Natural Iron Ore as Oxygen Carrier Modified with Rare Earth Metal for Chemical Looping Hydrogen Production

Abstract

Chemical looping hydrogen production (CLHG) represents a novel technology for H2 production. Natural iron ore is a potential oxygen carrier for CLHG but is facing a challenge of low deep reduction reactivity. This paper aims at promoting the reduction reactivity of iron ore and H2 production using Ce-doped and La-doped iron ore with an impregnation method. The oxygen carriers were characterized by SEM-EDX, XRD, and XPS. The reactivity and stability of the doped iron ore were evaluated in TGA. The CLHG process was carried out in a fixed bed system, and the effect of rare earth metal on oxygen carrier conversion and H2 production was evaluated. The results indicate that both Ce-doped and La-doped iron ore as oxygen carriers exhibited a higher reduction reactivity than the raw iron ore and a relatively stable redox performance at 900 °C after the initial activation process. Reasonable Ce loading (5–10%), La loading (2.5–15%), and temperature (above 850 °C) could promote oxygen carrier conversion and enhance H2 production. The La-Fe interaction enabled the iron ore to be oxidized to LaFeO3 (Fe3+) during water splitting, promoting H2 production. Carbon deposition was not formed during the reduction process, and H2 purity remained at 100% during the whole water splitting process.

Research Progress and Perspectives of Solid Fuels Chemical Looping Reaction with Fe-Based Oxygen Carriers

“…As the addition of KNO 3 in iron ore increases from 0 to 10%, not only the conversion of carbon but also the hydrogen production is accelerated. Gu et al 69 also used Ce-and La-doped iron ore to enhance the H 2 production via fast and deep reduction, and the results indicated that (i) no coke was formed during the entire oxygen carrier reduction process, and (ii) all oxygen carriers were 100% H 2 throughout the CLWS process. In addition, Zhu et al 173 reported the Cemodified iron oxide to improve the antiactivation of Fe-based sand at 700 °C on an Fe 2 O 3 oxygen carrier.…”

“…Since then, Fe-based oxygen carriers continued to develop in chemical looping reaction process. Fe-based oxygen carriers are widely applied in chemical looping combustion (CLC), − chemical looping gasification (CLG), − chemical looping reforming (CLR), − chemical looping water splitting (CLWS) − and oxygen carrier aided combustion (OCAC), , as shown in Figure . Fe-based oxygen carriers have the following characteristics: Low cost.…”

Chemical looping reforming: process fundamentals and oxygen carriers

“…And when nickel was introduced, the oxygen carrier was reduced to form Ni or Ni-Fe so that syngas was prepared in the presence of CO 2 . Different from the introduction of transition metal oxides, Gu et al [284] modified natural iron ore with rare earth metals, and found that the introduction of CeO 2 and La 2 O 3 both promoted the reactivity of iron ore, and no carbon deposits were found during the reduction process. The introduction of La 2 O 3 causes the formation of LaFeO 3 after the oxygen carrier is oxidized, which is beneficial to the H 2 production.…”

Effect of Supports on the Performance of La-Modified CoFe2O4 Oxygen Carriers in Chemical Looping Hydrogen Generation from Hydrogen-Rich Syngas

“…10,11 The oxygen transfer between the fuel reactor (FR), steam reactor (SR), and air reactor (AR) through OCs achieves the synergistic production of high-purity hydrogen with the internal separation of CO 2 . 12,13 In the previous study, 14 we proposed a novel CL cascade-coupled hydrogen generation (CL-CCHG) process to achieve efficient conversion and purification of hydrogen-rich syngas obtained from an auto-thermal CL reforming (CLRa) or CL gasification (CLG) process at the front end (Figure S1). This process avoids the use of water gas shift catalysts and CO 2 adsorbents, significantly reducing the energy consumption and cost of the post-treatment step.…”

“…Chemical looping (CL) is a novel alternative technology that uses oxygen carriers (OCs) to break down chemical reactions into multiple sub-reactions, optimizing material and energy distribution to achieve low cost and low emissions. − CL hydrogen generation (CLHG) is an energy-efficient, safe, and low-cost route. , The oxygen transfer between the fuel reactor (FR), steam reactor (SR), and air reactor (AR) through OCs achieves the synergistic production of high-purity hydrogen with the internal separation of CO 2 . , In the previous study, we proposed a novel CL cascade-coupled hydrogen generation (CL-CCHG) process to achieve efficient conversion and purification of hydrogen-rich syngas obtained from an auto-thermal CL reforming (CLRa) or CL gasification (CLG) process at the front end (Figure S1). This process avoids the use of water gas shift catalysts and CO 2 adsorbents, significantly reducing the energy consumption and cost of the post-treatment step.…”