The development of the surface of natural coal from Donets field in the course of thermolysis with KOH was studied. The dependences of the specific surface area of coal containing 90% carbon on the activation time, temperature (400–800°C), and KOH/coal ratio (0.75–4.5 g g−1) were determined. The effect exerted on the development of the porous coal structure by low-temperature (20±2°C) oxidative modification causing formation of oxygen functional groups and reorganization of the coal three-dimensional structure was studied.

The paper presents a brief historical review and innovation R&Ds of the IPOCC Department for Coal Chemistry.These R&Ds deal with coal mine exploitation problems, prevention of spontaneous combustion, dust control in mines, structural chemical features of coal with different genesis and stages of metamorphism and new methods for their modification and rational use.The methods for obtaining inexpensive sorbents from Ukrainian raw materials (including carbon containing waste) have been proposed.The problems of modern coal chemistry science studied in the IPOCC have been outlined.

Сопоставлены выходы газообразных продуктов (Н2, СО, СО2, CnH2n + 2, где n = 1–4) при щелочной активации бурого угля и параметры пористой структуры активированных углей. Показано, что выходы газообразных продуктов линейно коррелируют с величинами удельной поверхности и объемов пор. Установлены температурные области, в которых КОН вызывает дополнительное дегидрирование органического вещества угля без образования микропор (600–700°C) либо усиливает порообразование без выделения водорода (700–800°C).

The yields of gaseous products (H 2 , CO, CO 2 , and C n H 2 n + 2 , where n = 1–4) on the alkaline activation of brown coal and the porous structure parameters of activated carbons were compared. It was found that the yields of gaseous products linearly correlate with the specific surface areas and pore volumes. The temperature ranges in which KOH causes the additional dehydrogenation of the organic matter of coal without the formation of micropores (600–700°C) or strengthens pore formation without the release of hydrogen (700–800°C) were determined.

Обобщены данные о реакциях и процессах, протекающих в условиях щелочной активации углеродных веществ (УВ) – получения активированных углей (АУ) термолизом УВ в присутствии гидроксидов щелочных металлов МОН. Выделены наиболее существенные для активирования процессы: взаимодействие функциональных групп с МОН и образование интермедиатов – структур с группой С–О–М; трансформация их в металлсодержащие соединения (в основном М2СО3 и М2) в реакциях с углеродом, особенно с краевыми С-атомами на периферии графенов; восстановление М2СО3 и М2 до металла М, который интеркалируется в межслоевые пространства кристаллитов. Механизм щелочной активации наиболее подробно изучен для КОН как активирующего агента. Термоинициируемое восстановление оксида калия углеродом и интеркалирование металлического калия – два наиболее значимых процесса для развития микропористости АУ.

Data on the reactions and processes occurring under the conditions of the alkaline activation of carbon substances—the production of activated carbons by the thermolysis of carbon substances in the presence of alkali metal hydroxides MOH—are summarized. The following most important activation processes were recognized: (1) the interaction of functional groups with MOH and the formation of intermediate structures with the C-O-M group; (2) their conversion into metal-containing compounds (primarily, M 2 CO 3 and M 2 O) in reactions with carbon, especially, with terminal C atoms on the periphery of graphenes; and (3) the reduction of M 2 CO 3 and M 2 O to the metal M, which is intercalated into the interlayer spaces of crystallites. The mechanism of alkaline activation was studied in most detail for KOH as an activating agent. The thermally initiated reduction of potassium oxide with carbon and the intercalation of potassium metal are the two most important processes for the development of the microporosity of activated carbon.

Исследовано влияние степени метаморфизма (СМ) угля (Сdaf = 80–95.2%) на выход и характеристики активированных углей (АУ), получаемых в условиях щелочной активации (800°С, 1 ч, Ar) при соотношениях КОН/уголь 1 г/г. В этих условиях способность углей образовывать пористый материал снижается в ряду метаморфизма. Максимальную активируемость проявляет уголь марки Д (Сdaf = 80%), образуя материал с SBET = 1560 м2/г, V = 0.71 см3/г, Vmi = 0.51 см3/г. Минимальная активируемость (в условиях эксперимента ) обнаружена у антрацита (Сdaf = 95.2%), образующего АУ с плохо развитой пористостью (SBET = 306 м2/г, V = 0.15 см3/г, Vmi = 0.11 см3/г).

The effect of the rank of coal (C daf = 80−95.2%) on the yield and characteristics of activated carbons prepared under the conditions of alkaline activation (800°C, 1 h, Ar) at KOH/coal ratios of 1 g/g was studied. Under these conditions, the ability of coals to form porous materials decreased in the metamorphic series. Grade D coal (C daf = 80%) exhibited a maximum activation ability to form a material with S BET = 1560 m2/g, V Σ = 0.71 cm3/g, and V mi = 0.51 cm3/g. A minimum activation ability was found in anthracite (C daf = 95.2%), which forms activated carbon with poorly developed porosity (S BET = 306 m2/g, V Σ = 0.15 cm3/g, and V mi = 0.11 cm3/g).

The yield of gaseous products from brown coal and brown coal-KOH compound was studied in relation to the thermolysis temperature. The compositions of the gases formed in the presence of alkali and without it were compared. The alkali affects the course of thermolysis of the organic matter of coal and favors an increase in the fraction of hydrogen and alkanes in the thermolysis gases.

Изучены свойства нанопористых адсорбентов (НПА), полученных из бурого угля щелочной активацией с тепловым ударом (800°С). Установлены зависимости величины SBET и объемов макро-, мезо-, микропор и пор диаметром до 1 нм (НПА) от времени изотермической выдержки (до 90 мин) и природы щелочи (LiOH, NaOH, KOH). Сопоставлением изменений объемов пор и распределения их по размерам установлено, что адсорбент с наиболее развитой субнанопористой структурой формируется в начальной стадии (до 10 мин) активации. В этом материале около половины общего объема пор представлено порами с диаметром до 1 нм.

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.

Thermal-shock KOH activation has been used to produce nanoporous activated carbon from brown coal. The specific surface area, total pore volume, volumes of micropores and subnanometer pores were determined for activated carbons prepared at a varied alkali/coal ratio. Thermal shock was demonstrated to be more efficient for the development of surface area with SBET equaling up to 1700 m2/g in comparison to 1000 m2/g for thermally-programmed heating. Increasing the KOH/coal ratio in the activated mixture increases the total pore volume, the micropore volume, and also the volume of subnanometer pores. Thermal shock produces nanoporosity at lower KOH/coal ratios than respective low-rate heating processes of KOH activation.