TESTING FE-BASED CATALYSTS FOR DIRECT COAL-LIQUEFACTION USING IN-SITUELECTRON-SPIN-RESONANCE SPECTROSCOPY

In this work, nine Fe-based catalysts (Fe2O3/SO4(1), Fe2O3/SO4(2), Mo/ Fe2O3/SO4, Fe2O3/SnO2/SO4, Fe2O3/MoO4, Fe2O3/WO4, FeOOH/SO4, Mo/FeOOH/ SO4, and Fe7S8) are tested for their hydrocracking abilities of Blind Canyon coal using in situ high-temperature ESR (electron spin resonanc e) spectroscopy of coal free radicals. The catalysts are characterized for chemical phase and for their particle size by X-ray diffraction. The intensities N of the free radicals are measured from room temperat ure to 500 degrees C in flowing Hz gas, with and without the catalyst plus elemental sulfur loadings, in the ratios Fe/coal similar or equal to 1% and Fe/S = 1/2. It is found that, above about 350 degrees C, th e catalyst loaded samples yield higher N. A free-radical density ratio R = N(catalyst)/N(coal) at 400 degrees C is defined to measure the hy drocracking abilities of the catalysts. The experimental R values vary from a high of 2.45 for Fe2O3/WO4 to the lowest R = 1.10 for Mo/FeOOH /SO4. A plot of R vs % oil yield from the direct liquefaction experime nts of Pradhan et al. shows that % oil yield increases linearly with R demonstrating usefulness of the ESR technique for testing catalysts. This plot also shows that Mo-substituted catalysts give higher oil yie ld for the same R, presumably due to the hydrogenation effect of Mo.