Chromatographic adsorption apparatus

Chromatographic Adsorption Apparatus Electrical Connections of Le Boulenge Chronograph Schematic Diagram of Aberdeen Chronograph Camera Chronograph... 

The in sim characterization of catalysts was earned out in an apparatus which included a quadiupole mass-spectrometer and a gas chromatograph for TPO and H2 chemisorption measurements. In situ coking was performed by injecting a mixture of He and n-hexane vapor over the reduced catalysts at 500 C, In TPO experiments, ihe coked sample was heated at a rate of 8 C/min in a stream of 2 voL% O2 + 98% He. The amount of CO2 produced was recorded. The chemisorption of H2 was carried out in the same appanitus by a flow method after reduction or caking. The flow rate of carrier gas (Ar) was maintained at 25 ml/min and the volume of H2 injected was 0.062 ml/pulse. Since the partial piessiire of H2 was very low in this system, the hydrogenation of coke was never observed. Isobaric H2 chemisorption measurements with fresh catalysts were carried out in a static adsorption apparatus. Dehydrogenation of n-butane was carried out in a flow micro-rcactor in H2 atmosphere at LHSV = 3 h-l and H2/HC=1. Reaction products were... 

Multifunctional reactors. Apart from the applications exclusively in the reaction engineering field, fixed beds can also be found integrated in apparatus with separation purposes. Two major classes can be identified membrane [16, 17] and chromatographic (adsorptive) reactors [18]. In both cases, a familiar configuration involves a packed bed with a permeable, selective wall and/or packed with a catalyst/ adsorbent. The latter is found in simulated moving bed reactors [19, 20], which can be seen as an arrangement of several of these beds. The overall effect from the coexistence of reaction and separation functionalities is the increase of conversion in equilibrium-limited systems, which are shifted due to the simultaneous separation of the products. 

Experiments Sorption equihbria are measured using apparatuses and methods classified as volumetric, gravimetric, flow-through (frontal analysis), and chromatographic. Apparatuses are discussed by Yang (gen. refs.). Heats of adsorption can be determined from isotherms measured at different temperatures or measured independently by calorimetric methods. 

Extraction apparatus or headspace adsorption device Gas chromatograph with MS detector (El mode and optional Cl mode Hewlett-Packard)... 

There is a fundamental relationship described in chromatographic theory between the retention volume of a elution peak and the mid-point of a breakthrough curve achieved by operating the column under frontal analysis conditions (41 ). In the Henry s Law region of the adsorption isotherm, the net retention volume and its measurement can be used to describe the variation of sorbate breakthrough volume as illustrated in Figure 8. Utilizing the experimental apparatus described in the last section, retention volumes were measured as a function of pressure at 40°C (T =... 

Compared with chromatographic methods, this countercurrent distribution method is probably less efficient, the apparatus required is very much more complicated, and the labor involved is considerably greater nevertheless, it possesses several definite advantages over chromatographic methods. The chief of these is the absence of any solid phase, which may act as an adsorbent for the solutes. In partition chromatographic methods this adsorption may often lead to distortion of the bands and render fractionation very inefficient. The behavior of a solute on a countercurrent distribution depends only on its partition coefficient, which in most cases is constant, so that it is possible to calculate the exact theoretical distribution curve and this may be used as a very sensitive test for purity. 

The use of paper as a chromatographic medium is usually regarded as a typical partition system, where the stationary phase is water, held by adsorption on cellulose molecules, which in turn are kept in a fixed position by the fibrous structure of the paper. It is now realised, however, that adsorption of components of the mobile phase and of solutes, and ion exchange effects, also play a part, and that the role of the paper is by no means merely that of an inert support. The technique devised by Consden et al. has not undergone any fundamental changes, but there has been considerable improvement in detail, resulting partly from the wide variety of commercial apparatus which is available. Elaborate or expensive equipment is not essential, however, and good results can be obtained with quite simple apparatus and materials. 

The eluant systems used in adsorption chromatography are based on nonpolar solvents, commonly hexane, containing a small amount of a polar additive, such as 2-propanol. When the sample is applied, solute molecules with polar functionality will bond to the active sites on the packing they will subsequently be displaced by the polar modifier molecules of the eluant as the chromatogram is developed, and will pass down the column to be re-adsorbed on fresh sites. The ease of displacement of solute molecules will depend on their relative polarities. More polar molecules will be adsorbed more strongly, and hence will elute more slowly from the column. A system as described in Figure 4.1 may be used. It was the type of apparatus first used for chromatographic separations of the kind familiar today. 

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