THE PROPERTIES OF WATER LAYERS ON COAL SURFACES

The results of programmed thermodesorption investigations of water from coal surfaces are presented and correlated with the measurements of water adsorption and desorption from the gaseous phase at a temperature of 20^°C. From the data obtained, the activation energies of water molecules were calculated and possible structures of water adsorbed layers on the coal surfaces were suggested. On the basis of the DTA curve, the water adsorption heat on the coal surfaces 20^°C was calculated and presented in the form of dependence on water adsorption value from the gaseous phase.     

COPROCESSING OF COAL WITH HEAVY PETROLEUM CRUDES AND RESIDUA

ABSTRACT

This work investigates the coprocessing of coal in six different heavy petroleum crudes and residua. Coprocessing reactions of coal and the petroleum solvents are performed under three sets of constant reaction conditions, yielding informative comparative data for processing applications. Definitive comparisons of coal reactivity and solvolysis in the petroleum solvents have been obtained using solvent fractionation which provides a measure of the degree of upgrading achieved by the liquefied coal. Regressive reactions and low coal conversions are observed in coprocessing reactions in N₂ at 400^°C. Higher conversions and a reduction in regressive reactions are observed in H₂ at 400^°C. Catalytic hydrotreatment and higher temperature, 425^°C, result in increased coal conversion and a net production of pentane soluble materials. The amount of product fractions obtained from the upgrading of the coal alone is calculated. The effect of reaction temperature using different solvents and reaction conditions on the product slate is also examined.     

CHARACTERIZATION OF COAL CHARS FROM A FLASH PYROLYSIS PROCESS BY CROSS POLARIZATION/MAGIC ANGLE SPINNING 13C NMR

ABSTRACT

Chars from the Illinois Springfield (No. 5) Coal are prepared by flash pyrolysis at progressively higher charring temperatures. The results of a study of these chars by ¹³C NMR with CP/MAS indicate that the initial stage of heating (300^°C) produces a char with aromatic carbon fraction (f_ar) of 68%, and successive heating gives chars with f_ar of 70% (400^°C), 73% (500^°C), 89% (600^°C), 95% (700^°C), and 96% (800^°C). However, the actual amount of aromatic and aliphatic carbon in the char can be calculated by using the NMR measurements, the organic carbon content of the char, and the weight of the char. The calculated values show that the amount of aromatic carbon in char remains relatively constant at each temperature, but the amount of aliphatic carbon in char is reduced during higher temperature charring. At 600^°C, both a large reduction of the aliphatic carbon content and a maximum weight loss occur. Evidently, the aliphatic-bond carbon in coal is the principal source of volatiles derived from coal. The apparent increase in aromaticity (f_ar) of the char heated to progressively higher temperatures is due to the loss of aliphatic-bond moieties and reduction in volume of materials.     

RAPID PYROLYSIS OF EASTERN CANADIAN COALS BY FREE FALL REACTORS

Abstract

The effect of temperature was investigated on the rapid pyrolysis of Prince, Lingan and No. 26 coals in the temperature range of 525^° to 750^°C using a 600 cm high stainless-steel free fall reactor at atmospheric pressure.

The yields of char, condensibles and gaseous products were determined at 25^°C intervals. Gaseous products were analysed for H₂, CO, CO₂, CH₄ and C₂+.

Volatile product (condensible and gas) yields exceeded the volatile product in the A.S.T.M. methods at and above 700^°C.

Some experiments using Prince coal were repeated at reduced pressure (50 mm mercury) in both the 600 cm height stainless-steel and a 140 cm height quartz reactor in order to find out the effect of pressure and retention time.

The experimental results indicated that the condensable yield was higher at the lower pressure and at the shorter retention time. The effect of retention time was far more pronounced.     

