Analysis of carboxyl group in coal and coal aromaticity by Fourier transform infrared (FT-IR) spectrometry

Thirty-five SS coals as well as two Australian lignites were analyzed by Fourier transform infrared (FT-IR) spectrometry using the KBr tablet method; the SS coals are a series of standard coals produced in various countries. A selected zone 1800-1500 cm⁻¹ of the FT-IR spectrum obtained was deconvoluted, and the peak area for COOH group in coal was obtained. The content of COOH group in coal was calculated from the FT-IR analysis with the aid of the molar absorption coefficient, which had been derived using various aromatic carboxylic acids. On the other hand, the conventional chemical analysis (ion-exchange method) for the determination of COOH group in coal was carried out. When the 37 coals were tested, the COOH contents obtained from the FT-IR analysis were in good agreement with those from the chemical analysis. The zones of 3100-ca. 2990 cm⁻¹ and ca. 2990-2750 cm⁻¹ are assigned to aromatic CH and aliphatic CH, respectively. The ratio of peak area for the two peaks are appreciably correlated to the fraction of aromaticity (f_a) obtained from the solid-state ¹³C NMR analysis. In addition, the ash content could be roughly estimated from the crystal water peak in the FT-IR spectrum.     

Reaction of coal with quinoline during extraction

Yubari coal vitrite was extracted with quinoline at 420° C for 0–4 h and the products were separated into several fractions. Quinoline solubles (QS) and insolubles (QI) increased with time and the total recovered weight became nearly 200% of the original weight of the coal. A large part of this weight increase was due to the contribution of the formation of biquinoline and to quinoline addition to coal. Depolymerization to smaller molecules and polymerization to QI took place simultaneously via the addition of quinoline and the production of biquinoline.     

Synthesis and gas permeability of new polynorbornene dicarboximide with fluorine pendant groups

The new exo-N-3,5-bis(trifluoromethyl)phenyl-7-oxanorbornene-5,6-dicarboximide (TFmPhONDI, 2), was synthesized and polymerized via ring opening metathesis polymerization (ROMP) using tricyclohexylphosphine [1,3-bis(2,4,6-trimethylphenyl)-4,5-dihydroimidazolilydene][benzylidene] ruthenium dichloride (I) to produce the corresponding PTFmPhONDI (3). Gas permeability, diffusion and solubility coefficients of PTFmPhONDI (3) were determined by transient permeation for five gases He, CO₂, O₂, N₂ and CH₄. The larger gas permeability and diffusion coefficients of 3 compared to polynorbornene dicarboximides without fluorine pendant groups were attributed to a lower polymer chain packing due to the effect of the CF₃ groups in the lateral phenyl moiety pending at positions 3 and 5.     

陕西原煤中的氟含量及空间分布

对陕西6大产煤区中64个煤矿进行采样、分析,得到陕西原煤中氟含量及其空间分布特征,陕西原煤中氟含量的几何平均值为84 mg/kg;陕西原煤中氟含量的空间分布差异不大,南部地区煤中氟含量比北部地区煤中氟含量高;按照成煤时代划分,陕西原煤中氟含量由高到低依次为陕南煤田渭北石炭二叠纪煤田陕北石炭二叠纪煤田陕北三叠纪煤田黄陇侏罗纪煤田陕北侏罗纪煤田。     

A borate fusion method for the determination of fluorine in coal

A new analytical method has been developed for determining fluorine in coal. It incorporates a two stage sinter-fusion procedure using lithium carbonate, lithium tetraborate and zinc oxide. In the sinter stage, coal is ashed at 600 °C and the lithium carbonate and zinc oxide act as collectors to capture volatile species of fluorine. In the second stage, the ash residue is decomposed by fusion with the lithium carbonate and lithium tetraborate at 1050 °C. The fused material is dissolved in nitric acid and the fluoride in solution is determined using an ion selective electrode. The results for a number of coal samples including Certified Reference Materials are reported. These are in good agreement with the certified values and with the results obtained by proton induced gamma ray emission spectrometry. The good agreement confirms that no fluorine is lost during ashing/sintering of the coal and that complete dissolution of the residual ash is obtained by fusion with the lithium carbonate and lithium tetraborate The method is simpler and less labour intensive than pyrohydrolysis and is suitable for use in most commercial coal laboratories.     

