Caking and coking properties of the thermal dissolution soluble fraction of a fat coal

Effect of Ca2+ species with different modes of occurrence on direct liquefaction of a calcium-rich lignite

“…Iron species evolved from pyrite could rapidly transform into pyrrhotite and catalyze the hydrogen transfer reactions to enhance oil yield [6][7][8] and in contrast, char-forming reactions catalyzed by clay might limit the conversion of coal during liquefaction process [9]. Hence, demineralized treatment or solvent extraction has been applied to upgrade lignites for more efficient utilization and better understandings in coal structures [10][11][12][13][14]. Low-rank coals, as the preferred liquefaction feedstocks, contain significant amounts of exchangeable cations which are present in the form of carboxylic and phenic salts [15].…”

Influences of exchangeable metallic species on solvent extraction of Xiaolongtan lignite and characterization of the separated portions

“…With the increase of porosity and specific surface area, solvent molecules could interact more fiercely with the polymerization network of coal. The π-π interactions originally existing in coal structure might also be broken [24]. Therefore, this sharp increase could be attributed to release of ionic cross-links and HBs originally present in coal.…”

“…This difference is intriguing and possibly results from that Ca 2+ are mainly bound to aromatic structures and these aromatic carboxylates are insoluble in organic solvents [27]. Besides, the π-π interactions originally existing in coal structure might also be partially broken by solvent extraction, which could result in more arenes entering the extracts [24]. A clear feature of extracts obtained from extraction with THF is that these extracts are rich in HCs, probably because THF has strong extractability and similar polarity to oxygen-containing species present in coal.…”

Evaluation of coal‐related model compounds using tandem mass spectrometry

“…As a fossil resource, coal has an extremely complex composition and consists of a wide range of organic species . Nowadays, coal conversion covers many industrial fields including coking, liquefaction and gasification . However, coal utilization remains of low efficiency and environmentally unfriendly due to the lack of knowledge of the composition of coals and coal derivatives .…”