Catalytic degradation of high density polyethylene over microporous and mesoporous materials

L.B. PIERELLA; M.S. RENZINI

Cape Town-South Africa

Simposio; 4th International Mesostructured Materials Symposium (IMMS in short); 2004

Abstract   High-density polyethylene (HDPE) was converted to a mixed of lower and higher hydrocarbons over micro (ZSM-11zeolite with MEL structure) and mesoporous (MCM-41) modified materials. The main liquid hydrocarbons (LHC) were: benzene, toluene, xylenes (BTX), using Zn-, Mo-, and H-containing MEL-zeolites as catalysts. The Zn-zeolite exhibited the highest levels of LHC (>57 wt%) with BTX selectivity of 47 wt%. H-zeolite gave a higher gaseous fraction. Zn-MCM-41 produced mainly C5-C16 products. LPG (C3-C4) levels were interesting for all the samples. Thermo gravimetric analyses studies of mixtures catalyst/polymer, have been used to investigate the performance of different catalysts on degradation reactions of the polymer. The catalytic transformation of the polyolefin occurs at smaller temperature respect to thermo-decomposition of the pure HDPE (500°C). A one-pass reactor in the temperature range of 410-500oC and atmospheric pressure was employed. We observed the complete conversion of HDPE, in the range of temperatures studied. The synthesized and modified samples were characterized by TG-DSC, XRD, TPD-FID, FTIR and surface area by BET, in order to verify and to confirm –after cation incorporation- the crystallinity (for microporous materials) and regularity (for mesoporous materials) of the structures, stability and the type of active sites. The reactant was characterized by FTIR, XRD and TG-DSC. Reaction products were analyzed by gas chromatographic.  By means of the development of a competitive catalytic system, we determine the feasibility of the process of degradation of HDPE remainders towards the synthesis of gaseous and liquid hydrocarbons.