Supported Liquid Phase Research Articles

Supported Liquid Phase Catalyst coating in micro flow Mizoroki–Heck reaction

A Supported Liquid Phase Catalyst (SLPC) coating was successfully applied for the Mizoroki–Heck reaction in micro flow. Foremost, extended on stream operation was enabled and the on stream performance stability was verified. Stable catalytic activity was achieved during two consecutive runs totaling 50h, after an initial stabilization period. Further support for the catalytic stability was provided by the fact that no leached Pd was detected in the product. Highest obtained conversion was 94% at 230°C and a 26min residence time. When conversion was plotted versus residence time, the reaction was shown to fit the predictions of the kinetic model. To optimize the performance of the flow system, reaction conditions and different ligands for the catalyst were initially investigated in batch, as well as various different substrates. Ethylene glycol was found to be most effective as the solvent film, while the use of water led to degradation of the silica support.

Extraction of pyridine derivatives from human urine using electromembrane extraction coupled to dispersive liquid–liquid microextraction followed by gas chromatography determination

In the present work, some of pyridine derivatives were analyzed for the first time in complicated biological fluids by coupling electromembrane extraction with dispersive liquid–liquid microextraction (EME–DLLME). 3-Methylpyridine, 2,4-lutidine, quinoline and 4-dimethylaminopyridine (DMAP) were extracted from urine and water samples. Effective parameters on the efficiencies of EME and DLLME were optimized by one variable at a time method and face-centered central composite design (FCCCD), respectively. The supported liquid phase (SLM) employed for the extraction of the analytes was a mixture of 90% 2-nitrophenyl octyl ether (NPOE) and 10% di-(2-ethylhexyl) phosphate (DEHP) which was immobilized in the pores of a piece of hollow fiber. An electric field was applied to carry over the analytes into acceptor solution. The acceptor solution was transferred to 1mL of an alkaline solution (pH=13) and then DLLME procedure was performed. Preconcentration factors in the range of 40–263 and satisfactory repeatabilities (2.3<RSD%<5.3) were obtained in different matrices. The method offered a good linearity with coefficient of determination greater than 0.9948 and was utilized for determination and quantification of pyridine compounds in smokers׳ urine samples. The proposed technique can be introduced as a simple, fast and inexpensive method for diagnosis of smokers.

ChemInform Abstract: Immobilized Functional Ionic Liquids: Efficient, Green, and Reusable Catalysts

AbstractReview: 205 refs.

ChemInform Abstract: Transition Metal Complexes in Supported Liquid Phase and Supercritical Fluids — A Beneficial Combination for Selective Continuous‐flow Catalysis with Integrated Product Separation

AbstractReview: 158 refs.

Supported Liquid Phase Catalysis as a Novel Concept for Oxidative Dehydrogenation of Ethane

Supported Liquid Phase Catalysis as a Novel Concept for Oxidative Dehydrogenation of Ethane

Immobilized functional ionic liquids: efficient, green, and reusable catalysts

Ionic liquids (ILs) which are made up of cationic and anionic components can be designed to possess a definite set of properties. In this context, the term “designer solvents” has been used to demonstrate the potential of these environment-friendly ionic liquids in chemical reactions. Since these liquids are able to dissolve several transition metal complexes, they have often been employed in recent times in several catalytic reactions to enhance reaction rates and selectivities. The concept of “immobilized” liquids has been derived from supported liquid phase catalysts; the immobilization process transferring the desired catalytic properties of the liquids to solid catalysts could combine the advantages of ILs with those of heterogeneous support materials and various catalytically functional groups or active species. The immobilized functional ionic liquids (IFILs) capable to restrict many of the negative effects of the conventional ILs have successfully been used in various potent catalytic areas affording high catalytic activity. In this review, structural characteristics, properties and preparation of immobilized functional ionic liquids have been described and the results are compared with those of traditional ILs. Special emphasis has been paid to comprehend the mechanism of various catalytic processes using immobilized ionic liquids functionalized by different groups.

Occurrence of selective serotonin reuptake inhibitors in sewage and receiving waters at Spitsbergen and in Norway

A method for the determination of five selective serotonin reuptake inhibitors (citalopram, sertraline, fluoxetine, fluvoxamine and paroxetine) and four of their metabolites (desmethylcitalopram, didesmethylcitalopram, norfluoxetine and desmethylsertraline) in seawater and sewage influents and effluents, has been developed and validated. The method is based on a three-phase hollow-fibre supported liquid phase microextraction of 1.1 L samples, followed by high performance liquid chromatography with electrospray ionization and mass spectrometric detection. The detection limits varied between 17 pg/L (citalopram) and 618 ng/L (desmethylsertraline), and the quantification limits between 57 pg/L (citalopram) and 4.1 ng/L (desmethylsertraline). Sampling was done from February to August in 2007 on three different locations with dissimilarities concerning waste water treatment procedures. No significant difference in SSRI cleansing efficiency between merely sieving (Langnes STP, Tromsø) and a more advanced sewage treatment (VEAS STP, Oslo) was seen. All the investigated compounds are present in all waste water samples from these STPs, and a total concentration of SSRIs and metabolites up to 840 ng/L has been found. Untreated sewage samples have been collected in the small town Longyearbyen at Spitsbergen. Despite few inhabitants (2000), it was still possible to find traces of SSRIs in the waste water. In Tromsø and Longyearbyen the waste water is discharged into the sea, therefore seawater samples have been collected close to the outlets. The results show higher concentrations of SSRIs outside Longyearbyen than Tromsø, possibly due to the stronger tidal currents around Tromsø. However, the concentrations are quite low, not exceeding total concentrations of 3 ng/L.

