Effects of alkali and alkaline earth metals of inherent minerals on Fe-catalyzed coal pyrolysis

He, Renze; Deng, Jin; Deng, Xiaoling; Xie, Xiaoguang; Li, Yun; Yuan, Shenfu

doi:10.1016/j.energy.2021.121985

Cited by 24 publications

(8 citation statements)

References 49 publications

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“…These oxygen carriers inhibited the deoxygenation of intermediate volatiles by reacting directly with carbon via MM-char reaction pathways (eqs and ). For instance, Fe reacts with active oxygen sites which actives carbon sites and improves carbon conversion . This reaction mechanism is also suggested by an increase in the number of oxygen-containing aromatic compounds in the FCR + ROSH blend.…”

Section: Resultsmentioning

confidence: 92%

“…This indicates that secondary reactions by MM present in the increasing order of FCR D > FCR CF > FCR contributed to the secondary cracking of the complex PAH structures into light gases and aliphatic hydrocarbons via side-chain decomposition and hydrocracking reactions. Ca, Mg, and Fe which are associated with the cleat minerals and nonmineral inorganics have been associated with the promotion of such reactions during pyrolysis …”

Section: Resultsmentioning

confidence: 99%

“…Furthermore, the proportion of cleat fluxing minerals is higher for Sl 1.9 compared with Fl 1.9 and Fl 1.5 samples (Table ). MgO and CaO [derived from dehydroxylation of Ca(OH) 2 ] promoted deoxygenation and cleavage of oxygen-containing bonds while Fe, derived from the reduction of Fe 2 O 3 to Fe (eq ), promotes deoxygenation of carboxylic functional groups via catalytic Boudouard reactions . The addition of the ROSH composite to FCR D and FCR did not have a significant effect on the tar yields indicating that EMs do not contribute to the evolution of tars, but secondary reactions during transport of tar precursors through the hot ash layer …”

Section: Resultsmentioning

confidence: 99%

“…Ca, Mg, and Fe which are associated with the cleat minerals and nonmineral inorganics have been associated with the promotion of such reactions during pyrolysis. 14 The higher proportions of ethers and esters for the FCR CF and FCR D samples suggest that deoxygenation and dehydroxylation reactions of tars are promoted by EMs through cleavage of C−O and C−H bonds by secondary volatiles−MM interaction. 42 The proportions of all alkylated fractions are almost the same between the FCR D and FCR CF samples, while lowest for the FCR indicating the contribution of water-soluble cations and salts of carboxylic acids toward thermal desorption and decomposition of alkylated compounds and prevention of cross-linking reactions.…”

Section: Coal and Char Compositionsmentioning

confidence: 95%

“…Several researchers performed pyrolysis experiments to evaluate the catalytic effects of inherent and EMs of Chinese, Japanese, American, and Middle Eastern coals. – Fu et al studied and compared the individual reactivity effects of potassium chloride (KCl), CaO, and Fe 2 O 3 during pyrolysis of North Chinese low-rank coal and reported the catalytic potency in the order of Fe 2 O 3 > KCl > CaO. The three minerals resulted in three different reaction effects: KCl promoted the tar yield, CaO promoted the gas yield, and Fe 2 O 3 promoted the char yield.…”

Section: Introductionmentioning

confidence: 99%

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Catalytic Effect of Reactive Extraneous Mineral Composites on Char and Tar Distribution during Pyrolysis of Highveld Partially Oxidized Fine-Coal Reject and Its Beneficiated Residues

Mphahlele,

Matjie,

Bunt

2023

ACS Omega

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In this study, the South African partially oxidized fine-coal reject (FCR), which is associated with human health and environmental problems and sustains high disposal expenses, was subjected to density-separation, chemical fractionation, and demineralization experiments to isolate and evaluate the mode of occurrence of mineral-matter (MM) effects on the FCR pyrolysis. A unique composite of two reactive oxides (i.e., MgO and Fe2O3) and a hydrated oxide [i.e., Ca(OH)2] representing major extraneous coal–minerals were blended with either FCR, demineralized FCR, and its beneficiated samples to evaluate the yields of pyrolytic products and activation energy following a novel procedure. The properties of FCR samples and their pyrolytic products were determined by different analyses. Results indicate that the reactive oxides and a hydrated oxide composite addition increased the average activation energy (332.0–476.5 kJ/mol) for FCR due to the initial Ca(OH)2 decomposition and Fe2O3 reduction that took place under pyrolysis conditions. The FCR mineral-rich sink fractions achieved the highest carbon conversion (char yield = 78.8% and tar yield = 5.1%) compared to those of other samples (e.g., <1.9 g/cm3 float char yield = 87.3% and tar yield = 2.3%) evaluated due to higher proportions of calcite/dolomite/pyrite cleats and nonmineral inorganics (Ca, Mg, Na, and Fe) which catalyzed the pyrolysis reactions. On the other hand, CaCO3, CaMg(CO3)2, and metakaolinite formations in the char derived from a blend of reactive oxides and a hydrated oxide composite and FCR interfere with the pyrolysis reactions. Also, deoxygenation reactions were impeded by oxygen present in the reactive oxides and a hydrated oxide composite. The potent catalytic effects of cleat minerals and the extraneous minerals associated with cracking of heavy tars to lighter fractions open opportunities to further understand the mode of occurrence of MM present in FCR during utilization in global pyrolysis. This may reduce waste disposal costs, health-hazards, air-pollution, and FCR volumes and augments feed-coals.

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Section: Resultsmentioning

confidence: 92%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Coal and Char Compositionsmentioning

confidence: 95%