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Silica solid phase profile

In the design of upflow, three phase bubble column reactors, it is important that the catalyst remains well distributed throughout the bed, or reactor space time yields will suffer. The solid concentration profiles of 2.5, 50 and 100 ym silica and iron oxide particles in water and organic solutions were measured in a 12.7 cm ID bubble column to determine what conditions gave satisfactory solids suspension. These results were compared against the theoretical mean solid settling velocity and the sedimentation diffusion models. Discrepancies between the data and models are discussed. The implications for the design of the reactors for the slurry phase Fischer-Tropsch synthesis are reviewed. [Pg.108]

Kaolinite is an important constituent of many lateritic profiles, and a common product of hydrolysis it tends to be abundant where there is free-drainage. The reaction progressively separates silica in aqueous solution from aluminium, which remains in the solid phase (as kaolinite or gibbsite). [Pg.62]

Figure 10.16 Comparison of calculated (solid line) and experimental (symbols) band profiles. General conditions L = 25 cm dc = 4.6 mm Fi, = 1 mL/min (a,c,d) or 2 mL/min (b) N = 5000 plates, (a) Benzyl alcohol on silica. Mobile phase solution of THF in n-hexane (15 85). Sample sizes (mmol) 1, 0.0025 2, 0.00625 3, 0.0125 4,0.025 5, 0.060 6, 0.075. (b) Acetophenone on silica. Mobile phase mixture of ethyl acetate and -hexane (2.5 97.5). Sample sizes (mmol) 1, 0.025 2 0.05 3 0.075 4 0.1 5 0.125. (c) Benzyl alcohol on oc-tadecyl silica. Mobile phase, methanol/water (20 80) sample sizes (mmol) 1, 0.02 2,0.05 3, 0.10 4, 0.15. (d) Phenol on octadecyl chemically bonded silica. MobUe phase mixture of methanol and water (20 80). Sample sizes 1, 0.015 mmol 2 0.03 mmol 3 0.045 mmol 4 0.06 mmole 5 0.075 mmol. Reproduced with permission from S. Golshan-Shirazi and G. Guiochon, Anal. Chem., 60 (1988) 2634 (Figs. 7 to 10). 1988, American Chemical Society. Figure 10.16 Comparison of calculated (solid line) and experimental (symbols) band profiles. General conditions L = 25 cm dc = 4.6 mm Fi, = 1 mL/min (a,c,d) or 2 mL/min (b) N = 5000 plates, (a) Benzyl alcohol on silica. Mobile phase solution of THF in n-hexane (15 85). Sample sizes (mmol) 1, 0.0025 2, 0.00625 3, 0.0125 4,0.025 5, 0.060 6, 0.075. (b) Acetophenone on silica. Mobile phase mixture of ethyl acetate and -hexane (2.5 97.5). Sample sizes (mmol) 1, 0.025 2 0.05 3 0.075 4 0.1 5 0.125. (c) Benzyl alcohol on oc-tadecyl silica. Mobile phase, methanol/water (20 80) sample sizes (mmol) 1, 0.02 2,0.05 3, 0.10 4, 0.15. (d) Phenol on octadecyl chemically bonded silica. MobUe phase mixture of methanol and water (20 80). Sample sizes 1, 0.015 mmol 2 0.03 mmol 3 0.045 mmol 4 0.06 mmole 5 0.075 mmol. Reproduced with permission from S. Golshan-Shirazi and G. Guiochon, Anal. Chem., 60 (1988) 2634 (Figs. 7 to 10). 1988, American Chemical Society.
Figure 11.21 Comparison of experimental (symbols) and calculated (solid lines) individual elution profiles. 2-phenylethanol and 3-phenylpropanol. Calculations made with the forward-backward scheme, the coefficients of the competitive isotherm Langmuir model derived from the single-component isotherms, and a rectangular injection profile. Column 25 cm long, packed with 10 mm Vydac ODS silica. Mobile phase methanol-water, (50 50), 1 mL/min. (a) Sample size 7.6 mg of 2-phenylethanol and 21.1 mg of 3-phenyl-l-propanol. (b) Sample size 30.1 mg of 2-phenylethanol and 10.2 mg of 3-phenyl-l-propanol. Inset Band profiles calculated for a sample twice as large, using a competitive Langmuir isotherm model. Reproduced with permission from AM. Katti and G. Guiochon, J. Chromatogr., 499 (1990) 21 (Figs. 4, 6 and 7). Figure 11.21 Comparison of experimental (symbols) and calculated (solid lines) individual elution profiles. 2-phenylethanol and 3-phenylpropanol. Calculations made with the forward-backward scheme, the coefficients of the competitive isotherm Langmuir model derived from the single-component isotherms, and a rectangular injection profile. Column 25 cm long, packed with 10 mm Vydac ODS silica. Mobile phase methanol-water, (50 50), 1 mL/min. (a) Sample size 7.6 mg of 2-phenylethanol and 21.1 mg of 3-phenyl-l-propanol. (b) Sample size 30.1 mg of 2-phenylethanol and 10.2 mg of 3-phenyl-l-propanol. Inset Band profiles calculated for a sample twice as large, using a competitive Langmuir isotherm model. Reproduced with permission from AM. Katti and G. Guiochon, J. Chromatogr., 499 (1990) 21 (Figs. 4, 6 and 7).
Figure 8.3b shows that the initial polymerization rate (Rpo) is not linearly dependent on the monomer concentration (here, the initii polymerization rates were estimated by extrapolating the polymerization rate data to t = 0). The initial rate levels off for the initial monomer concentration larger than about 2.0mol/l, possibly because of a rapid buildup of polymer around the silica-supported catalyst particles. The initial polymerization rate profile can be fitted experimentally using the following Langmuir-type equation where it is assumed that the monomer sorption equilibrium is established between the solid phase and the liquid phase ... [Pg.144]

