Intensification of thermal coal and coke oxidation by metal oxides and their precursors

Oxidation process of bituminous coal, anthracite, and coke obtained after pyrolytic treatment of the corresponding fuels (bituminous coal and anthracite) modified with activating additives in the form of Cu(NO₃)₂ and Fe(NO₃)₂ in the amount of 5 wt% was studied. Application of the additives was carried out by incipient wetness impregnation method with preliminary dissolution of the additive in a water-alcohol solution with a volume ratio of C₂H₅OH/H₂O=50/50. Additionally modified samples were subjected to thermal treatment at a temperature corresponding to the decomposition of the considered metal nitrates (about 220 °C) to ensure close contact between additives (metal oxides) and carbon materials. Oxidation process was performed by thermogravimetric analysis at a heating rate of 10 °C/min in the temperature range 45-1000 °C at atmospheric pressure. It has been established that application of activating additives in the form of metal oxides and their precursors helps to reduce the initial temperature of intense oxidation (Δt_i = 15-80 °C) and to shift the process to the low-temperature region as a whole. Mass spectrometric analysis was used to determine the qualitative composition of the gas-phase oxidation products. Decrease in the initial temperature of intense oxidation contributed to a decrease in the intensity of NO_x release in the region of high temperature oxidation of the carbon residue.