Applied Coal Petrology

Chapter 6. Direct Coal Liquefaction

6.1. Introduction

The principal objective of coal liquefaction is the production of liquid hydrocarbon distillate products from a coal's mostly aromatic structure to be used as transportation fuels or chemicals. In broad terms, to generate petroleum-like products finely crushed coal (∼85% minus 0.074 mm) is prepared as a slurry with a process-derived vehicle oil, preheated and pumped into a heated (400–500°C) pressure vessel (6.9–71.0 MPa) in the presence of hydrogen gas with or without a catalyst for some duration (30–150 minutes). Under these conditions and depending on heating rate and maximum temperature, thermal ruptures of chemical bonds occur. In addition to acting as a carrier medium, the vehicle disperses ...