Linking Solid-State Reduction Mechanisms to Size-Dependent Reactivity of Metal Oxide Oxygen Carriers for Chemical Looping Combustion

Alalwan, Hayder A.; Augustine, Logan J.; Hudson, Blake G.; Abeysinghe, Janaka P.; Gillan, Edward G.; Mason, Sara E.; Grassian, Vicki H.; Cwiertny, David M.

doi:10.1021/acsaem.0c02029

Cited by 15 publications

(9 citation statements)

References 34 publications

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“…This means that the reduction of CO2 percentages by adding 21% of methanol is 69, 59, and 60% at 6, 4, and 2 N.m, respectively. It can be noticed that the reduction percentages for CO gas are higher than that of CO2, which is attributed to the high oxygen content of methanol that oxidizes CO to CO2 [13]. The aromatic content of diesel fuel is one of the main reasons in the formation of NOx gases because it increases the flame temperature leading to an increase in NOx formation.…”

Section: Resultsmentioning

confidence: 99%

Identifying the impact of methanol-diesel fuel on the environment using a four-stroke CI engine

Hassan¹,

Alalwan²,

Malik³

et al. 2023

J Appl Eng Science

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This work aims to investigate the influence of blending diesel fuel with different percentages of methyl alcohol on reducing the emission of exhaust gases. The study was performed using a laboratory diesel engine, which is an internal combustion, single-cylinder, and four-strokes engine. The study involved investigating three volume percentages of methyl alcohol (methanol), which are 7, 14, and 21. The emission results of the blending fuels were compared with that of non-blending fuel. The analysis of the exhaust gases was done under three engine loads, which are two, four, and six N.m, with a constant speed of 2000 rpm. The analysis involves measuring carbon oxides (CO and CO2), unburned hydrocarbons (HC), nitrogen oxides (NOx), and particulate matter (PM). The results showed a positive impact of methanol on reducing the emission of all gases except NOx. Increasing the methanol ratio increases the reduction of the emissions of CO, CO2, PM, and HC, where the highest reductions of the gaseous emissions were observed with the percentage of 21% of methanol under all engine loads. Specifically, the drop recorded by using 21% of methanol was 69-83% for CO, 60-69% for CO2, 80-83% for HC, and 25-30% for PM. These reductions in emissions are assigned to the high oxygen content of methyl alcohol that influences the complete combustion of diesel. On the other hand, the NOx emission increased by 135-346%, but a possible reduction in these emissions can be achieved through a proper engine modification. The results of this investigation provide essential insights that would inspire using methanol as a fuel additive with modifying the diesel engines to be compatible with blending fuel.

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Section: Resultsmentioning

confidence: 99%

Identifying the impact of methanol-diesel fuel on the environment using a four-stroke CI engine

Hassan¹,

Alalwan²,

Malik³

et al. 2023

J Appl Eng Science

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“…37,38 Figure 2 shows the plots of G(a) versus t under different a (0.1 $ 0.9) at different tem- reduced phase and initial phase shows greater reactivity than the initial particles as creation of oxygen vacancies in the reduced particle bulk. 41,42 At higher temperature, the reduction process, as well as rate-determined steps, would be expected to occur more quickly,…”

Section: Kinetic Modelsmentioning

confidence: 99%

“…And, the increase in reactivity over time at certain temperature is not notable, as the products, reduction of oxygen carrier, require higher energy to release its lattice oxygen. 41,43,44 After getting the most probable mechanism function, reaction rate k(T) of oxygen releasing for oxygen carriers was obtained. Based on Equation ( 7), the A and E can be got.…”

Section: Kinetic Modelsmentioning

confidence: 99%

“…The results showed that the process of oxygen releasing for oxygen carriers can be described by A model with different model exponentials. Adding K + wouldn't change type of the most probable mechanism function of oxygen releasing process.Generally, for A model, the rates of oxygen releasing reaction is determined by the dynamic process of nucleus formation, nuclei growth, and ingestion [39][40][41]. A mixed-phase oxygen carrier with the T A B L E 2…”

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confidence: 99%

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Effects of introducing foreign ion K on the reduction kinetics of oxygen carriers in chemical looping air separation process

