Chapter 10 - HYDROGENATION AND REDUCTION

Abstract

This chapter presents the hydrogenation and reduction of Victorian brown coals to study the chemical structure of brown coal and the mechanism of coal reduction. It describes the chemical and physical processes involved in the conversion (reduction) of brown coals to liquid products with particular regard to (1) the effects of coal characteristics (organic structure and inorganic material present); (2) the role of the slurring solvent; (3) the role of the pyrolytic decomposition of the coal; (4) the nature and role of catalysts or promoters in hydrogen transfer reactions between hydrogen gas and donor solvents and/or direct transfer to the coal; and (5) the yield and nature of the primary liquid products. It has been established that Victorian brown coal is well suited as a feedstock for liquefaction. A fundamental reason for this position is the presence in brown coal of a significant amount of long chain, predominantly aliphatic, material with a high atomic H/C ratio. A good correlation has been established between the atomic H/C ratio for all coals and the yield of oil products. For a fixed atomic H/C ratio, however, the quality of the product from the higher rank coal is usually superior to that from the brown coal principally because it contains less oxygen. The subsequent hydro-treating step to upgrade the product may, therefore, require a lower reaction severity.