STUDY OF THE PROCESS OF CARBONIZATION OF POWDERED CELLULOSE GRANULES IMPREGNATED WITH AgNO3 AND Pd(NO3)2

Abstract

A comparative study of the process of carbonization of powdered cellulose granules and powdered cellulose granules impregnated with silver and palladium nitrate salts was carried out. The process was carried out in the temperature range 200–600 °С. The influence of the presence of metals on the course of carbonization of powdered cellulose and the features of the reduction of silver and palladium during carbonization were studied by IR spectroscopy and X-ray phase analysis. It has been established that the presence of silver in powdered cellulose does not affect the yield of carbonized material. The presence of palladium in powdered cellulose leads to the fact that the yield of carbonizate in the temperature range of 300–600 °C is reduced relative to the yield of carbonizate simply from powdered cellulose. It has been established by IR spectroscopy that impregnation with salts and subsequent drying at 90 °C of powdered cellulose granules leads to the appearance of carboxyl groups in it, which are not observed in unimpregnated powdered cellulose. With an increase in the heat treatment temperature to 200 °C, the amount of these groups in the silver-containing material increases sharply, while in the palladium-containing material it remains unchanged. A significant increase in the number of C=O groups in the palladium-containing material begins at 300 °C. The increased relative content of C=O groups in the metal-containing material is also preserved in the temperature range of 300–500 °C. The presence of metals in powdered cellulose at pyrolysis temperatures of 300–500 °C leads to a decrease in the content of C=C groups in the carbon matrix relative to methylene (methine) groups. At 600 °C, the carbon matrix of all coals is completely carbonized. X-ray diffraction analysis recorded the appearance of metallic silver and palladium in metal-containing coals at a temperature of 300 °C As the carbonization temperature increases, the content of crystalline Ag(0) and Pd(0) in coals increases. No other forms of silver and palladium are found in the temperature range of 300–600 °С. Testing of metal-containing coals in a model reaction of hydrogen peroxide decomposition showed: in silver-containing carbonizates, the availability of silver particles for H2O2 increases due to an increase in the pyrolysis temperature; in Pd/C, an additional factor that increases the availability of metal particles is the interaction of palladium with carbonizate during pyrolysis.