While it is well known that certain pulverized coals can be liquified above ground in controlled conditions of solvent, pressure, and temperature; liquefaction of other coals is difficult to achieve. In the face of an increased demand for energy, and on considering the abundant supply of coal in parts of the United States, innovative research has been initiated to attempt to liquify coal in-situ using well-bore techniques which are essentially the same as those employed for petroleum production. In attempting in-situ liquefaction, the coal reaction face is essentially unpulverized, and liquefaction generally requires high temperatures (>400°C) and pressures (>2000 psi).The liquefaction processes involved in the hydrogenation or solution mining of coal are dependent upon both physical and chemical properties involving the structure and composition (including mineral impurities and trace elements) of the coal, the solvent, the surface area exposed - including particle size, homogeneity, cracks, pores, etc. - pressure, temperature, and catalyst. All of these properties in a consonant manner will control the rate and extent of liquefaction.
In situ acoustic-based analysis system for physical and chemical properties of the lower Martian atmosphere
