Comparative Study of the Properties of the Coal Extractive and Commercial Pitches

Abstract

Three extractive pitches were produced by using thermal dissolution of the medium-ranked coals at 380 °C in anthracene oil. The empirical properties such as the chemical composition, solubility in quinoline and toluene, softening point, and content of carcinogenic polycyclic hydrocarbons, and also molecular and structural parameters of the extractive pitches were characterized in comparison with three commercially available pitches, including typical coal-tar pitch, petroleum-derived pitch, and blended pitch derived from the mixture of coal tar with petroleum feedstock. The molecular and structural properties of pitches were studied using FTIR, 1H and 13C NMR, and XRD techniques. It was shown that the average molecule of the extractive pitches was composed of predominantly aromatic rarely substituted pericondensed nuclei, such as that in coal-tar pitch. The spatial structures of both the extractive and reference pitches consisted of predominantly disordered carbon matter with a small amount of rather ordered nanosized “graphite-like” stacks. In terms of the technical specifications, the extractive pitches irrespective of the coal used met the requirements for the pitch binder and resembled commercial blended petro-coal-tar pitch. A remarkable merit of the extractive pitches compared to coal-tar pitch was low carcinogenicity (two to three times as low).

Solvolysis of Bituminous Coal in Coal- and Petroleum-Derived Commercial Solvents

“…A suite of different coal-derived and petroleum-derived commercial hydrocarbon fractions was chosen for coal dissolution: HCST, heavy coal semicoking tar (provided by Leninsk-Kuznetsk Semicoking Plant); CT, coal tar (Altai-Coke Joint-Stock Company); AFCT, anthracene fraction of coal tar (Coke Joint-Stock Company); HGOCC, petroleum-derived feedstock for the production of carbon black (it consisted largely of heavy gas oil from the catalytic cracking of petroleum residues); LGOP, light gas oil from the naphtha pyrolysis 20 using an experimental unit equipped with a 2 L stainless steel autoclave dissolver with a mechanical stirrer (speed 150 rpm). The autoclave was loaded with coal/ solvent slurry, purged carefully with nitrogen, and hermetically sealed.…”

“…The coal dissolution process was carried out following previously optimized conditions using an experimental unit equipped with a 2 L stainless steel autoclave dissolver with a mechanical stirrer (speed 150 rpm). The autoclave was loaded with coal/solvent slurry, purged carefully with nitrogen, and hermetically sealed.…”

“…From the coal extracts obtained, pitch samples were derived. Their chemical composition, molecular and structural characteristics, and empirical properties were compared with those for the commercial coal- and petroleum-derived pitches . It was found that, in terms of the chemical composition and empirical properties, the extractive pitches resembled the commercial pitch sample derived from the blended mixture of coal tar and petroleum feedstock.…”

Thermal Dissolution of Bituminous Coal in Heavy Coal Semicoking Tar and in Binary Blends with the Anthracene Oil

“…The coal dissolution process was performed following previously optimized procedures [13] at 350 and 380 °С for 1 h without hydrogen and catalyst. The autoclave was loaded with coal/solvent slurry, purged carefully with nitrogen and hermetically sealed.…”

The Composition and Properties of Soluble Products from the Coal ThermoSolvolysis with Hydrocarbon Residues and Blends as Solvents

“…The use of commercial hydrocarbon residues as the non-recycling solvents for coal dissolution can be a promising way because it allows co-processing of the hydrocarbon residues with coal into high value added demanded chemicals and fuels, in addition to significant savings in solvent regeneration. We studied recently [13][14][15][16] the dissolution of various coals at mild temperature to produce quinoline-soluble substances using a variety of commercially available coal-and petroleum-derived hydrocarbon fractions as solvents. The dissolution of bituminous coals in the liquid-phase solvent medium at a mild temperature of 350-380 °C was supposed to occur through depolymerization via weak linkages between the aromatic units.…”