Heavy metal poisoned and regeneration of selective catalytic reduction catalysts.

Abstract

Being poison to heterogeneous catalysts, Pb and As are important metals in the study of industrial NOx emission reductions. A series of V2O5-WO3/TiO2-SiO2 catalysts poisoned by Pb and As were prepared through wet impregnation. The regeneration effect of deionized water, acid solution, complexing agent, and alkali solution on a poisoned catalyst was evaluated through experimental and theoretical calculations. For a Pb-poisoned catalyst, deionized water, acetic acid, and triethylenetetramine were used to wash. NOx conversion rate on the Pb-V2O5-WO3/TiO2-SiO2 catalyst increased from approximately 59.49% to 95.70%, which is 98.43% of the efficiency of the original fresh catalyst. As for an As-poisoned catalyst, deionized water, acetic acid solution, and sodium carbonate solution were used to wash, and the NOx conversion rate on the As-V2O5-WO3/TiO2-SiO2 catalyst increased from approximately 64.05% to 80.76%, which is 98.45% of the original efficiency of the fresh catalyst. The specific surface areas of the lead and arsenic regeneration catalyst were 46.41 m2/g and 45.95 m2/g respectively, approximately 14.00% and 11.02% higher than that of the poisoned catalyst (40.71 m2/g and 41.39 m2/g).The study provides a new method for the regeneration of SCR catalysts, which is particularly applicable for regenerating a large number of Pb- and As-poisoned catalysts.