Comparison of catalyst life and performance employing the conversion capacity concept. Issue 11 (14th July 2021)

• Record Type: Journal Article
• Authors: Parikh, Apoorv P.; Parikh, Vihang P.; Parikh, Parimal A.
• Is Part Of: International journal of chemical kinetics. Volume 53:Issue 11(2021)
• Page Start: 1178
• Page End: 1183
• Publication Date: 2021-07-14
• Subjects: catalyst deactivation -- catalyst life -- conversion capacity -- deactivation coefficient; Chemical kinetics -- Periodicals; 541.394
• DOI: 10.1002/kin.21523
• Languages: English
• ISSNs: 0538-8066

Abstract

Abstract: Researchers frequently come across catalyst performance reported as either conversion or rate of reaction as a function of time on stream. When different publications reported data in different manners, comparison of the performance of even similar catalysts becomes difficult. The same situation arises when catalytic behavior is shown at different space velocities. This is because catalyst deactivation characteristics depend on space velocity in addition to rate constants for the main chemical reaction as well as the deactivation process. To circumvent this difficulty, we have furthered the concept of conversion capacity originally brought out by Janssens ( J. Catal ., 2009;264:130–137) for methanol/dimethyl ether conversions. Conversion capacity was defined by him as the maximum amount of the reactant converted by the time the catalyst affords zero conversion. He developed equations for the first‐order main‐ and deactivation‐ reaction. However, many reactions of practical importance are of order two. We have developed expressions for the second‐order reactions to determine conversion capacity and also the time required for reaching 50% of the initial conversion, t 0.5 for the reaction occurring in a plug flow reactor. Here we have given the example calculations for conversion capacity for the reaction of methane tri‐reforming taking data from two different published articles reporting conversion and rate of reaction as a function of time‐on‐stream. We further show the usefulness of these two parameters as giving information not only on the life of the catalysts but also their relative catalytic performance by drawing parallels between reported information and values determined here. Still, a word of caution is necessary. Expression for rate versus time on stream is valid for a linear relationship. Also, values of conversion capacity and t 0.5 obtained by expressions given here are qualitative in nature and should be used for comparison purposes rather than attaching any physical significance to them.