Inhibiting Fe–Al Spinel Formation on a Narrowed Mesopore-Sized MgAl2O4 Support as a Novel Catalyst for H2 Production in Chemical Looping Technology

Hafizi, Ali; Rahimpour, Mohammad Reza

doi:10.3390/catal8010027

Cited by 19 publications

(9 citation statements)

References 33 publications

(42 reference statements)

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“…Regarding Fe-based oxygen carriers, promoter materials such as Al 2 O 3 [78,79,80,81,82], MgO [83,130], TiO 2 [84,85,86], SiO 2 [87], MgAl 2 O 4 [88,89,90,91,103], CaO [92,93], ZrO 2 [94,95,96] and CeO 2 [22,97,98,99,100] have received extensive scientific attention in the past decades. However, these promoters can easily lead to solid-solid transformation with iron oxides during a continuous cycling process [127].…”

Section: Improvements To Oxygen Carriersmentioning

confidence: 99%

Advanced Chemical Looping Materials for CO2 Utilization: A Review

Galvita

Poelman

et al. 2018

Materials

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Combining chemical looping with a traditional fuel conversion process yields a promising technology for low-CO2-emission energy production. Bridged by the cyclic transformation of a looping material (CO2 carrier or oxygen carrier), a chemical looping process is divided into two spatially or temporally separated half-cycles. Firstly, the oxygen carrier material is reduced by fuel, producing power or chemicals. Then, the material is regenerated by an oxidizer. In chemical looping combustion, a separation-ready CO2 stream is produced, which significantly improves the CO2 capture efficiency. In chemical looping reforming, CO2 can be used as an oxidizer, resulting in a novel approach for efficient CO2 utilization through reduction to CO. Recently, the novel process of catalyst-assisted chemical looping was proposed, aiming at maximized CO2 utilization via the achievement of deep reduction of the oxygen carrier in the first half-cycle. It makes use of a bifunctional looping material that combines both catalytic function for efficient fuel conversion and oxygen storage function for redox cycling. For all of these chemical looping technologies, the choice of looping materials is crucial for their industrial application. Therefore, current research is focused on the development of a suitable looping material, which is required to have high redox activity and stability, and good economic and environmental performance. In this review, a series of commonly used metal oxide-based materials are firstly compared as looping material from an industrial-application perspective. The recent advances in the enhancement of the activity and stability of looping materials are discussed. The focus then proceeds to new findings in the development of the bifunctional looping materials employed in the emerging catalyst-assisted chemical looping technology. Among these, the design of core-shell structured Ni-Fe bifunctional nanomaterials shows great potential for catalyst-assisted chemical looping.

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Section: Improvements To Oxygen Carriersmentioning

confidence: 99%

Advanced Chemical Looping Materials for CO2 Utilization: A Review

Galvita

Poelman

et al. 2018

Materials

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“…[ 7,12,13 ] However, since iron oxide and alumina can form spinel structures at high temperatures, which limits the reduction of oxygen carriers, it is important to improve the reduction kinetics of oxygen carriers. [ 12,14 ] Some studies have reported the use of the self‐diffusion characteristics of alkali metals to improve the reduction kinetics of the OCs. [ 7,13,15,16 ] However, alkali metals volatilize and deactivate at high temperatures, which prevents the oxygen carrier from being reused in multiple cycles and corrodes the reactor.…”

Section: Introductionmentioning

confidence: 99%

Research of coal‐direct chemical looping hydrogen generation with iron‐based oxygen carrier modified by NaAlO₂

Zhang

et al. 2020

Can J Chem Eng

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This study reports a high-performance modified oxygen carrier (OC) in a three-cycle chemical looping process in which coal is used as the raw feedstock to produce hydrogen. A series of experiments of coal-direct chemical looping hydrogen generation (CLHG) were conducted in a batch fluidized bed reactor, in the absence or presence of the NaAlO 2. The experimental results indicated that the carbon conversion and hydrogen yield reached 87.0% and 1.30 L Á g −1 , respectively, when the coal/oxygen carrier (Fe4Al6) mass ratio was 1:20. However, FeO was the main product of the reduction process with Fe4Al6, which limits the production of hydrogen during steam oxidation. Therefore, NaAlO 2 was used to improve the reaction performance of the OC. The carbon conversion and hydrogen production of NaAlO 2-loaded oxygen carriers were 10.7% and 9.6% higher than Fe4Al6, respectively. X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET), and temperatureprogrammed reduction (TPR) techniques were used to characterize the oxygen carriers. According to the XRD analysis results, the addition of 5 wt% NaAlO 2 can generate NaFeO 2. The unique layer structure of NaFeO 2 can loosen the structure between Fe 2 O 3 and Al 2 O 3. Thus, the surface morphology and pore structure of the oxygen carrier were improved, which are responsible for the enhancement in reactivity rather than the catalytic effects of the alkali metal. The cycle performance of the Na0.5Fe4Al6 remained stable after multi-redox cycles, and no serious sintering phenomena were observed; in addition, the carbon conversion and hydrogen yield remained above 86% and 1.40 L Á g −1 , respectively. K E Y W O R D S chemical looping, crystal structure, Fe 2 O 3 /Al 2 O 3 , H 2 production, sodium modification 1 | INTRODUCTION Currently there is growing interest in using hydrogen as a clean energy carrier since it can provide a high Jinshuai Li and Xiuli Zhang contributed equally to this work.

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“…[18]), H 2 evolution [25], and CO 2 reduction [26,27]. Six other papers focus on conventional catalysis ("dark" reactions), reporting efficient H 2 production [28,29], synthesis of ethanol and butanol [30], direct conversion of CO 2 and methanol to dimethyl carbonate [31], water purification [32], and advanced characterization of catalysts by X-ray absorption fine structure (EXAFS) spectroscopy [33]. The majority of studies have been performed with particulate catalysts (nanoparticles (NPs)), but organized nanostructures, such as nanotubes (TiO 2 /Cu x O y [18], carbon nanotubes (CNTs) [30,32]) and nanowires (CeO 2 [31]) have also been used.…”

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confidence: 99%

“…They found that the surface reduction under H 2 atmosphere formed acidic/alkaline sites on the catalyst surface, and thus significantly improved catalytic activity, reducing the activation energy barrier from 74.7 to 41.9 kJ/mol. Complex catalytic studies were performed by Hafizi and Rahimpour for catalytic H 2 production [28]. The effect of alumina and Mg-Al spinel as the support for the formation of Fe 2 O 3 catalyst was investigated.…”

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confidence: 99%