Premium
Kinetics of the CO oxidation by O 2 and N 2 O over Cu‐Cr/Al 2 O 3
Author(s) -
Dekker Nico J. J.,
Hoorn Johan A. A.,
Stegenga Sander,
Kapteijn Freek,
Moulijn Jacob A.
Publication year - 1992
Publication title -
aiche journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.958
H-Index - 167
eISSN - 1547-5905
pISSN - 0001-1541
DOI - 10.1002/aic.690380307
Subject(s) - chemistry , oxygen , reactivity (psychology) , kinetics , catalysis , adsorption , redox , order of reaction , reaction rate constant , reaction rate , analytical chemistry (journal) , inorganic chemistry , physics , organic chemistry , alternative medicine , pathology , quantum mechanics , medicine
The oxidation of CO by O 2 and N 2 O over an oxidized 10 wt. % Cu‐Cr/Al 2 O 3 catalyst (Cu:Cr=1:1) has been studied by temperature‐programmed reactivity measurements (400–550 K) over a wide range of partial reactant pressures, including inhibition by CO 2 . The CO oxidation rate is zeroth‐order in oxygen and has orders between 0‐1 in CO and N 2 O, depending on the gas‐phase composition. Mechanistic information from literature combined with the kinetic data resulted in the selection of an Eley‐Rideal‐type of kinetic model without a priori assumptions on rate‐determining processes. The model consists of the oxidation of reduced sites by O 2 and/or N 2 O, followed by a reaction with CO, yielding a surface intermediate that releases CO 2 in a consecutive step. CO 2 inhibits both by reversible adsorption on oxidized and reduces sites, the latter under formation of the surface reaction intermediate. Apart from the surface oxidation by O 2 , the reaction rates of all assumed elementary processes are of the same order of magnitude and, therefore, determine the overall rate. The surface oxidation by oxygen is about four orders of magnitude larger, which explains the zeroth‐order in oxygen and the observation that oxygen first reacts with CO before N 2 O is able to oxidize CO. The obtained activation energies of the elementary processes agree with values in the literature for corresponding systems.