Examinando por Autor "Garagorri, E."

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Catalytic conversion of low-density polyethylene using a continuous screw kiln reactor
(ELSEVIER, 2002) Aguado, José; Serrano, D. P.; Escola, J. M.; Garagorri, E.
Both thermal and catalytic cracking of low-density polyethylene (LDPE) have been investigated using a screw kiln reactor. Thermal degradation gives rise to a broad product distribution whereas catalytic cracking over Al-MCM-41 leads mainly to hydrocarbons within the gasoline range (C5 ¿ C12) with selectivities up to 80%. The increase of the screw speed between 3 and 15 rpm in the catalytic experiments allows the plastic feed rate to be varied in the range 20 ¿ 41 g/h. The changes observed in the TOF values when varying the screw speed point out a decrease of the activity per site with increasing residence times, which may be due to the catalyst deactivation or to a contribution of the degradative extrusion at higher screw speeds. Likewise, a certain increase in the selectivity towards the gasoline fraction is observed at short residence times. On the other hand, PIONA analyses indicate that, regardless of the screw speed, the main components of the gasoline are olefins (50%) and isoparaffins (20%) whereas the aromatic content is always below 6%, with a proportion of benzene lower than 0.1%.
Feedstock recycling of agriculture plastic film wastes by catalytic cracking
(ELSEVIER, 2004) Serrano, D.P.; Aguado, José; Escola, J. M.; Garagorri, E.; Rodríguez, J. M.; Morselli, L.; Palazzi, G.; Orsi, R.
Feedstock recycling by catalytic cracking of a real plastic film waste from Almeria greenhouses (Spain) towards valuable hydrocarbon mixtures has been studied over several acid catalysts. The plastic film waste was mostly made up of ambient degraded low-density polyethylene (LDPE) and ethylene-vinyl acetate copolymer (EVA), the vinyl acetate content being around 4 wt %. Nanocrystalline HZSM-5 zeolite (crystal size ¿ 60 nm) was the only catalyst capable of degrading completely the refuse at 420ºC despite using a very small amount of catalyst (plastic / catalyst mass ratio of 50). However, mesoporous catalysts (Al-SBA-15 and Al-MCM-41), unlike it occurred with virgin LDPE, showed fairly close conversions to that of thermal cracking. Nanocrystalline HZSM-5 zeolite led to 60 wt % selectivity towards C1 - C5 hydrocarbons, mostly valuable C3 - C5 olefins, what would improve the profitability of a future industrial recycling process. The remarkable performance of nanocrystalline HZSM-5 zeolite was ascribed to its high content of strong external acid sites due to its nanometer dimension, which are very active for the cracking of bulky macromolecules. Hence, nanocrystalline HZSM-5 can be regarded as a promising catalyst for a feasible feedstock recycling process by catalytic cracking.
Performance of a continuous screw kiln reactor for the thermal and catalytic conversion of polyethylene - lubricating oil base mixtures
(ELSEVIER, 2003) Serrano, D. P.; Aguado, José; Escola, J. M.; Garagorri, E.
Both thermal and catalytic cracking of mixtures consisting of low-density polyethylene (LDPE) and a lubricating oil base have been investigated in a continuous screw kiln reactor, provided with two reaction zones operating at different temperatures (T1/T2). The incorporation of the lubricating oil into the plastic leads to a significant decrease in its viscosity which favours the mixture flow through the reactor. Thermal cracking at 450/500ºC of LDPE-lubricating oil base mixtures with compositions ranging from 40/60 to 70/30 w/w % led in all cases to their almost complete conversion (~ 90 %) towards a broad spectrum of C1-C40 hydrocarbons. Catalytic cracking of a 70/30 (w/w %) LDPE - lubricating oil base mixture over mesoporous Al-MCM-41 catalysts at 400/450ºC proceeded with lower activity with regards to the pure LDPE catalytic cracking. This result is related to both the lower reactivity of the oil compared to the pure polyolefin and to the poisoning of the catalyst acid sites by sulphur/nitrogen - containing compounds present in the lubricant oil base. However, at higher temperatures (450/500ºC), complete conversion of the mixture was attained over both Al-MCM-41 and nanocrystalline HZSM-5 (n-HZSM-5) catalysts. Al-MCM-41 materials leads mainly to C5 - C12 products (65 % selectivity) whereas lighter hydrocarbons were formed preferentially over n-HZSM-5 (63 % selectivity towards C3 - C5 compounds). These results demonstrate that the screw kiln reactor is an efficient system for the continuous processing of plastic - lubricant oil mixtures by thermal and catalytic treatments.