Effects of chlorobenzene treatment on coal structure and liquefaction behaviour

This chapter discusses the effects of chlorobenzene and nonpolar solvent treatments on liquefaction behavior that is extremely varied and depends both on the coal and liquefaction regime used. The treatments give rise to significant but nonuniform, conformational changes in the macromolecular structure of bituminous coals. Solvent swelling, Nuclear Magnetic Resonance (NMR), and vitrinite reflectance measurements indicate that the increase in microporosity is accompanied by the formation of additional hydrogen bonds, with aromatic moieties. Solvent treatment leads to a more energy-minimized conformation with more microporosity and hydrogen bond cross-links. The driving force is sufficiently high to offset the possible loss of entropy from arising from the reduced mobility of the segments of the macromolecular structure. The ordering of aromatic moieties is less pronounced in the high energy-minimized conformations obtained after solvent treatment.