High Temperature Chemi-Sorption of Mercury on a Non-Carbonaceous Substrate

Sequestration of mercury vapor from combustion sources constitutes a currently important environmental problem. Whereas previous work has been concerned with physi-sorption of Hg on activated carbon, this work deals with chemi-sorption of Hg at high temperatures on an engineered sorbent, hereafter referred to as MinPlus sorbent. The feedstock for the current 50,000 t/yr sorbent manufacturing process consists of products derived from paper recycling processes.

A stream of pure air containing a known concentration of elemental mercury was passed through a fixed bed of MinPlus sorbent held at high temperature, and it was shown to capture up to 100% of the inlet mercury. The net adsorption of Hg was found to be temperature dependent, and is assumed to be the result of a combination of competing activation and deactivation rate processes. Under these benchscale test conditions we found a maximum adsorption at about 870ºC. Above 870ºC and the long residence times applied in fixed bed testing, deactivation of the sorbent can set in.