scholarly journals Devolatilization of Residual Biomasses for Chemical Looping Gasification in Fluidized Beds Made up of Oxygen-Carriers

Energies ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 311
Author(s):  
Andrea Di Giuliano ◽  
Stefania Lucantonio ◽  
Katia Gallucci
Keyword(s):  
Fluidized Beds ◽  
Oxygen Carrier ◽  
Reaction Model ◽  
Chemical Looping ◽  
Oxygen Carriers ◽  
First Order ◽  
Fluidizing Agent ◽  
Mitigate Climate Change ◽  
Bubbling Beds ◽  
Better Than

The chemical looping gasification of residual biomasses—operated in fluidized beds composed of oxygen-carriers—may allow the production of biofuels from syngas. This biomass-to-fuel chain can contribute to mitigate climate change, avoiding the accumulation of greenhouse gases in our atmosphere. The ongoing European research project Horizon2020 CLARA (G.A. 817841) investigates wheat-straw-pellets (WSP) and raw-pine-forest-residue (RPR) pellets as feedstocks for chemical looping gasification. This work presents experimental results from devolatilizations of WSP and RPR, in bubbling beds made of three different oxygen-carriers or sand (inert reference), at 700, 800, 900 °C. Devolatilization is a key step of gasification, influencing syngas quality and quantity. Tests were performed at laboratory-scale, by a quartz reactor (fluidizing agent: N2). For each pellet, collected data allowed the quantification of released gases (H2, CO, CO2, CH4, hydrocarbons) and mass balances, to obtain gas yield (ηav), carbon conversion (χavC), H2/CO ratio (λav) and syngas composition. A simplified single-first order-reaction model was adopted to kinetically analyze experimental data. WSP performed as RPR; this is a good indication, considering that RPR is similar to commercial pellets. Temperature is the dominating parameter: at 900 °C, the highest quality and quantity of syngas was obtained (WSP: ηav = 0.035–0.042 molgas gbiomass−1, χavC = 73–83%, λav = 0.8–1.0); RPR: ηav = 0.036–0.041 molgas gbiomass−1, χavC = 67–71%, λav = 0.9–1.0), and oxygen-carries generally performed better than sand. The kinetic analysis suggested that the oxygen-carrier ilmenite ensured the fastest conversion of C and H atoms into gases, at tested conditions.

The Sustainable Capability Research on Copper- and Iron-Based Oxygen Carrier

2010 ◽  
Vol 146-147 ◽  
pp. 1398-1401
Author(s):  
Lei Chen ◽  
Jing Jin ◽  
Hui Wei Duan
Keyword(s):  
Oxygen Carrier ◽  
Pure Oxygen ◽  
Chemical Looping ◽  
Oxygen Carriers ◽  
Reaction Ratio ◽  
Iron Based ◽  
Reduction And Oxidation ◽  
The One ◽  
The Comparative Study ◽  
Better Than

Chemical-looping combustion (CLC) is a new kind of efficient method to separate CO2. At present, most of CLC research focuses on the development of oxygen carriers. The sustainable capability is the one of important standards to evaluate performance of oxygen carrier. The iron- based and copper- based oxygen carrier were chosen in this paper. The comparative study between the analytically pure oxygen carriers and the prepared oxygen carriers with Al2O3 were made according to the reactivity of reduction and oxidation. The data was obtained by the TGA, SEM and XRD. The results show that the prepared carriers with Al2O3 are greatly improved both in reaction ratio and sustainable capability, and Fe- based oxygen carrier is better than the Cu- based oxygen carrier in the sustainable capability.

scholarly journals Reverse Water–Gas Shift Chemical Looping Using a Core–Shell Structured Perovskite Oxygen Carrier

Energies ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 5324
Author(s):  
Minbeom Lee ◽  
Yikyeom Kim ◽  
Hyun Suk Lim ◽  
Ayeong Jo ◽  
Dohyung Kang ◽  
...  
Keyword(s):  
Metal Oxide ◽  
Oxygen Carrier ◽  
Dark Field ◽  
Water Gas Shift ◽  
Unit Weight ◽  
Core Shell ◽  
Chemical Looping ◽  
Oxygen Carriers ◽  
Reverse Water Gas Shift ◽  
Water Gas

