyst and oxidant, respectively. Benzene was dissolved in the aqueous catalyst phase and reacted with oxygen to form phenol. Phenol was preferentially extracted into the benzene phase, thus suppressing the formation of over-oxidized byproducts. During the reaction, the catalyst was oxidized and deactivated. To regenerate the catalyst, a regenerator was installed into the system. Hydrogen was fed to the regenerator to reduce the deactivated catalyst, but no significant improvement of the system performance was observed without the presence of a second catalyst. Pd sheet in the regenerator allowed the system to run very stably, and the system was easy to shut down and start up.

The hydrogenation of cinnamaldehyde by supported aqueous phase (SAP) catalyst of RhCl(TPPTS) 3: Selectivity, kinetic and mass transfer aspects

The hydrogenation of trans-cinnamaldehyde catalysed by a supported aqueous phase catalyst of RhCl(TPPTS) 3 [TPPTS: trisodium salt of tris(m-sulfophenyl)phosphine] on silica was investigated in terms of the product selectivity, reaction kinetics and mass transfer characteristics. The hydrogenation is selective at the C C bonds in cinnamaldehyde giving hydrocinnamaldehyde as the main product. To achieve high selectivity (99.9%), it is necessary to employ a low initial concentration of cinnamaldehyde (0.076 M). The selectivity also depended on the reaction operating conditions (pressure, temperature, catalyst loading) and the water content property of the SAP catalyst. Optimum water content of the SAP catalyst giving maximum activity was obtained when the pore volume of the supports was completely filled with water. The overall order of reaction was first-order and therefore the conventional three-phase slurry model was applied to the SAP system for the mass transfer analysis. The gas–liquid mass transfer and the reaction resistances were the controlling steps of comparable significance, while liquid–solid mass transfer resistance was negligible in this system. Under similar conditions, the SAP catalyst gave a lower reaction rate than the analogous biphasic catalyst.

Hydroformylation of long-chain alkenes with new supported aqueous phase catalysts

In this paper the development and investigation of a new type of immobilized catalyst for the hydroformylation of long-chain alkenes is presented. The catalyst system consisted of the well known metal complex carbonylhydrido-tris-( m-sulfo-triphenylphosphine)-rhodium which was immobilized on activated carbon treated at high temperature. As starting materials 1-hexene, 1-decene, 1-tetradecene, 2-hexene and 2,3-dimethyl-2-butene were used. For all linear α-olefins the same n/ iso ratio in the product of 2:1 was determined. The reaction rate decreased with increasing chain length and sterical hindrance of the alkene double bond. All hydroformylation experiments were performed in a stirred semi-batch reactor. Catalyst leaching turned out to be a function of solvent polarity. Using n-heptane as solvent the immobilized catalyst remained stable on the carrier. The activity of the immobilized catalyst decreased compared to the homogeneous catalyst system. Water content was identified to be one of the most significant parameters of the reaction rate. The simulation of experimental data was modelled by a semi-empirical rate law. Within the simulation the reaction scheme consisting of hydroformylation, isomerization and aldol reaction was simultaneously calculated. It was possible to determine the reaction orders of all components, rate constants and the activation energies of all reactions.

Two or More CH Bond(s) Formed by Addition to CC Multiple Bonds

AbstractFor Abstract see ChemInform Abstract in Full Text.

Sustainable vanadium(V)-catalyzed oxybromination of styrene: Two-phase system versus ionic liquids

Abstract Oxybromination reaction of styrene was performed in a two-phase system of water/ionic liquids (ILs). The aim of the work was to make the mild and efficient two-phase system previously developed for the vanadium(V)-catalyzed oxybromination of alkenes, inspired by the activity of haloperoxidase enzymes, even more interesting from a sustainable point of view. As in that case, a brominating intermediate was formed from the metal catalyst, H2O2, and bromide ion in the acid aqueous phase, but chlorinated solvents were replaced with ILs. [bmim+][PF6 -], [bm2im+][PF6 -], [bmim+][BF4 -], [bmim+][CF3SO3 -], and [bmim+][(CF3SO2)2N-] were tested. We report on interesting results in terms of reaction rates and selectivities.