HYDROLIQUEFACTION OF TEXAS LIGNITE IN COAL- AND PETROLEUM-DERIVED SLURRY OILS

ABSTRACT

Hydroliquefaction of Texas lignite (68.5%. C daf) was conducted in a batch autoclave under hydrogen in a coal–derived slurry oil at 90 bar initial pressure for temperatures of 380–460^° C and residence time of 15–60 minutes, or a vacuum distillate from petroleum at 435^° C for 60 minutes and initial H₂–pressure of 60–150 bar, or a vacuum residue from the same petroleum at 435 and 460^° C for 60 minutes and initial H₂–pressure of 90–150 bar or tetralin at 435^°C, 60 minutes and 90 bar initial H₂–pressure. Red mud plus sodium sulfide were added as a catalyst for all experiments. Lignite conversion ranged from 50 to 83%. The products were separated into gases, residue, asphaltenes, oils B,P. above 200^° C, oils B.P. below 200^° C. Total liquid products from coal reached 57% in coal-derived slurry-oil, 56% in vacuum distillate and 64% in vacuum residue at optimum conditions with 32% of product oil B.P. below 200^° C in vacuum distillate and 24% in vacuum residue. When coprocessing lignite with vacuum residue at 120 bar initial pressure, 435^°C and 60 minutes residence time the total mass balance presented an oil yield of 73%. with 32% boiling below 200^°C.     

LIQUEFACTION OF BEYPAZARI LIGNITE USING NiCl2-KCl-LiCl CATALYSTS. 1. DIFFERENCE IN SOLID AND MOLTEN SALT CATALYSIS

ABSTRACT

Liquefaction of Beypazan lignite in tetralin using NiCl₂-KCl-LiCl (14:36:50 molar percentages) as catalyst was investigated. Effects of the catalyst/lignite ratio and temperature were determined in experiments done at 275°C, 300°C and 360°C. Liquid products were separated into oils, asphaltenes and asphaltols by a solvent extraction method. Yield of liquefaction increased with temperature in all experiments, the highest yield was observed in experiments performed at the eutectic temperature of the catalyst mixture. The highest yields of oils were 20% and 30% with a catalyst/coal ratio of 0.5 at 275°C and 300°C, respectively. The activity of the catalyst increased in experiments in which the catalyst was molten. The yield of asphaltenes were not affected with increases in the catalyst/coal ratio in the experiments done at 275°C or 300°C in which the catalyst mixtures were in solid state. Asphaltene yields decreased from 25% to less than 5% with increasing values of catalyst/coal ratio and the asphaltol yields remained constant at 10% between catalyst/coal ratios of 0.25 and 1.00 and suddenly increased to 30% and 40% for catalyst/coal ratios of 1.50 and 2.00, respectively, at 360°C. The molecular weights of the oils decreased from 340 to a minimum value of 245 as the catalyst/coal ratio was increased from 0 to 1.00 in experiments done at 360°C where the catalyst was molten. As the catalyst/coal ratio was further increased from 1.00 to 2.00 the molecular weight increased to 310.It seemed that the N1Cl₂-KCl-LiCl catalyst mixture in all catalyst/coal ratios was more efficient in molten phase than it was used as a solid mixture.     

STEAM GASIFICATION OF BALMER COAL IN THE PRESENCE OF LIGNITE ASH

ABSTRACT

Steam gasification of blends prepared from Balraer coal and the ash from combustion of Onakawana lignite was performed in a fixed bed reactor. The blends were prepared by co-slurrying followed by drying. In the presence of 20 wt % ash the gasification rate doubled at 830° and 930°C. Direct blending of coal and lignite resulted In an overall increase in carbon conversion at 830°C but had no effect at 930°C.     

Solid + liquid phase equilibria in the hydroxylammonium nitrate + water system

Abstract

The binary solid + liquid phase diagram has been measured for the water + hydroxylammonium nitrate (HAN) system. The phase diagram is a simple eutectic type with the eutectic at 231.5 K (41.7°C) and a mole fraction HAN of 0.281 (wt fraction HAN - 0.676).

The enthalpy of fusion of the HAN was determined from the solid + liquid results to be 11 ± 2 kJ·mol^?1. The HAN was obtained from Southwestern Analytical Chemicals, Inc. as an approximately 2.8 molar solution. The water was removed by vacuum drying over a three month time period, but the sample still contained some impurity. The impurity level calculated from the change in melting temperature with fraction melted is 0.040 mole fraction. Chemical analysis indicates the sample contains 0.005 mole fraction HNO₃ and 0.007 mole fraction NH₄NO₃, with N₂H₅NO₃ absent. The remainder of the impurity could be water, but this is not known for sure.

