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

Deactivation of Cu-SAPO-34 by urea-related deposits at low temperatures and the regeneration

J Environ Sci (China). 2019 Jul:81:43-51. doi: 10.1016/j.jes.2019.02.008. Epub 2019 Feb 18.

Authors

Yue Ma¹, Xiaodong Wu², Junyu Zhang³, Rui Ran³, Zhichun Si⁴, Duan Weng⁵

Affiliations

¹ The Key Laboratory of Advanced Materials of Ministry of Education, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China. E-mail: yue-ma16@mails.tsinghua.edu.cn.
² The Key Laboratory of Advanced Materials of Ministry of Education, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China. E-mail: yue-ma16@mails.tsinghua.edu.cn,. Electronic address: wuxiaodong@tsinghua.edu.cn.
³ School of Environment, Tsinghua University, Beijing 100084, China.
⁴ Graduate School at Shenzhen, Tsinghua University, Shenzhen City 518055, China.
⁵ The Key Laboratory of Advanced Materials of Ministry of Education, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China. E-mail: yue-ma16@mails.tsinghua.edu.cn,; Graduate School at Shenzhen, Tsinghua University, Shenzhen City 518055, China. Electronic address: duanweng@tsinghua.edu.cn.

PMID: 30975329
DOI: 10.1016/j.jes.2019.02.008

Abstract

Selective catalytic reduction (SCR) with urea catalyzed by Cu-SAPO-34 is an effective method to eliminate NO_x 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.

Keywords: Biuret; Cu-SAPO-34; Deactivation; SCR; Urea.

MeSH terms

Cold Temperature
Copper / chemistry*
Models, Chemical
Nitric Oxide / chemistry
Spectroscopy, Fourier Transform Infrared
Urea / chemistry*
Vehicle Emissions / analysis*
Zeolites / chemistry*

Substances

SAPO-34
Vehicle Emissions
Zeolites
Nitric Oxide
Copper
Urea