Properties of the solid thermolysis products of brown coal impregnated with an alkali

The mechanism of formation of a porous active carbon framework is considered, and the properties of the solid thermolysis products of brown coal (Aleksandriisk deposit, Ukraine) with potassium hydroxide are studied. The yields of the solid thermolysis products (Y _STP, %) and potassium humates, the rate of the interaction of the solid thermolysis products with KOH at 700–900°C, the specific surface areas (S _BET, m²/g), the adsorption capacities for methylene blue (A _MB, mg/g) and iodine (A _I, mg/g), and the specific activities of surface areas A _MB ^′ = A _MB/S _BET and A _I ^′ = A _I/S _BET (mg/m²) are determined under variation of the KOH/coal ratio (R _KOH < 18 mol/kg) and temperature (110–900°C).     

Formation of the pore structure of brown coal upon thermolysis with potassium hydroxide

The pore-structure characteristics of active carbons prepared by the thermolysis (800°C) of brown coal impregnated with potassium hydroxide were studied. The dependence of the specific surface area, total pore volume, micropore volume, micropore fraction, and micropore size distribution on the KOH/coal weight ratio R _KOH ≤ 1.0 g/g was found. Condensation processes with the formation of a low-porosity material were predominant at low ratios of R _KOH ≤ 0.1 g/g. The development of a micropore structure was observed at R _KOH ≥ 0.1 g/g, and it increased as R _KOH was increased to 1.0 g/g. It was hypothesized that pore formation was due to the thermally initiated reactions of the structural fragments of coal with KOH molecules, which occurred within the framework of coal.     

Lead adsorption on brown coal activated with potassium hydroxide

The adsorption of lead ions (from an aqueous solution of Pb(AcO)₂) by activated carbons based on brown coal from the Aleksandriisk deposit (Ukraine) was studied. The activated carbons were prepared by the heating (800°C; 1 h) of coal impregnated with potassium hydroxide at KOH/coal weight ratios to 2 g/g. The kinetics of the process was studied, and the adsorption isotherms of Pb²⁺ ions were obtained in the region of initial salt concentrations of 0.001–0.1 mol/dm³. The adsorption data were compared with the adsorption capacity of an OU-B commercial adsorbent.     

Composition of hydrogenation products of Borodino brown coal

The composition of liquid products of hydrogenation of brown coal from the Borodino deposit was determined by means of ¹³C NMR spectroscopy and chemical thermodynamics methods. It was shown that the group composition of the liquid hydrogenation products at thermodynamic equilibrium is predictable from the elemental composition of the organic matter of parent coal.     

褐煤弱氧化产物的成分分析

利用石油醚、氯仿对褐煤进行分级萃取,将萃余煤进行碱性弱氧化.GC/MS对褐煤和氧化产物的萃取液进行成份分析,并采用面积归一化法确定各成份的相对含量.实验表明:原煤石油醚萃取液中鉴定了46种组分,主要以烃类(80.2%)和酯类(14.3%)为主;萃余氧化煤的石油醚萃取液中鉴定了44种为氧化产物,与原煤组分相比,其中烃类(43.3%)相对含量减少,酯类(18.9%),醇类(15%),芳香烃(6.5%),酚类(6.1%),烯烃(4.6%),酸类(2.2%)相对含量增加.这表明在该氧化条件下可以使分子结构发生变化从而得到其它有机化学品.     

Adsorption of sulfur dioxide onto activated carbons prepared from oil‐palm shells impregnated with potassium hydroxide

Adsorption of sulfur dioxide (SO₂), a gaseous pollutant, onto activated carbons prepared from oil‐palm shells pre‐treated with potassium hydroxide (KOH) impregnation was studied. Experimental results showed that SO₂ concentration and adsorption temperature affected significantly the amount of SO₂ adsorbed and the equilibrium time. However, sample particle sizes influenced the equilibrium time (due to effect of diffusion rate) only. Desorption at the same temperature of adsorption and a higher temperature of 200 °C confirmed the presence of chemisorption due to pre‐impregnation. Impregnation with different activation agents was found to have limited effect on the inorganic components of the sample. Compared with the activated carbon pre‐treated with 30% phosphoric acid (H₃PO₄) that had larger BET and micropore surface areas, the sample impregnated with 10% KOH had a higher adsorptive capacity for SO₂, which was closely related to the surface organic functional groups of the sample. In general, the activated carbon prepared from oil‐palm shell impregnated with KOH was more effective for SO₂ adsorption and its adsorptive capacity was comparable to some commercial activated carbons. © 2000 Society of Chemical Industry     

