Effect of Temperature on the Sulfidation of Limestone at Reducing Atmosphere

Sulfidation experiments with limestone were performed in a pressurized thermogravimetric analyzer(Thermax 500) under noncalcining conditions.The effects of reaction temperature(700—950 ℃) on sorbent conversions were analyzed.Morphological studies with scanning electron microscope(SEM) were carried out to obtain the pictures of solid surface to illustrate the changes in particle structure. Nitrogen adsorption measurements were used to determine the physical properties of such samples as surface area and pore volume.Experimental results show that temperature greatly affects the reaction between CaCO3 and H2S,and the initial reaction rate increases with temperature;however,it is not necessary to obtain a high final conversion at high temperatures.Poor conversion of the sample upon reaction with H2S is caused by sintering of CaS product layer,which can be seen from SEM photographs.At higher temperature,the sintering of sample is more serious.In addition,CO2 also accelerates the sintering of CaS,resulting in a decrease in sulfidation rate.