Effect of catalyst precursors on coal reactivity in catalytic hydropyrolysis

✍ Scribed by C.E. Snape; C.J. Lafferty; H.P. Stephens; R.G. Dosch; E. Klavetter

• Publisher: Elsevier Science
• Year: 1991
• Tongue: English
• Weight: 346 KB
• Volume: 70
• Category: Article
• ISSN: 0016-2361
• DOI: 10.1016/0016-2361(91)90128-w

✦ Synopsis

The use of dispersed sulphided molybdenum and hydrous titanium oxide (HTO) catalysts enable tar yields in excess of 60% daf coal to be obtained for bituminous coals in fixed-bed hydropyrolysis using relatively mild conditions. However, it was found that a key difference between hydropyrolysis and batchwise hydrogenation is that the active form of the catalyst must be formed at a lower temperature in hydropyrolysis in order to be effective because of the much higher heating rates used. Thus, ammonium dioxydithiomolybdate which decomposes to form a sulphided MO compound below 250°C and Pd-exchanged HTO, where the Pd is reduced below 100°C have been found to be particularly effective (-0.2%. MO required to achieve maximum conversion). Molybdenum naphthenates and iron sulphides are much less effective in hydropyrolysis than in direct liquefaction because the active phases (MO& and pyrrhotite) are not appreciably formed below about 400°C. Preliminary results indicate that low concentrations of MO (about 0.02%) have considerable activity when ion-exchanged onto HTO-coated coals.