2nd International Conference on Chemical Looping, 26-28 September 2012, Darmstadt, Germany 1 Manganese-silica combined oxides as oxygen carrier for chemical-looping combustion Dazheng JING 1, *, Eveline Y.S.I.M. HERMANS 1 , Henrik LEION 1 , Magnus RYDÈN 2 , Tobias MATTISSON 2 , Jasper VAN NOYEN 3 , Anders LYNGFELT 2 1 Department of Environmental Inorganic Chemistry, Chalmers University of Technology, SE- 412 96 Gothenburg, Sweden 2 Department of Energy and Environment, Chalmers University of Technology, SE-41296 Gothenburg, Sweden 3 Flemish Institute for Technological Research (VITO), Unit Materials, B-2400 Mol, Belgium *Dazheng Jing, dazheng@chalmers.se Abstract – Manganese oxide is a potential oxygen carrier for chemical-looping combustion and has many promising features. A number of recent studies show that it is possible to alter the properties of manganese oxides by combining it with other oxides, such as oxides of Fe, Ni, Mg and Si. These metal oxides have been shown to have high reactivity with fuel gas and may also have CLOU properties. Here, CLOU (Chemical Looping with Oxygen Uncoupling) is the ability of an oxygen carrier to release gaseous oxygen in a chemical looping fuel reactor, with which the fuel can react directly. This paper presents results from an experimental investigation of several different Mn-Si-based oxygen carrier particles. Six different samples were produced by spray-drying, in which between 2 wt% and 50 wt% Si was added to Mn 3 O 4 . For one of the samples, 20 wt% Fe 2 O 3 was also added in addition to 10 wt% SiO 2 , resulting in a Mn-Fe-Si-based oxygen carrier. The reactivity of the oxygen carrier particles was investigated in a laboratory fluidized bed reactor, in which each sample was subject to reduction by the gaseous fuels methane and syngas (50% H 2 , 50% CO) followed by oxidation with a gas mixture of O 2 and N 2 . All the particles provided full conversion of syngas and relatively high methane conversion, when using an oxygen carrier to fuel ratio of approximately 57 kg/MW for methane. A maximum CO 2 yield of 98.1% was achieved by the sample with 30 wt% SiO 2 at 950°C, which was the best among the investigated samples. The lowest CO 2 yield was 73.1%, contributed by the sample with 2 wt% SiO 2 . Influence of Fe 2 O 3 was not clearly determined since this gave results similar to the samples with the same Si content but without Fe. As for CLOU properties, a small release of oxygen was shown by some of the materials, particularly for the sample with Fe. 1 Introduction Emissions of greenhouse gases to the atmosphere are believed to be the main reason for global warming. Of the different anthropogenic greenhouse gases, carbon dioxide contributes the most to the global warming, which is because it is emitted in much larger quantities than other greenhouse gases. Among all anthropogenic CO 2 emissions, burning of fossil fuels generating electricity constitutes a large part of these emissions. Meanwhile fossil