Deactivation of Cu-SAPO-34 by urea-related deposits at low temperatures and the regeneration
Yue Ma , Xiaodong Wu , Junyu Zhang , Rui Ran , Zhichun Si , Duan Weng
DOI:10.1016/j.jes.2019.02.008
Received September 30, 2018,Revised , Accepted February 07, 2019, Available online February 18, 2019
Volume 31,2019,Pages 43-51
Selective catalytic reduction (SCR) with urea catalyzed by Cu-SAPO-34 is an effective method to eliminate NOx from diesel exhaust. However, urea-related deposits may form during cold-start and urban driving due to low exhaust temperatures. The activity of Cu-SAPO-34 at 175°C is significantly degraded by urea exposure, and 300°C is required for regeneration. Through in-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and temperature-programmed hydrolysis studies, the dominant stable deposit at 175°C is identified as biuret, which can be eliminated at 300°C. The urea-derived deactivation and regeneration mechanisms of Cu-SAPO-34 were compared with those of anatase-supported catalysts.
