Abstract
A hierarchically structured zeolite (self-pillared pentasil; SPP) comprised of MFI nanosheets or lamellae has been synthesized in various Si/Al ratios and mesoporosities. It turns out that a simple removal of ethanol in a synthesis sol resulted in increased mesoporosity, while the additional reduction of water further increased mesoporosity. In addition, we could synthesize the SPP particle with the actual Si/Al ratio as low as ∼23 with a modest mesoporosity. With these hierarchically structured SPP particles, we further conducted copper impregnation on them in order to use as a hydrocarbon (HC) trap. The resulting Cu-impregnated SPPs could not only adsorb HCs in the exit gas stream including water vapor, but also serve as an active oxidizer of HCs. Specifically, Cu-impregnated SPP with an actual Si/Al ratio of ∼22 and medium mesoporosity exhibited very high performance in cold-start trap tests; desirably adsorbing propene and toluene even in the presence of 10 vol% steam, holding them up to higher temperatures (90 °C for propene and 190 °C for toluene), and furthermore, oxidizing the hydrocarbons. The preferred adsorption can be attributed to the larger amount of exchanged Cu2+ ions in SPP particles with a lower Si/Al ratio, while the additional oxidation was due to the CuO particles dispersed on the SPP surface. However, the hydrothermal stability test revealed that the zeolite structure in the Cu-impregnated SPPs was collapsed and transformed into another undesired phase, thus losing the above-mentioned adsorption ability. Nevertheless, the corresponding oxidation performance was well maintained, indicating the robust, active role of the CuO particles.
Original language | English |
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Pages (from-to) | 78-93 |
Number of pages | 16 |
Journal | Catalysis Today |
Volume | 314 |
DOIs | |
Publication status | Published - 2018 Sept 15 |
Bibliographical note
Funding Information:This work was supported by the Super Ultra Low Energy and Emission Vehicle (SULEEV) Engineering Research Center ( 2016R1A5A1009592 ) and by the C1 Gas Refinery Program ( 2015M3D3A1A01064957 ) through National Research Foundation (NRF) of Korea. These grants were funded by the Korea government (Ministry of Science and ICT) . In addition, this research was supported by Korea University Future Research Grant . This research was also supported by the KBSI project ( E37300 ). A part of SEM characterization and all of TEM characterization were carried out at the Korea Basic Science Institute (KBSI). In particular, all authors thank Dr. Eunjoo Kim for her acquiring TEM images and KBSI for allowing the usage of their HTREM instruments. Appendix A
Publisher Copyright:
© 2018 Elsevier B.V.
Keywords
- Cold start
- Copper impregnation
- Hydrocarbon trap
- Mesoporosity
- Self-pillared pentasil (SPP) particles
ASJC Scopus subject areas
- Catalysis
- General Chemistry