Abstract
The impact of large-pore zeolite beta (BEA) on the performance of model monolithic Pt/Pd/Al2O3 diesel oxidation catalyst is investigated in terms of hydrocarbon (HC) storage capacity, light-off, and oxidation. Dodecane (C12) is employed as the model HC to elucidate BEA loading impact on catalyst performance during temperature-programmed oxidation of CO and C12 and mixtures in the absence of feed water. A C12 pre-storage experiment protocol quantifies storage at room temperature, the effect of C12 storage on light-off temperature, and the extent of release and conversion of C12. The temperature ramp experiments indicate a negligible impact of the zeolite on the individual reactant (CO and C12) light-offs. Co-feed experiments (HC + CO simultaneous feed) reveal light-off inhibition by CO and C12 in addition to that by pre-stored C12. This trend is consistent for all zeolite loading levels. During both co-feed and C12 pre-storage experiments, an intermediate zeolite loading results in a decreased CO light-off temperature when compared to the zeolite-free catalyst. This beneficial effect is attributed to the zeolite providing alternative storage sites for the HC, thereby mitigating the inhibition on the CO light-off by freeing up precious metal sites for CO oxidation. However, the highest zeolite loading catalyst has an increased CO light-off temperature in C12 pre-storage experiments compared to the catalyst with intermediate loading. This trend reversal is attributed to the kinetic and/or transport inhibitory effect of stored C12 which overcomes the enhancement at lower loadings. The data indicate that the highest zeolite loading yields the highest percentage of stored C12 converted to CO2, a finding relevant for HC trap catalyst design. The study findings suggest a need to optimize the zeolite loading for the desired operating conditions to achieve desired light-off and HC trapping and conversion. The impact of feed water will be investigated in future work to evaluate the generality of these findings.
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.