We obtained a melting temperature for the impure sample of HAN of 315.9 K (42.7°C). The melting point corrected to zero impurity is 317.7 ± 1 K (44.5°C).     

EFFECT OF SOLVOLYTIC EXTRACTION AND PYROLYSIS PRETREATMENTS ON THE TOEMPRATURE STEAM GASIFICATION REACTTVITY OF COAL AND REDUCTION OF TAR FORMATION IN PRODUCT GASES

ABSTRACT

Pre-extraction of Talcher coal ( a bituminous coal) in anthracene oil was found to be a beneficial treatment for enhancing the reactivity for steam gasification of coal. Similarly, anthracene oil followed by liquid paraffin extraction of coal was also found to be a-better pretreatment for the steam gasification of coal. Anthracene oil extraction at 270°Cand steaming of coal at 650°C had almost equal effect on steam gasification of coal. Pyrolysis in steam of pre-extracted coals was found to further enhance the reactivity of coal for steam gasification. The studies were further confirmed by carrying out thermogravimetric analysis of pretreated coals in steam atmosphere. Degree of cross-linking in pretreated coals was studied by measurement of swelling of coal in quinoline. The formation of tar in gaseous product was reduced as a result of pre-extraction and steam pyrolysis of coal prior to their gasification in steam.     

VARIATION IN THE CHEMICAL NATURE OF ASPHALTENES WITH THE PROCESS,THE COAL AND THE REACTION CONDITIONS

ABSTRACT

Average structure data for twelve asphaltenes are reported, based on ¹³C- and H- n.m.r. spectroscopy combined with elemental, molecular weight and functional group analyses. The asphaltenes were from supercritical gas extraction, flash pyrolysis and hydrogenation of a brown and a bituminous coal. The effect of the reaction temperature and, for hydrogenation, the catalyst and solvent on the nature of the asphaltene produced was studied. The asphaltene obtained from supercritical gas extraction of the brown coal at 350°C was the least aromatic (f_a = 0.44) with the highest H/C atomic ratio (1.16) and probably consists mainly of single ring aromatlcs with about half of the aromatic sites substituted. A significant proportion of the carbon in this asphaltene is in long alkyl chains and the hydroxyl content is high. Whereas, the asphaltenes produced by hydrogenatlon of the bituminous coal at 450°C were far more aromatic with more highly condensed but less substituted aromatic ring systems and few, if any, long alkyl chains, together with a lower hydroxyl content. The asphaltenes obtained from the brown coal are less aromatic with less condensed aromatic ring systems but a higher degree of aromatic substitution than those produced from the bituminous coal under the same conditions. The asphaltenes formed at 450°C had lower H/C atomic ratios, molecular weights and degree of aromatic substitution, but higher aromaticities Ohan those produced at 35O°C or 400°C under like processing conditions. The asphaltene produced in the presence of both stannous chloride catalyst and tetralin was less aromatic than when either of these species was absent.     

Ammonium perchlorate decomposition: Neat and solution1

Abstract

The thermal decomposition of ammonium perchlorate (AP) was examined over a broad temperature range (215°C to 385°C) in solution and condensed phase. Over the entire temperature range, the decomposition, as monitored by loss of ammonium ion, appeared first-order out to 70% decomposition. Up to about 350°C the decomposition of AP in methanol (5wt% AP) proceeded at a rate similar to neat AP, but the AP in aqueous solution (20wt%) decomposed considerably slower than the neat material. Activation energies and frequency factors were determined for each experimental condition. In addition, decomposition products, both gaseous and condensed phase, were identified and quantified. For neat AP decomposition, the following reaction stoichiometries were determined.

At low temperatures, decomposition of ammonium perchlorate in methanol proceeded at a similar rate to that of neat AP. In contrast to decomposition of neat AP, the only nitrogen-containing decomposition product was nitrogen gas, while chlorine appeared only as chloride. The presence of CO and CO₂ as decomposition gases and chromatographic analysis of the solvent indicated interaction between methanol and AP. The decomposition of AP in water was slowed, but product distribution was not significantly different than that of neat AP.     

