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

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 H-2 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 C-2-C-5 and aromatics fractions, with better control of the composition of the C-2-C-5 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.