Liquid products of the hydropyrolysis of brown coal form the Lena basin

Liquid hydrocarbon products were obtained by the hydropyrolysis of brown coal from a deposit in the northern Lena basin on an iron-containing catalyst. The individual and group compositions of gasoline and diesel fractions were determined with the use of capillary chromatography and chromatography-mass spectrometry. The gasoline fraction with a boiling point to 180°C was characterized by a high octane number; it mainly contained monocyclic aromatic hydrocarbons and normal alkanes. The diesel fraction mainly consisted of bi- and tricyclic aromatic hydrocarbons and C₁₃–C₁₉ n-alkanes.     

Forms of potassium in coal and its combustion products

High resolution X-ray absorption spectroscopy utilizing synchrotron radiation as a light source was used to probe the bonding and structure of potassium in coal and coal-derived products. The potassium sites in coals of various ranks and in the products of thermochemical processing were identified by comparison of unknown spectra with those of a wide range of selected potassium model compounds and minerals. For most coals examined, potassium was found to occur in a site in illite, a layered clay related to muscovite. Such coals included subbutuminous, high and low volatile bituminous, cannel and anthracite types. The lower rank subbituminous and lignite coals show other forms of alkali, where potassium appears to be in a noncrystalline environment. Examination of the near-edge spectra fails to reveal similarities between potassium in low-rank coal and in any organically bonded potassium model compounds such as carboxylic, phenolic, benzoic, phthalimide or intercalated groups. It is possible that the exchangeable potassium is still inorganically associated on disordered clay surfaces, though this remains equivocal. Thermal treatment of potassium-bearing phases inherent to coals generally leads to formation of a potassium aluminosilicate glass. Samples include those obtained from flash pyrolysis, gasification, laboratory combustion and a large scale pressurized fluidized-bed combustor including bed material, scrubbing hot cyclones, and quench-cooled pins for vapour phase deposition. No potassium sulphates were observed in the deposits.     

Liquid products of the alkaline activation of brown coal from the Aleksandriiskoe deposit

The liquid products of the alkaline activation of brown coal from the Aleksandriiskoe deposit (800°C; 1 h; activator, KOH) were studied by thermal analysis, IR spectroscopy, and ¹H and ¹³C NMR spectroscopy. They were formed in ∼30% yield; they consisted of pyrogenic water (∼50%) and a resinous mixture of organic substances with increased hydrogen and oxygen contents and decreased carbon and sulfur contents. On heating, potassium hydroxide completely decomposed the quinoid structures of coal, decreased the concentration of aromatic components in resin, and increased the concentrations of CH₃-, -CH₂-, and OH-groups. This is consistent with the well-known thermally initiated reactions of alkaline degradation and dehydrogenation at high temperatures (400–800°C). The thermal lability of resinous products was evaluated, and the heats of combustion (32.4–32.7 MJ/kg) were determined; the latter values indicate that these products can be used as fuel.     

Carbonization of trichloroethanes with anhydrous potassium hydroxide

Chemical dehydrochlorination of 1,1,1‐ and 1,1,2‐trichloroethanes with anhydrous potassium hydroxide (KOH) in the presence of a poly(ethylene glycol) oligomer as phase transfer catalyst leads to polymeric carbons with partly carbynoid structures. The FTIR spectra show a strong band at 2130 cm⁻¹ and FT‐Raman exhibits a strong line at around 1900 cm⁻¹, either of which is interpreted as the CC C stretching mode of the linear carbon chain with alternating carbon–carbon triple and single bonds (polyyne). Carbons prepared by this technique are amorphous nanoparticles with diameters in the 30–50 range nm. After iodine doping they have dc conductivities of 10⁻³ S cm⁻¹. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 185–189, 2000     

片状氢氧化钾生产中废碱的回收工艺

邢台矿业集团金牛钾碱分公司片状KOH生产工艺如下:将质量分数为32%的KOH溶液通过两效降膜蒸发,得到质量分数为48%的液碱产品,再通过升膜蒸发及降膜浓缩,使之成为质量分数为90%的熔融碱,经过片碱机制得片状氢氧化钾.     