Reverse water–gas shift chemical looping (RWGS-CL) offers a promising means of converting the greenhouse gas of CO2 to CO because of its relatively low operating temperatures and high CO selectivity without any side product. This paper introduces a core–shell structured oxygen carrier for RWGS-CL. The prepared oxygen carrier consists of a metal oxide core and perovskite shell, which was confirmed by inductively coupled plasma mass spectroscopy (ICP-MS), XPS, and high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) measurements. The perovskite-structured shell of the prepared oxygen carrier facilitates the formation and consumption of oxygen defects in the metal oxide core during H2-CO2 redox looping cycles. As a result, amounts of CO produced per unit weight of the core–shell structured oxygen carriers were higher than that of a simple perovskite oxygen carrier. Of the metal oxide cores tested, CeO2, NiO, Co3O4, and Co3O4-NiO, La0.75Sr0.25FeO3-encapsulated Co3O4-NiO was found to be the most promising oxygen carrier for RWGS-CL, because it was most productive in terms of CO production and exhibited long-term stability.

Review of Hydrogen Production from the Steam-Iron Process by Chemical-Looping Combustion

2014 ◽  
Vol 953-954 ◽  
pp. 966-969 ◽  
Author(s):  
Long Fei Wang ◽  
Shu Zhong Wang ◽  
Ming Luo
Keyword(s):  
Hydrogen Production ◽  
Solid Fuel ◽  
Process Development ◽  
Oxygen Carrier ◽  
Energy Conversion Efficiency ◽  
High Reactivity ◽  
Future Research ◽  
Pure Hydrogen ◽  
Chemical Looping ◽  
Oxygen Carriers

Chemical looping hydrogen production (CLH) is a promising method for pure hydrogen production, which not only can improve energy conversion efficiency and reduce environmental pollution, but also can separate carbon dioxide. This paper try to review the present chemical looping hydrogen process development on the screening of oxygen carrier particles of gaseous fuel and solid fuel, the design of proper reactors, and the system simulation. The design of solid fuel CLH system and the development of oxygen carriers with high reactivity and abrasion resistance for solid fuel at high temperature and pressure will be future research focuses.

scholarly journals Syngas Generation from Methane Using a Chemical-Looping Concept: A Review of Oxygen Carriers

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Kongzhai Li ◽  
Hua Wang ◽  
Yonggang Wei
Keyword(s):  
Oxygen Carrier ◽  
Cost Savings ◽  
Oxygen Storage ◽  
Pure Oxygen ◽  
Chemical Looping ◽  
Oxygen Carriers ◽  
Gaseous Oxygen ◽  
Solid Oxides ◽  
Oxidation Of Methane ◽  
Gaseous Oxidant

Conversion of methane to syngas using a chemical-looping concept is a novel method for syngas generation. This process is based on the transfer of gaseous oxygen source to fuel (e.g., methane) by means of a cycling process using solid oxides as oxygen carriers to avoid direct contact between fuel and gaseous oxygen. Syngas is produced through the gas-solid reaction between methane and solid oxides (oxygen carriers), and then the reduced oxygen carriers can be regenerated by a gaseous oxidant, such as air or water. The oxygen carrier is recycled between the two steps, and the syngas with a ratio of H2/CO = 2.0 can be obtained successively. Air is used instead of pure oxygen allowing considerable cost savings, and the separation of fuel from the gaseous oxidant avoids the risk of explosion and the dilution of product gas with nitrogen. The design and elaboration of suitable oxygen carriers is a key issue to optimize this method. As one of the most interesting oxygen storage materials, ceria-based and perovskite oxides were paid much attention for this process. This paper briefly introduced the recent research progresses on the oxygen carriers used in the chemical-looping selective oxidation of methane (CLSOM) to syngas.

scholarly journals Computational Fluid Dynamics Modeling of the Fuel Reactor in NETL's 50 kWth Chemical Looping Facility

