Agricultural Waste Derived Catalysts for Low Temperature SCR Process: Optimization of Preparation Process, Catalytic Activity and Characterization

Abstract

ABSTRACT Carbon-based catalytic materials have received significant attention for low temperature flue gas denitrification (DeNOx) process, due to their physicochemical properties and ease of modification. To improve the DeNOx efficiency, preparation of biochar catalyst supports was conducted that included the acid treatment of the agricultural wastes rice straw, corn cobs and lotus leaves. Taguchi experimental design (34) was employed to screen suitable carbon materials and optimize the preparation parameters of the biochar. All of the acid-modified and unmodified samples were evaluated to determine their performance and they were characterized by using SEM, BET and FT-IR analysis. The experimental and characterization results showed that acid modification of the biochars improved their DeNOx performance, which may have been due to the changes in the physical and chemical properties of the carbon material following the acid treatment. The optimum combination in the acid modification procedure was found to be the use of lotus leaf carbon treated with an acid/mass ratio of 1.50 and a pyrolysis temperature of 800°C. The biochar prepared using these optimum preparation parameters were then employed as a carrier to support an active catalyst component (MnOx). The lotus leaf biochar supported 10 wt% manganese catalyst prepared using ultrasonic impregnation method exhibited nearly 90% NOx conversion at 250°C at a high space velocity of 45, 000–1, and it exhibited strong resistance to H2O. Additional studies showed that higher redox capacity and suitable surface acidity were two of the deciding factors in the improved low temperature SCR performance of the 10% Mn/LBC catalysts.