Oxidation Catalysts for Elemental Mercury in Flue Gases—A Review

Abstract

Abstract:The removal of mercury from flue gases in scrubbers is greatly facilitated if the mercury is present as water-soluble oxidized species. Therefore, increased mercury oxidation upstream of scrubber devices will improve overall mercury removal. For this purpose heterogeneous catalysts have recently attracted a great deal of interest. Selective catalytic reduction (SCR), noble metal and transition metal oxide based catalysts have been investigated at both the laboratory and plant scale with this objective. A review article published in 2006 covers the progress in the elemental mercury (Hg el ) catalytic oxidation area. This paper brings the review in this area up to date. To this end, 110 papers including several reports and patents are reviewed. For each type of catalyst the possible mechanisms as well as the effect of flue gas components on activity and stability are examined. Advantages and main problems are analyzed. The possible future directions of catalyst development in this environmental research area are outlined.

Increased co-oxidation activity for mercury under hot and cold site coal power plant conditions – Preparation and evaluation of Au/TiO2-coated SCR-DeNOx catalysts

“…Au and V 2 O 5 activesites are known to adsorb mercury on their surface [17,29]. Surface experimental studies conducted on the SCR catalysts suggested that V 2 O 5 -active sites oxidize elemental mercury via Langmuir-Hinshelwood mechanism with both adsorbed Hg el and HCl species reacting to form weakly adsorbed HgCl 2 which is subsequently desorbed from the catalyst surface [7].…”

“…Ammonia, to a certain degree, and in a very pronounced manner the simultaneous presence of NH 3 and NO, will cause reduced mercury oxidation activity of SCR-DeNOx catalysts [19,21]. Due to these inhibitive effects, mercury oxidation takes place mostly at the outlet of an SCR reactor after most of NH 3 has been used up in the DeNOx reaction [7,22].…”

“…The catalytic oxidation of Hg el can be achieved as a co-benefit of SCR units for nitrogen oxides (NOx) reduction (DeNOx) [7]. V 2 O 5 -based SCR-DeNOx catalysts have been commercially available since the 1980s, and are the most commonly implemented technology for the reduction of nitrogen oxides (NOx).…”

Coal Fired Flue Gas Mercury Emission Controls

“…Moreover, considering that mercury brain content ranging from 2.5 to 10 M has already been associated to delayed psychomotor development in cases of exposure to minimal amounts of mercury poisoning, it was recently suggested that exposure to levels ten times lower could also lead to genotoxic consequences on the developing central nervous system, pointing to the need of reviewing the tolerance values published in 1990 by the WHO [67].…”

The Performance of Electron-Mediator Modified Activated Carbon as Anode for Direct Glucose Alkaline Fuel Cell

“…In recent years, with the rapid development of global industrialization, environmental problems caused by fossil fuel combustion are becoming more and more serious [1][2][3][4][5]. As possible alternatives of fossil fuel, biomass resources-one of the renewable energy sources-has attracted much attention [6][7][8][9][10].…”