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.     

Stepwise extraction of brown coal from the Sergeevskoe deposit

The mechanism of the stepwise dissolution of coal was investigated. It was found that the step-by-step demineralization of extraction residues facilitated the quantitative extraction of bitumoids and their acid constituents. The acids were separated in accordance with bond types, and the individual composition of the resulting fractions was analyzed. It was established that more than a third of the organic matter of the test coal has aliphatic nature.     

Nanoporous brown coal adsorbents prepared by alkaline activation with thermal shock

The properties of nanoporous adsorbents prepared from brown coal by alkaline activation with thermal shock (800°C) were studied. The dependences of the value of S _BET and the volumes of macropores, mesopores, micropores, and pores to 1 nm in diameter in the nanoporous adsorbents on isothermal exposure time (to 90 min) and the nature of alkali (LiOH, NaOH, and KOH) were determined. The comparison of changes in pore volumes and pore size distributions indicated that the adsorbent with the most developed subnanopore structure was formed at the initial stage (to 10 min) of activation. In this material, about a half of the total pore volume consisted of pores with diameters to 1 nm.     

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.     

Preparation of waxes and humic acids from brown coal from the Sergeevskoe deposit

The comparative extraction of coal with organic solvents was performed. Humic acids were separated from solid residues. The yields, particle-size distributions, and chemical compositions of the resulting products were analyzed. It was demonstrated that brown-coal wax and humic fertilizers can potentially be obtained using coal from the Sergeevskoe deposit.     

Chemical composition of various petrographic constituents of brown coal from the Balakhtinskoe deposit

The ozonolytic destruction of the organic matter of the semibright and dull lithotypes of brown coal from the Balakhtinskoe deposit and the component composition of the products were studied. It was established that the organic matter of fusinite brown coal is more reactive with respect to ozone. The products obtained from it were characterized by the presence of aliphatic acids with shortened carbon chains and an increased concentration of hydroxy acids.     

Characteristic properties of brown coal lithotypes from the Tevshiin Govi deposit in Mongolia

The organic and mineral compositions and the technological properties of brown coals of the clarain and fusain types from the Tevshiin Govi coal deposit in Mongolia are characterized. The reactivity of petrographical lithotypes toward the process of ozonolysis was evaluated, and the composition of their ozonolysis products was studied.     

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.     

Nanoporosity development in the thermal-shock KOH activation of brown coal

Thermal-shock KOH activation of brown coal (800 °C, KOH/coal ratio 1 g/g) was shown to produce nanoporous activated carbon with more developed surface area than thermally-programmed heating (S_BET up to 1700 vs 1000 m²/g). Increasing the KOH/coal ratio (up to 1 g/g) in the activated mixture increases the total pore volume (0.14–1.0 cm³/g), the micropore volume (0.03–0.71 cm³/g), and also the volume of subnanometer pores (0.01–0.40 cm³/g). Thermal shock produces nanoporosity at lower KOH/coal ratios (0.5-1.0 g/g) than respective low-rate heating KOH activation.     

Paramagnetic properties of brown coal from the Kiyaktinskoe deposit before and after mechanical treatment and electron irradiation

Results of a study of the paramagnetic characteristics of brown coal from the Kiyaktinskoe deposit (Kazakhstan) in a native state and after mechanical treatment and electron irradiation are reported. The effects of these actions on changes in the paramagnetic properties of the test coal and on the intensification of a coal hydrogenation process are discussed. It was found that the concentration of free radicals changed only slightly after mechanical treatment in a ball mill at room temperature in an atmosphere of air, whereas the concentration of Fe³⁺ ions noticeably increased. Upon the electron irradiation of coal, the dose dependence of the concentration of free radicals passed through a maximum at a dose of 100 kGy. At the same radiation dose, the yield of a kerosene-gas oil fraction upon the hydrogenation of Kiyaktinskoe coal increased, and the total yield of liquid products increased upon the irradiation of coal and a catalyst (bauxite 094) to a dose of 100 kGy. It was hypothesized that Fe³⁺ ions, which were additionally formed upon coal grinding and irradiation, can serve as an internal catalyst in the course of coal hydrogenation.     

