Characterization and Evaluation of Prepared Fe2O3/Al2O3 Oxygen Carriers for Chemical Looping Process

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Chemical looping hydrogen generation (CLHG), as a new technology involved in chemical looping combustion (CLC) process and steam-iron process, has attracted attention for clean energy generation and efficient energy conversion. A systematic investigation of spinel NiFeAlO 4 has led to characterization of a well-defined self-supported oxygen carrier which was prepared by solid state reaction. The redox behavior of NiFeAlO 4 shows the enhancement on the resistance to agglomeration exceeding previously reported CLC process using similar compositions including Fe 2 O 3 , NiO and NiFe 2 O 4 without any inert support. Moreover, the high CO 2 conversion and H 2 generation by NiFeAlO 4 oxygen carrier under a fixed-bed reactor (FxBR) were obtained. The reaction mechanism of NiFeAlO 4 subjected to the isothermal stepwise reduction in a sequence of varying durations by XRD was also demonstrated, which provided with a novel function of selfsupported and agglomeration-resistant characteristic in the oxygen carrier system.

Section: Introductionmentioning

confidence: 99%

Use of Spinel Nickel Aluminium Ferrite as Self-Supported Oxygen Carrier for Chemical Looping Hydrogen Generation Process

Kuo

Huang

Hsu

et al. 2015

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“…oxygen carriers were examined by a field emission scanning electron microscope (FESEM) have been clearly described in previous publication. (Chiu et al, 2014) …”

Section: Introductionmentioning

confidence: 99%

Chemical Looping Gasification of Charcoal with Iron-Based Oxygen Carriers in an Annular Dual-Tube Moving Bed Reactor

2016

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Charcoal used as solid fuel for chemical looping gasification (CLG) with Fe 2 O 3 /Al 2 O 3 oxygen carriers was investigated in an annular dual-tube moving bed reactor (ADMBR). Pure CO 2 and steam/CO 2 mixture were used to gasify the charcoal in a fixed bed reactor. More combustible gases, CO and H 2 , were observed in the outlet gas streams for charcoal gasification conducted with steam/CO 2 mixture than those with only CO 2 . The yields of fuel gases were determined to modify the equation of oxygen carrier-to-fuel ratio (ϕ) for moving bed operation. More CO and H 2 were generated for charcoal gasification conducted in the moving bed reactor operated with higher oxygen carrier-to-fuel ratios. The heat demand for experiment conducted in the ADMBR was calculated to be 60% of output processing capacity due to the heat consumptions of fuel gasification. In sum, ADMBR is technically feasible to be a fuel reactor for partial oxidization of charcoal by CLG to achieve syngas production under appropriate operating conditions without auxiliary fuel.

“…11, the reduction conversion for experiments conducted with FeAl320-S10 pellets was decreased from about 90% to 70% after operated for 20 redox cycles, indicating that the recyclability of Fe 2 O 3 was considerably improved with Al 2 O 3 support. Chiu et al (2014) indicated that the conversion of Fe 2 O 3 pellet was decayed rapidly after the second redox cycle. However, the conversion of Fe 2 O 3 /Al 2 O 3 pellet was maintained at above 70% during continuous redox cycling.…”

Section: Resultsmentioning

confidence: 99%

“…Insignificant deactivation, agglomeration, carbon deposition, and attrition were observed by Abad et al (2007) using the Al 2 O 3 -supported Fe 2 O 3 oxygen-carriers for natural gas or syngas combustion in a thermogravimetric analyzer. Chiu et al (2014) reported that Fe 2 O 3 /Al 2 O 3 oxygen carriers demonstrated reasonable oxygen conversion and delivered high CO 2 yields for chemical looping combustion of methane and syngas (CO/H 2 ) in a fixed bed reactor. Ku et al (2014) revealed that the completely methane combustion was achieved for experiments carrier out with Fe 2 O 3 /Al 2 O 3 in a moving bed fuel reactor, and carbon deposition was significantly reduced.…”

Section: Introductionmentioning

confidence: 99%

Preparation of Fe2O3/Al2O3 and Fe2O3/TiO2 Pellets as Oxygen Carrier for Chemical Looping Process

Lin

et al. 2017

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Fe-based oxygen carriers supported by Al 2 O 3 and TiO 2 were prepared as pellets for chemical looping combustion in this study. Over 90% conversions were obtained for most experiments operated in the TGA; however, experiments conducted with FeTi320 pellets exhibited higher conversions than those with FeAl320. The prepared pellets sintered at higher temperatures always exhibited higher crush strength. The crush strength of prepared FeAl320 and FeTi320 pellets were decreased for experiments conducted with greater starch content, because the more pore spaces are formed in the original places of the starch grains. For experiments conducted in the fixed bed reactor, the prepared pellets exhibited relatively high conversion. The conversions of FeTi320 were remained to be about 80% with increasing starch content because high porosity (approximately 50%) was formed for 0-20% starch contents of FeTi320 pellets after 10 redox cycles. Less porosity was formed after 20 redox cycles for experiments conducted with FeAl320 pellets prepared with higher starch contents. Therefore, the conversion of FeAl320 pellets was elevated with increasing starch content. Iron content for inner part of prepared pellets was significantly decreased after operated for 20 redox cycles, while iron content for outer part of pellets were increased. It is suggested that the iron ions may diffuse onto the surface of oxygen carriers to react with oxygen during the oxidation period.