NEW APPROACH TO COAL STRUCTURE THROUGH ITS EVOLUTION DURING DRY CATALYTIC-HYDROGENATION

Citation
Am. Mastral et al., NEW APPROACH TO COAL STRUCTURE THROUGH ITS EVOLUTION DURING DRY CATALYTIC-HYDROGENATION, Energy & fuels, 11(2), 1997, pp. 483-490
Citations number
48
Categorie Soggetti
Engineering, Chemical","Energy & Fuels
Journal title
ISSN journal
08870624
Volume
11
Issue
2
Year of publication
1997
Pages
483 - 490
Database
ISI
SICI code
0887-0624(1997)11:2<483:NATCST>2.0.ZU;2-1
Abstract
Coal structure and its evolution in catalytic hydrogenation are studie d in this work. The hydrogenation experiments were performed in tubing bomb reactors, in the absence of solvent, with an initial pressure of 10 MPa of H-2, and for a reaction time of 30 min; iron sulfide was th e catalyst precursor. The characterization of the solid residues was p erformed by different techniques, especially solvent swelling in pyrid ine and surface and porosity studies. The swelling values are related to the topological structure rather than to the density in noncovalent cross-linkages. The evolution of that structure is monitored by calcu lating the average number of carbon atoms between cross-link points, f inding that at mild hydrogenation conditions (350 degrees C for low-ra nk coals, 400 degrees C for bituminous coals) the solid residues prese nt a structure with longer chains of aromatic clusters than in the par ent coals. This would seem to be due to the release of heteroatom-cont aining moieties and the prevention of cross-linking reactions by the c atalyst. The textural characterization showed that there is a relation ship between the increase of the skeletal density and chain length; th e structure becomes more compact and ordered in the absence of low mol ecular weight or noncovalently bonded material.