Mercury occurrence modes in coal and the sulfur–mercury removal performance during coal pyrolysis

Abstract

The mild pyrolysis of coal provided a promising alternative method for mercury and sulfur emission control before coal combustion. In the work, the occurrence modes of mercury in one lignite and two bituminous coals were characterized by temperature-programmed decomposition with acid leaching. The removal performance of sulfur-mercury was also investigated by mild pyrolysis under weak oxidizing atmosphere. The results showed that the contents of organic-bound mercury, pyrite-bound mercury, and ash-bound mercury were in the range of 35-55%, 15-45%, and 10-45%, with their release temperature in the range of 250-650, 500-700, and >700°C, respectively. Sulfur and mercury were removed by fast pyrolysis at 500°C under 2%O 2 − N 2 atmosphere, and the proportion of Hg 2+ in gas phase increased. The results indicated that the oxygen had participated in the decomposition of the mercury-containing and sulfur-containing compounds, and some stable mercury-containing and sulfur-containing compounds were easier for decomposition under weak oxidizing atmosphere at low temperature. The removal efficiency of sulfur and mercury significantly increased under weak oxidizing atmosphere by fast pyrolysis. It was because fast pyrolysis could accelerate the breakup of molecular bonds associated with sulfur-mercury at a low temperature. The pore structure of char produced by fast pyrolysis was improved, which was favorable for sulfur containing gas and mercury release.

Pore structure and VOCs adsorption characteristics of activated coke powders derived via one‐step rapid pyrolysis activation method

“…With fewer volatile and more carbon contents, much less pores are rapidly founded at the beginning of the pyrolysis activation process of Jinhua and Zhundong coals. In addition, since there is much less volatile need to evaporate out in the raw material, these pores become important spaces for the activation gases to diffuse in and fully contact with the coal matrix, leading to the development of more mesopore structure in JHC and ZDC 41 …”

Efficient Removal of Elemental Mercury from Coal-Fired Flue Gas over Sulfur-Containing Sorbent at Low Temperatures

“…The method of temperature-programmed decomposition (TPD) was widely used to identify the occurrence modes of Hg in coals. − Hg-TPD was used to identify the mercury species in the used sorbent, and Figure shows the desorption profiles of Hg. There was a well-resolved peak at about 200 °C, which could be ascribed to the release of β-HgS. , …”