Local structures of metals dispersed on coal. 5. Effect of coal, catalyst precursor, and catalyst preparation method on the structure of iron species during heat treatment and steam gasification

Yamashita, Hiromi; Tomita, Akira

doi:10.1021/ie00015a003

Cited by 15 publications

(12 citation statements)

References 7 publications

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“…The first mass lose stage between 80 and 120 • C resulted from the dehydration reaction, and the other dramatic peak around 150 • C was ascribed to the decomposition of Fe(N). The DTG results of Fe(C) ( Figure 3b) showed that a dramatic peak occurred at about 100 • C because of the crystal water removal, and the other two peaks appeared at 205 and 380 • C, respectively, indicating that more complicated chemical reactions and changeable iron species occurred for Fe(C) in the thermal process, which is in agreement with that reported by Yamashita and Tomita [23,24]. For pyrolysis of EX without catalyst ( Figure 4a), approximately 77.88% of the compounds contained in EX were removed before 700 °C, for which the residual yield remained almost unchanged.…”

Section: Thermal Behaviors Of Extract With/without Catalystsupporting

confidence: 90%

“…With the separate addition of Fe(N) and Fe(C), the average value of EX-Fe(N) and EX-Fe(C) was obviously decreased to 122.17 and 102.39 kJ/mol, respectively, indicating that Fe-based catalysts facilitate the cracking of EX, leading to an increase in EX reactivity, and making the pyrolysis reactions more available. Moreover, the catalytic effect of Fe(C) was higher than Fe(N), which may be due to the appearance of ferrous ion [24,29] in the thermal treatment of Fe(C).…”

Section: Kinetic Analysismentioning

confidence: 96%

“…Fu et al [5] considered that Fe-based catalyst facilitated the decomposition of aliphatic chains and O-containing structures, thereby the weight loss for EX-Fe(N) and EX-Fe(C) dramatically increased in the temperature range 200-500 °C. Yamashita et al [24] studied the local structures of Fe(NO3)3 and FeCl3 during the thermal treatment of ironloaded brown coal. The iron species of Fe(NO3)3 were exhibited mainly as atomically dispersed Fe or ultrafine FeOOH blow 650 °C, while that of FeCl3 easily aggregated to crystalline FeO at 500 °C.…”

Section: Thermal Behaviors Of Extract With/without Catalystmentioning

confidence: 99%

“…It is believed that the reactions in a certain temperature range are generally related to the cleavage of specific chemical bonds in coal pyrolysis, and the decomposition of C ar -C al and C ar -O structures generally occurs at temperatures above 550 • C [28]. Fu et al [5] considered that Fe-based catalyst facilitated the decomposition of aliphatic chains and O-containing structures, thereby the weight loss for EX-Fe(N) and EX-Fe(C) dramatically increased in the temperature range 200-500 • C. Yamashita et al [24] studied the local structures of Fe(NO 3 ) 3 and FeCl 3 during the thermal treatment of iron-loaded brown coal. The iron species of Fe(NO 3 ) 3 were exhibited mainly as atomically dispersed Fe or ultrafine FeOOH blow 650 • C, while that of FeCl 3 easily aggregated to crystalline FeO at 500 • C. Moreover, Zhao et al [29] demonstrated that ferrous ions, such as Fe 3 O 4 and FeO, possessed a better catalytic effect for cracking the coal structure in the pyrolysis, which is due to the mass loss ratio of EX-Fe(C) being enlarged more than that of EX-Fe(N) after the temperature reached 450 • C.…”

Section: Thermal Behaviors Of Extract With/without Catalystmentioning

confidence: 99%

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Study on the Catalytic Pyrolysis Mechanism of Lignite by Using Extracts as Model Compounds

