Improved Coal Liquefaction Using Carbon-Supported Hydrogenation Catalysts: Final Technical Report for the Period October 1983-March 1987

摘要

Various carbons have been prepared (or obtained from commercial sources) and their potential application as catalyst supports investigated, with and without modification to the surface functionality by nitriding and oxidation. Relatively large amounts of nitrogen (3.74%) were introduced into a commercially prepared mesopore carbon (Ambersorb XE-348), which was therefore selected as the principal carbon support. Compared to catalysts prepared upon the original and preoxidized supports (by impregnation with a 90% H sub 2 O/10% EtOH solution of ammonium tetrathiomolybdate), low metal loadings (3% wt Mo) on the nitrided (at 873 sup 0 K for 1.5 h) support resulted in greatly enhanced hydrogenative activity, as evidenced by the higher asphaltene conversion to oils, with low attendant coke deposition. In the temperature range 648 to 723 sup 0 K at short reaction times (up to about 2 h) and an initial hydrogen pressure of 6.9 MPa, apparent activation energies of 44.7 and 35.2 kcal mol sup -1 , respectively, were obtained for the noncatalyzed and catalyzed (3% wt Mo on the prenitrided Ambersorb XE-348) conversion of coal asphaltene into oils. The corresponding preexponential factors were 1.3 x 10 sup 9 s sup -1 and 6.3 x 10 sup 6 s sup -1 . Since catalytic activity is reported to be influenced by the nature of the metal-containing precursor, catalysts were prepared by the impregnation of different porous carbons with ammonium heptamolybdate and two organometallic precursors: molybdenum-acetylacetonate and molybdenumtricarbonyltriacetonitrile. The activities of the sulfided catalysts were measured for thiophene hydrodesulfurization in a continuous flow, atmospheric pressure reactor. For a given support and at similar metal loadings, the organometallic precursors conferred much higher HDS activities than the ammonium salt precursors. 150 refs., 41 figs., 32 tabs. (ERA citation 13:000034)