Hou

Qiao

et al. 2021

Env Prog and Sustain Energy

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In the previous work, YBaCo 4 O 7 + δ and Y 0.2 Ti 0.05 Dy 0.75 BaCo 4 O 7 + δ monolithic oxygen carriers worked at low temperature, were reported with good reactivity in oxygen absorption and desorption. Oxygen carriers reacted at low temperature can save amount of energy for the chemical looping air separation process. The objective of this work is to explore the detailed effect of new foreign ion K + on reaction process of oxygen releasing and the reduction kinetics for YBaCo 4 O 7 + δ and Y 0.2 Ti 0.05 Dy 0.75 BaCo 4 O 7 + δ monolithic oxygen carriers in fixed-bed reactor. The results showed that introducing K + can improve the reaction rate of oxygen releasing. The process of oxygen releasing can be described by A model with different model exponentials of 2, 3, and 4. Adding K + promotes reaction of oxygen releasing. The apparent activation energies and pre-exponential factor of oxygen releasing process range from 23.11 to 29.72 kJ/mol and 12.46 to 29.73 min À1 , respectively. The kinetic model of oxygen releasing process of monolithic oxygen carriers is established based on obtained kinetics parameters. The got kinetics parameters could be used for designing of a chemical looping air separation reactor.

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“…The rest 5% H 2 is produced by water splitting technologies, which are more expensive than SMR (e.g., $6/kg H 2 vs <$2/kg H 2 for SMR). Chemical looping (CL) is a thermochemical process emerged in recent decades as a potential hydrogen production technology. − Collectively known as chemical looping hydrogen (CLH), the process undergoes consecutive oxidation and reduction cycles over a solid oxygen carrier (OC) such as oxides . During the reduction cycle, a fuel (as a reducer) such as methane is oxidized, partially or fully depending on the application, by the lattice oxygen in an OC, producing reduced solid OC and oxidized gas-phase chemicals such as syngas.…”

Section: Introductionmentioning

confidence: 99%

Fe₃O₄/ZrO₂ Composite as a Robust Chemical Looping Oxygen Carrier: A Kinetics Study on the Reduction Process

Tang

Huang

2021

ACS Appl. Energy Mater.

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FeO x is the most popular choice of oxygen carriers for the chemical looping hydrogen (CLH) reactor and solid oxide iron−air redox battery (SOIARB) due to its earth abundance, low cost, and high oxygen content. However, the performance of an Fe/FeO x chemical looping cycle is critically limited by the reduction kinetics of FeO x . Aimed at understanding and ultimately improving the kinetics of FeO x reduction, we here report a kinetics study on isothermal H 2 reduction of an Fe 3 O 4 /ZrO 2 composite (derived from Fe 2 O 3 /ZrO 2 ) and pure Fe 3 O 4 (derived from Fe 2 O 3 ) as an oxygen carrier in a CLH and SOIARB environment. We observe that the prevailing oxide form, on which the reduction kinetics is carried out, under 10% H 2 O−Ar in 600−800 °C, is Fe 3 O 4 . We show that the reduction of Fe 3 O 4 to Fe follows two consecutive steps and can be reasonably described by phenomenological chemical-controlled and diffusion-controlled kinetic models. We also demonstrate that the presence of ZrO 2 is critical in preventing Fe particles from sintering, obtaining reliable kinetic data, and stable operation of overall chemical looping cycles. The obtained kinetic parameters provide firsthand data for engineering and design of practical CLH reactors and SOIARBs.

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Linking Solid-State Reduction Mechanisms to Size-Dependent Reactivity of Metal Oxide Oxygen Carriers for Chemical Looping Combustion

Cited by 15 publications

References 34 publications

Identifying the impact of methanol-diesel fuel on the environment using a four-stroke CI engine

Identifying the impact of methanol-diesel fuel on the environment using a four-stroke CI engine

Effects of introducing foreign ion K on the reduction kinetics of oxygen carriers in chemical looping air separation process

Fe₃O₄/ZrO₂ Composite as a Robust Chemical Looping Oxygen Carrier: A Kinetics Study on the Reduction Process

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Linking Solid-State Reduction Mechanisms to Size-Dependent Reactivity of Metal Oxide Oxygen Carriers for Chemical Looping Combustion

Cited by 15 publications

References 34 publications

Identifying the impact of methanol-diesel fuel on the environment using a four-stroke CI engine

Identifying the impact of methanol-diesel fuel on the environment using a four-stroke CI engine

Effects of introducing foreign ion K on the reduction kinetics of oxygen carriers in chemical looping air separation process

Fe3O4/ZrO2 Composite as a Robust Chemical Looping Oxygen Carrier: A Kinetics Study on the Reduction Process

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Product

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Fe₃O₄/ZrO₂ Composite as a Robust Chemical Looping Oxygen Carrier: A Kinetics Study on the Reduction Process