The aim of the work was to systematically investigate the adsorption of C6-C8 hydrocarbons on silica alumina gels for a concentration range relevant in natural gas processing and to develop prediction models for the adsorption equilibrium and the adsorption dynamics, thus supporting the design and optimisation of the processing plants.</br> For the silica alumina gel Sorbead H as well as a modified variant experimental equilibrium isotherms for pure hydrocarbons and for binary hydrocarbon mixtures at 25 °C - 75 °C were determined and isosteric adsorption enthalpies were calculated. In the investigation of single-component adsorption, the aromatic hydrocarbons showed the highest adsorption capacity and enthalpy compared to the other hydrocarbons due to their electrostatic properties. Also an increasing capacity as well as enthalpy with increasing C-chain length of the hydrocarbons could be determined. A comparison of the investigated adsorbents shows a higher capacity and enthalpy of the adsorbent with a higher proportion of micropores for all analysed adsorptives, due to the larger number of energetically high-quality adsorption sites.
In addition, a temperature-dependent model based on the adsorption potential and the Freundlich equation was derived and adapted to the measurement data that describes most systems with very good accuracy and allows an initial estimation of the temperature dependence of the adsorption enthalpy.</br>To describe the adsorption dynamics of single-component adsorption, a physical model based on the linear driving force approach was used and compared with experimental breakthrough curves. A high accuracy of the simulation model was found.
Based on the findings of single-component adsorption, the binary adsorption behaviour of C6C8 hydrocarbons was experimentally investigated and the applicability and accuracy of the ideal adsorbed solution theory (IAST) for predicting the binary adsorption equilibrium was evaluated. For all measured two-component systems IAST describes the real adsorption state with very good accuracy. A correlation of prediction accuracy with the ideality of the systems as well as with surface coverage and the loading difference of the adsorptive was found.
To investigate adsorption dynamics, binary breakthrough curve experiments were carried out and compared with a dynamic simulation model based on pure component parameters. The dynamic breakthrough curves of the binary hydrocarbon mixtures could be predicted very accurately with the model, whereby both systems of strongly differently adsorbing components as well as systems with components of similar adsorption affinity are described very precisely.
|Advisor:||Bathen , Dieter|
|School:||Universitaet Duisburg-Essen (Germany)|
|Source:||DAI-C 81/5(E), Dissertation Abstracts International|
|Keywords:||C6-C8 hydrocarbons, Silica alumina gels, Aromatic hydrocarbons|
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