Recent advances in heavy metal poisoning mechanism and regeneration methods of selective catalytic reduction (SCR) denitration catalyst

Abstract

Selective catalytic reduction (SCR) denitrification technology is the most widely used, mature and efficient flue gas denitrification technology because of its high denitrification efficiency, good selectivity and clean process. However, heavy metals in flue gas can result in deactivation and deterioration of SCR catalysts by poisoning active sites on catalyst. Therefore, it is necessary to study the heavy metal poisoning mechanism and anti-heavy metal poisoning measures of SCR catalyst for reducing the operating cost of SCR denitrification system. This paper reviews the new research progress of the poisoning mechanism of different heavy metals on SCR catalysts (including vanadium-based catalysts, manganese-based catalysts, cerium-based catalysts). Various anti-heavy metal poisoning measures and mechanisms (e.g., doping metal and nonmetal elements, etc.) were summarized. Results show that the deposition of heavy metals on SCR catalyst causes the catalyst pores to be blocked, which reduces the specific surface area and pore volume of the catalyst and destroys the active sites on catalyst surface, thereby eventually leading to physical or/and chemical poisoning of catalyst. The anti-poisoning ability of SCR catalysts can be effectively improved by doping with metals or non-metals and using and synthesizing of carrier materials. Besides, the regeneration measures of SCR catalysts poisoning by heavy metals were also reviewed systematically. Solution wet washing, thermal reduction method and composite method are the common methods for the regeneration of heavy metal-poisoning SCR catalysts. Finally, the prospects and future directions for the development of heavy metal poisoning of selective catalytic reduction (SCR) denitration catalyst are presented.