Fate of the chlorine and fluorine in a sub-bituminous coal during pyrolysis and gasification

The fate of the chlorine and fluorine present in a sub-bituminous coal from Indonesia during pyrolysis and gasification has been studied with fixed and entrained bed reactors. The rate profile for HCl evolved in the temperature programmed pyrolysis exhibits the main and shoulder peaks at 480 and 600 °C, respectively. Model experiments and subsequent Cl 2p XPS measurements show that HCl reacts with metal impurities and carbon active sites at 500 °C to be retained as inorganic and organic chlorine forms, from which HCl evolves again at elevated temperatures. It is suggested that the HCl observed in the coal pyrolysis may originate from the above-mentioned chlorine functionalities formed by secondary reactions involving the nascent char. In the CO₂ gasification of the 900 °C char at 1000 °C and 2.5 MPa, any measurable amounts of HCl and HF could not be detected even at a high conversion of 75 wt% (daf), suggesting the accumulation of these halogens in the residual char. When the coal is injected into an O₂-blown, entrained bed gasifier at 1200-1400 °C under 2.6 MPa, the partial oxidation proceeds to a larger extent at a higher O₂/coal ratio, whereas the chlorine and fluorine are enriched in the remaining char, and the extent of the enrichment at the latter stage of gasification is larger with the fluorine. The XPS measurements of the chars reveal the presence of the broad F 1 s peak, which can cover a wide range of binding energies attributable to inorganic and organic fluorine. The halogen enrichment during gasification is discussed in terms of secondary reactions of HCl and HF with char.     

Reaction of coal with nitrogen in a microwave discharge

In a microwave discharge in nitrogen, high-volatile bituminous coal produces gaseous products, namely hydrogen cyanide, acetylene, small amounts of cyanogen and lowmolecular-weight hydrocarbon gases, and nitrogen-containing compounds, in addition to the usual hydrogen and carbon oxides. The reaction of coal in the nitrogen discharge occurs in two stages: interaction of active nitrogen with the coal molecule to cause rapid volatilization of gaseous products, and slow gasification of residual char by active nitrogen. Various factors influencing product type, yield, and distribution are examined. Under conditions where the gaseous products can be quickly quenched or removed, as by trapping at a very low temperature, more than 42% of carbon in the coal can be converted mainly to hydrogen cyanide and acetylene, which together constitute about 90% of the total products.     

Reaction of catalysts with mineral matter during coal gasification

After a review of mineral matter of German hard coal, its reactions with catalysts during gasification with steam to form new crystalline phases are dealt with. Products of commercial plants and laboratory experiments were investigated by means of microscopy, XRD, XRF and microprobe analysis.     

Supercritical gas extraction of coal with hydrogen-donor solvents

An investigation of the effect of a hydrogen-donor component in the solvent used for supercritical gas extraction was undertaken. Extraction of three Australian coals with toluene, with decalin and with these solvents containing small amounts of tetralin was investigated. There was a significant improvement in conversion by addition of 5% tetralin to the solvent. Other hydrogen donors were also effective. The improvement in conversion was shown to be due to hydrogen donation rather than to a change in the physical properties of the solvent. The increase in conversion was greater for a brown coal than for a bituminous coal of the same hydrogen to carbon atomic ratio. The pre-asphaltene content of the extract increased with conversion.     

Innovative approach of low carbon and efficient utilization of coal resources: The polygeneration system of a combination of the gasified coal gas and the pyrolyzed coal gas to form the synthetic gas

The present status of fossil energy resources in China reveals the fact that coal is the main energy supplier and the increasing and massive exploitation of coal and its application process such as coal burning cause serious environmental pollution which is the common concern of the government and the people.     

