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Title: DUAL PHASE MEMBRANE FOR HIGH TEMPERATURE CO2 SEPARATION

This project is intended to expand upon the previous year's research en route to the development of a sustainable dual phase membrane for CO{sub 2} separation. It was found that the pores within the supports had to be less than 9 {micro}m in order to maintain the stability of the dual phase membrane. Pores larger than 9 {micro}m would be unable to hold the molten carbonate phase in place, rendering the membrane ineffective. Calculations show that 80% of the pore volume of the 0.5 media grade metal support was filled with the molten carbonate. Information obtained from EDS and SEM confirmed that the molten carbonate completely infiltrated the pores on both the contact and non-contact size of the metal support. Permeation tests for CO{sub 2} and N{sub 2} at 450-750 C show very low permeance of those two gases through the dual phase membrane, which was expected due to the lack of ionization of those two gases. Permeance of the CO{sub 2} and O{sub 2} mixture was much higher, indicating that the gases do form an ionic species, CO{sub 3}{sup 2-}, enhancing transport through the membrane. However, at temperatures in excess of 650 C, the permeance of CO{sub 3}{sup 2-}more » decreased quite rapidly, while predictions showed that permeance should have continued to increase. XRD data obtained form the surface of the membrane indicated the formation of lithium iron oxides on the support. This layer has a very low conductivity, which drastically reduces the flow of electrons to the CO{sub 2}/O{sub 2} gas mixture, limiting the formation of the ionic species. These results indicate that the use of stainless steel supports in a high temperature oxidative environment can lead to decreased performance of the membranes. This revelation has created the need for an oxidation resistant support, which can be gained by the use of a ceramic-type membrane. Future research efforts will be directed towards preparation of a new ceramic-carbonate dual phase membrane. The membrane will based on an oxide ceramic support that has an oxidation resistance better than the metal support and high electronic conductivity (1200-1500 S/cm) in the interested temperature range (400-600 C).« less
Authors:
; ;
Publication Date:
OSTI Identifier:
838118
DOE Contract Number:
FG26-02NT41555
Resource Type:
Technical Report
Resource Relation:
Other Information: PBD: 1 Dec 2005
Research Org:
University of Cincinnati (US)
Sponsoring Org:
(US)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; CARBONATES; CERAMICS; ELECTRONS; GASES; IONIZATION; IRON OXIDES; LITHIUM; MEMBRANES; MIXTURES; OXIDATION; OXIDES; STABILITY; STAINLESS STEELS; TRANSPORT; X-RAY DIFFRACTION