Influence of sodium on deactivation and regeneration of SCR catalyst during utilization of Zhundong coals

Abstract

Zhundong coals have a super huge reserve and many excellent characteristics. However, the sodium content in Zhundong coal is extremely high, which can accelerate the deactivation of the V‐W‐TiO2 selective catalytic reduction (SCR) catalysts. In the present work, the solution impregnation method was adopted to investigate the effect of alkali metals deposition on the SCR catalysts, while various approaches were employed to regenerate the poisoned catalysts. Experimental results indicate that sodium deposition significantly deactivates the catalytic performance of SCR catalysts and sodium hydroxide (NaOH) presents the most serious deactivation. The catalytic ability of sodium poisoned catalyst is only slightly recovered by water washing, whereas it could be improved to approach that of the fresh catalyst by acid solution washing. The regeneration effect of sulfation with SO2 is between those of water washing and acidic solution washing. Further characterizations validated that the deactivation is mainly caused by the damage of surface acid sites. Acidic solution can remove more than 75 wt% of the deposited sodium and provide new acid sites on catalyst surface. Therefore, acidic solution washing is a satisfactory method to regenerate poisoned SCR catalysts for power plants firing high‐sodium coals. © 2016 Curtin University of Technology and John Wiley & Sons, Ltd.

Investigation on elemental mercury removal and antideactivation performance of modified SCR catalysts

“…NO removal efficiency for V‐W/Ti and 0.5 Na is 96.5% and 80.3%, respectively. The decrease may be caused by the damage of acid sites of catalyst, which is closely related to the catalytic activity . η ′ of the modified catalyst is similar to that of the rudimentary catalyst because the values of NO removal efficiency are high enough.…”

Enhancement of SCR performance of monolithic Mn–Ce/Al2O3/cordierite catalysts by using modified deposition precipitation method

“…A widely used commercial catalyst for this process is V 2 O 5 –WO 3 (MoO 3 )/TiO 2 , which is generally located upstream of the electrostatic precipitator and desulfurizer to avoid reheating of the flue gas. However, the high concentration of ash and SO 2 in the flue gas reduces the performance and life of the catalyst . Hence, it is of enormous potential to develop highly active low‐temperature SCR catalysts positioned downstream of the electrostatic precipitator and desulfurizer where the flue gas temperature is below 200°C …”

Bioethanol as a potential eco‐friendlier feedstock for catalytic production of fuels and petrochemicals

“…207 McMahon 209 reported that the regeneration of SCR catalysts such as vanadium oxide or metal-substituted zeolites can be cheaper than the regeneration of SCR catalysts when the catalyst is relatively new or when the SCR process is not running continuously. Several researchers (studying regeneration [210][211][212][213][214][215] ) have found that the performance of poisoned catalysts can be partially restored by washing with H 2 O, H 2 SO 4 , NH 4 Cl, and/or catalyst precursor solutions and also by washing and treatment with gaseous SO 2 . When it comes to restoring a substantial proportion of the original catalyst activity, the amount to which these rejuvenation approaches are effective varies considerably from one catalyst to another.…”