Hydrogenation of coals catalysed by Mo effect and transformation of porous texture

• Published in: Fuel (Guildford) Vol. 74; no. 11; pp. 1709 - 1715
• Main Authors: Maldonaldo-Hodár, Francisco J., Rivera-Utrilla, José, Mastral, Ana M., Izquierdo, M.Teresa
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.11.1995; Elsevier
• Subjects: Applied sciences; coal liquefaction; Energy; Exact sciences and technology; Fuel processing. Carbochemistry and petrochemistry; Fuels; Mo catalysts; pore structure; Solid fuel processing (coal, coke, brown coal, peat, wood, etc.); pore structure; coal liquefaction; Mo catalysts; Molybdenum Sulfide minerals; Lignite; Catalysts; Pore structure; Coal; Hydrogenation; Molybdenum; Bituminous coal; Textures
• ISSN: 0016-2361; 1873-7153
• DOI: 10.1016/0016-2361(95)00167-4

The hydrogenation of 24 coals (LV bituminous to lignite) in the presence of Mo was studied. The hydrogenation temperatures were 300, 350 and 400°C, the hydrogen pressures 5 and 10 MPa, and the reaction time 30 min. At 300°C the Mo salts deposited on the coals do not decompose to the active MoS 2 state, so the hydrogenation process is not significantly different from that in the absence of a catalyst and is influenced by the ease of diffusion, with a consequent increase in conversion with increasing macropore volume. At 350 and 400°C, MoS 2 acts as a good catalyst and conversion is much greater than in the absence of a catalyst. Under these conditions, opening of pores in the coals has been detected as conversion increases; micropores develop to macropores in such a manner that the MoS 2 particles can penetrate progressively into pores originally inaccessible, so an increase in the micropore volume or surface area favours conversion. This pore-opening is accompanied by an increase in cross-link density. At 5 MPa of H 2, and increasing with temperature, some of the radicals formed are incorporated into the macromolecular structure by repolymerization reactions which result in blockage of the microporosity.