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Ronald W. Breault ◽  
Justin Weber ◽  
Doug Straub ◽  
Sam Bayham
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Oxygen Carrier ◽  
Fixed Bed ◽  
Nucleation And Growth ◽  
Chemical Looping ◽  
Gravimetric Analysis ◽  
Oxygen Carriers ◽  
Dynamics Modeling ◽  
Fuel Reactor

The National Energy Technology Laboratory (NETL) has explored chemical looping in its 50 kWth facility using a number of oxygen carriers. In this work, the results for methane conversion in the fuel reactor with a hematite iron ore as the oxygen carrier are analyzed. The experimental results are compared to predictions using CPFD's barracuda computational fluid dynamics (CFD) code with kinetics derived from the analysis of fixed bed data. It has been found through analytical techniques from thermal gravimetric analysis data as well as the same fixed bed data that the kinetics for the methane–hematite reaction follows a nucleation and growth or Johnson–Mehl–Avrami (JMA) reaction mechanism. barracuda does not accept nucleation and growth kinetics; however, there is enough sufficient variability of the solids dependence within the software such that the nucleation and growth behavior can be mimicked. This paper presents the method to develop the pseudo-JMA kinetics for barracuda extracted from the fixed bed data and then applies these values to the fuel reactor data to compare the computational results to experimental data obtained from 50 kWth unit for validation. Finally, a fuel reactor design for near complete conversion is proposed.

scholarly journals Na-β-Al2O3 stabilized Fe2O3 oxygen carriers for chemical looping water splitting: correlating structure with redox stability

2021 ◽  
Author(s):  
Nur Sena Yüzbasi ◽  
Andac Armutlulu ◽  
Thomas Huthwelker ◽  
Paula Abdala ◽  
Christoph Müller
Keyword(s):  
Fossil Fuels ◽  
Oxygen Carrier ◽  
Chemical Looping ◽  
Oxygen Carriers ◽  
Cycle Number ◽  
X Ray ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Edx Analyses ◽  
H2 Yield

Chemical looping is an emerging technology to produce high purity hydrogen from fossil fuels or biomass with the simultaneous capture of the CO2 produced at the distributed scale. This process requires the availability of stable Fe2O3-based oxygen carriers. Fe2O3-Al2O3 based oxygen carriers exhibit a decay in the H2 yield with cycle number due to the formation of FeAl2O4 that cannot be re-oxidized. In this study, the addition of sodium (via a sodium salt) in the synthesis of Fe2O3-Al2O3 oxygen carriers was assessed as a means to counteract the cyclic deactivation of the oxygen carrier. Detailed insight into the oxygen carrier’s structure was gained by combined X-ray powder diffraction (XRD), X-ray absorption spectroscopy (XAS) at the Al, Na and Fe K-edges and scanning transmission electron microscopy/energy-dispersive X-ray spectroscopy (STEM/EDX) analyses. The addition of sodium prevented the formation of FeAl2O4 and stabilized the oxygen carrier via the formation of a layered structure, Na-β-Al2O3 phase. The resulting material, Na-β-Al2O3 stabilized Fe2O3, showed a very high H2 yield of ca. 13.3 mmol/g during 15 cycles.

scholarly journals LaFe1-xNix as a Robust Catalytic Oxygen Carrier for Chemical Looping Conversion of Toluene

2021 ◽  
Vol 12 (1) ◽  
pp. 391
Author(s):  
Haiming Gu ◽  
Juan Yang ◽  
Guohui Song ◽  
Xiaobo Cui ◽  
Miaomiao Niu ◽  
...  
Keyword(s):  
Oxygen Carrier ◽  
Fixed Bed ◽  
Chemical Looping ◽  
Oxygen Carriers ◽  
Carbon Gasification ◽  
Syngas Production ◽  
Toluene Conversion ◽  
Substituted Ferrite ◽  
Tar Model Compound ◽  
H2 Yield

