Thermal oxidation of iron nanoparticles and its implication for chemical‐looping combustion

Abstract

BACKGROUND: Chemical looping combustion (CLC) is a promising environmentally friendly technology in which the greenhouse gas CO 2 can be readily separated at high-purity, therefore providing an effective method of carbon capture. Its performance, however, is limited by the kinetics of oxidation of the oxygen carrier, whose size is typically in the range of micrometers to millimetres. This paper reports a new idea using metallic nanoparticles as potential oxygen carriers to improve the performance of chemical looping combustion.

Study of Oxidation and Combustion Characteristics of Iron Nanoparticles under Idealized and Enginelike Conditions

“…highest slope of TGA curve) for the micron-sized sample was shifted to noticeably higher temperatures, in the range of 700-800 K. Maximum conversion rate for the nanopowder grades occurred at approximately 500-600 K, while a conversion ratio of at least 90% had been achieved at T = 650 K, which is similar to findings reported in [14] for TGA of iron nanoparticles of 45 -400 nm under air. With the exception of a clear trend between Fe50 and Fe70, an apparent correlation between conversion rate and the APPS of the nanopowders examined could not be readily identified.…”

Kinetics of the oxidation of an electroexplosion iron nanopowder during heating in air

“…The effective activation energy of the oxidation of INP was determined from the lnk lin = f(1/T) depen dence by using the data obtained under isothermal con ditions at 250-370°С (Table 4): Е а = 100 ± 7 kJ/mol. Note that it is impossible to use data on the rate of oxi dation under conditions of linear heating for calculat ing Е а in the case of the INP, as suggested in [17], since its oxidation is accompanied by the self heating of the sample and the transition of the process from quasi isothermal to nonisothermal even at low rates of growth of the temperature of the thermoanalyzer fur nace. In this case, the processing of nonisothermal data gives overestimated values of the activation energy, which, depending on the degree of conversion can vary for the same sample [17].…”

“…For highly dispersed powders, the published data differ significantly [14][15][16][17]. It was shown [14] that, with increasing fraction of submicron particles in the powder, the oxidation begins at a lower temperature and occurs in two stages under conditions of linear heating.…”

“…In the first stage, fine particles oxidize to form Fe 2 O 3 . Using nonisothermal data (180-600°С) for electroexplosion iron nanopowder (d max ≈ 100 nm), the authors of [17] obtained Е а = 87-183 kJ/mol, depending on the degree of conversion. The kinetic data in [17] were analyzed based on the equation 4Fe + 3O 2 = 2Fe 2 O 3 , although the phase composition of the oxidation products is expected to be different at low temperatures.…”

Efficient synthesis of iron nanoparticles by self‐agglomeration in a fluidized bed

“…Iron nanoparticles (Fe NPs) have a vast range of potential applications in powder metallurgy, chemical engineering, and the biomedical and environmental industries, such as components of magnetic fluids, catalysts for the Fischer‐Tropsch synthesis and carbon nanotube growth, magnetic resonance imaging (MRI) contrast agents, nickel‐iron batteries, thermal batteries, and sorbents for environmental remediation . In recent years, Fe NPs have been considered for use as oxygen carriers (OCs) in chemical looping combustion (CLC) systems …”