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Bridging the Gaps Between Experimental and Mechanistic Catalysis Research: A Case Study with CO Oxidation Over a Pd/Al 2 O 3 Catalyst
Author(s) -
Ren Jiazheng,
Cheng Kai,
Li Ming,
Zhao Songjian,
Li Haoran,
Chen Yongsheng
Publication year - 2019
Publication title -
chemcatchem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.497
H-Index - 106
eISSN - 1867-3899
pISSN - 1867-3880
DOI - 10.1002/cctc.201900839
Subject(s) - catalysis , activation energy , chemistry , thermodynamics , reaction rate , reaction mechanism , work (physics) , chemical reaction engineering , redox , rate equation , chemical reaction , diffusion , chemical engineering , kinetics , inorganic chemistry , organic chemistry , physics , quantum mechanics , engineering
Temperature (T), concentrations of the reactants (C), and the corresponding reaction rate (r) are three important quantities for catalyst evaluation especially for mechanistic studies, however, even today experiments have not strictly met the needs. In this work, CO oxidation reactions are conducted over a Pd/Al 2 O 3 catalyst. It is found that steady‐state tests together with the use of catalyst front temperature are necessary to reveal the average intrinsic catalytic performance. More importantly, for the first time, analytical solutions are obtained for T, C, and r within the catalyst bed from solving the differential equation governing general energy balance in the reaction system. Subsequently, it is found that the conventional differential reactor conditions do not result in accurate measurement of true reaction rate as generally believed. The reaction appears to follow a reaction mechanism below 50 % CO conversion probably involving chemical bond cleavage with an apparent activation energy of 194 kJ/mol while above 79 % conversion a 15 kJ/mol activation energy is observed suggestive of diffusion being the rate determining step.