Determination of total fluorine in coal by use of oxygen flask combustion method with catalyst

A rapid and convenient analytical method has been developed for the determination of total F in coal by use of oxygen flask combustion (OFC) method with catalyst. Coal was combusted with excessive oxygen in a quartz flask and the resulting gas was absorbed in water, and the fluoride ion in the solution was determined with a fluoride-ion selective electrode (F-ISE). Seven certified reference materials of coal were tested. The effects of the repetition of OFC procedure, the use of catalyst, and the particle size of coal were investigated. The F concentrations in these coals determined by the proposed method gave good recoveries for their certified or reference values. The use of proper catalyst was necessary especially when coals of high F concentrations (above ca. 150 μg g⁻¹) were analyzed. For the catalyst, the combined use of WO₃ and Sn was the most efficient, and the mechanism was studied. Twenty brands of Japanese standard coals (SS coals) were analyzed by the present method, and the data were compared to those obtained from the pyrohydrolysis method.     

Reaction of coal with 1,2,3,4-tetrahydroquinoline in a perfluorocarbon medium

Three very different coals show similar behaviour when heated with low concentrations of 1,2,3,4-tetrahydroquinoline (THQ : COAL = 0.2) at 250°C in a perfluorocarbon liquid. The coals all approach 33–35 % ultimate solubility (measured in pyridine) at similar rates, with little incorporation of THQ into the coal. This transformation is attributed to a low-temperature chemical reaction between THQ and coal. Appreciable coal conversion is only observed in media in which organic molecules have limited solubility, such as perfluorocarbon liquids and water. Under similar conditions, tetralin and a variety of amines other than THQ do not effect similar coal transformations. Among model compounds, consisting of various linkages connecting phenyl groups, only disulphide and ester linkages were observed to react under conditions of the coal transformation. A poly(phenyl ester)polymer, however, was found not to react. Substituents on the phenyl groups may be required to activate bonds for reaction with THQ under the conditions of this experiment.     

大粒度煤块气化特性研究

分别以H_2O(g)和CO_2为气化剂,采用自制的煤炭地下气化模拟实验装置完成大颗粒鹤壁烟煤和晋城无烟煤的气化模拟实验,用便携式气体分析仪对煤气组分进行测定,并用SEM分析气化后的半焦,考察了气化剂种类、气化温度和气化时间对2种煤气化反应特性的影响。结果表明:CO_2为气化剂时,反应温度越高,煤气中CO,H_2,CH_4含量越多,煤气热值也越高;以H_2O(g)为气化剂时,H_2含量随着反应温度升高增大,CO含量则先增大后降低,CH4明显降低。气化温度1 000℃时煤气热值最高,鹤壁煤和晋城煤热值分别达13.12 MJ/m~3和11.25 MJ/m~3;气化进行30 min时反应速率最大,60 min时热值最高;相同气化剂条件下鹤壁烟煤的煤气热值高于晋城无烟煤煤气;相同煤种条件下H_2O(g)为气化剂时的煤气热值高于CO_2。     

德士古煤气制甲醇工艺浅析

通过对三种典型煤气化方法的比较，给出了采用德士古装置的理由。对选用德士古水煤浆加压气化、NHD净化、低压甲醇合成与精馏制甲醇工艺的优势逐一进行了分析。     

Fuel gas from coal

The gasification of coal to produce a low-calorific-value fuel gas was widely practice prior to World War 2. Simple, single-stage producer gasifiers were used to supply kilns, brickworks, metallurgical furnaces, etc. These all but disappeared during the era of cheap natural gas and crude oil. The rising energy costs in the 1970s have led to a renewed interest in coal-derived fuel gas, and new coal gasifiers are being constructed which have higher capacity, higher efficiency and lower pollution than the old producer gasifiers. There are four main criteria which determine, to some extent, the type of coal gasification system employed. These are: capacity, distance for the gas to travel, required cleanliness of the gas, and coal characteristics. Three gasification processes, which are suitable for converting coal to fuel gas, are described: the FW-Stoic two-stage gasifier, the Esso Chemically Active Fluid Bed, and the U-Gas Industrial Fuel Gas Plant.     

高挥发分气煤变质研究及应用

针对高挥发分印尼煤的煤质特性,研究了其煤质在不同环境下的氧化变质规律,得出了该印尼煤的合理使用期限,提出抑制变质的措施并应用于实际生产中,为扩展炼焦煤资源进行了有益的探索与实践。