‘Uphill’ permeation of carbon dioxide across a composite molten salt-ceramic membrane

E.I Papaioannou,H Qi,I.S Metcalfe

doi:10.1016/j.memsci.2015.03.013

E.I Papaioannou, H Qi + Show 1 more

Open Access

https://doi.org/10.1016/j.memsci.2015.03.013

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Journal: Journal of Membrane Science	Publication Date: Mar 14, 2015
Citations: 19	License type: cc-by

Affiliation: Newcastle University

Abstract

Here, we show how a membrane can be designed and operated to achieve ‘uphill’ permeation of carbon dioxide against its own chemical potential difference by employing the transport of carbonate ions with coupled ‘downhill’ permeation of oxygen. Absolute values of the carbon dioxide permeability of the order of 106 Barrers are achieved experimentally over more than 200h of operation. These permeabilities are some four orders of magnitude greater than polymeric gas separation membranes. We believe that these high permeabilities are due to the effective use of the oxygen chemical potential difference across the membrane as a driving force for carbonate transport.

Highlights

One approach to membrane design for selective carbon dioxide permeation is to fabricate a device consisting of two phases, one a carbonate-conducting mixture of molten alkali-metal carbonates and the other a predominantly electron-conducting solid phase [1]
The morphology, microstructure, phase structure and elemental analysis of the membrane were characterised by a scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS) (Rontec Quantax 1.2 FEI XL30 ESEM-FEG) and X-ray diffraction (XRD) (PANalytical Empyrean Diffractometer operated in reflection mode, CuKα)
It is important to note that these techniques were not employed in-situ and the carbonate is in the solid state at the time of characterisation

Summary

Introduction

One approach to membrane design for selective carbon dioxide permeation is to fabricate a device consisting of two phases, one a carbonate-conducting mixture of molten alkali-metal carbonates and the other a predominantly electron-conducting solid phase [1]. (The alternative would be to operate the membrane under conditions where there would be a significant change in gas composition on both sides between inlet and outlet This mode of operation does not readily yield useful kinetic information.) We develop a robust methodology for determining permeation rates when the gas-phase component of interest (here carbon dioxide) is to be fed to both sides of the membrane. This dynamic permeation rate determination is complemented here by long term steady permeation rate determination

Experimental

Membrane characterisation

CO2 ‘uphill’ permeation

Conclusions