Simultaneous removal of Cd and Pb from flue gases using in-situ generated nano-sized sorbents

Abstract

A laboratory-scale system incorporating a high temperature furnace has been utilized to study the reaction of heavy metal species and sorbents. The interaction between heavy metal species (cadmium and lead) and sorbents for different injection conditions is studied. Three different sorbents, a solid phase pillar intercalated clay (PICL) and two in-situ generated silica and titania, are used for capture of the heavy metals. The in-situ generated silica agglomerates had a high surface area and suppressed nucleation of cadmium and lead species vapors over all injection conditions. The mean particle size of the resultant heavy metals - silica complex is significantly larger than that of heavy metals alone. It can be tuned for effective capture in existing particle control devices. However, in-situ generated titania showed spherical form due to slow collision characteristic time and hindered to grow by heavy metal species. It showed smaller particle size distribution compared to silica except for injection TiO2 precursor into the first furnace and then injection heavy metal species into the second furnace. The solid phase pillar intercalated clay sorbent was not stable at 1000 degrees C, and structural changes resulted. The PICL sorbent showed low removal efficiency of heavy metals.