Mechanochemical effects in coal conversion. 1. Coal hydrogenation in gaseous hydrogen aided by mechanical energy

Hydrogenation experiments with a Pennsylvania anthracite coal were carried out in H₂ under the following conditions: with simultaneous grinding; with grinding and the addition of 1% tin; without simultaneous grinding; and without grinding but with the addition of SnCl₂ (1% Sn). Temperature was maintained at 442 °C and pressure at ≈6.8 MPa gauge (1000 psig). By eliminating or minimizing the effects of heating that were due to grinding, and of size and mass transfer, the net effects on hydrogenation of the above conditions were examined. SnCl₂, as expected, increased the light products, both gaseous and liquid. Grinding substantially increased the heavy oil products (MW ≈ 280), but not the light fractions. The effect of grinding in combination with the addition of tin was very similar to the effect of SnCl₂. A simple mechanistic scheme is postulated to represent these effects. Rationale of the mechanochemical effects is presented. Some preliminary results of the e.s.r. measurements regarding these effects are also included.