Gaseous products of the thermolysis of brown coal impregnated with potassium hydroxide

The yields of gaseous products (H₂, CO, CO₂, and C _n H_2n + 2 at n = 1−4) from brown coal and brown coal-KOH compounds were determined under conditions of nonisothermal heating (4°C/min) to 800°C followed by an isothermal exposure (1 h, 800°C). It was found that, in the presence of the alkali, the yields of H₂, CO, C₂H₆, and C₃H₈ increased; the yields of CO₂ and CH₄ decreased; and the formation of isobutane was completely suppressed. Changes in the gas compositions were explained by the alkali degradation of C-C bonds in the organic matter of coal and by the thermally initiated dehydrogenation and dealkylation reactions of arene and alkane structural fragments, in which KOH molecules served as H-atom donors in the formation of H₂ and alkanes.     

Properties of adsorbents prepared by the alkali activation of Aleksandriisk brown coal

Highly microporous adsorbents (micropore fraction of ～70%) were prepared by the alkali activation-thermolysis (800°C, 1 h) of brown coal (C ^daf = 70.4%) in the presence of potassium hydroxide at the KOH/coal weight ratio R _KOH ≤ 2.0 g/g. The dependences of the specific surface areas and adsorption capacities of the adsorbents for methylene blue (A_MB, mg/g), iodine (A_I, mg/g), and hydrogen (\(A_{H_2 } \), wt %) on R _KOH were determined. The adsorbents obtained at R _KOH ≥ 1.0 g/g exhibited developed specific surface areas and good adsorption characteristics (A_I = 1000–1200 mg/g, A_MB = 200–250 mg/g, and \(A_{H_2 } \) ≤ 3.16 wt % at 0.33 MPa). The high capacity for hydrogen allowed us to consider brown coal adsorbents as promising materials for use as hydrogen accumulators.     

Characteristics of coal from the Kushmurun deposit

The chemical analysis of coal from the Kushmurun deposit in Kazakhstan and its ash was performed. Data on the X-ray diffraction and thermal analysis of the coal ash are given. The chemical activity of the coal was determined. The specific heat capacity of the coal was studied by dynamic calorimetry, and its heat of combustion was calculated.     

Sorbent production from low-ash brown coal

The process for the production of a sorbent upon the carbonization of low-ash brown coal in a fluidized bed in a temperature range of 700–850°C was studied. The dependences of the main characteristics of the sorbent on temperature and the fraction of processed coal were found. The characteristics of the lignite sorbent obtained by the TERMOKOKS-KS technology are presented.     

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).     

Some compounds separated from depolymerized brown coal

The petroleum ether-soluble fraction of the methylated depolymerized product was fractionated by liquid and gas chromatography and the chemical formulae of nine crystalline substances that were isolated were determined completely or partially. Another two compounds (Figure 6, peaks 18, 23, 0.42%) were also separated and their structure was approximately determined. Seven other peaks (4.11%) were also identified as similar to fractions from liquid chromatography already discussed. Because of over lapping yields in Table 1 and text, the total characterized was only 4.8% of the depoly merized coal, and the total separated about 6.0% (Table 1). From these compounds, suggestions are made for the course of the depolymerization process and for the structure of the coal.     

Structural study of hexane-soluble products from hydroliquefaction of three Yallourn brown coal lithotypes over molten salt catalysts

The hexane-soluble fractions of hydroliquefied products from three Yallourn brown coal lithotypes have been separated into five fractions by combined silica-alumina packed column chromatography. Analyses of various fractions by g.c.-m.s. permitted the identification of ≈50 components in the saturate fraction and 40 components in the diaromatic fraction, together with 30 components in the monoaromatics. The components identified were quite similar among hexane-soluble portions of all three lithotypes. A marked predominance of even carbon number alkane (C₂₃-C₂₉) was observed in the hydrocarbon fractions from pale lithotype over $\text{ZnCl}{}_2\text{KCl}$, and medium light lithotype over both pure ZnCl₂ and $\text{ZnCl}{}_2\text{KCl}$. However, medium dark lithotype over both melt catalysts produced a saturate fraction with an odd carbon number(C₂₂-C₂₈) preference. Based on spectral methods, Soxhlet extracts obtained from untreated lithotypes (hexane and benzene solubles) were characterized as complex mixtures of higher molecular weight(300–1000) aliphatic hydrocarbons, which were supposed to be a precursor of the saturates produced from the corresponding lithotype in the catalytic hydroliquefaction.