Phenanthrene Extraction of Bituminous Coal

Abstract

Three bituminous coal samples were extracted at 350°C. with phenanthrene, labeled in one series with tritium, in another with C 14 . The extract yield was 80-90%. Results: converting coal to soluble products breaks C-H bonds; 10-15% of the hydrogen content of the coal exchanged with that of the phenanthrene during extraction; 3-8% chemically linked phenanthrene was found in the extracts; less than 1% hydrogen exchange took place between pure model compounds (anthracene, p-benzyl--phenol) and tritiated phenanthrene under similar experimental conditions. Thus, chemical reactions take place during phenanthrene extraction of bituminous coals. The role of phenanthrene in this process is probably an interaction with the free radicals which are formed in the thermal decomposition of coal.jy|ost solvents which have been used for coal extraction can be divided into two groups. Extraction with the first group of solvents is based on purely physical effects and gives low extract yields. Most monocyclic aromatic compounds belong to this group. On the other hand, the extract yield is high when coal is treated with hydroaromatic solvents at higher temperatures. In that process chemical interactions take place, and hydrogen is transferred from the solvent to the coal substance. The higher yields with hydroaromatic solvents result from the hydrogenative cleavage of carbon-carbon and carbonoxygen linkages in the coal polymer and the formation of lower molecular weight, more soluble materials. The results of Orchin and co-workers (I, 2) on the extraction of coal with phenanthrene and other polynuclear aromatic compounds do not fit into this classification. They reported that at a temperature of about 350°C. phenanthrene and other related angular condensed aro-1

Suppression of Coke Formation during Bitumen Pyrolysis

“…Some hydrogen exchange was reported for phenanthrene as solvent with coal, but almost no exchange took place with anthracene. 17 In addition, little support was found that the ipso-mechanism was a significant contributor in coal dissolution by 1methylnaphthalene. 18 Yet, naphthalene was capable of reducing the coke from 7.5 ± 0.2% for neat bitumen pyrolysis to 3.8 ± 0.5% for bitumen diluted in naphthalene.…”

Methods for the preparation of coal-tar pitch

“…This is evident by the fact that the amount of the obtained pitch product was greater than the amount of the organic matter of coal loaded into an autoclave. Ear lier [62], the chemical binding of a solvent (phenan threne) with the products of thermal dissolution of coal was demonstrated by an isotopic marker method. Thus, the introduction of an additional solvent amount is required for performing a process with cir culating solvent.…”

Characterization of carbon black adsorbates and artifacts formed during extraction

“…In previous papers we have outlined a general approach based on interaction forces for the classification of solvents and adsorbents (9,10). This treatment accounts for individual interaction forces in terms of specific solubility parameters which are derived mainly from properties of the pure compounds themselves.…”

“…One approach which we pursued for the extraction of PAH from these materials was based on the assumption that the strongly adsorbed PAH were insufficiently extractable with benzene (the normal solvent for such extractions). A literature report on the solubilization of a large percentage of a coal sample with refluxing phenanthrene (9) led us to consider higher aromatics as being more likely to extract the PAH. As a first trial we conducted extractions of several carbon black samples with refluxing naphthalene at reduced pressure.…”