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Bad Kostritz, Germany

Santos J.C.,Jacobs Engineering | Rodrigues A.E.,Chemiewerk Bad Kostritz
AIChE Journal | Year: 2016

The separation of ethylene from ethane is particularly complex due to their similar physical properties. Cryogenic distillation is the most common technology employed for this separation and is one of the most expensive operations in industry, being the driving force for the ongoing research to find a more cost-effective alternative. In the present work, a gas-phase simulated moving bed (SMB) bench unit was employed to produce polymer-grade ethylene from ethane/ethylene mixtures, using binderless 13X zeolite beads as adsorbent, and propane as desorbent. The achieved performance parameters demonstrated the high efficiency of the current technology, since ethylene was obtained with a purity of 99.8%, a recovery of 99.8%, and a productivity of 59.7 kgC2H4·h-1· madsorbent-3. Considering the encouraging results obtained it is fair to say that the gas-phase SMB is a competitive and strong candidate as alternative to the conventional process, especially when combined with enhanced performance adsorbents, such as binderless zeolites. © 2016 American Institute of Chemical Engineers. Source

Silva J.A.C.,Polytechnic Institute of Braganca | Cunha A.F.,University of Porto | Schumann K.,Chemiewerk Bad Kostritz | Rodrigues A.E.,University of Porto
Microporous and Mesoporous Materials | Year: 2014

The 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. Source

Silva J.A.C.,Polytechnic Institute of Braganca | Schumann K.,Chemiewerk Bad Kostritz | Rodrigues A.E.,University of Porto
Microporous and Mesoporous Materials | Year: 2012

The sorption equilibrium of CO 2 and CH 4 in binderless beads of 13X zeolite has been investigated between 313 and 373 K and pressure up to 4 atm. The amount adsorbed of CO 2 and CH 4 is around 5.2 mmol/g ads and 1.2 mmol/g ads, respectively, at 313 K and 4 atm. Comparing these values with the ones in literature the value of CO 2 is 20% higher than in CECA 13X binder pellets. It is also found that isotherms are pronounced Type I for CO 2 and almost linear for CH 4. The CO 2 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/g ads.atm for CO 2 and 0.45 to 0.27 mmol/g ads.atm for CH 4 between 313 and 373 K, respectively. The heats of sorption at zero coverage are 43.1 kJ/mol for CO 2 and 9.2 kJ/mol for CH 4. 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≥7.02×10-2rc2Dc. Based on such criteria it is shown that crystal diffusivity of CO 2 in 13X can be measured macroscopically by ZLC, being the same measurement for CH 4 practically impossible. The crystal diffusivity of CO 2 measured experimentally is 5.8 × 10 -15 m 2/s and 1.3 × 10 -15 m 2/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 CH 4 were measured under an equilibrium regime. © 2012 Elsevier Inc. All rights reserved. Source

Roelofs F.,Chemiewerk Bad Kostritz | Vogelsberger W.,Friedrich - Schiller University of Jena
Journal of Physical Chemistry C | Year: 2013

The solubility of two commercially available microscale quartz powders in water under biological-like conditions is investigated. The experimental results are evaluated by common phenomenological theories and by complete analysis of the Gibbs free energy of the system particles-solution (gradient method). The different theories are compared with each other, and the interrelations between the theories are discussed. The application of the gradient method always leads to the best agreement between experimental results and theory because the gradient model considers the simultaneous changes of both particle size and particle concentration during dissolution. The optimal values of saturation concentrations and dissolution rate constants are determined by statistical analyses and by calculation of the coefficient of determination. The expected influence of temperature on the dissolution behavior is confirmed. Higher values of the crystal strain of the quartz samples result in higher values of the dissolution rate constant and more rapid dissolution. The saturation concentrations and rate constants determined for the commercially available quartz samples are at least 1 order of magnitude larger than most values reported in the literature for natural quartz. In accordance with statements found in the literature, this fact should be taken into account for the assessment of the potential health risk of the investigated commercially available quartz powders. © 2013 American Chemical Society. Source

Narin G.,University of Porto | Narin G.,Usak University | Martins V.F.D.,University of Porto | Campo M.,University of Porto | And 7 more authors.
Separation and Purification Technology | Year: 2014

In this work 13X zeolite binderless beads were tested as a new promising material for polymer-grade olefin production from olefin/paraffin mixtures by VPSA technology. In order to characterize the adsorbent and its potential for the target separations, the equilibrium isotherms of propane, propylene, ethane and ethylene were measured gravimetrically on a 13X zeolite binderless sample, in a temperature range from 50 °C to 150 °C and pressure up to 5 bar. Dynamic studies were performed at 100 °C and 1.5 bar in a fixed-bed single-column unit. The adsorbent under evaluation presented high olefin selectivity, with values between 7 and 9 for the C2 pair and about 8 for the C3 pair. A mathematical model was proposed and validated by the breakthrough experiments. With this model, pilot scale 5-step VPSA cycles were successfully designed and tested experimentally to produce polymer-grade olefins. © 2014 Elsevier B.V. All rights reserved. Source

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