Analysis of light-off features of DOC with an exhaust containing CO and different HCs.

Rama Krishna  Dadi, University of Houston

Analysis of light-off features of DOC with an exhaust containing CO and different HCs

Authors: Rama Krishna Dadi, Keyvan Daneshvar, Dan Luss, Vemuri Balakotaiah, William.S. Epling, Christos M. Kalamaras

A global kinetic model is developed for set of oxidation reactions on different bimetallic catalysts of Pt and Pd in a DOC with a feed containing CO, C₂H₄, C₇H₈, C₆H₁₄, C₂H₆ and NO. The model is used to investigate the sensitivity of the kinetic parameters with catalyst ratios [1]. The exotherm generated by the oxidation of low-temperature igniting species can be used to increase the C1 based conversion of HCs [2]. The light-off behavior of various species is investigated on dual layer and dual brick configurations of Pt and Pd in DOC. Dual layer/brick catalysts have an improved HCs light-off performance compared to pure Pt, Pd and Pt: Pd (1:1).

Dual layer catalyst of Ag-BEA (Ag wt%=2.5) zeolite and oxidation catalyst is used to reduce the HC emissions during the cold-start period. The kinetic model is developed for the HC trap, which stores toluene and hexane at low temperatures. HC trap is efficient in storing toluene, which is released from zeolite when the oxidation catalyst is hot enough to oxidize it. However, the trap is not beneficial for storage of hexane since desorption temperature of hexane is much lower that the temperature at which it gets oxidized [3].

References

1. Daneshvar, R.K. Dadi, D. Luss, V. Balakotaiah, S.B. Kang, C.M. Kalamaras, W.S. Epling, Experimental and modeling study of CO and hydrocarbons light-off curves on Pt-Pd/γ-Al₂O₃ diesel oxidation catalysts, Chemical Engineering Journal, 323 (2017) 347-360.
2. K. Dadi, D. Luss and V. Balakotaiah, Dynamic hysteresis in monolith reactors and hysteresis effects during co-oxidation of CO and C₂H₆, Chemical Engineering Journal 297(2016) 325-340.
3. B. Kang, C. Kalamaras., V. Balakotaiah., W.S. Epling, Hydrocarbon Trapping over Ag-Beta Zeolite for Cold-Start Emission Control.Catalysis Letters, 147(6) (2017) 1355-1362.

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