Structured Zeolite Adsorbents for CO2 Separation
Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
Gas separation processes have many industrial applications. One way to separate a gas from a mixture is by selectively adsorbing it. Zeolites are microporous crystalline aluminosilicates with unique properties used for many processes including gas adsorption. Currently, traditional adsorbents in the form of beads and pellets are used in adsorption processes. But when high throughputs are required, high pressure drop and mass transfer resistance in pellet beds lead to decreased productivity and recovery and increased energy demand. For these reasons, structured adsorbents characterized by low pressure drop and better mass transfer are becoming increasingly important. In this work, structured adsorbents in the form of steel monoliths coated by a thin zeolite NaX film were prepared and used for CO2 adsorption from a CO2/N2 mixture. A new method for the synthesis of zeolite NaX films on steel monoliths was developed. The obtained films were homogeneous, ca 3 μm thick and were almost free from sediments and secondary products. With the CO2 breakthrough experiments it was demonstrated that the steel monoliths coated with zeolite had much lower adsorption capacity per unit volume of bed as compared to the zeolite pellets. However, the mass transfer zone (MTZ) of the breakthrough curves obtained using the monoliths was much narrower than the MTZ for the zeolite pellets indicating that the mass transfer resistance in the monoliths was very low due to the low thickness of the zeolite film. Narrow MTZ together with the low pressure drop commonly observed for the monoliths could give a possibility to reduce cycle time in cyclic adsorption processes, increasing productivity and reducing energy demand. Compared to the zeolite coated ceramic cordierite monoliths investigated earlier, the coated steel monoliths had a higher adsorption capacity and almost as narrow MTZ, with a higher mass transfer coefficient, as obtained from the numerical modeling. This makes zeolite coated steel monolith a better alternative for the adsorption processes. After further optimizations, zeolite coated steel monoliths could be employed to improve the performance of the gas separation processes.
Place, publisher, year, edition, pages
2012. , 87 p.
Physics Chemistry Maths
Fysik, Kemi, Matematik
IdentifiersURN: urn:nbn:se:ltu:diva-54900Local ID: bd3adbe0-b7ff-4670-82f0-244678e94318OAI: oai:DiVA.org:ltu-54900DiVA: diva2:1028281
Subject / course
Student thesis, at least 30 credits
Chemical Engineering, master's level
Validerat; 20120612 (anonymous)2016-10-042016-10-04Bibliographically approved