Novel New Oxygen Carriers for Chemical Looping Combustion of Solid Fuels

Abstract

Several bimetallic oxygen carriers, MFe 2 O 4 (M = Co, Ni, Cu, Mg, Ca, Sr, and Ba) and MnFeO 3 , prepared by the precipitation method in a microwave and the direct decomposition method, were tested for potential use in the application of chemical looping combustion (CLC) of solid fuels. Thermogravimetric analysis (TGA) was used to study their reduction rate, oxidation rate, and cyclic reduction/oxidation properties. Comparative experimental data of novel bimetallic ferrites and pure Fe 2 O 3 and CuO showed that all bimetallic ferrites had better reduction rates than pure Fe 2 O 3 . The Group 2 metal ferrites had better reduction and oxidation rates than transition-metal ferrites. BaFe 2 O 4 was the highest performing among all bimetallic ferrites during both reduction and oxidation reactions. The reduction rate of BaFe 2 O 4 is comparable to that of CuO at higher reaction temperatures (>900°C). A 10 wt % loading of an inert support on the surface of the bimetallic oxygen carriers significantly decreased the particle agglomeration during the cyclic tests, which contributed to a better cyclic reaction performance.

Examining SrCuO2 as an oxygen carrier for chemical looping combustion

“…The pure chemical used for the oxide synthesis as CuO was tested in terms of thermal resistance. The literature shows that pure CuO has the disadvantage of having a low melting point (1080°C) [14]. In this work, the deformation of the formed CuO pellet was observed at 630°C, with melting at 1100°C, that agrees well with the values reported previously [28].…”

“…Recently, synthetic mixed materials have also been investigated intensively due to their emerging CLC properties [10][11][12]. The complex oxide materials can potentially solve many problems associated with conventional monometallic oxygen carriers [13,14] because addition of other oxides improves the structural properties of the monometallic oxygen carriers by considerably expanding their stability over multiple redox cycles [15][16][17]. They have also been proven to increase both the thermal resistance and the oxygen transport capacity [18].…”

“…Examples of the complex oxide materials that are receiving considerably increased attention are the spinel system of Cu-Mn-O [17], CoWO 4 [22], the MFe 2 O 4 type, where M is either Co, Ni, Cu, Mg, Ca, Sr or Ba [14], and also perovskite-type materials such as La 1-x Sr x M y Fe 1-y O 3-d [10], or LaMn 1-x Co x O 3±d [23], and La 1-x Sr x FeO 3 [20]. In the literature [14], several bimetallic oxygen carriers of the MFe 2 O 4 type, where M is either Co, Ni, Cu, Mg, Ca, Sr or Ba and also MnFeO 3 were prepared by the precipitation method and were finally tested for potential use in chemical looping combustion of hard coal. Based on collected TG data, bimetallic ferrites were proven to have better reduction rates than the Fe 2 O 3 alone.…”

Progress in oxygen carrier development of methane-based chemical-looping reforming: A review

“…Among various transition metals, Ni, Cu, Fe, Mn and Co are feasible candidates to be used in CLC systems [48][49][50] although they possess some disadvantages: the low reactivity of Fe, Mn and Co; low melting points and high agglomeration for Cu; and toxicity concern for Ni. Fig.…”

Chemical and calcium looping reforming for hydrogen production and carbon dioxide capture

“…The release of gaseous oxygen is important for gasification of solid fuels, because in principle they must first be gasified by H 2 O or CO 2 before reaction with the oxygen carrier can take place, and this is an inherently slow step. Arguably, the most promising of these is CuO, which can release O 2 in the reaction (Eqn (16.15)), although the ability of Mn to perform in the presence of other metals such as iron makes it a potentially important candidate (Imtiaz, Hooseini, & M€ uller, 2013) and the area of doping less reactive systems such as the iron one to improve performance is receiving increasing attention, especially where coal combustion is considered (Fan & Siriwardane, 2014):…”