Catalytic Oxidation and Adsorption of Elemental Mercury over CuCl₂-Impregnated Sorbents

Abstract

CuCl 2 -impregnated sorbents were employed to remove elemental mercury from flue gas. Three carriers including neutral Al 2 O 3 , artificial zeolite, and activated carbon have been investigated in this research. The performances of these prepared sorbents have been tested in a bench-scale fixed-bed reactor under different simulated flue gas atmospheres and temperatures (333−573 K). CuCl 2 -impregnated activated carbon showed the best adsorption ability. However, CuCl 2 -impregnated neutral Al 2 O 3 and zeolite have demonstrated an adsorption rate similar to that of CuCl 2 -impregnated activated carbon in the early stage of the tests (5 min), and they achieved relatively high mercury oxidation efficiencies. These non-carbon sorbents could remarkably enhance the technoeconomical properties of mercury removal in coal-fired power plants and have great potentials in industrial application. The appropriate mercury capture temperature for these sorbents is 333−473 K. The possible mechanisms of elemental mercury oxidation have been discussed.

Simultaneous Control of Elemental Mercury/Sulfur Dioxide/Nitrogen Monoxide from Coal-Fired Flue Gases with Metal Oxide-Impregnated Activated Carbon

“…An earlier study also confirmed that main peaks of Cu 2p 3/2 were from 926 to 939 eV and Cu + and (Du et al, 2014). Du et al (2014) also showed that after Hg 0 removal test in the simulated flue gas, the spectrum area ratio of Cu + to Cu 2+ increased from 0.19 to 0.45, which should stem from the oxidation of Cu + by the oxidizing flue gas components. The oxidation of impregnated metal oxides is also expected in our test environment, in which great amounts of O 2 and HCl are present.…”

“…Liu and Liu (2013) suggested that activated coke doped with V metal oxide had high activities in adsorption and oxidation, which are the key mechanisms for multipollutants removal in coal-fired flue gas. Du et al (2014) indicated that CuCl 2 -impregnated activated carbon had higher adsorption ability for Hg 0 as compared to those for CuCl 2 -impregnated neutral Al 2 O 3 and zeolite at 60-300°C.…”

“…Subsequently increasing the temperature from 100 to 140 and 200°C caused a decrease in removal from 95% to 55% and 27%, respectively. Another study noted that the total adsorbed rate of Hg 0 for CuCl 2 -impregnated activated carbon was decreased from 90% to 73% when the temperature rose from 60 to 200°C; when the temperature increased to 300°C, the total adsorbed rate was only 6.3% (Du et al, 2014). The superior Hg 0 performance of CuO x /CAC at 350°C is not thoroughly clear at this time, but may stem from its high surface area/ microporosity and effective, amorphous, and well distributed Cu functional groups in the activated carbon.…”

Influences of Copper(II) Chloride Impregnation on Activated Carbon for Low-Concentration Elemental Mercury Adsorption from Simulated Coal Combustion Flue Gas

“…Besides sulfur, activated carbon impregnated with metal salts has demonstrated the competitive adsorption performance to those treated with sulfur. Copper salts, such as CuCl 2 and Cu(NO 3 ) 2 , have been extensively investigated as impregnation agents since they can not only increase the adsorption capacity of lowconcentration Hg 0 but also enhance the oxidation of Hg 0 into water-soluble Hg 2+ for activated carbon (Williams et al, 1997;Vidic et al, 2001;Kim et al, 2005;NguyenThanh et al, 2005;Lee et al, 2008;Lee et al, 2009a, b, c;Zheng et al, 2012;Li et al, 2013;Du et al, 2014;Liu et al, 2015;Yang et al, 2016a, b, c, d). Lee et al (2009a) suggested that activated carbon containing CuCl 2 may possess different sites available for Hg 0 oxidation and Hg adsorption, and the resulted oxidized Hg generated from the reactions between Hg 0 and CuCl 2 may be re-adsorbed at other available sites of the CuCl 2 -treated activated carbon.…”

Performance of CuOx–neutral Al2O3 sorbents on mercury removal from simulated coal combustion flue gas

“…CuCl 2 modified non-carbon sorbents have been shown to be promising mercury sorbents [15,16]. Copper, a transition metal, may have special catalytic effects for mercury oxidation due to its ability to store/release oxygen via the redox shift between Cu 2+ and Cu + [17].…”