Dynamic behavior of the forms of sulfur in the low-temperature hydropyrolysis of coal at high pressure

Five kinds of American noncoking bituminous coal which are different forms of sulfur were used to carry out hydropyrolysis for desulfurization. Hydropyrolysis was performed at conditions of hydrogen stream, 30kg/cm{sup 2} and 500{sup 0}C. Organic sulfur decreases rapidly and transfers into gas and tar. Pyrite is reduced to ferrous sulfide. The reduction to metallic iron cannot be neglected for some kinds of coal. Nonisothermal simulation was carried out concerning the change of sulfur-form distribution with time by applying the dynamic model. Frequency factors on reaction were determined for all kinds of coal. Microscopic observation indicated that exinite was at first discomposed and disappeared during heating up and at the same time gaps or voids developed around the pyrite in vitrinite owing to the reduction of pyrite to ferrous sulfide. This reduction proceeded further to metallic iron with the time elasping. The relationships between change of frequency factors ratio and time-averaged internal surface area in heat-up period, releasing rate of organic sulfur into volatile matters, and exinite content in raw coal were determined. 6 refs., 9 figs., 5 tabs.