Direct investigation of reacting coals by diffuse reflectance infrared spectrometry

Diffuse reflectance (DR) infrared spectrum of solids at high signal-to-noise ratio (SNR) have been made on pulverized coal samples. In order to adapt the technique to the monitoring of chemical changes which take place while reactions are taking place, two new instrumental developments, a new cell and a different optical configuration for DR infrared spectrometry to accomodate the new cell were made. The new cell allows reactions to be studied at temperatures as high as 600/sup 0/C, and the reaction products may be continuously swept out of the cell, permitting characterization by a wide range of other instrumental techniques. These developments are described in some detail and have been used to follow the low temperature (150/sup 0/C) air oxidation of a low volatile bituminous coal as an illustration of the potential of DR spectrometry for monitoring coal reactions. This reaction is very slow, but the data give a good indication of the type of results that might be obtained for other much faster reactions such as pyrolysis and hydrogenation with or without catalyst present. (BLM)