97/00834 Coal liquefaction method

Abstract

Catalysts of the CoMo type were prepared on four different surface-modified alumina supports: (1) TiO2-coated by impregnation, (2) ZrO2-coated by impregnation, (3) TiO2-coated by deposition, and (4) carbon-coated by pyrolysis. These catalysts were used in a catalytic coal liquefaction microreactor. The coke deposits on the spent catalysts were investigated using 13C solid-state nuclear magnetic resonance techniques of cross polarization with magic angle spinning (CP-MAS) and dipolar dephasing (DD). CP-MAS 13C spectral data of the coke deposits were used to quantify the aromatic and aliphatic carbon types, and 13C DD spectral data of the same samples to quantify the aromatic quaternary carbon types, from which the aromatic cluster size of the coke deposits was determined. Catalysts which promote the most coke deposition were found to perform poorly in terms of coal liquefaction conversion. The aromatic cluster size of the coke deposited on the spent catalysts appears to depend on the initial pore volume of the fresh catalyst and on the percentage of surface coating of the alumina support.