Effects of mineral matter and temperatures on conversion of carboxylic acids and their derivatives during pyrolysis of brown coals

Kou, Jiawei; Bai, Zongqing; Bai, Jin; Guo, Zhenxing; Li, Wen

doi:10.1016/j.fuproc.2016.06.001

Cited by 12 publications

(6 citation statements)

References 43 publications

(57 reference statements)

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“…4a, in addition to the bands at 1593 and 3429 cm −1 assigned to the aromatic C=C and O-H stretching modes [25], some additional functional groups are detected for DPC-A compared with DPC. The vibrational band at 902 cm −1 is attributed to ether groups, those at 1345 and 2866 cm −1 are assigned to carboxylic groups [26], and that at 2918 cm −1 is associated with C-H stretching [27]. Diverse combinations of oxygen with C can also be observed in the high-resolution XPS spectra (Fig.…”

Section: Resultsmentioning

confidence: 87%

Pomelo peel-derived lamellar carbon with surface oxygen functional groups for high-performance supercapacitors

2021

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As they are easily and reproducibly obtained, biomass-derived carbons have received intensive research attention as electrode materials for energy storage devices. In contrast to three-dimensional carbon derived from pomelo peel by traditional KOH processes, two-dimensional carbon derived from pomelo peel is produced through modified processes in this work. The derived lamellar carbon has a large surface area (1927 m 2 g −1 ) and is rich in surface oxygen functional groups. Owing to these advantages, as the electrode of a supercapacitor, it delivers a very high capacitance (398 F g −1 at 1 A g −1 ) in an aqueous electrolyte and a high energy density (21 Wh kg −1 at a power density of 180 W kg −1 ) in an ionic liquid. Additionally, it exhibits good cycling stability; after 10,000 cycles, 95% of the capacitance is retained. This good performance makes it a promising electrode for supercapacitors.

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Section: Resultsmentioning

confidence: 87%

Pomelo peel-derived lamellar carbon with surface oxygen functional groups for high-performance supercapacitors

2021

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“…Therefore, the growing CO 2 mainly comes from the breaking of −C−O− bonds with low energy in tar. 23 The volume percentages of C 2 + increase from 9.71 vol % of Blank-A to 10.10 vol % of 5:1-A. This is closely related with cleavage of the alkyl or alkenyl side chains, which is affected by the circulating ash.…”

Section: Resultsmentioning

confidence: 95%

“…When tar passes through metal oxides in the circulating ash layer, the stability of the π-electron clouds will be destroyed and bond cleavage will occur. Therefore, the growing CO 2 mainly comes from the breaking of −C–O– bonds with low energy in tar . The volume percentages of C 2 + increase from 9.71 vol % of Blank-A to 10.10 vol % of 5:1-A.…”

Section: Resultsmentioning

confidence: 99%

“…It was found that the mineral activity increased in the order of quartz ≪ kaolinite < pyrite ≪ calcite/dolomite. Kou et al 23 used two Chinese brown coals to investigate the effects of minerals on the conversion of carboxylic acids and their derivatives in pyrolysis volatiles. The results showed that minerals could catalyze the decomposition of carboxylic dimers and thus promoted the generation of RCOOAr and anhydrides.…”

Section: Introductionmentioning

confidence: 99%

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Secondary Catalytic Effect of Circulating Ash on the Primary Volatiles from Slow and Fast Pyrolysis of Coal

