Deactivation Mechanism of the Commercial V₂O₅–MoO₃/TiO₂ Selective Catalytic Reduction Catalyst by Arsenic Poisoning in Coal-Fired Power Plants

Abstract

Arsenic, a toxic component in coal-fired flue gas, is poisonous to the commercial selective catalytic reduction (SCR) denitrification catalysts. To unveil the arsenic poisoning mechanism on commercial SCR catalysts, fresh and 1 year used arsenicpoisoned plate-type V 2 O 5 −MoO 3 /TiO 2 catalysts from a coal-fired power plant in the Inner Mongolia Province of China were systematically analyzed with SCR activity and characterization experiments. The results indicated that the plate-type V 2 O 5 −MoO 3 / TiO 2 catalysts possessed a certain ability to resist arsenic poisoning. The average denitrification efficiency of the poisoned catalysts was maintained over 70% at 350 °C, even though the arsenic content was as high as 7 wt %, compared to the denitrification efficiency of 87.35% for the fresh catalyst. Characterization results indicated that both physical and chemical factors resulted in the deactivation of catalysts by arsenic. The surface area and amount of surface acid sites of the used catalysts decreased, which inhibited the adsorption of ammonia. The redox capacity of the used catalysts also decreased as a result of the increase of tetravalent vanadium (V 4+ ) and the decrease of surface chemisorbed oxygen. Furthermore, catalysts at different installation positions in the SCR system had different denitrification activities and deactivation mechanisms. The major deactivation factor for the catalysts in the top layer was physical blockage, while the chemical deactivation was dominant for the catalysts in the middle layer.

Advances in De-NOx Methods and Catalysts for Direct Catalytic Decomposition of NO: A Review

“…There are four combinations of vanadium-based catalysts used in coal power plants in China, including V 2 O 5 /TiO 2 , V 2 O 5 –WO 3 /TiO 2 , V 2 O 5 –MoO 3 /TiO 2 , and V 2 O 5 –WO 3 –MoO 3 /TiO 2 . V 2 O 5 is the active component; WO 3 and MoO 3 are the additives; and TiO 2 is used as a carrier. − The catalysts used in the HC-SCR reaction mainly include precious metals and zeolites, and the catalyst formed by loading Ag on γ-Al 2 O 3 shows good catalytic activity and hydrothermal stability. , To further improve the de-NO x performance, Satokawa et al found adding H 2 to the reaction atmosphere is helpful. Choi et al reported that adding Pt to the Ag/γ-Al 2 O 3 catalyst can reduce the active temperature significantly and improve the hydrothermal and sulfur resistance of the catalyst.…”

Deactivation Influence of HF on the V2O5–WO3–TiO2 SCR Catalyst

“…This ratio increases significantly from 0.190 to 0.601 when the catalyst is deactivated by HF from 400 to 300 °C. Lu et al 45 found that the redox capacity of deactivated samples decreased as a result of the increase of tetravalent vanadium (V 4+ ). It is believed that the decrease of V 5+ amount is one of important reasons for the decrease in the SCR catalytic activity.…”

A Critical Review on Removal of Gaseous Pollutants Using Sulfate Radical-based Advanced Oxidation Technologies

“…In the past few decades, many gaseous pollutants control technologies have been developed. In these technologies, wet flue gas desulfurization (WFGD) and selective catalytic reduction (SCR) denitration are the two most widely used SO 2 and NO x removal technologies. − Activated carbon adsorption is the main removal technology of heavy metals, Hg and As, from gas stream. − Alcohol amine absorption and catalytic oxidation are the most widely used treatment technologies of gaseous H 2 S. − The mainstream removal technologies of VOCs are rich due to huge types of VOCs and their different characteristics. Adsorption, absorption, condensation, and catalytic combustion are the common VOCs removal technologies. − Supporting Information (SI) Figure S1 shows the classification of these gaseous pollutants common removal technologies.…”