Preparation and properties of sorbents from the coals of Mongolia

The textural and sorption properties of sorbents prepared by the thermal steam activation of the semicokes of brown and black coals from nine deposits of Mongolia were studied. Their properties were compared with the properties of sorbents prepared from Borodino brown coal and Kuznetsk black coal. A common extremal dependence of the volume of mesopores and the specific surface area on combustion losses was found: a maximum specific surface area of 600-700 m(2)/g was reached at a combustion loss of 50-60%. Among the Mongolian samples, the sorbents obtained from the brown coals of the Baganuur, Bagankhai, and Shivee Ovoo deposits exhibited the highest surface areas and sorption capacities for iodine. Nearly linear dependence of sorption capacity on specific surface area was found. The sorbents prepared from Borodino brown coals under identical conditions were characterized by a higher degree of combustion losses because of the increased concentrations of catalytically active calcium compounds in them.