We compare in Figures 10.16a to 10.16d [70] the experimental band profiles in overloaded elution (symbols) and the profiles calculated for elution performed in normal and reversed phase chromatography (solid lines). Figure 10.16a corresponds to the elution of large bands of benzyl alcohol on silica with a THF/n-hexane solution. Figure 10.16b corresponds to the elution of acetophenone on silica with a (97.5 2.5) mixture of n-hexane and ethyl acetate. Figure 10.16c illustrates the profiles of bands of benzyl alcohol eluted on CIS silica by a methanol/water solution. Figure 10.16d corresponds to the elution of phenol on C18 chemically bonded silica with a (20 80) mixture of methanol and water. In all four cases. [Pg.519]

Figure 15.8 Comparison between experimental (symbols) and calculated (solid lines) band profiles of lysozyme in gradient elution. Experimental conditions column dimensions 150 X 4.6 mm packing 5 f/m particles of C18 silica (Vydac), 300 Apores Vq = 1.81 mL temperature 30"C initial mobile phase composition 10% ACN. ( ) 1 mL injection (0.40 mg, Ly = 2.9%) (x) 2 mL injection (0.81 mg, Ljr = 5.8%) (+) 3 mL injection (1.21 mg, Ly = 8.7%) and (o) 4 mL injection (1.62 mg, Lf = 11.6%). Solution concentration 0.405 mg/mL. (a) Gradient rate l%ACN/min. (b) Gradient rate 0.5%ACN/min. Reproduced with permission of Wiley-Liss Inc., a subsidiary of John Wiley Sons, Inc. from M.Z. El Fallah and G. Guiochon, Biotechnol. Bioeng., 39 (1992) 877 (Fig. 6). 1992, John Wiley Sons. Figure 15.8 Comparison between experimental (symbols) and calculated (solid lines) band profiles of lysozyme in gradient elution. Experimental conditions column dimensions 150 X 4.6 mm packing 5 f/m particles of C18 silica (Vydac), 300 Apores Vq = 1.81 mL temperature 30"C initial mobile phase composition 10% ACN. ( ) 1 mL injection (0.40 mg, Ly = 2.9%) (x) 2 mL injection (0.81 mg, Ljr = 5.8%) (+) 3 mL injection (1.21 mg, Ly = 8.7%) and (o) 4 mL injection (1.62 mg, Lf = 11.6%). Solution concentration 0.405 mg/mL. (a) Gradient rate l%ACN/min. (b) Gradient rate 0.5%ACN/min. Reproduced with permission of Wiley-Liss Inc., a subsidiary of John Wiley Sons, Inc. from M.Z. El Fallah and G. Guiochon, Biotechnol. Bioeng., 39 (1992) 877 (Fig. 6). 1992, John Wiley Sons.
Bon and coworkers carried out a study on the fate of the nanoparticles throughout solids-stabilized emulsion polymerization [119], A quantitative method based on disk centrifugation was developed to monitor the amount of nanoparticles present in the water phase in solids-stabilized emulsion polymerizations of vinyl acetate, methyl methacrylate, and butyl acrylate. The concentration profile of nanoparticles in the water phase as a function of monomer conversion agreed with theoretical models developed for the packing densities in these systems [120]. Noteworthy was that in the case of silica-nanoparticle-stabilized emulsion polymerization of vinyl acetate, the event of late-stage limited coalescence, leading to small armored non-spherical clusters, could be predicted and explained on the basis of the concentration profiles and particle size measurements. Adjusting the amount of silica nanoparticles prevented this phenomenon. [Pg.43]

Removal of impurities in the vapor phase can be achieved by the passage of the vapor through a solid bed of large surface area materials (Ruhl, 1971). Molecular sieves and silica gel are most commonly used for this purpose. No adsorption equilibrium is established, but a mass transfer zone is formed in which the quantity of adsorbed impurity decreases to zero (see Figure 19). The width and the profile of this mass transfer zone depend on the temperature, the flow velocity, the concentration of the components to be adsorbed, and on the kind and granularity of the adsorbing material. [Pg.35]

Studying adsorption from solution of polymer mixtimes is of great interest for the theory of PCM because many binders for composites are two-and more-component systems. The presence of two components determines the specificity of the properties of the boundary layers formed by two different polymeric molecules. From another point of view, as the large majority of polymer pairs is thermodynamically immiscible,there may arise interphase layers between two components in the border layer at the interface. The selectivity of adsorption of various components, which is a typical feature of adsorption from mixture, leads to the change in composition of the border layer as compared with composition in the equilibrium solution. This fact, in turn, determines the non-homogeneity in distribution of components in the direction normal to the solid surface, i.e., creates some compositional profile. As compared with stud3ung adsorption from solution of individual polymers, adsorption from mixture is studied insufficiently. The first investigations in this field were done " for immiscible pair PS-PMMA on silica surface, in conditions remote from the phase separation. It... [Pg.43]


See other pages where Silica solid phase profile is mentioned: [Pg.211]    [Pg.106]    [Pg.3506]    [Pg.3557]    [Pg.477]    [Pg.226]    [Pg.520]    [Pg.120]    [Pg.252]    [Pg.1050]    [Pg.1218]    [Pg.198]    [Pg.583]    [Pg.20]    [Pg.109]    [Pg.418]    [Pg.517]    [Pg.261]    [Pg.279]    [Pg.6]    [Pg.421]    [Pg.465]    [Pg.441]    [Pg.441]    [Pg.455]    [Pg.212]    [Pg.1060]    [Pg.441]   
See also in sourсe #XX -- [ Pg.118 ]




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