280218 Using CaxLa1-xMn1-yXyO3 As Oxygen Carriers for Chemical-Looping Combustion

Wednesday, October 31, 2012: 1:08 PM
301 (Convention Center )
Tobias Mattisson1, Ali Hedayati2, Abdul-Majeed Azad3, Magnus Ryden1 and Henrik Leion2, (1)Department of Energy and Environment, Chalmers University of Technology, Gothenburg, Sweden, (2)Department of Chemical & Biological Engineering, Chalmers University of Technology, Gothenburg, Sweden, (3)Department of Chemical and Environmental Engineering, The University of Toledo, Toledo, OH

A new group of oxygen carrier (OC) materials based on the calcium manganate perovskite CaMnO3-d have been investigated for use in chemical-looping combustion.   CaMnO3-d  is an ABO3-type of perovskite which is endowed with interesting properties by virtue of oxygen non-stoichiometry which creates mobile charge carriers by way of doping at the A- and B-sites in the parent compound. In this project compounds of the formula CaxLa1-xMn1-yXyO3+d (CLMX) were investigated as oxygen carrier materials.  A matrix of potential substituted CaxLa1-xMn1-yXyO3 (X = Fe, Ti, Cu, Mg) (CLMX) perovskites were synthesized using mechanical homogenization of primary solids in a rotary evaporator followed by drying and calcination at 1300°C. The resulting powders were subjected to net-shaping and particle fabrication via extrusion followed by crushing and sieving.  The oxygen release properties and the reactivity with methane and syngas were investigated using a batch fluidized batch reactor made of quartz.  A sample of 15 g of particles and a fuel flow of 450 Nml/min was used for all reactivity experiments. All of the materials showed high rates of oxygen release to the gas phase at 950°C, or so called uncoupling properties.  In addition the reactivity with methane was high, approaching 100% conversion for some of the materials at 950°C.  The oxygen carrier doped with Cu showed defluidization during the reducing period, which could explain the somewhat lower reactivity of this material.  The syngas conversion to CO2 and H2O was complete for all investigated materials.  The oxidized and reduced samples were also analyzed using x-ray powder diffraction.  Although the mechanical strength of the samples were somewhat low for use in a industrial CLC unit, the reactivity and very good uncoupling properties certainly make this low-cost system very interesting for CLC with different types of fuel.

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