Browsing by Author "Schumann, Kristin"
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- Adsorption equilibrium and diffusion ofmethane and carbon dioxide on binderless beads of 13X zeolitePublication . Silva, José A.C.; Schumann, Kristin; Rodrigues, AlírioEquilibrium and kinetics of sorption of CO2 and CH4 on a new type of binderless on of 13X zeolite. The equilibrium data is measured in a breakthrough apparatus and the kinetic data by the ZLC technique.
- Binary adsorption of CO2/CH4 in binderless beads of 13X zeolitePublication . Silva, José A.C.; Cunha, Adelino F.; Schumann, Kristin; Rodrigues, AlírioThe binary sorption CO2 and CH4 in binderless beads of 13X zeolite has been investigated between 313 and 473 K and total pressure up to 5 atm through fixed bed adsorption experiments. The amount adsorbed of CO2 and CH4 is around 4.7 mmol/gads and 0.4 mmol/gads, respectively, at 313 K and 3.7 atm in a 50/50 equimolar mixture. In a 25(CO2)/75(CH4) mixture the amount adsorbed is 4.0 and 0.84 mmol/g at the same temperature and pressure. Experimental selectivities CO2/CH4 range from 37 at a low pressure of 0.667 atm to approximately 5 at the high temperature of 423 K. Comparing these values with the ones in literature CO2 adsorption capacity is 20% higher than in CECA 13X binder pellets. The CO2/CH4 binary isotherms were fitted with the extended Fowler model that takes into account interaction between adsorbed molecules at adjacent sites suggesting a moderate attraction between CO2 and CH4. The model is validated through a graphical method using the single component isotherm parameters. The breakthrough curves measured show a plateau of pure CH4 of approximately 6 min depending of the operating conditions chosen.
- Sorption and kinetics of CO2 and CH4 in binderless beads of 13X zeolitePublication . Silva, José A.C.; Schumann, Kristin; Rodrigues, AlírioThe sorption equilibrium of CO2 and CH4 in binderless beads of 13X zeolite has been investigated between 313 and 373 K and pressure up to 4 atm. The amount adsorbed of CO2 and CH4 is around 5.2 mmol/gads and 1.2 mmol/gads, respectively, at 313 K and 4 atm. Comparing these values with the ones in literature the value of CO2 is 20% higher than in CECA 13X binder pellets. It is also found that isotherms are pronounced Type I for CO2 and almost linear for CH4. The CO2 isotherms were modeled using a simple deviation from Langmuir isotherm that takes into account interaction between adsorbed molecules at adjacent sites (Fowler model) suggesting a moderate repulsion. Henry’s constants range from 143 to 11.1 mmol/gads.atm for CO2 and 0.45 to 0.27 mmol/gads.atm for CH4 between 313 and 373 K, respectively. The heats of sorption at zero coverage are 43.1 kJ/mol for CO2 and 9.2 kJ/mol for CH4. The sorption kinetics has been investigated by the Zero-Length Column technique (ZLC). Recipes to analyze ZLC desorption curves in pellets of adsorbents are reviewed and it is derived a criteria which indicates that for the sorption rate be measured macroscopically the time of the experiment (that should be above a few seconds) is directly calculated with the following expression: t0:1 7:02 10 2 r2c Dc. Based on such criteria it is shown that crystal diffusivity of CO2 in 13X can be measured macroscopically by ZLC, being the same measurement for CH4 practically impossible. The crystal diffusivity of CO2 measured experimentally is 5.8 10 15 m2/s and 1.3 10 15 m2/s at 373 and 313 K, respectively. These values are comparable to the ones measured by a frequency response and pulse chromatography techniques reported in literature. The ZLC desorption curves for CH4 were measured under an equilibrium regime
- Sorption of carbon dioxide on binderless beads of 13XPublication . Silva, José A.C.; Schumann, Kristin; Rodrigues, AlírioThe sorption equilibrium of CO2 and CH4 in binderless beads of 13X zeolite has been investigated between 313 and 373 K and pressure up to 4 atm. The amount adsorbed of CO2 and CH4 is around 5.2 mmol/gads and 1.2 mmol/gads, respectively, at 313 K and 4 atm. Comparing these values with the ones in literature the value of CO2 is 20% higher than in CECA 13X binder pellets. The crystal diffusivity of CO2 measured experimentally by the ZLC technique is 5.8×10-15 m2/s and 1.3×10-15 m 2/s at 373 and 313 K, respectively. These values are in the same order magnitude of the ones measured by a frequency response and pulse chromatography techniques reported in literature. The ZLC desorption curves for CH4 were measured under an equilibrium regime and no kinetic data is obtained.