Developments and Applications of Supported Liquid‐Phase Catalysts

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Synthesis of cyclic carbonates from carbon dioxide and epoxides using alkali metal halide supported liquid phase catalyst

Supported liquid phase catalysts (SLPC) were prepared from high surface area porous silica, polyethylene glycol (PEG), alkali metal halides and used for the synthesis of cyclic carbonates from carbon dioxide and epoxides. These catalysts was found to be highly active and selective for the synthesis of cyclic carbonates. The catalytic activity strongly depends on the nature of the supported alkali metal halide. The amount of alkali metal salt incorporated in the catalyst is one of the most important factor governing the catalytic performance. Effect of various reaction parameters such as pressure, temperature, catalyst loading, surface area of support was also studied in detail.

A comparative study of supported aqueous- and ethylene glycol-phase catalysts in stilbene hydrogenation: Influence of the different modes of dispersion of supported liquids

Supported liquid phase catalysts (SLPC) containing water-soluble Pd complexes were used for hydrogenation of stilbene in toluene. When water is loaded on a silica gel support, the catalytic activity of SLPC increases with the amount of the water. In contrast, when ethylene glycol (EG) is used as the supported liquid, the activity does not depend on the amount of EG loaded. These results can be explained by differences in the mode of dispersion of the supported liquids over the support.

Developments and Applications of Supported Liquid Phase Catalysts

Supported liquid phase catalyst (SLPC) is one of effectively heterogenized homogeneous catalysts using organometallic complexes as active components, which are dissolved in a small quantity of liquid phase dispersed in the form of isle or film on the surface of supports. The SLPC has successfully been applied for several chemical transformations and this article will review recent results with respect to the preparation and catalytic performance, the applicability to continuous flow operations, and the capability of multifunctional catalysis. Keywords: One-pot hydrogenation, cinnamaldehyde, Heck reaction, Hydroformylation, toluene

Supported Fluorous Phase Catalysis on PTFE, Fluoroalkylated Micro‐ and Meso‐porous Silica

AbstractNew perfluoroalkylated micro‐ and mesoporous silica, along with powdered Teflon, have been evaluated as solid supports for supported fluorous phase catalysis in a model reaction; the hydrogenation of styrene using a fluorous analogue of Wilkinson’s catalyst. Each support material showed catalytic activity and catalyst‐leaching behaviour related to its surface area and was consistent with supported liquid phase catalysis. However, catalyst decomposition on the silica supports resulted in substantial reductions in activity on catalyst recycle. In contrast, although activity and leaching levels on PTFE were poorer, the supported catalyst was recycled successfully.

Cyclohexene Reactivity over Palladium Acetate Supported in Liquid Phase

The competitive reactions of cyclohexene: disproportionation and dehydrogenation were studied over a supported-liquid phase catalyst (SLPC) of palladium acetate solved in a stationary phase employing two different techniques: pulsed and flow micro-reactor, where the products of reaction are analysed by gas chromatography. The effect of the liquid phase (comparing an aliphatic phase, squalane, with a polar phase, Triton), the reaction environment (comparing He, N2 and air) and the process conditions (temperature and reactant concentration) have been studied. Although continuous deactivation was observed in all the cases, the catalyst supported on the apolar phase presents better performance, whereas the disproportionation reaction only takes place at no oxidant conditions and the operation conditions only affect to the selectivity of the reaction. A kinetic model for the reaction, taking into account the catalyst deactivation has been proposed, and kinetic and deactivation constant were calculated by fitting the model to the experimental data. Arrhenius parameters were obtained from measured data at several temperatures.

