KEPCO Journal on Electric Power and Energy, Vol. 2, No. 2, June 2016 Manuscript received March 14, 2016, revised April 15, 2016, accepted April 18, 2016 ISSN 2465-8111(Print), 2466-0124(Online), DOI http://dx.doi.org/10.18770/KEPCO.2016.02.02.285 This paper is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License. This paper is available online at http://journal.kepco.co.kr 285 Performance Comparison of Spray-dried Mn-based Oxygen Carriers Prepared with γ-Al 2 O 3 , α-Al 2 O 3 , and MgAl 2 O 4 as Raw Support Materials Jeom-In Baek * †, Ui-Sik Kim * , Hyungeun Jo * , Tae Hyoung Eom * , Joong Beom Lee * , Ho-Jung Ryu ** * Creative Future Lab., KEPCO Research Institute, Korea Electric Power Corporation, Korea 105 Munji-ro Yuseong-gu, Daejeon 34056, Republic of Korea ** Climate Change Research Division, Korea Institute of Energy Research, Korea 152 Gajeong-ro Yuseong-gu, Daejeon 34129, Republic of Korea † perbaek@kepco.co.kr Abstract In chemical-looping combustion, pure oxygen is transferred to fuel by solid particles called as oxygen carrier. Chemical-looping combustion process usually utilizes a circulating fluidized-bed process for fuel combustion and regeneration of the reduced oxygen carrier. The performance of an oxygen carrier varies with the active metal oxide and the raw support materials used. In this work, spray- dried Mn-based oxygen carriers were prepared with different raw support materials and their physical properties and oxygen transfer performance were investigated to determine that the raw support materials used are suitable for spray-dried manganese oxide oxygen carrier. Oxygen carriers composed of 70 wt% Mn3O4 and 30 wt% support were produced using spray dryer. Two different types of Al2O3, -Al2O3 and -Al2O3, and MgAl2O4 were applied as starting raw support materials. The oxygen carrier prepared from -Al2O3 showed high mechanical strength stronger than commercial fluidization catalytic cracking catalyst at calcination temperatures below 1100 C, while the ones prepared from -Al2O3 and MgAl2O4 required higher calcination temperatures. Oxygen transfer capacity of the oxygen carrier prepared from -Al2O3 was less than 3 wt%. In comparison, oxygen carriers prepared from -Al2O3 and MgAl2O4 showed higher oxygen transfer capacity, around 3.4 and 4.4 wt%, respectively. Among the prepared Mn-based oxygen carriers, the one made from MgAl2O4 showed superior oxygen transfer performance in the chemical-looping combustion of CH4, H2, and CO. However, it required a high calcination temperature of 1400 °C to obtain strong mechnical strength. Therefore, further study to develop new support compositions is required to lower the calcination temperature without decline in the oxygen transfer performance. Keywords: Carbon dioxide, chemical looping combustion, oxygen carrier, manganese oxide I. INTRODUCTION Post-2020 Climate Agreement adopted at Confernce of Parties (COP21) decided to cap the increase in the global average temperature to well below 2 C above pre-industrial levels. Carbon capture and storage (CCS) is recognized as one of the major options to mitigate CO 2 emission. Among the carbon capture technologies, post-combustion and pre-combustion technologies require a CO 2 capture facility to separate CO 2 from a gas stream. The installation and operation of the CO 2 capture facility result in considerable a efficiency loss and increase in energy cost. Oxyfuel combustion has been studied as an alternative carbon capture technology which does not need a CO 2 capture facility because CO 2 is inherently separated during fuel combustion. However, the cost to produce pure oxygen from air is still too high to apply oxyfuel combustion to a commercial scale. Chemical-looping combustion (CLC) has been noticed as another promising technology with the feature of inherent separation of CO 2 without a capture facility. CLC also uses pure oxygen for fuel combustion. However, the oxygen required for fuel combustion is supplied by a solid particle containing oxygen, or an oxygen carrier (OC). It is expected that the cost penalty and the system efficiency loss accompanied by CO 2 capture will be less in CLC than other CO 2 capture technologies [1]–[3]. A circulaing fluidized-bed process which is consisted of two interconnected fluidized-bed reactors, a fuel reactor and an air reactor, is usually used in a CLC process as shown in Fig. 1. An OC transfers oxygen from air to fuel while circulating between the two reactors. In the fuel reactor, the OC gives its oxygen to the fuel for fuel combustion. The fuel is oxidized and emits CO 2 and H 2 O. In the air reactor, the reduced OC is regenerated to oxidized state by receiving oxygen in the air supplied into the air reactor. The flue gas from the fuel reactor theoretically contains only CO 2 and H 2 O. Pure CO 2 can be obtained after condensation of H 2 O. Therefore, the OC requires excellent physical properties suitable for the fluidized-bed process applications and high oxygen transfer performance for complete combustion of fuel. Long term durability to endure cyclic redox reaction at high temperatures is also important to be a quality OC. An OC is composed of acive metal and support. The active metal transfers oxygen and the support enhances physical and chemical properties of OC such as porosity, surface area, dispersion of metal oxide, and mechanical strength. Oxidized- and reduced-forms of primary transition metal, NiO-Ni, Mn 3 O 4 - MnO, Fe 2 O 3 -Fe 3 O 4 , and CuO-Cu, are commonly studied forms of active metal for CLC of gaseous fuels in a temperature range of 800 to 1200 °C . The oxygen ratios of each pair are 21.4, 7.0, 3.3, and 20.1, respectively. NiO has been the most extensively studied metal oxide for CLC because it has high oxygen ratio and NiO-based OCs have high oxygen transfer capacity, good reactivity, and superior physical properties [4][5]. However, NiO