Asphaltene derived from brown coal was hydrogenated in the temperature range 375-450 °C with and without the addition of a sulphided nickel molybdate catalyst at initial hydrogen pressures from 2 to 10 MPa and the products were characterized by elemental analysis, non-aqueous titration for acidic oxygen, and 1H n.m.r. spectroscopy. Supported molybdate-type catalysts and conventional first stage iron- and tin-based catalysts only affected the amount but not the chemical structure of recovered asphaltene from reactions of asphaltenes with hydrogen. It is concluded that both the reactant and product asphaltenes are fairly homogeneous and rapidly break down to form radical fragments when reacted in tetralin at temperatures ≈ 400 °C. The major influence of catalysts under these conditions is to decrease the fraction of these radicals which polymerize relative to that which forms oils by hydrogen abstraction reactions.
- brown coal