This content is not included in
your SAE MOBILUS subscription, or you are not logged in.
Development of NOx Trap System for Commercial Vehicle - Basic Characteristics and Effects of Sulfur Poisoning -
Technical Paper
2004-01-0580
ISSN: 0148-7191, e-ISSN: 2688-3627
Annotation ability available
Sector:
Language:
English
Abstract
Since a NOx trap catalyst cyclically releases and reduces NOx with rich exhaust gas, generating of a rich spike becomes important for application to diesel engines, which always operate with overall lean combustion. In addition, a NOx trap catalyst is poisoned and degraded in performance by the presence of SO2 in the exhaust gas.
When the NOx absorbing efficiency thus decreases, it is necessary to regenerate the catalyst by a sulfur purge (desulfation) process in order to remove SO2. It is apparent that there are many factors and effects to understand before one can apply this catalyst system to a diesel engine, therefore we have carried out an inquiry into a performance of the NOx catalyst used the model gas equipment with known gas mixtures. The rich spike was generated with diesel fuel (light oil), resulting in a transient equivalence ratio spike > 1, to simulate diesel exhaust gas. Results indicated a NOx conversion efficiency exceeding 90% after optimizing the diesel fuel addition method. Moreover, the transient mode engine tests showed an average conversion efficiency exceeding 70%.
However, during the engine tests the performance began to decrease due to degradation assumed to result from SO2 poisoning. It was then important to establish the optimum sulfur purge method during model gas testing. The sulfur desorption rate was improved by alternating between rich and lean gas at a 600°C temperature. Following regeneration of the degraded catalyst (after SO2 poisoning), sulfur desorption and performance recovery were observed.
However, since the sulfur purge requires a high catalyst temperature, fuel consumption and thermal catalyst stability are items to be mindful of. We note that low-sulfur fuel is preferred for the NOx trap catalyst.
Recommended Content
Authors
Topic
Citation
Takahashi, Y., Takeda, Y., Kondo, N., and Murata, M., "Development of NOx Trap System for Commercial Vehicle - Basic Characteristics and Effects of Sulfur Poisoning -," SAE Technical Paper 2004-01-0580, 2004, https://doi.org/10.4271/2004-01-0580.Also In
Diesel Emissions on CD-ROM from the SAE 2004 World Congress
Number: SP-1835CD; Published: 2004-03-08
Number: SP-1835CD; Published: 2004-03-08
References
- Matsumoto Shin-ichi et al. “NOx Storage-Reduction Catalyst for Lean-Burn Engine,” Catalysis Society of Japan 39 3 1997
- Asanuma Takamitsu et al. “Effect of sulfur-free Aromatics-free diesel Fuel on Vehicle Exhaust emissions using Simultaneous PM and NOx Reduction System” SAE Paper No. 2003-00-73 2003
- Nakatani Koichiro et al. “Simultaneous PM and Nox Reduction System for Diesel engines” SAE Paper No. 2002-01-0957 2002
- Ohki Hisashi et al. “DPNR Control Technology of Diesel Engine for Passenger Car,” JSAE Paper No. 2002252 2002
- Parks Jim et al. “Durability of NOx Absorbers: Effects of Repetitive Sulfur Loading and Desulfation,” SAE Paper No. 2002-01-2880 2002
- Hosjti S. et al. “Impact of Sulfur on the NOx Trap Catalyst Activity Poisoning and Regeneration Behavior,” SAE 2000-01-1874 2000
- Minamikawa Jinichi et al. “Development of a Simultaneous Reduction System of PM and Nox for Light-Duty Truck,” JSAE Paper No. 20035567 2003
- Nakatsuji Tadao et al. “A catalytic NO reduction in periodic lean and rich excursions over Rh supported on oxygen storage capacity materials,” Elsevier Science B.V. 38 2002 101 116
- Enoki Kazuhiro et al. “NOx reduction system for diesel engine with highly sulfur tolerance,” JSAE Paper No. 20035658 2003