Changes of infrared absorption wave number of aromatic-ring C=C bond of vitrinite and their significance

The humilith series of lignite, long-flame coal, gas coal, fat coal, coking coal, lean coal, meagre coal and anthracite are measured by FIR-1600 infrared spectrophotorneter. The variation curve between the infrared absorption wave number of aromatic-ring C=C bond of vitrinite and its reflectance values are gained, which shows the shift of infrared absorption wave number of aromatic-ring C=C bond of humic coals towards lower wave number with the increase of coalification. It is believed that the coal rank of humilith series can be determined and more evolutional information about coal composition and structure can be obtained by the infrared spectroscopic method.