Heck reaction with a silica-supported Pd-TPPTS liquid phase catalyst: effects of reaction conditions and various amines on the reaction rate

Supported liquid phase catalysts (SLPC) were prepared using a porous silica, ethylene glycol (EG), and triphenylphosphine trisulfonate sodium salt (TPPTS) and used for the Heck reaction of iodobenzene (PhI) and butyl acrylate (BA) in the presence of amine. The reaction rate depends on the concentration of Pd-TPPTS complex in the supported EG phase, not on the total quantity of Pd-TPPTS. The rate increases linearly with the PhI concentration. The reaction rate also increases linearly with the concentrations of BA and triethylamine (Et 3N) when these are low. However, a plateau and a maximum of the rate are seen with further increasing the concentrations of BA and Et 3N, respectively. As a result of the complex of these modes of the dependence, the reaction rate increases with the total concentration of PhI, BA and Et 3N in an order of two. The dependence of the reaction rate on those concentrations with a palladium-triphenylphosphine (Pd-TPP) homogeneous catalyst is quite similar to that with SLPC. The reaction rate depends also on the type of the amine used. Tributylamine (Bu 3N) gives faster reaction rates than Et 3N with both SLPC and Pd-TPP. However, such an effect of trihexylamine (Hex 3N) is seen only with Pd-TPP. In the SLPC system, Hex 3N gives almost the same rate as that with Et 3N. Promotive effect of recycle use of the SLPC sample is also affected by the type of the amine.

A porous carbon membrane reactor for the homogeneous catalytic hydration of propene

A porous carbon membrane contactor was studied to determine whether such a reactor could be used for homogeneous catalytic reactions. The hydration of propene, catalysed by an aqueous solution of phosphoric acid, was selected as a suitable model reaction. Experiments at high pressure and temperature were conducted in a laboratory-scale gas phase continuous reactor equipped with a flat carbon membrane contactor. It was shown that reasonably stable operation of the reactor could be achieved at high operating pressures by tailoring the porous structure of the carbon membrane and coupling the reactor with an on-line feedback pressure controller. The reactor operated in a mass transfer limited regime due to mass transfer resistance in the liquid filled membrane pores. Periodic oscillation of transmembrane pressure was shown to reduce mass transfer resistance and considerably improve the overall reactor performance. A dynamic model of the reactor was developed and the results of simulations compared favourably with experiments and the performance of a commercially operated conventional reactor employing a supported liquid phase (SLP) catalyst.

In situ XAFS Characterization of Supported Homogeneous Catalysts

Heterogenization of homogeneous catalysts explores the cross-fertilization of homogeneous and heterogeneous catalysts to combine most of their advantages. The molecular dispersion of active sites in these materials limits the application of conventional spectroscopic techniques utilized for the characterization of heterogeneous catalysts. The X-ray absorption spectroscopy is the most suitable tool to characterize the molecular species present in these catalysts because this technique is sensitive to short-range structural orders, element-specific and amenable to in situ studies. X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) studies for selective examples of supported homogeneous catalysts are reviewed. Supported liquid phase catalysts (supported Wacker-type catalysts for CO oxidation), intercalated homogeneous catalysts, supported metal complexes for the olefin polymerization and tethered homogeneous catalysts are included.

Palladium-based supported liquid phase catalysts: influence of preparation variables on the activity and enhancement of the activity on recycling in the Heck reaction

Supported liquid phase catalysts (SLPC) were prepared using a porous silica, ethylene glycol, palladium acetate, and triphenylphosphine trisulfonate sodium salt (TPPTS). The SLPC samples prepared were used for Heck reaction of iodobenzene and butyl acrylate with triethylamine base in toluene and the influence of catalyst preparation conditions was examined. The rate of reaction depends on the concentration of palladium–TPPTS complexes in the dispersed phase of ethylene glycol but not on the quantity of the dispersed liquid used. The SLPC sample can be easily separated by simple filtration and it is recyclable; interestingly, the rate of reaction is promoted on the repeated runs, due to the formation and accumulation of Et 3NHI adduct in the dispersed phase.

Lattice Monte Carlo simulations of the activity of supported liquid-phase catalysts: Part I. Uniform liquid distributions

We introduce a new model aimed at the analysis of the activity of supported liquid phase catalysts. The model is based on the statistical Monte Carlo approach and takes into account the properties of the support pore system, the properties of the filling liquid and the characteristics of liquid distribution. The predictions of the model are compared with a large body of experimental data and demonstrate good agreement with them.

Influence of the carrier on the catalytic performance of impregnated phosphoric acid in the hydration of ethylene

The hydration of ethylene was studied at 300°C and 50 bar using phosphoric acid impregnated silica, titania, mixed silica/titania, zinc oxide/titania, tin oxide/titania, zirconia and niobic acid carriers. The time on stream of “solid phosphoric acid” i.e. phosphoric acid on silica is limited because of the crystallization of the silica carrier to β-crystobalite. The addition of titania to the carrier of the well-known “solid phosphoric acid” catalyst results in a decrease of the catalytic activity in the hydration. The phosphoric acid is strongly bound to the surface of this carrier. The activity of the “solid phosphoric acid” is related to the presence of the liquid form of the deposited phosphoric acid (SLP=supported liquid phase catalyst). The determination of the amount of free phosphoric acid gives an indication of the state of phosphoric acid on different carrier materials. This amount was determined by measuring the acid which could be leached out by submerging the catalyst in water. The activity of carrier materials impregnated with phosphoric acid could not be correlated to the concentration of acid sites at strengths of −8.2< H 0≤−3.0.

ChemInform Abstract: Supported Liquid Phase Catalysis in Selective Oxidation

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.