Aromatic hydrocarbon obtaining from the degradation of LDPE

MARÍA S. RENZINI; LILIANA B. PIERELLA

Córdoba, Argentina

Conferencia; 9a Conferencia Latinoamericana de Físico-Química Orgánica, 9th Latin American Conference on Physical Organic Chemistry; 2007

The catalytic transformation of plastic remainders is an alternative of real importance like process of recovery of CH (chemistry recycled of polymer). Low density polyethylene (LDPE) was converted to a mixed of lower and higher hydrocarbons over microporous ZSM-11 zeolites modified by the incorporation of Zn2+ and H+. The catalysts were characterized by XRD (crystallinity >98 %), Surface area (>380 m2/g by BET) and zinc content (2.83 wt % by AA). We can see a diminution of the decomposition temperature of pure LDPE from 470°C to 370 and 386°C, employing H-ZSM-11 and Zn-ZSM-11, respectively. A Fixed-bed reactor at 400-500°C, atmospheric pressure, N2 as carrier gas and as 60 min reaction time, was employed. Reaction products were analyzed by gas chromatographic and mass spectrometry. We observed the complete conversion of LDPE in the range of temperatures studied. It is not observed effect of the temperature in the liquid and gaseous products. The higher yield to gaseous hydrocarbons was obtained over H-ZSM-11 zeolite and the higher yield to liquid hydrocarbons was reached with Zn-ZSM-11. An important aromatic hydrocarbons (AHC) production is observed with both the catalysts used. In previous table we can see an increase of the total AHC with the increase of the temperature for Zn-ZSM-11 y H-ZSM-11 zeolites, respectively. These behaviour may be attributed to the higher temperatures favours the occurrence of the secondary cracking, recombination, cyclation and aromatization reactions. The higher AHC production of Zn-containing zeolite than H-zeolite is due to higher values of Lewis acid sites. Employing microporous materials with Zn or H, as active sites and using a catalytic system as we described in this work, it is possible to use LDPE waste as a source of more valuable products at 400-500 °C.