Chemical looping biomass gasification is a novel technology converting biomass into syngas, and the selection of oxygen carrier is key for efficient tar conversion. The performance of LaFe1-xNix as a robust catalytic oxygen carrier was investigated in the chemical looping conversion of toluene (tar model compound) into syngas in a fixed bed. LaM (M = Fe, Ni, Mn, Co, and Cu) was initially compared to evaluate the effect of transition metal on toluene conversion. LaFe (partial oxidation) and LaNi (catalytic pyrolysis) exhibited better performance in promoting syngas production than other oxygen carriers. Therefore, Ni-substituted ferrite LaFe1-xNix (x = 0, 0.2, 0.4, 0.6, 0.8 and 1) was further developed. The effects of Ni-substitution, steam/carbon ratio (S/C), and temperature on toluene conversion into C1 and H2 were evaluated. Results showed that the synergistic effect of Fe and Ni promoted toluene conversion, improving H2 yield yet with serious carbon deposition. Steam addition promoted toluene steam reforming and carbon gasification. With S/C increasing from 0.8 to 2.0, the C1 and H2 yield increased from 73.9% to 97.5% and from 197.7% to 269.6%, respectively. The elevated temperature favored toluene conversion and C1 yield. LaFe0.6Ni0.4 exhibited strong reactivity stability during toluene conversion at S/C = 1.6 and 900 °C.

scholarly journals Preventing Agglomeration of CuO-Based Oxygen Carriers for Chemical Looping Applications

2021 ◽  
Author(s):  
Qasim Imtiaz ◽  
Andac Armutlulu ◽  
Felix Donat ◽  
Muhammad Awais Naeem ◽  
Christoph Müller
Keyword(s):  
Thin Films ◽  
Focused Ion Beam ◽  
Pechini Method ◽  
Ion Beam ◽  
Oxygen Carrier ◽  
Structural Instability ◽  
Chemical Looping ◽  
Oxygen Carriers ◽  
Promising Alternative ◽  
Main Challenge

Chemical looping combustion (CLC) is a promising alternative to the conventional combustion-based, fossil fuel conversion processes. In CLC, a solid oxygen carrier is used to transfer oxygen from air to a carbonaceous fuel. This indirect combustion route allows for effective CO<sub>2</sub> capture since a sequestrable stream of CO<sub>2 </sub>is inherently produced without any need for energy-intensive CO<sub>2</sub> separation. From a thermodynamic point of view, CuO is arguably one of the most promising oxygen carrier candidates for CLC. However, the main challenge associated with the use of CuO for CLC is its structural instability at the typical operating temperatures of chemical looping processes, leading to severe thermal sintering and agglomeration. To minimize irreversible microstructural changes during CLC operation, CuO is commonly stabilized by a high Tammann temperature ceramic, e.g., Al<sub>2</sub>O<sub>3</sub>, MgAl<sub>2</sub>O<sub>4</sub>, etc. However, it has been observed that a high Tammann temperature support does not always provide a high resistance to agglomeration. This work aims at identifying descriptors that can be used to characterize accurately the agglomeration tendency of CuO-based oxygen carriers. CuO-based oxygen carriers supported on different metal oxides were synthesized using a Pechini method. The cyclic redox stability and agglomeration tendency of the synthesized materials was evaluated using both a thermo-gravimetric analyser and a lab-scale fluidized bed reactor at 900 °C using 10 vol. % H<sub>2</sub> in N<sub>2</sub> as the fuel and air for re-oxidation. In order to study the diffusion of Cu(O) during redox reactions, well-defined model surfaces comprising thin films of Cu/CuO and two different supports, viz. ZrO<sub>2</sub> or MgO, were prepared via magnetron sputtering. Energy dispersive X-ray (EDX) spectroscopy on focused ion beam (FIB)-cut cross-sections of the thin films revealed that Cu atoms have a tendency to diffuse outward through most of the films of the support material under redox conditions. The support that inhibits the outward movement of Cu(O), i.e. avoiding the presence of low melting Cu on the oxygen carrier surface, is found to provide the highest agglomeration resistance. The support MgO was found to possesses such diffusion characteristics.

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