PMID- 34061273
OWN - NLM
STAT- MEDLINE
DCOM- 20211012
LR  - 20220218
IS  - 1614-7499 (Electronic)
IS  - 0944-1344 (Print)
IS  - 0944-1344 (Linking)
VI  - 28
IP  - 40
DP  - 2021 Oct
TI  - Effects of thermal treatments on characteristics and morphological variations in 
      the deposits of urea-SCR systems.
PG  - 56711-56726
LID - 10.1007/s11356-021-14057-4 [doi]
AB  - Selective catalytic reduction (SCR) systems are employed by automobile 
      manufacturers for the abatement of environmental pollutants like oxides of 
      nitrogen (NO(x)) emitted from exhaust gases of diesel engines. In SCR, the 
      urea-water solution (UWS) is injected to exhaust gases in the form of a spray to 
      generate the reducing agent NH(3). Deposit formation at lower temperatures is a 
      major concern with this technology. The deposits not only create backpressure but 
      also leak NH(3) to the environment as they deplete. It is very important to know 
      the depletion characteristics of deposits formed at lower temperatures in order 
      to assess the NH(3) leakage to the environment when the engine exhaust gases 
      attain higher temperatures. In the present work, deposits formed at a 
      low-temperature range of 150-200 degrees C for continuous run along with UWS injection 
      were investigated. Additionally, they were aged at 300 degrees C in the absence of UWS to 
      check the variation in characteristics with the rise of temperature. By 
      gravimetric analysis, it is inferred that the deposits formed at higher pre-age 
      temperatures are less prone to depletion as the temperature increases. The 
      elemental analysis using energy-dispersive X-ray spectroscopy (EDX) indicates 
      slight variation in carbon, nitrogen and oxygen compositions for all the pre-age 
      conditions. As an extended study, the byproducts at pre-age and post-age 
      conditions were investigated through X-ray diffraction (XRD). The compounds like 
      cyanuric acid (CYA) and biuret were not observed when pre-age samples were aged 
      at 300 degrees C. Instead, the compounds like ammelide, ammeline, triuret and melamine 
      were observed. Scanning electron microscope (SEM) study revealed morphological 
      changes in both pre-age and post-age samples. Further, the crystallinity 
      variations were also observed for the changes in the heating cycles during 
      deposit formation. The gravimetric analysis of deposits in pre-age and post-age 
      conditions helps in predicting the amount of deposits for transient load cycles.
CI  - (c) 2021. The Author(s).
FAU - Prabhu S, Sadashiva
AU  - Prabhu S S
AD  - Department of Mechanical and Manufacturing Engineering, Manipal Institute of 
      Technology, Manipal Academy of Higher Education, Manipal, Karnataka, 576104, 
      India. ss.prabhu97@gmail.com.
FAU - Natesan, Kapilan
AU  - Natesan K
AD  - Department of Mechanical Engineering, Nitte Meenakshi Institute of Technology, 
      P.B.No.6429, Yelahanka, Bangalore, Karnataka, 560064, India.
FAU - Nayak, Nagaraj Shivappa
AU  - Nayak NS
AD  - KBAT Technologies Private Limited, Pune, Maharashtra, 411033, India.
LA  - eng
PT  - Journal Article
DEP - 20210601
PL  - Germany
TA  - Environ Sci Pollut Res Int
JT  - Environmental science and pollution research international
JID - 9441769
RN  - 0 (Vehicle Emissions)
RN  - 8W8T17847W (Urea)
SB  - IM
MH  - Catalysis
MH  - Oxidation-Reduction
MH  - *Urea
MH  - *Vehicle Emissions
PMC - PMC8500864
OTO - NOTNLM
OT  - Deposits
OT  - Morphology
OT  - NOx
OT  - Selective catalytic reduction
OT  - Thermal treatment
OT  - Urea
COIS- The authors declare no competing interests.
EDAT- 2021/06/02 06:00
MHDA- 2021/10/13 06:00
PMCR- 2021/06/01
CRDT- 2021/06/01 12:25
PHST- 2020/09/19 00:00 [received]
PHST- 2021/04/19 00:00 [accepted]
PHST- 2021/06/02 06:00 [pubmed]
PHST- 2021/10/13 06:00 [medline]
PHST- 2021/06/01 12:25 [entrez]
PHST- 2021/06/01 00:00 [pmc-release]
AID - 10.1007/s11356-021-14057-4 [pii]
AID - 14057 [pii]
AID - 10.1007/s11356-021-14057-4 [doi]
PST - ppublish
SO  - Environ Sci Pollut Res Int. 2021 Oct;28(40):56711-56726. doi: 
      10.1007/s11356-021-14057-4. Epub 2021 Jun 1.