PRODUCTS FROM FLASH PYROLYSIS OF A TURKISH LIGNITE IN A FREE-FALL REACTOR UNDER VACUUM

ABSTRACT

Flash pyrolysis of a Turkish lignite under vacuum in a free-fall reactor was examined at a temperature range of 400 - 800 °C. Gaseous products were analysed with an on-line GC equipped with a manuel injection valve. Solvent fractionation was applied to the liquid product to separate preasphaltenes, asphaltenes and oils fractions. Two particle distributions of the lignite were used: ?0.315+0.2 mm and ?0.1 mm. The liquid yield increased with temperature up to 650 °C and, thereafter decreased for the larger particles. The maximum liquid yield, excluding pyroltic water, was found to be 8 % wt (dal) at 650 °C. In the case of the smaller particles the liquid yield increased steadily with temperature and the yield of liquid, excluding pyrolytic water, was 5.9 % wt (da) at 850 °C. The gaseous product yield also increased with temperature for both size fractions, and CO and CO₂ in the gaseous products were present in large amounts.     

Polarization and Polarizability of the Binary Mixtures of Tetraethylene Glycol With Benzene and Toluene at 20°C and 30°C

Abstract

The refractive index of the binary mixtures of tetraethylene glycol (TETEG) with benzene and toluene at 20°C and 30°C and atmospheric pressure have been measured at the whole composition range of mixtures. The polarizabiltiy (α), atomic polarization (P_a), solvated radii (r), and excess refractive indices (n^DE) were calculated and represented in figures versus concentration.     

THE INCREASE OF EFFICIENCY OP PINE OIL BY HEATING AND USAGE IN THE FLOTATION OF OXIDIZED AHASRA COAL

ABSTRACT

The effect of heating temperature and time on the efficiency of pine oil was examined in the flotation of oxidized Amasra Coal in this work. Samples were taken from waste heap Amasra Coal which were collected in 1973–1978 and stored in atmospheric conditions. The optimized impeller speed was 1000 rpm, aeration rate was 35 ml/s and solid content of the pulp was 20% in the flotation tests. Motorin was added to the pulp as a collector. The pine oil was heated to 50^°C, 75^°C, 106^°C, 125^°C, 150^°C, 175^°C, 200^°C and used as a frother. The flotation resulta indicated that 125^°C was suitable temperature for heating. Increasing the heating time increased the efficiency of pine oil. The recovery of combustibles also Increased depending on the increase in the amount of oil heated for 5 hours at 125^°C.     

EFFECT OF IRON CATALYST ON THE COMPOSITION OF OIL FROM COAL LIQUEFACTION

ABSTRACT

The effect of two iron catalysts, red mud and CGS S-G, as well as C0-Mo/AI₂O3 and Ni-Mo/Al₂03 commercial catalysts on the composition of oil derived from the liquefaction of Japanese subbituminous coal have been investigated comparatively by conventional autoclave experiments at 440 and 450^°C under initial hydrogen pressure of 85kg/cm² G with tetralin to coal weight ratio of 3. From the results obtained at 450^°C, total conversion and the yield of gas revealed almost same level with four catalysts, but the oil product from molybdenum catalysts showed higher yield than that from iron catalysts. CGS S-G catalyst also showed higher yield of oil product than red mud catalyst. Reaction behavior of two iron catalysts were also tested by solvent recycle mode experiments.     

PRODUCTION OF HIGH QUALITY LIQUID FUELS FROM COAL BY MILD PYROLYSIS OF COAL-LIME MIXTURES

Abstract

The most recent studies of coal devolatilization processes have emphasized maximisation of liquids yield by use of extreme process conditions such as high heating rate. The liquids produced by such processes are often unsuitable for utilization without extensive upgrading. The aim of the study reported here was to optimize product quality by use of relatively mild conditions. Low-temperature devolatilization (slow heating to 500° to 650°C in a batch reactor) of coal in the presence of CaO (10 to 20 weight percent) can produce a relatively high-quality liquid fuel (containing low sulfur, low oxygen, low viscosity, low Conradson carbon residue, and low pour point). Compared to that occurring in rapid heat-up processes, the residence time of both the liquid and gaseous products is significantly greater in a batch or fixed-bed slow-heating system. It is proposed that this increased residence time facilitates greater secondary reactions of the primary products in the coal bed with the added CaO. The H/C (atomic) ratio of the liquids generated in such a relatively simple devolatilization system can vary between 1.3 and 1.5 for high-volatile coals such as Illinois No. 6 or Pittsburgh No. 8. The presence of CaO in the fuel bed markedly reduces H₂S in the gas phase and decreases sulfur and oxygen heteroatoms in the liquids.     