赤峰某地褐煤制取腐植酸钾实验研究

以内蒙古赤峰某地褐煤为原料,分别采用氢氧化钾溶液、氢氧化钾与碳酸钾混合溶液两种提取液,进行了制备腐植酸钾的条件实验和正交实验,探究提取剂用量、固液比、热处理时间对腐植酸提取率的影响。结果表明,制备腐植酸钾的优化工艺条件为:在90℃下水浴1 h,固液质量比1∶10,氢氧化钾与碳酸钾混合液浓度1.0%+0.5%。在此优化条件下,腐植酸钾提取率87.2%。水溶性腐植酸含量52.5%,氧化钾含量22.6%,水不溶物含量9.5%,p H值11.0,水分含量约1.5%。     

赤峰某地褐煤制取腐植酸钾实验研究

以内蒙古赤峰某地褐煤为原料,分别采用氢氧化钾溶液、氢氧化钾与碳酸钾混合溶液两种提取液,进行了制备腐植酸钾的条件实验和正交实验,探究提取剂用量、固液比、热处理时间对腐植酸提取率的影响。结果表明,制备腐植酸钾的优化工艺条件为:在90℃下水浴1 h,固液质量比1∶10,氢氧化钾与碳酸钾混合液浓度1.0%+0.5%。在此优化条件下,腐植酸钾提取率87.2%。水溶性腐植酸含量52.5%,氧化钾含量22.6%,水不溶物含量9.5%,p H值11.0,水分含量约1.5%。     

Porosification behaviour of LTCC substrates with potassium hydroxide

The demand to meet advanced substrate requirements in terms of electrical, mechanical, thermal, and dielectric properties has led to an increasing interest in low temperature co-fired ceramics (LTCC). However, LTCC materials suffer from high permittivity. We recently showed that the wet-chemical porosification under acidic conditions allows the reduction of the permittivity of LTCCs in the as-fired state. In the present study, potassium hydroxide solution was employed as an alternative etchant which features a suitable bearing plane for further metallization lines. Various characterization techniques, including scanning and transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction analysis, and electron energy loss spectroscopy were used for investigation of the morphology and chemical composition of the substrates. Three-dimensional information of the surface topography was acquired by means of MeX^® Alicona software and the obtained roughness parameters confirmed the advantage of the proposed approach over acid treatment when targeting an enhanced surface quality.     

Thermal oxidation of high-modulus carbon fibers impregnated with potassium nitrate

Thermal oxidation of ultra-high-modulus Sigrafil UHM-3 carbon fibers (C-fibers) was performed by using potassium nitrate as an oxidizing agent. The impregnating solution consisted of 0.5–10 wt% KNO₃ in a water/methanol (3:1) mixture. Thermal treatment of the impregnated C-fibers was performed at 600 or 800°C in nitrogen or air, respectively. Furthermore, the influence of a subsequent treatment with 60% sulfuric acid was investigated. The thermal treatment of the impregnated C-fibers in nitrogen caused no change in their mechanical properties, whereas in the case of treatments in air, fiber damage was observed as indicated by a decrease in the tensile strength as well as by an increase of the BET surface area. Therefore, further investigations were carried out in a nitrogen atmosphere. An increase of the C-fibers' interlaminar shear strength (ILSS) from 22 to 40 MN/m² without loss of mechanical properties was achieved by impregnation with solutions of <5 wt% KNO₃. Impregnating solutions with higher concentrations damaged the fibers, however. A further increase of the ILSS to 57 MN/m² was obtained by subsequent treatment after the salt decomposition step with 60% sulfuric acid.     

Effects of brown coal quality and process parameters on the hydroliquefaction of brown coal

During the development of the HVB process the influence of different parameters on the process have been investigated. In this Paper the influence of the properties of the brown coal on the process is reported. It is shown that: (1) the petrographical composition of Rhenish brown coal has virtually no effect on the HVB process; (2) the problems of sedimentation caused by the ash composition of the brown coal can be overcome by a particular thermal pretreatment of the coal; and (3) the moisture content of the brown coal is of minor importance for the technical realization of the HVB process.     

Corrosion as a process determining the efficiency of porous nickel plates impregnated with nickel hydroxide

The methods used for the impregnation of porous nickel plates in alkaline batteries are compared. The effect of the corrosion process on these plates in terms of the efficiency, capacity and life of nickel-cadmium batteries with sintered electrodes is examined.