Selective hydrogenation of cinnamaldehyde in biphasic system catalysed by chlorotris ( M-trisulphonato triphenylphosphine) rhodium (I) complex, [formula omitted

The selective hydrogenation of cinnamaldehyde by a RhCl ( TPPTS ) 3 aqueous solution, ex situ synthesised from RhCl 3 · nH 2 O and TPPTS (tris( M-sulphonatophenyl)phosphine) with pH control by NaOH solution, was investigated under a biphasic (water/toluene) system in a batch reactor. The hydrogenation more usually occurred at C C bonds, giving hydrocinnamaldehyde as the main product. Important parameters were varied carefully in order to maximise the selectivity toward hydrocinnamaldehyde for which the highest selectivity of 99.9% was achieved. Both the kinetic and mass transfer aspects were also evaluated and the results implied that the biphasic system was under mass transfer control. In addition, supported aqueous phase (SAP) catalysts of the RhCl ( TPPTS ) 3 solution supported on fine silica were prepared and tested for the selective hydrogenation of cinnamaldehyde under similar conditions for comparison and they gave a very high selectivity to hydrocinnamaldehyde which was an advantage, although their activity was lower than the biphasic catalysts. The mass transfer characteristic in SAP catalysis was also evaluated using a first-order film model.

Mass-Transfer Effects in the Biphasic Hydroformylation of Propylene

The hydroformylation of propylene to butyraldehyde is an important industrial process. In this reaction system, carbon monoxide, hydrogen, and propylene are converted to n-butyraldehyde in an aqueous phase containing a water-soluble rhodium catalyst. This reaction system consists therefore of three different phases: the aqueous catalyst phase, the organic butyraldehyde phase, and the gas phase. A modeling study indicated that an optimum value of the production rate is reached at a certain power input. It was shown that mass transfer plays an important role in this reaction system and that accurate knowledge of the mass-transfer parameters in the gas-liquid-liquid system is necessary to predict and to optimize the production rate. Mass-transfer experiments with CO, H 2 , and propylene in water and in solutions consisting of water with different amounts of n-butyraldehyde were carried out in a stirred autoclave. The results indicated that the addition of small amounts of butyraldehyde caused a relatively small increase increase in k L a, which was probably caused by a larger increase of the gas-liquid interfacial area, a, accompanied by a decrease in the mass-transfer coefficient, k L . Near the point of maximum solubility of butyraldehyde, a strong (factor of 3) increase in k L a was observed. The most logical explanation for this is an increase in k L , because measurement of the interfacial area did not show such an increase. This increase in k L , i.e., the disappearance of the initial decrease, might be due to the disappearance of the rigid layer of butyraldehyde molecules at the gas-liquid interface by formation and spreading of a butyraldehyde layer around the bubble.

EFFECTS OF CATALYST AND CORE MATERIALS ON THE MORPHOLOGY AND PARTICLE SIZE OF MICROCAPSULES

In this article, an interfacial polymerization method was employed for micro encapsulation. The wall material was polyurea and the core materials were diethyl (o-) phthalate, dibutyl (o-) phthalate and dioctyl (o-) phthalate. Poly (vinyl alcohol) (PVA) was used as protective colloid and GPE2040 was used as emulsifier. The effects of catalyst in different phases and core materials with different hydrophobicities on the morphology and particle size were studied. It was found that the surface of microcapsules form catalyst in aqueous phase were smoother and the average size was smaller than that with the catalyst in the organic phase and higher hydrophobicity gave smoother morphology.