Zhang

Pan

et al. 2018

Energy Fuels

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The lab-scale fixed-bed pyrolyzer by circulating ash as heat carrier was used to study the secondary catalytic effect of circulating ash on the primary volatiles from slow and fast pyrolysis of coal. Different mass ratios of ash to coal were layered in the pyrolyzer. Combined with the simulated distillation analysis, gas chromatograph-mass spectrum (GC-MS), and elemental analysis, the yields and compositions of gas, tar, and semicoke were analyzed. The results show that circulating ash catalyzes the cracking of primary volatiles generated by both slow and fast coal pyrolysis. CO2 is very sensitive to the proportion of circulating ash; it mainly comes from the breaking of −C–O– bonds with low energy in tar. After adding circulating ash, the gas yield increases while the tar quality is improved despite the reduction in tar yield. Circulating ash is beneficial to the cracking of oxygen-containing, nitrogen-containing, and sulfur-containing bonds in asphalt. The components with carbon numbers of ≥26 in tar can be upgraded and then results in the growing yields of ≤C25 components. Circulating ash can increase the tar saturation in the secondary catalytic reaction. This study can provide basic data for the effect of secondary catalytic as well as the heating rate on the coal pyrolysis by circulating ash as solid heat carrier.

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“…There are three main types of intrinsic metal elements in coal: , water-soluble state, metal ions dissolved in pore water; organically bound state: metal elements in the form of H or oxygen-containing functional groups in coal by adsorption, ion exchange, or coordination; and discrete mineral matters. Some scholars have separated inorganic minerals from organic matter by inorganic acid washing, such as nitric acid, sulfuric acid, hydrofluoric acid, , hydrochloric acid, or combined acid pickling, − and analyzed the effect of demineralization on coal structures. Studies have shown that the addition of nitric acid tends to cause oxidation and nitrification of coal, and the introduction of nitro groups causes a large change in the coal structure and morphology .…”

Section: Introductionmentioning

confidence: 99%

Experimental Study on Catalytic Action of Intrinsic Metals in Coal Spontaneous Combustion

Qiao

Deng

et al. 2023

ACS Omega

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In order to study the effect of inherent metals in coal on spontaneous combustion, Hongmiao lignite and Hongqingliang long-flame coal were demineralized by hydrochloric acid, the raw coal and demineralized coal were characterized by Fourier transform infrared spectrometry, X-ray diffraction, and synchronous thermal analysis experiments, and the corresponding ash content was detected by inductively coupled plasma mass spectrometry. The results show that the effect of demineralization on the volatile matter of low-rank coal is small, and the change of crystallite structure is not significant. The removed parts are mainly water-soluble salts and soluble minerals, such as carbonates and metal ions, that are not tightly bound to the organic matter of coal structure. The removed metal elements are mainly alkali metals Na and K, alkaline earth metals Ca, Mg, Sr, and Ba, and transition metals Fe, Mn, Ti, and so forth. The temperatures corresponding to the end of weight loss, ignition, and maximum weight loss rates were elevated on the thermogravimetric curves of the demineralized coal samples. The heat absorbed by evaporation of water in coal and the heat released by oxidation and combustion of coal are decreased to different degrees, indicating that the spontaneous combustion tendency of coal after demineralization is reduced, and alkali metal, alkaline earth metals, and transition metals in coal have a catalytic effect on spontaneous combustion of coal. After adding the metal chelating agent ethylenediaminetetraacetic acid (EDTA), the apparent activation energy decreased by 33.08 and 2.42%, respectively. EDTA and the alkali metal, alkaline earth metal, or transition-metal ions formed a stable chelate in coal. The catalytic activity of metals is weakened or even lost, thereby inhibiting spontaneous combustion of coal, and verifying the catalytic effect of internal metals in coal on the spontaneous combustion of coal.

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Effects of mineral matter and temperatures on conversion of carboxylic acids and their derivatives during pyrolysis of brown coals

Cited by 12 publications

References 43 publications

Pomelo peel-derived lamellar carbon with surface oxygen functional groups for high-performance supercapacitors

Pomelo peel-derived lamellar carbon with surface oxygen functional groups for high-performance supercapacitors

Secondary Catalytic Effect of Circulating Ash on the Primary Volatiles from Slow and Fast Pyrolysis of Coal

Experimental Study on Catalytic Action of Intrinsic Metals in Coal Spontaneous Combustion

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