et al. 2019

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Understanding the catalytic pyrolysis mechanism of lignite is of great significance for obtaining a high yield of the target products or designing high-efficiency catalysts, which are generally derived by using simple model compounds, while the ordinary model compounds cannot represent the real atmosphere of lignite pyrolysis owing to the simple structures and single reactions. Based on the coal two-phase model, the extractable compounds are the important compositions of coal, which can reflect the partial characteristics of raw coal while obtaining a high extraction yield. Hence, a better understanding of the interaction between the coal structure and catalyst can be inferred by using a mobile phase in coal as model compounds instead of conventional simple compounds. In this work, tetrahydrofuran extracts of lignite were chosen as model compounds to study the catalytic pyrolysis mechanism with separate addition of Fe(NO3)3 and FeCl3 by using a thermogravimetric combined with mass spectrometry. It was found that about 77.88% of the extracts were vaporized before 700 °C, and the residual yield was 22.12%. With the separate addition of 5 wt % of Fe(NO3)3 and FeCl3, the conversion of the extracts increased to 84.38% and 89.66%. Meanwhile, the final temperature decreased to 650 and 550 °C, respectively. The addition of Fe(NO3)3 and FeCl3 promoted the breakage of aliphatic chains at approximately 150 °C, leading to the generation of CH4 and H2 in the temperature range 100–200 °C, which were nearly invisible for that without catalyst. The addition of iron-based catalysts allowed more CO2 formation at approximately 200 °C since they enabled efficient promotion of the cleavage of carboxyl functionals at lower temperatures. The enlarged peak of H2O and CH4 at approximately 500 °C means that iron-based catalysts are significant for the cleavage of methoxy groups in the catalytic respect. Aromatic side chains facilitated cracking at approximately 500 °C, leading to more light aliphatics and aromatics generation in this temperature range.

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Section: Thermal Behaviors Of Extract With/without Catalystsupporting

confidence: 90%

Section: Kinetic Analysismentioning

confidence: 96%

Section: Thermal Behaviors Of Extract With/without Catalystmentioning

confidence: 99%

Section: Thermal Behaviors Of Extract With/without Catalystmentioning

confidence: 99%

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Study on the Catalytic Pyrolysis Mechanism of Lignite by Using Extracts as Model Compounds

et al. 2019

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“…The alkali metals, C -O -M bond (where M can be Fe, Na, K or Ca) was seen to be formed which effected the C -C bond and hence catalysed the gas phase reaction. 46) Yamashita et al 47) found that during devolatilization, the chemical form of iron species changed stepwise as follows with high temperature. Thus, a rapid increase of the burnout is expected in the following order: coconut shell blends > palm shell blends > MC.…”

Section: Effect Of Blending On Gas Phase Reactionmentioning

confidence: 99%

Structural Transformation of Agricultural Waste/Coke Blends and Their Implications during High Temperature Processes

et al. 2011

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With a sharp increase in demand and production, palm oil wastes, (i.e. empty fruit bunches, fibre and shells) are generated, out of which a large amount ends up in landfill. In such a context, alternative solutions are needed to reduce the impact of these agricultural wastes on the environment. The present paper investigates the effect of addition of agricultural waste materials on the combustion behavior of its blends with metallurgical coke (MC). Two types of agricultural waste materials, palm shell and coconut shell, were mixed in different proportion with MC, while the gas phase reactions were studied at 1 200°C in a drop tube furnace (DTF). In the tested conditions, the blends containing agricultural waste materials indicated higher combustion efficiencies compared to MC alone. Carbon structure analysis were performed through 13 CP/MAS NMR spectroscopy showing various groups of carbons present in the agricultural waste samples ranging from aliphatic to aromatic carbons. The morphology of the samples was studied through Scanning Electron Microscope (SEM). SEM provided a qualitative description of the pore structure in the raw samples as well as the changes occurring following the gas phase reactions in the DTF. It was found that the particles derived from the wastes became increasingly deformed and lost their cell lumen. Surface area measurements were found to be in good agreement with the SEM images, supporting the higher combustion efficiency of the blends in comparison to coke alone. The present study suggests that agricultural waste materials have the potential to partially replace MC, as an auxiliary fuel in metallurgical processes.

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XAFS Analysis and Applications to Carbons and Catalysts

Yamashita

2003

Carbon Alloys

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Local structures of metals dispersed on coal. 5. Effect of coal, catalyst precursor, and catalyst preparation method on the structure of iron species during heat treatment and steam gasification

Cited by 15 publications

References 7 publications

Study on the Catalytic Pyrolysis Mechanism of Lignite by Using Extracts as Model Compounds

Study on the Catalytic Pyrolysis Mechanism of Lignite by Using Extracts as Model Compounds

Structural Transformation of Agricultural Waste/Coke Blends and Their Implications during High Temperature Processes

XAFS Analysis and Applications to Carbons and Catalysts

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