Pd-modified beta zeolite for modulated hydro-cracking of low-density polyethylene into a paraffinic-rich hydrocarbon fuel

• Published in: Applied catalysis. B, Environmental Vol. 277; p. 119070
• Main Authors: Pyra, Kamila, Tarach, Karolina A., Śrębowata, Anna, Melián-Cabrera, Ignacio, Góra-Marek, Kinga
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 15-11-2020; Elsevier BV
• Subjects: Acidity; Aromatic compounds; Catalysts; Coke; Density; Hydrocarbon fuels; Hydrocarbons; Hydrocracking; Hydrogen storage; LDPE cracking; Low density polyethylenes; Operando IR spectroscopy; Palladium; Polyethylene; Regeneration; Saturated hydrocarbons; Selectivity; Zeolite beta; Zeolites; Zeolite beta; Palladium; Acidity; Operando IR spectroscopy; LDPE cracking
• ISSN: 0926-3373; 1873-3883
• DOI: 10.1016/j.apcatb.2020.119070

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•Pd-modified beta zeolite of the similar texture, structure and acidity as H-zeolite.•Saturated hydrocarbons produced using only self-generated H2 or hydrogen transfer reactions.•High selectivity towards a C2-C5 fraction, with high isoparaffinic and aromatic content.•Operando FTIR study evidences a retardation in the coke forming reactions.•The catalyst undergoes auto-regeneration.
The catalytic properties of a microporous beta zeolite and Pd-loaded analogue were assessed in the cracking of low-density polyethylene (LDPE). The idea behind this study was to investigate the potential of zeolite beta from a different perspective, aiming at producing a hydrocarbon fuel, i.e. formed by saturated hydrocarbons, without the addition of external H2 but using the self-generated hydrogen, or hydrogen-transfer reactions. For this, a catalytic system was carefully prepared and compared to the bare beta zeolite; a protonic Pd-containing beta zeolite has a similar texture, structure and acidity features as in the base zeolite. The characterisation showed that this catalyst was achieved. The operando FTIR catalytic results indicated that the Pd-beta zeolite reaches a high selectivity towards the C2-C5 and aromatics fractions, with better control of the composition of the C2-C5 fraction leading to high isoparaffinic content, and a relatively low share of olefinic compounds. Additionally, the retardation in the coke forming reactions was evidenced, due to the high Pd-hydrogenation efficiency. Further insights were rationalized about the coke content and the catalyst auto-regeneration. From the process point of view, it was found that the use of a beta zeolite having well-dispersed Pd is an effective way to upgrade the LDPE into a paraffinic-rich hydrocarbon fuel.