Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.723308
Title: Development and optimisation of regenerative adsorbent structures for carbon dioxide and contaminants removal
Author: Hong, Wan Yun
Awarding Body: University of Bath
Current Institution: University of Bath
Date of Award: 2016
Availability of Full Text:
Access from EThOS:
Access from Institution:
Abstract:
This thesis presents the research on the development and optimisation of energy efficient adsorbent monoliths and foam-monoliths for the removal of carbon dioxide (CO2) and other contaminants such as hydrogen sulfide (H2S) and water (H2O) vapour from the biogas stream. Zeolite and MIL-101(Cr) monoliths and carbonate-based zeolite foammonoliths of novel chemical formulations have been manufactured, characterised and tested for adsorption. Using the prepared adsorbent monoliths as models, their kinetic adsorption and gas flow dynamic performances have also been evaluated and compared with packed beds of commercially available adsorbent beads. The research mainly comprised of three parts. The first part was concerned with the manufacturing, characterising and optimising the adsorbent monoliths and foammonoliths. The adsorbent monoliths and foam-monoliths have been fabricated successfully using the unique paste extrusion technique described in this thesis. This includes monoliths of 13X zeolite, LiLSX zeolite, 5A zeolite, clinoptilolite and MIL-101(Cr) and foam-monoliths of K2CO3/13X zeolite and Na2CO3/13X zeolite. The incorporation of a decomposable pore former such as Licowax C micropowder PM into their paste formulations were found to improve their structural porosity, adsorption performance and mass transfer. It has been found that the best type of adsorbent structure for CO2 adsorption were 13X zeolite and purified MIL-101(Cr) monoliths and K2CO3/13X zeolite foam-monoliths. The CO2 adsorption performances of purified MIL-101(Cr) monoliths and K2CO3/13X zeolite foam-monoliths have been shown to be comparable to a packed bed of 13X zeolite beads (in terms of effectiveness of the adsorbent bed utilisation and equilibrium adsorption capacity on mass basis, respectively). This confirmed that the prepared adsorbent monoliths and foam-monoliths were potential adsorbent structures for CO2 adsorption. The second part involved testing the prepared adsorbent monoliths and foammonoliths with single (such as CO2, CH4 and H2S) and mixed (such as CO2/CH4 and CO2/CH4/H2O vapour) gases under different operating conditions to assess their dynamic adsorption performances for biogas upgrading. 13X zeolite and MIL-101(Cr) monoliths and K2CO3/13X zeolite foam-monoliths were used as model adsorbent structures in single and mixed gas adsorption experiments. The study has shown that 13X zeolite monoliths and K2CO3/13X zeolite foam-monoliths have excellent adsorption performances for CO2, H2S and H2O vapour and they could upgrade the biogas to a high quality (i.e., up to about 98% vol. CH4). For purified MIL-101(Cr) monoliths, it was discovered that they have relatively good adsorption performance for CO2, H2S, CH4 and H2O vapour and they could upgrade the biogas to a moderate quality (i.e., up to about 67% vol. CH4). In both humid and dry conditions, K2CO3/13X zeolite foam-monoliths were found to have the highest selectivity of CO2 over CH4 compared to 13X zeolite and purified MIL-101(Cr) monoliths. The third part was related to the evaluation and comparison of kinetic adsorption and gas flow dynamic performances of the prepared adsorbent monoliths with those of packed beds of adsorbent beads. In these studies, LiLSX zeolite monoliths and beads were used as model adsorbent structures. The kinetic adsorption study has discovered that LiLSX zeolite monoliths have slightly higher overall mass transfer resistance than packed beds of LiLSX zeolite beads. It has been shown that the overall mass transfer resistance in monoliths could be reduced by decreasing the channel diameter and increasing the wall thickness. The gas flow dynamic study found that the mass transfer in monoliths was not contributed by the axial dispersion of gases and this was in contrast to the mass transfer in packed beds. LiLSX zeolite monoliths were found to have lower pressure drop compared to packed beds of LiLSX zeolite beads. This showed that the biogas upgrading process would be more energy efficient using adsorbent monolith/foammonolith systems compared to packed bed systems.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.723308  DOI: Not available
Share: