Search

Benefiting a renewable source of precious hydrocarbons and getting rid of a huge environmental pollutant like polystyrene is the cry of the day. Waste polystyrene (PS) represents a source of valuable chemical products like styrene and other aromatics. Therefore, metals decorated montmorillonite (Mt) catalysts were prepared using Mg, Zn, Al, Cu and Fe and were evaluated for the tertiary recycling of waste polystyrene. The metal decorated catalysts characterized by N 2 adsorption/desorption, XRD & SEM techniques. 20% Fe/Mt and 5% Al/Mt were found with high activity for the production of liquid products and good selectivity for the production of low molecular weight aromatic products like styrene, toluene and ethylbenzene, etc. The yield of toluene, ethylbenzene, styrene and α-methylstyrene was 8.49 wt.%, 5.13 wt.%, 49.28 wt.% and 2.80 wt.%, respectively using 5% Al/Mt catalyst and it was 10.15 wt.%, 6.42 wt.%, 50.93 wt.% and 2.31 wt.%, respectively using 20% Fe/Mt catalyst. The results showed that among the metal decorated Mt catalysts used, 5% Al/Mt and 20% Fe/Mg were found to be the most effective catalyst for selective conversion into aromatics. The products contained styrene monomer as a major along with toluene, ethylbenzene and α-methylstyrene value added products. Thus, it was possible to demonstrate the feasibility of catalytic degradation as an alternative technology for the chemical recycling of waste PS. [ABSTRACT FROM AUTHOR]

In the present study, the thermo-catalytically obtained oils from the degradation of waste high-density polyethylene (HDPE) using MgCO3 as a catalyst were characterized by GC-MS in order to find out their detailed composition. It was found that all the fractions were mainly composed of saturated hydrocarbons with good percentages of unsaturated hydrocarbons. Some aromatic and cyclic hydrocarbons were also identified with small proportions. Although the thermal oil was obtained with double degradation of HDPE, still it contains relatively higher hydrocarbons as compared to the catalytic oil obtained with single step degradation. The composition of the thermal and catalytic oil can be differentiated as; the latter is composed of relatively higher quantities of lighter hydrocarbons as compared to the former one. Moreover the catalytic oil contains relatively greater proportion of cyclic and branched hydrocarbons which can impart improved fuel properties to the oil. Thus the catalyst has influenced the degradation product in terms of enhanced pyrolysis and effective formation of cyclic hydrocarbons. [ABSTRACT FROM AUTHOR]

This paper presents results regarding the effect of various process conditions on the performance of a zeolite catalyst in pyrolysis of high density polyethylene. The results show that polymer catalytic degradation can be operated at relatively low catalyst content reducing the cost of a potential industrial process. As the polymer to catalyst mass ratio increases, the system becomes less active, but high temperatures compensate for this activity loss resulting in high conversion values at usual batch times and even higher yields of liquid products due to less overcracking. The results also show that high flow rate of carrier gas causes evaporation of liquid products falsifying results, as it was obvious from liquid yield results at different reaction times as well as the corresponding boiling point distributions. Furthermore, results are presented regarding temperature effects on liquid selectivity. Similar values resulted from different final reactor temperatures, which are attributed to the batch operation of the experimental equipment. Since polymer and catalyst both undergo the same temperature profile, which is the same up to a specific time independent of the final temperature. Obviously, this common temperature step determines the selectivity to specific products. However, selectivity to specific products is affected by the temperature, as shown in the corresponding boiling point distributions, with higher temperatures showing an increased selectivity to middle boiling point components (C8-C9) and lower temperatures increased selectivity to heavy components (C14-C18). [ABSTRACT FROM AUTHOR]

Waste management of plastics through conversion into valuable hydrocarbons is in high demand. The degradation of WEPS was investigated in a Pyrex batch reactor using Cu metal, Cu-Al 2 O 3 , Cu-Mmn and Cu-AC catalysts. Catalysts with the maximum products were characterized for BET surface area and SEM in comparison to their supporting materials. Cu supported catalysts were found to increase the selectivity of low molecular weight aromatic hydrocarbons as compared to Cu metal and the supports. Among the supported catalysts, 20% Cu-Al 2 O 3 was found to have moderate activity and high selectivity to yield desirable low molecular weight aromatic hydrocarbons. The BET surface area increased only in the case of 20% Cu-Al 2 O 3 , whereas the SEM images of 20% Cu-Al 2 O 3 reveal aggregated porous structures with apparent active Cu metal which provide high surface area for the degradation of WEPS. The yield of styrene monomer was 60.48%, toluene 10.98%, ethylbenzene 9.92% and methylstyrene was 3.66% using 20% Cu-Al 2 O 3 catalyst. [ABSTRACT FROM AUTHOR]