Supported aqueous phase catalysis: a new kinetic model of hydroformylation of octene in a gas–liquid–liquid–solid system

The kinetics of the [Rh 2(μ-S t Bu) 2(CO) 2(TPPTS) 2] catalyzed hydroformylation of 1-octene by supported aqueous phase catalysis has been investigated under mild conditions (0.5–1 MPa, 353–373 K). The effect of 1-octene and catalyst concentration and partial pressure of hydrogen and carbon monoxide on the rate of reaction has been studied. The rate was found to be first-order with respect to catalyst concentration and partial order with respect to partial pressure of hydrogen. However, when partial pressure of carbon monoxide and 1-octene concentration increased, the rate showed a typical case of substrate-inhibited kinetics. A rate equation has been proposed, considering that each particle of supported aqueous phase catalyst is a microreactor, where the reaction takes place at the aqueous/organic interface. The kinetic model showed the good agreement with the experimental data, being the average relative error of estimation less than 7%. The kinetic parameters have been evaluated for different temperatures. The activation energy was found to be 71 kJ/mol.

Hydroformylation of linalool in a supported aqueous phase catalyst by immobilized rhodium complex: kinetic study

In this paper, we report on the kinetics of linalool hydroformylation using supported aqueous phase catalysis (SAPC). Hydroformylation of linalool by SAPC has been carried out in the presence of toluene as the solvent and using [Rh 2(μ-S t Bu) 2(CO) 2(TPPTS) 2]=[D2] as the catalyst supported on the silica DS50. The effects of temperature, pressure and concentrations of catalyst, water and linalool on the monoterpene conversion have been investigated. The rate was found to be first order with respect to catalyst and olefin concentrations and hydrogen and carbon monoxide pressure. A kinetic model was fitted to the observed data, and it was found to predict the rates with a good agreement. The activation energy was found to be as low as 14.5 kcal mol −1.

Supported rhodium and supported aqueous-phase catalyst, and supported rhodium catalyst modified with water-soluble TPPTS ligands

Two types of novel catalysts: supported rhodium and supported aqueous-phase (SAP/Rh-SiO 2), and supported rhodium modified with water-soluble TPPTS ligands (TPPTS-Rh/SiO 2), were prepared. Hydroformylation of 1-hexene showed that SAP/Rh-SiO 2 and TPPTS-Rh/SiO 2 catalyst processed high activity for aldehydes and especially high selectivity towards aldehydes and high n/ i- ratio of aldehydes. These results were significantly different from the performances of Rh/SiO 2 catalyst, but very comparable to those of SAP catalyst. 31 P NMR spectrum of TPPTS-Rh/SiO 2 catalyst demonstrated that TPPTS ligands chemically bonded to highly dispersed rhodium metal particles. It make clear the reason that yield of aldehydes of SAP/Rh-SiO 2 was nearly the sum of the yield of SAP catalyst and the yield of TPPTS-Rh/SiO 2 catalyst, while all of catalytic selectivities were equal, because SAP/Rh-SiO 2 was actually made up of SAP and TPPTS-Rh/SiO 2 catalysts. The catalytic performance of TPPTS-Rh/SiO 2 catalyst strongly depended on the molar ratio of P:Rh, which was similar to that of SAP catalyst to a certain extent.

Palladium-catalyzed telomerization of butadiene with ethylene glycol in liquid single phase and biphasic systems: control of selectivity and catalyst recycling

Abstract The palladium-catalyzed telomerization of 1,3-butadiene (Bu) with ethylene gylcol (EG) has been studied in liquid single phase and aqueous biphasic systems. All important parameters have been examined, including temperature, catalyst system, catalyst concentration, Bu/EG ratio, P/Pd ratio, solvent and reaction time. In homogeneous phase mixtures of 2-(2,7-octadienyloxy)ethanol ( 1a ) and 2-(1-ethenyl-5-hexenyloxy)ethanol ( 1b ) were formed in yields up to 60%, but also ditelomers ( 2 ) and butadiene dimers ( 3 ) were produced in significant amounts. In aqueous biphasic systems, however, using a palladium catalyst with the triphenylphosphinetrisulfonate (TPPTS) ligand, the monotelomers 1a and 1b were obtained in 80% yield with more than 95% selectivity. A mechanism is proposed explaining the observed differences in selectivity. The aqueous catalyst phase could be recycled six times resulting only in a slight decrease of activity. The products 1a and 1b were hydrogenated in quantitative yield to the corresponding saturated compounds 2-octyloxyethanol ( 6a ) and 2-(1-ethyl-hexyloxy)ethanol ( 6b ) using a Pd/Al 2 O 3 catalyst under mild conditions. The products can be used for a variety of applications like plasticizers, cosmetics and solvents.

