Catalytic cracking of polyethylene over nanocrystalline HZSM-5: Catalyst deactivation and regeneration study |
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| Affiliation: | 1. Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea;2. GS Caltex R&D Center, Daejeon 34122, Republic of Korea;1. Chemical and Environmental Engineering Group, ESCET, Rey Juan Carlos University, c/ Tulipán s/n, 28933 Móstoles (Madrid), Spain;2. Unit of Thermochemical Processes, IMDEA Energy, Av. Ramón de la Sagra 3, 28935 Móstoles (Madrid), Spain;1. Department of Chemical Engineering, Sahand University of Technology, Sahand New Town, P.O. Box: 51335-1996, East Azerbaijan, Iran;2. Environmental Engineering Research Center, Department of Chemical Engineering, Sahand University of Technology, Sahand New Town, Iran;1. Chemical Process & Energy Resources Institute (CPERI), Centre for Research and Technology Hellas (CERTH), 6th km Charilaou – Thermi Road, P.O. Box 361, 57001 Thessaloniki, Greece;2. School of Science & Technology, International Hellenic University (IHU), 14th km Thessaloniki – Moudania, 57001 Thessaloniki, Greece;3. Inorganic Chemistry and Catalysis, Debye Institute for Nanomaterials Science, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht, the Netherlands;4. Thermochemical Processes Unit, IMDEA Energy Institute, 28935, Móstoles, Madrid, Spain;5. Chemical and Environmental Engineering Group, ESCET, Rey Juan Carlos University, 28933, Móstoles, Madrid, Spain;6. SILKEM, d.o.o., Tovarniška cesta 10, SI - 2325 Kidričevo, Slovenia;7. NMR Spectroscopy, Bijvoet Center for Biomolecular Research, Utrecht University, Padualaan 12, 3584 CH Utrecht, the Netherlands;8. Organic Chemistry and Catalysis, Debye Institute for Nanomaterials Science, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht, the Netherlands;1. Institute of Chemical Engineering and Technology, University of the Punjab, Lahore 54590, Pakistan;2. Department of Petroleum and Chemical Engineering, Sultan Qaboos University, Muscat 123, Oman |
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| Abstract: | In this work, catalytic cracking of low density polyethylene (LDPE) over nanocrystalline HZSM-5 zeolite in a batch reactor at 340 °C was carried out with the aim of study both the catalyst resistance to deactivation and the catalyst regeneration process. For looking into the catalyst deactivation, consecutive polyethylene cracking experiments were carried out. Subsequently, the same reactions has been also performed but by regenerating the zeolite after each experiment by promoting coke combustion at 550 °C under air flow. Zeolites used were two samples of nanocrystalline HZSM-5 with very different textural properties (sample A, with most of its surface corresponding to zeolitic micropores and sample B with a considerable amount of external surface, mesopores and super-micropores) in order to study the effect of their textural properties in the deactivation and regeneration experiments. Although conversion and activity values reached over both samples are quite high taking into account the mild conditions used, sample B shows a very much higher initial activity than A due to its improved textural properties. In both samples two different deactivation mechanisms occur: a reversible deactivation by coke deposition removable by the regeneration procedure, and an irreversible or permanent deactivation by other factors. Deactivation of sample B occurs faster due to the higher amount of coke deposited on this material. However, the improved textural properties of this catalyst supposes an advantage for the regeneration process, since coke deposited either on the external surface or on the super-micropores and mesopores, makes easier the regeneration procedure. |
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