Oxygen Transport Membranes: A Material Science and Process Engineering Approach

This thesis describes several fundamental aspects on the membrane-integrated oxy-fuel combustion process and can be divided in two parts: 1) The development and characterization of membrane materials; 2) The design, simulation and evaluation of a coal-fired power plant, coupled with a membrane module. A simple and easy method to measure the oxygen nonstoichiometry of a perovskite material is described in chapter 2. A Computing Fluid Dynamic (CFD) model is developed in chapter 3 to describe the oxygen gradient in a commonly used oxygen permeation set-up, as used to determine the oxygen ionic conductivity of a membrane. Chapter 4 provides the development of a CO2-stable membrane (Ta doped SrCo0.8Fe0.2O3-δ (SCF)) as can be used for the membrane-integrated oxy-fuel combustion process. In chapter 5 it is found that the CO2 tolerance of the SCF membrane is affected by the ambient oxygen partial pressure: mixing 5% oxygen to CO2 can prevent the membrane from degradation. In chapter 6 of this thesis a membrane-integrated oxy-fuel combustion process is designed, and this process is simulated in Unisim for evaluation. In this final chapter, some general conclusions are drawn from the previous chapters, and some recommendations are given for future work.