High Temperature Oxygen Production

A potential alternative to produce clean coal technologies would be to combust fossil fuels in pure oxygen instead of air, which contains approximately 78% nitrogen by volume. If nitrogen was removed from the process, flue gas streams would have a much higher concentration of CO₂, reducing or eliminating the need for costly CO₂ capture. Moreover, NO_X emissions and the subsequent need for processing would be reduced significantly. The main problem with this method is separating oxygen from the air. This is usually completed cryogenically which requires a lot of energy (for a typical 500MW coal-fired power station supplying pure oxygen requires at least 15% of the electricity the plant generates annually). Cryogenic air separation technology for producing high purity oxygen is energy intensive and requires air to be cooled to about - 300 degree Fahrenheit for separation. The cold oxygen must be heated to high temperatures in order to couple this air separation process with coal power plants. The high cost of producing oxygen, however, has made oxy-combustion a cost-prohibitive option for commercial use in most power plants. Developing technologies in oxygen and ion transport membranes have the potential to reduce the cost of oxygen production and increase oxy-combustion's cost-effectiveness.

In this research, multicomponent oxides containing Mn in different oxidation states were explored as reactants for two-step high temperature high purity oxygen production. High temperature reduction and oxidation of these compounds were carried out in an inert gas and air atmosphere, respectively, using TGA-DSC. For synthesized manganese-based oxide materials to separate air, they should be able to incorporate oxygen atoms in to their crystal structure and release oxygen at the same or elevated temperatures while varying the oxygen partial pressure of the system.

                                                                                  

The results obtained from TGA-DSC showed all investigated compounds can produce high purity oxygen at elevated temperatures. Details of multicomponent oxides  preparation, characterization, and high temperature conversion of the oxides under reduction and oxidation conditions  will be discussed.