Advisor(s) - Committee Chair
Wei-Ping Pan, John Riley, John Reasoner, Chen-Lin Chou
Department of Chemistry
Master of Science
The behavior of chlorine and sulfur in Illinois coals and during pyrolysis and combustion their forms in the coals were evaluated by combined Thermogravimetry/Fourier Transform Infrared Spectroscopy/ Ion Chromatography (TG/FTIR/IC) techniques. It was found that more than 90% of chlorine in Illinois coals was liberated as HC1 gas during pyrolysis and combustion in the temperature range of approximately 3000 - 600°C, with the amount reaching the maximum around 440°C. Similarity of the HC1 and NH3 release profiles during pyrolysis of IBC-109 indicates that the forms of chlorine in coal is associated closely with the forms of nitrogen, and that the chlorine may be bonded to the basic nitrogen-sites on the inner walls of coal micropores.
Approximately more than 60% of the total sulfur in the coals was evolved mainly as SO2 and COS in the 250°C-750°C range during combustion. Except for SO2 and COS, H2S was a major gaseous sulfur-containing product observed during coal pyrolysis. The release rates of the gaseous sulfur species reached several peaks at some points within the temperature ranges during pyrolysis and combustion, and these peaks were due to the emissions of several types of the sulfur in different forms present in the coals.
The effect of chlorine removal from high chlorine Illinois coal on its reactivity was also investigated by TG/FTIR/IC techniques. The weight loss behavior of the leached coals was significantly different from that of the raw coal (IBC-109) during combustion. The release profiles of gaseous chlorine (HCl) and sulfur species (SO2 and COS) of the leached coals are significantly different from those of the raw coal.
The effect of the addition of CaCO3 and Ca(OH)2 on the behavior of chlorine and sulfur during combustion of high chlorine and medium sulfur Illinois coal was investigated by TG/FTIR/IC techniques. Thermogravimetry showed no significant difference in weight loss between IBC-109 and its sorbent mixtures, Coal-CaCO3 and Coal-Ca(OH)2. However, addition of 5% Ca(OH)2 or 6% CaCO3 to IBC-109, may not only reduce emission of chlorine by about 48% or 20%, but also reduce emission of total sulfur by about 68% or 52% during combustion.
Chemistry | Physical Sciences and Mathematics
Shao, Dakang, "Behavior of Chlorine & Sulfur During Coal Pyrolysis & Combustion" (1992). Masters Theses & Specialist Projects. Paper 2845.