Abstract
Compensation phenomena in heterogeneous catalysis take the form of a linear correlation between activation energy E and pre-exponential factor ln A; its occurrence may, however, be due to the use of `apparent' rather than `true' Arrhenius parameters. It is shown by model calculations using the Langmuir–Hinshelwood bimolecular rate equation, and experimentally using Pt-catalysed hydrogenolysis of C 3H 8 and of n-C 4H 10, that E app increases with P H, as expected. These values of E app show compensation. Apparent Arrhenius parameters for many different Pt and Pd catalysts and for various reactions lie close to a common compensation line. Alkane activation requires dehydrogenative chemisorption, which is endothermic; this causes E app to exceed E true, and accounts for the dependence of E app on alkane chain length, and the very high values sometimes observed. Compensation occurs as a result of using constant reactant pressures, which give inconstant surface concentrations.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
