The effect of pressure and solvent quality on first stage coal liquefaction with dispersed catalysts

Dispersed catalysts, both molybdenum and iron based, have been shown to be effective for coal liquefaction. Most studies have tested the effectiveness of these catalysts at moderate to high hydrogen pressures, on the order of 1500 to 2500 psig (10.3 to 17.2 MPa). Coal liquefaction at lower pressures is well known. Hydrogen donor solvents, such as tetralin and dihydrophenanthrene, are capable of transferring hydrogen to the coal at low pressures, less than 400 psig (2.8 MPa). This study is aimed at exploiting a combination of dispersed catalyst activity with donor solvent quality to reduce the overall pressure of first stage coal liquefaction. Two questions are being addressed in this study. The first is how effective are dispersed catalysts for hydrogenation at lower pressures and the second is to what extent are dispersed catalysts capable of catalyzing the transfer of hydrogen to the coal. This paper presents preliminary studies aimed at addressing these two questions with model coal liquefaction solvents PANASOL (non-hydrogen donor) and tetralin (hydrogen donor).