Thermally Durable Zeolite Based SCR Catalysts for Controlling NOx Emissions in Diesel Exhaust to Meet BS VI Norms
Published January 9, 2019 by SAE International in United States
Downloadable datasets for this paper availableAnnotation of this paper is available
From the recent past, automotive exhaust emission management strategies has been progressing towards an alternative for vanadia based selective catalytic reduction (V-SCR) of NOx in diesel powered vehicles. Some of the major inadequacies of existing V-SCR technology were as follows: poor thermal endurance (deteriorates at 550°-600°C), volatilization of harmful vanadium into environment and inadequate NO2 conversion.
Metal incorporated zeolite systems, (the metals being preferably selected from transition metal elements), has gained momentum for commercial DeNOx applications. However, the major challenge with this zeolite SCR (Z-SCR) was its low thermal/hydrothermal stability. In the current study, it has been attempted to overcome this by various zeolites and metals combinations. Various combinations of metallic Z-SCR were extensively studied for their low and high temperature activities. The host zeolites were selected on the basis of various properties such as surface area, crystallinity, crystal size and pore opening etc. The active transition metals were also selected based on its affinity to react and attach with the zeolytic framework elements. It has been observed that when the selected transition metal is substituted in small pore zeolites, the resultant Z-SCR gains high thermal and hydrothermal stability. It was also observed that, in addition to the selection of the zeolites & transition metals, the choice of binder, plays a vital role in achieving the required DeNOx activity in the wide temperature range (180°C - 650°C).
Z-SCR washcoat derived from above combinations were coated on a ceramic substrate. And the developed new technology washcoats have been undergone proprietary treatment. The washcoats were evaluated for physical properties as well as its DeNOx activity. It was found to have excellent adhesion, high surface area and optimal NH3 adsorption capacity. The coated ceramic substrates were tested on simulated gas test bench (SGTB) for its DeNOx activity and it was found that the total NOx conversion reaches higher than benchmark and meeting BS VI norms. The catalysts have been tested again as aged on the simulated gas test bench for its DeNOx activity and it has been found that the total NOx conversion has been substantially enhance ed.
CitationMuthusamy, V., Harkonen, M., Kumar, A., Trigunayat, A. et al., "Thermally Durable Zeolite Based SCR Catalysts for Controlling NOx Emissions in Diesel Exhaust to Meet BS VI Norms," SAE Technical Paper 2019-26-0130, 2019, https://doi.org/10.4271/2019-26-0130.
Data Sets - Support Documents
|[Unnamed Dataset 1]|
|[Unnamed Dataset 2]|
|[Unnamed Dataset 3]|
|[Unnamed Dataset 4]|
- Nova, K. and Tronconi, E., Urea SCR Technology for deNOx after Treatment of Diesel Exhausts (Springer, 2014), doi:10.1007/978-1-4899-8071-7.
- Brandenberger, S., Kröcher, O., Tissler, A., and Althoff, R., “The State of the Art in Selective Catalytic Reduction of NOx by Ammonia Using Metal-Exchanged Zeolite Catalysts,” Catal. Rev. Sci. Eng. 50:492, 2008.
- Parekh, A., Iorio D. J., Khurana, I., Shih, A., et al, “New Insight into the mechanisms and Active Site Requirements of Low Temperature NOx SCR with ammonia on Cu-SSZ-13 Zeolites,” Cummins, June 2013.
- Metkar, P.S., Balakotaiah, V., and Harold, M.P., “Experimental and Kinetic Modeling Study of NO Oxidation: Comparison of Fe and Cu-Zeolite Catalysts,” Catalysis Today 184(1):115, 2012.
- Grossale, A., Nova, I., Tronconi, E., Chatterjee, D. et al., “The Chemistry of the NO/NO2-NH3 Fast SCR Reaction over Fe-ZSM5 Investigated by Transient Reaction Analysis,” J. Catal. 256(2):312, 2008.
- Olsson, L., Sjovall, H., and Blint, R.J., “A Kinetic Model for Ammonia Selective Catalytic Reduction over Cu-ZSM-5,” Appl. Catal. B 81:3, 203-4, 2008.
- Hallstrom, K. and Shah, S., “Emission Control Options and Optimization for BSVI Heavy Duty Diesel Applications,” SAE Technical Paper 2017-26-0120, 2017, doi:10.4271/2017-26-0120.