Polysaccharides: Natural Polymeric Supports for Aqueous Phase Catalysts in Allylic Substitution Reactions.

ChemInformVolume 33, Issue 44 p. 206-206 Natural Products Polysaccharides: Natural Polymeric Supports for Aqueous Phase Catalysts in Allylic Substitution Reactions. Paulette Buisson, Paulette Buisson Lab. Materriaux Catal. Catal. Chim. Org., CNRS, ENSCM, F-34053 Montpellier, Fr.Search for more papers by this authorFrancoise Quignard, Francoise Quignard Lab. Materriaux Catal. Catal. Chim. Org., CNRS, ENSCM, F-34053 Montpellier, Fr.Search for more papers by this author Paulette Buisson, Paulette Buisson Lab. Materriaux Catal. Catal. Chim. Org., CNRS, ENSCM, F-34053 Montpellier, Fr.Search for more papers by this authorFrancoise Quignard, Francoise Quignard Lab. Materriaux Catal. Catal. Chim. Org., CNRS, ENSCM, F-34053 Montpellier, Fr.Search for more papers by this author First published: 19 May 2010 https://doi.org/10.1002/chin.200244206AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume33, Issue44November 5, 2002Pages 206-206 RelatedInformation

Aqueous phosphine–Rh complexes supported on non-porous fumed-silica nanoparticles for higher olefin hydroformylation

Non-porous fumed-silica nanoparticles were used as supports for the first time to immobilize water-soluble complex HRh(CO)(P( m-C 6H 4SO 3Na) 3 ( 1) [P( m-C 6H 4SO 3Na) 3, i.e. trisodium salt of tri-( m-sulfophenyl)-phosphine, TPPTS] to obtain supported aqueous-phase catalysts (SAPC) (fumed-SiO 2-SAPC) for hydroformylation of 1-hexene. The experimental results proved that the structure of support and the support hydration were the determining factors contributing to the hydroformylation performance. The fumed-SiO 2-SAPC where the water-soluble rhodium complexes were well dispersed onto the external surface of the silica nanoparticles presented a higher hydroformylation performance over a relatively wider range of support hydration as compared to the SAPC with conventional porous granular-SiO 2 support (porous SiO 2-SAPC). A positive effect on the reaction performance was observed from the particle size and surface area of the fumed-silica nanoparticles. The hydroformylation performance with fumed-SiO 2-SAPC was promoted by an addition of basic alkali metal salts such as Na 2CO 3, K 2CO 3, and NaH 2PO 4, which depressed the oxidation of ligand TPPTS to OTPPTS [OTPPTS, i.e. trisodium salt of tri-( m-sulfophenyl)-phosphine oxide, OP( m-C 6H 4SO 3Na) 3] as evidenced by 31 P NMR observation.

Toward a better understanding of the stability of supported platinum catalysts in aqueous phase under hydrogen atmosphere at room temperature

Various Pt/alumina and Pt/silica catalysts were in situ reduced and treated at room temperature under nitrogen or hydrogen in aqueous media of various pH (pH 0.7, HCl; pH 6, water; pH 10, NH 4OH). Then, the catalysts were filtered, dried and activated by a direct reduction under hydrogen at 500 °C. The dispersions of the different samples were determined from transmission electron microscopy (TEM) and/or chemisorption measurements. On the in situ reduced Pt/silica samples, a sintering of platinum is observed under hydrogen bubbling, whatever the pH of the solution and the initial platinum particle size of the catalyst. On the Pt/alumina catalysts, the sintering is less marked and depends on the initial dispersion of the catalyst and on its particle size distribution. Thus, even a redispersion was observed in the case of the Pt/alumina catalysts of low initial dispersion treated in HCl medium (pH 0.7).