MOSSBAUER SPECTROSCOPIC STUDY OF IRON CATALYST IN COAL HYDROLIQUEFACTION——Ⅱ. ON THE TRANSFORMATION AND THE HYDROGENATION ACTIVITY OF FERRIC OXIDE UNDER VARIOUS REACTION CONDITIONS
Weng Sihao(East China Normal University, Shanghai) Wu Youqing Gao Jinsheng(East China University of Chemical Technology, Shanghai) Zhao Changgen Wu Zheng(East China Normal University, Shanghai)
In the hydroliquefaction lignite, ~(57)Fe Mossbauer spectra of solid residues with an original S/Fe atomic ratio of 0.25, and sampled at different time intervals showed that about 90% of the α-Fe_2O_3 was reduced to Fe_3O_4 and the other 10% was reduced to Fe_(1-x)S and then to Fe-S superparamagnetic phase (SPM). The dominant active Fe-bearing phase which is responsible for enhancing the liquefaction yield is Fe_3O_4 spinel when the original S/Fe atomic ratio is less than 0.25 and is non-stoichiometric hexagonal pyrrhotite Fe_(1-x)S when the ratio is equal to 2.5. The pyrrhotite posseses significantly higher catalytic activity than magnetite. Increase in reaction temperature results in finer catalyst grains and therefore enhances the conversion of the coal to liquid products.