One Pot Optimized Synthesis of Cu-SAPO-34/Cordierite with HF and the Properties of NH3-SCR for NOx Removal

Abstract

Cu-SAPO-34/cordierite catalysts, prepared via in situ hydrothermal synthesis technique with various HF content, of which the morphology and crystal structure were characterized by XRD and SEM, respectively. The activity of the catalysts prepared above for selective catalytic reduction (SCR) of NO_x was evaluated with a fixed-bed reactor in simulated diesel vehicle exhaust. The results indicated that HF content played great roles on crystallization and catalytic properties of the samples. Loading amount and relative crystallinity of Cu-SAPO-34 were both increased along with the increasing n(HF)/n(Al₂O₃) ratio in the range of 0.01-0.03. The grain size became smaller and more uniform. The samples, crystallized for 24 h, have already showed a higher de-NO_x activity and a stronger anti-aging property, over which the NO_x conversion rate at the space velocity of 12 000 h^-1 could reach higher than 95 % from 320 to 600 °C. As for the sample of n(HF)/n(Al₂O₃) = 0.03, NO_x conversion rate could reach higher than 80 % from 380 to 560 °C at the space velocity of 36 000 h^-1 and reached higher than 50 % from 460 to 580 °C after the aging treatment.