Abstract
Effects of selenium and red-mud/selenium catalysts were examined on liquefaction of Taiheiyo coal mainly under hydrogen pressure of 10.1 MPa at 723K. It has been shown that in naphthalene/hydrogen system both selenium and red-mud/selenium catalysts give higher yields of pyridine solubles and benzen solubles by enhancing hydrogen transfer from gas phase to liquids than those obtained in tetralin/ hydrogen system without catalysts. In addition, the activity of selenium as a catalyst and as a mutual promoter of red-mud is higher than that of sulfur.
Experiments were also made on liquefaction of Big Brown lignite using selenium dioxide catalyst to compare the selectivity of the catalyst with those of conventional liquefaction catalysts. These catalysts are classfied roughly into two types. One is the type which promotes the production of asphaltenes and oils, while another enhances that of water and gases. The selenium dioxide catalyst belongs to the former.
It is thus concluded that selenium and selenium dioxide are effective on hydro-genation reaction of solvent during initial stage of coal liquefaction.