Novel high-energy ionic molecules deriving from new monovalent and divalent 4-oxyl-3,5-dinitropyrazolate moieties

ABSTRACT

In recent years, the exploration of a practical strategy for novel energetic molecules with high energy and low sensitivity is very desirable but highly challenging. Novel ionic energetic molecules have attracted much attention in this area due to their prominent advantages including low sensitivities, high thermal stability, and excellent energy performances. Herein, five different ionic energetic molecules based on new monovalent and divalent 4-oxyl-3,5-dinitropyrazolate moieties with enhanced oxygen balance have been synthesized, characterized and evaluated as potential high-energy materials. Thermal stability, sensitivities and energy output test were measured and studied in detail. The heats of formation and energetic parameters were calculated by using Gaussian 09 suite of programs and EXPLO 5 code. The results suggest that all as-prepared new molecules exhibit good thermal stability with high decomposition temperature (3, 231°C; 5, 160°C; 6, 185°C; 7, 180°C; 8, 213°C), and relative low sensitivity (IS > 20 J, FS = 324 N). Inheriting the significant oxygen content of monovalent and divalent 4-oxyl-3,5-dinitropyrazolate moieties, they also possess good energy properties (v _D = 8238 ~ 9208 m s^?1, P = 26.8 ~ 36.7 GPa, V _o = 481.8 ~ 959.4 L kg^?1), which make them competitive high-energy materials.     

THE EXTRACTION OF COALS WITH PYRIDINE AND TOLUENE AT 350°C

ABSTRACT

The extraction of three coals with mixtures of toluene and pyridine at 350^°C were compared. The conversion of both the bituminous and sub-bituminous coals Increased as the amount of pyridine in the mixture Increased up to ca 60% pyridine at a constant gas density of 0.64 g/ml. However, there was no Improvement in conversion for the brown coal when toluene was replaced with pyridine. The difference between pyridine and toluene conversion decreased as the gas density decreased. The high solvent efficiency of pyridine is probably due to the unshared pair of electrons on the nitrogen atom. Addition of other compounds with an unshared pair of electrons on a nitrogen or an oxygen atom also Increased conversion In toluene supercritical gas extraction of a bituminous coal at 350^°C and a constant solvent density.     

CONTRIBUTION TO THE SEPARATION OF ACIDIC COMPONENTS FROM COAL LIQUEFACTION OIL

ABSTRACT

The naphtha fractions of coal hydrogenation products (IBP-130^°C) were separated by successive extraction with potassium hydroxide solution. Basic oil was also separated from the residue. The extracted fractions were analyzed by H-NMR and FI mass spectroscopy. It is concluded that the consecutive extraction with dilute potassium hydroxide solution should be capable of fractional separation of acidic oil from coal oil and further separation of individual component may be done by increasing the consecutive extraction steps.     

1,3,3-trinitroazetidine (TNAZ). Study of thermal behaviour. Part II

Abstract

Thermal behavior of TNAZ (1,3,3 - trinitroazetidine) was studied by using differential scanning calorimetry (DSC), differential thermal analysis (DTA), and thermogravimetryc analysis (TGA).

It was found out that TNAZ is thermally more stable than RDX, but less stable than HMX and TNT. The reaction of intensive thermal decomposition starts at 183–230 °C, depending on heating rate, while the first exothermic reaction was observed at 178 °C at the heating rate of 1 °C/min.

By applying multiple heating rate DSC measurements and Ozawa's method the activation energy of 161.3 kJ/mol and pre-exponential factor of 8.27·10¹³ 1/s were calculated from DSC peak maximum temperature-heating rate relationship. By the same method the activation energy of 157.5 kJ/mol and pre-exponential factor of 4.55·10¹³ 1/s were calculated from DTA peak maximum temperature.

By applying Flynn-Wall isoconversional method it was calculated from DSC measurements that the activation energy equals between 140 and 155.6 kJ/mol at degrees of conversion ranging between 0.3 and 0.7, while pre-exponential factor ranges between 7.8·10¹² and 1.92·10¹³ 1/s.