Diffusion, adsorption and catalytic studies by gas chromatography

Katsanos, Nicholas A.; Thede, Richard; Roubani‐Kalantzopoulou, F.

doi:10.1016/s0021-9673(97)00968-0

Cited by 106 publications

(99 citation statements)

References 145 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…This concept makes it possible to control the selectivity and contact time of the analytes with the catalyst. Whereas reactions during chromatographic separations were often considered to be serendipitous [16][17][18] or interfering side effects, appearing as overlapping peak profiles with plateau formations, [19,20] we have used this information to investigate the reaction kinetics of a broad variety of substrates.To put this strategy into practice we focused on hydrogenations over Pd nanoparticles embedded in an inert polydimethylsiloxane matrix without any interfering protecting shell (for example, tetraalkylammonium salts as surfactants).[21] We prepared a methylvinylsiloxane-dimethylsiloxane copolymer (4.5 % Si(O)(CH 3 )(CH=CH 2 ) groups) to coordinate Pd ions to the vinyl groups. Hydridomethylsiloxane-dimethylsiloxane copolymer (25.7 % Si(O)(CH 3 )H groups) was added to this mixture to reduce Pd 2+ to Pd 0 and to crosslink with the other copolymer in a Pd-catalyzed hydrosilylation reaction to form a stabilizing matrix (Figure 1).…”

mentioning

confidence: 99%

High‐Throughput Screening of Catalysts by Combining Reaction and Analysis

et al. 2007

View full text Add to dashboard Cite

Dedicated to Süd-Chemie on the occasion of its 150th anniversaryDiscovering new catalysts is crucial to the development of sustainable chemical processes for industrial applications as well as for broadening the spectrum of synthetic methodologies and techniques in chemistry. The prerequisite for the directed design of catalysts is understanding how the kinetics, in other words, the activation barrier, in the mechanism of catalysis is controlled by the structural parameters.[1] To identify rate-determining elementary steps and to develop models, comprehensive experimental kinetic data of a broad variety of substrates are necessary. Microfluidic devices integrating chemical synthesis and analysis on the same chip [2][3][4][5] are one promising approach for parallelized highthroughput (ht) kinetic measurements of catalysts with minute material consumption.[6] A unique technique for studying configurational changes in chiral compounds is dynamic chromatography [7] combining molecular interconversion and analysis under precisely controlled conditions. Recently, we reported [8] a unified equation to directly access reaction rate constants of first-order reactions of such experiments. However, commonly used (micro)reactors, in which the reaction, separation, and quantification of conversion are performed consecutively, are limited to the study of single reactions, because competing reactions lead to undefinable reaction kinetics. Here we show for the hydrogenation over highly active Pd nanoparticles and the ring-closing metathesis over the Grubbs second generation catalyst that the synchronous combination of catalysis and separation makes it possible to efficiently perform ht reaction rate measurements (147 reactions per hour) of substrate libraries. The catalytic systems for these multiphase reactions (gas-liquid-solid) were prepared by embedding the catalysts in polysiloxanes, which serve as both solvent and selective stationary separation phase. Furthermore this system can be used for cascade reactions or for preparative synthesis to produce the target compounds.Typically, multiphase catalytic systems, which play a predominant role in industrial processes, are difficult to investigate because the interaction of the substrate with the catalyst is controlled by the mass transfer between the different phases, and therefore the apparent reaction rate is composed of the inherent reaction rate and diffusion rates. To reduce this effect, the interfacial area must be increased. Microstructured reaction systems intrinsically have a high specific interfacial area per volume, only dependent on the radius of the reaction channels; that is, for capillaries with inner diameters between 250 and 100 mm the specific interfacial area per volume ranges from 16 000 to 40 000 m 2 m À3 . Microfluidic systems are currently revolutionizing chemical synthesis, [9][10][11][12][13] because physical processes can be more easily controlled, low operation volumes minimize reagent consumption, and detection is integrated.[14] However, there are s...

show abstract

mentioning

confidence: 99%

High‐Throughput Screening of Catalysts by Combining Reaction and Analysis

et al. 2007

View full text Add to dashboard Cite

show abstract

“…The RF-GC method, by which the present experimental results were obtained, has been described several times in the literature, particularly in two recent reviews (12,15). The apparatus and procedure closer to that of the present work are given in Ref.…”

Section: Methodsmentioning

confidence: 90%

Interrelations between Adsorption Energies and Local Isotherms, Local Monolayer Capacities, and Energy Distribution Functions, as Determined for Heterogeneous Surfaces by Inverse Gas Chromatography

Katsanos

Iliopoulou

Plagianakos

et al. 2001

Journal of Colloid and Interface Science

Self Cite

View full text Add to dashboard Cite

“…The data were corrected for gas-phase diffusion using the van Deemter equation as demonstrated by Katsanos et al (1998). The Henry's law coefficient was calculated via the net retention volume V N : …”

Section: Experimental Set-upmentioning

confidence: 99%

Combination of a Dielectric Continuum Model with Inverse Gas Chromatography for the Characterization of Solid Surfaces

Mehler

Thielmann

2002

Adsorption Science & Technology

View full text Add to dashboard Cite

ABSTRACT:The use of a dielectric continuum model for the characterization of solid surfaces was combined for the first time with inverse gas chromatography. Extension of dielectric continuum models to adsorption from the gaseous phase allowed the distributed surface properties of solid surfaces to be determined. An inverse gas chromatograph was used for the measurement of adsorption equilibria as a quick alternative to time-consuming measurements by gravimetric or volumetric set-ups. Combination of the two techniques allowed the rapid determination of the distributed properties of solid surfaces to be effected and the results were interpreted in a fundamental physical sense. This led to a novel and promising way for the rapid and exact characterization of solid surfaces.

show abstract

Diffusion, adsorption and catalytic studies by gas chromatography

Cited by 106 publications

References 145 publications

High‐Throughput Screening of Catalysts by Combining Reaction and Analysis

High‐Throughput Screening of Catalysts by Combining Reaction and Analysis

Interrelations between Adsorption Energies and Local Isotherms, Local Monolayer Capacities, and Energy Distribution Functions, as Determined for Heterogeneous Surfaces by Inverse Gas Chromatography

Combination of a Dielectric Continuum Model with Inverse Gas Chromatography for the Characterization of Solid Surfaces

Contact Info

Product

Resources

About