Research On The Ammoxidation Process Of Brown Coal

The kinetics of ammoxidation of brown coal, a gas-liquid-solid three phase reaction, was studied in a high-pressure stirred reactor. The effect of stirring speed and particle size on the reaction was studied. The results showed that the effect of internal and external diffusion on the reaction could be eliminated when the particle size less than 60 mesh and the stirring speed up to 750r·min^-1.Under the environment of Polymath 6.0, the data were processed with nonlinear model. The kinetics equation was established as following:The characteristic of humic acid (HA) was studied. The results gave a basis for research of reaction mechanism. The significant groups content of HA were analyzed, such as carboxyl group, carbonyl group, methoxyl group and total acidic group. The variation regularity of the groups with the time and reaction conditions during the ammoxidation process were investigated. The results showed that these groups content were changed evidently during the ammoxidation process. The carboxyl group content and total acidic group content were increased, the carbonyl group content and methoxyl group content were decreased. The reaction temperature and pressure of oxygen effected the ammoxidation evidently. In the same reaction time, the higher the reaction temperature and pressure of oxygen were, the more carboxyl group content and total acidic group content were and the fewer methoxyl group content and carbonyl group content were. But the effect of concentration of ammonia was not evident. When the concentration of ammonia was elevated, the methoxyl group content and carbonyl group content decreased a little and the carboxyl group content and total acidic group content did not change almostly.