AIR OXIDATION OF TURKISH BEYPAZARI LIGNITE .2. EFFECT OF DEMINERALIZATION ON STRUCTURAL CHARACTERISTICS IN OXIDATION REACTIONS AT 150-DEGREES-C

Date

1994-01-01

Author

AZIK, M
YURUM, Y
GAINES, AF

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Demineralized (HCl/HF) samples of Beypazari lignite were oxidized in air at 150 degrees C for up 120 h in a ventilated oven. Elemental analyses, diffuse reflectance Fourier transform infrared (DRIFT), solid-state C-13 CP/MAS/TOSS NMR, and pyrolysis mass (PY-MS) spectroscopies as well as solvent swelling were used for the characterization of the oxidized and unoxidized samples. It was found that the removal of 90.1% of the mineral matter from Beypazari lignite facilitated the access of oxygen into the coal structure and permitted the occurrence of diffusion-controlled reactions. This was confirmed by the observation of linear relationships between the decrease in the intensity of aliphatic CH2 and CH3 groups, the increase of the O/H atomic ratio and the decrease in the aliphatic factor, and the square root of the duration of oxidation. It was observed from swelling measurements in pyridine before and after the oxidation that aryl esters and anhydrides, which were the major oxidation products, probably acted as covalent cross-links. Aliphatic groups oxidized more rapidly than aromatic structures and, in fact, methylenes oxidized more rapidly than methyls. The decrease in the intensity of the molecular ion series alkylphenols, alkyldihydroxybenzenes, alkylbenzenes, and alkylnaphthalenes arising from pyrolysis mass spectrometry of oxidized samples was approximately consistent with the corresponding increase in the intensity of CO2+, CH3COOH+, and CO+ molecular ions.

Subject Keywords

Fuel Technology, Energy Engineering and Power Technology, General Chemical Engineering

URI

https://hdl.handle.net/11511/67008

Journal

ENERGY & FUELS

DOI

https://doi.org/10.1021/ef00043a030

Collections

Engineering, Article

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AIR OXIDATION OF TURKISH BEYPAZARI LIGNITE .1. CHANGE OF STRUCTURAL CHARACTERISTICS IN OXIDATION REACTIONS AT 150-DEGREES-C AZIK, M; YURUM, Y; GAINES, AF (American Chemical Society (ACS), 1993-05-01) The oxidation of Beypazari lignite was carried out in air at 150-degrees-C for up to 168 h. Oxidized samples were withdrawn from a ventilated oven at different periods of time and characterized by elemental analysis, diffuse reflectance Fourier transform infrared (DRIFT), solid-state C-13 CP/MAS/TOSS NMR, and pyrolysis mass (Py-MS) spectroscopies. It was found that oxidation influenced the organic structure and the inorganics at different periods of the oxidation. Iron(II) sulfate was formed in 24 h, during...
Thermal Analysis of Crude oil lignite mixtures by Differential Scanning Calorimetry Kök, Mustafa Verşan (Elsevier BV, 1994-04-01) Thermal characterization of lignite, crude oils and their 10 and 20% mixtures were investigated by differential scanning calorimetry (d.s.c.). The calorific value of the lignite increased in mixtures depending on the crude oil type. In pyrolysis runs, temperature ranges where distillation and visbreaking occur were identified for the crude oils studied. The effect of heating rate was also studied, and higher reaction temperatures and higher heat flow rates were observed at d.s.c. peak thermograms with incre...
DESULFURIZATION OF BOLU-GOYNUK LIGNITE USING CUPRIC CHLORIDE OGUZ, M; OLCAY, A (Elsevier BV, 1992-02-01) Cupric chloride oxidation of Bolu-Goynuk lignite was studied using a four-level factorial design with four process variables: temperature, time. cupric chloride concentration and particle size of the lignite. The main aim was to remove the organic sulphur from the lignite. Maximum organic sulphur removal was achieved by the oxidation of lignite with a particle size of 0.3 mm at 150-degrees-C for 210 min using 50 g CuCl2 per 100 ml of solution.
ELECTROKINETICS OF OXIDIZED COAL SARIKAYA, M; OZBAYOGLU, G (Elsevier BV; 1990-01-01) Electrokinetic measurements were carried out in order to determine the properties of oxidized coal surfaces over a wide pH range both in the presence and absence of various metal ions and flotation collectors. It was found that polyvalent cations, such as Fe++, Fe+++ and Al+++ decreased the zeta potential to zero and then reversed the charge. In the presence of cationic collectors, the negative value of zeta potential of oxidized coal was driven positive, below 9.3 to 10.9 depending on the type and concentr...
SCANNING ELECTRON-MICROSCOPY OF TREATED BITUMINOUS COALS HUAI, HY; GAINES, AF; FLINT, CD (Elsevier BV, 1992-11-01) Scanning electron microscopy of particles of three bituminous coals (78.5% C, 81.7% C and 89.9% C d.a.f.) which had been treated with pyridine, methanol, bromine, air, sulfuric acid, ammonia and alkylating agents showed that the reagents produced significant changes in the morphology of the particles. The particles cracked and disintegrated in ways which appear to be characteristic of the disruption of hydrogen bonding, the volume and thermal changes accompanying local reactions and of the breakage of C-C b...

Citation Formats

M. AZIK, Y. YURUM, and A. GAINES, “AIR OXIDATION OF TURKISH BEYPAZARI LIGNITE .2. EFFECT OF DEMINERALIZATION ON STRUCTURAL CHARACTERISTICS IN OXIDATION REACTIONS AT 150-DEGREES-C,” ENERGY & FUELS, pp. 188–193, 1994, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/67008.