Characterization of Novel Sorbents for Mercury Removal at Elevated Temperature

Abstract

The novel carbonate sorbents of Mg–Al–CO3 and (Mg3−x, Cux)–Al–CO3, were synthesized by co-precipitation method with individual nitrate salt of metal ions under alkaline conditions. The synthetic sorbent was characterized by analysis techniques such as BET surface area analysis, X-ray diffraction (XRD), and scanning electron microscopy (SEM). Elemental mercury capture experiments were carried out in a fixed-bed reactor including Hg permeation source, furnace, and Hg analyzer, which was conducted at temperature ranging from 30 to 300 o C. The major results showed that the surface area of material was significantly increased via incorporating Cu2+ into Mg–Al–CO3, accordingly enhancing Hg retention capacity of sorbents. SEM imagines displayed the layer appearance of Mg/Al and Mg/Cu/Al sorbents. Crystalline analysis indicated lamella structure accompanied with metal oxides within materials. Mercury removal tests demonstrated that the breakthrough time increased with temperature by adding transition metals to Mg–Al–CO3 as (Mg3−x, Cux)–Al–CO3. Hg uptake by the (Mg3−x, Cux)–Al–CO3 sorbent rapidly increased with elevated temperature up to 200 o C and reached the maximum capacity of 12.93 μg/g, and then gradually decreased after 300 o C. Surface area and unique properties of transition metals are the reason toward improving Hg capture sorbent. These results represent the feasibility of using such Hg sorbents for elemental mercury removal under elevated temperature conditions, and the detail mechanism is needed to be further studied.