Effect of steam conversion parameters on the activated coal characteristics

Abstract

Due to with the environmental pollution, there is tightening of emission standards for pollutants of energy facilities. Some countries have introduced a limitation on mercury emissions. The effective sorbent for mercury capture is activated carbon (AC), it is a product of partial steam conversion of wood or coal. The perspective technology is the coal activation in the bed in the boiler furnaces of TPP. In this paper the results of studying the effect of the steam conversion parameters in a bed with external heating on the porous structure and sorption properties of activated carbon are presented. AC samples with different conversion degrees were produced at temperatures of 800 °C and 900 °C in the laboratory bed reactor. The volume and surface area of micropores, mesopores and macropores were measured by the BET method using the isotherms of nitrogen desorption at 77 K. The pore size distribution was determined by the BJH method. All produced samples had the average pore size about 3–4 nm. Most of the pores were micropores. For the produced samples pore volume by water and sorption of iodine, molasses and methylene blue were determined. It is shown that iodine sorption is proportional to the micropores volume, molasses sorption is proportional to the mesopores volume and methylene blue sorption is proportional to the macropores volume. To produce AC with high sorption of molasses and methylene blue, it is necessary to proceed the conversion at 900 °C.