Page 119 - New Trends In Coal Conversion

82 New Trends in Coal Conversion

Table 3.6 Sorbents for the removal of trace elements from gas streams
Sorbent Element Temperature range
Based on zeolites Hg Low temperatures, up
to 400 C

• Impregnated with sulfur
• Impregnated with iodides
• Ag and Hg ion exchanged
Based on activated carbon (AC) Hg at higher temperatures Low temperatures, up

also Cd, Pb to 300 C
• AC
• AC impregnated with sulfur,
chlorine, iodides
• Oxidized AC
Siliceous materials V, Pb, Ni, Zn at low High temperatures
temperatures also Hg, 600-1000 C

• Mg, Ca, Al silicates Cd low temperatures

• Mixed silicates, silicate-fly ash e.g., < 100 C
mixtures, impregnated siliceous
materials

Based on alumina Pb At up to 700 C
• Activated alumina gel,
• alumina coated steel wool
• Alumina impregnated with alkali
carbonate or phosphate
Calcium compounds Hg, Zn, V, Ni at low Hg at up to 300e400
temperature As at high C, V, Ni, As at high
• Hydrated lime/fly ash temperature temperatures
• Limestone/fly ash, limestone/
silica
• Hydrated lime þ Sn, limestone,
calcium chloride

Other materials Hg, V, Ni, Pb, As V, Ni at up to 550 C
As at high temperatures
• MgO, Mg(OH) 2 ,
• Cr, Ni compounds
• Fe compounds, e.g., blast furnace
dust

Data from CIEMAT, 1998. Flue gas cleaning. European Commission DG XVII Clean Coal Technology Handbook, Section
5, Madrid/Brussels; Zevenhoven, R., Kilpinen, P., 2001. Control of Pollutants in Flue Gases and Fuel Gases.
TKK-ENY-4, Espoo, Finland, Helsinki University of Technology.