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Detailed kinetic modelling of automotive exhaust NO x reduction over rhodium catalyst
Author(s) -
Su Qingyun,
Xie Liang,
Li Yanbin,
Qiao Xinqi
Publication year - 2014
Publication title -
the canadian journal of chemical engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.404
H-Index - 67
eISSN - 1939-019X
pISSN - 0008-4034
DOI - 10.1002/cjce.22021
Subject(s) - rhodium , catalysis , chemistry , reaction mechanism , kinetic energy , elementary reaction , decomposition , kinetics , atmospheric temperature range , adsorption , reaction rate , thermodynamics , organic chemistry , physics , quantum mechanics
The reduction of NO with CO and H 2 as the reductants was investigated on the rhodium‐based catalyst over a temperature range of 150–400 °C. Micro‐kinetic modelling method was utilized to compare the activities of CO and H 2 . Quasi‐elementary mechanisms of NO‐CO and NO‐H 2 consisting of 11 and 25 steps, respectively, were proposed. The reaction steps and kinetic parameters were derived from literature and some parameters were optimized to fit the experimental data. Furthermore, to verify the validity range of the developed mechanism, the reaction intermediate N 2 O reduction by CO and by H 2 over Rh were investigated. Over a wide range of reaction conditions, the detailed mechanism predicted experimental results quite well for both NO and N 2 O conversions with CO and/or H 2 as reductant. The phenomenon that NO‐CO and NO‐H 2 reactions commenced at similar temperature can be interpreted by the hindered H 2 dissociative adsorption steps by extensive NO adsorption. Reaction profiles such as fractional coverages, reaction pathway and sensitivity analysis provided valuable insight into the reaction systems. N 2 O plays a crucial role in N 2 formation for both NO‐CO and NO‐H 2 reaction systems. The routes involving N 2 O formation and decomposition were identified as the dominant pathway in N 2 formation at low temperatures.