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2006
Mastral, José Francisco; Berrueco, César; Gea, M; Ceamanos, Jesús
Catalytic degradation of high density polyethylene over nanocrystalline HZSM-5 zeolite Artículo de revista
En: Polymer Degradation and Stability, vol. 91, no 12, pp. 3330–3338, 2006, ISSN: 01413910.
@article{Mastral2006a,
title = {Catalytic degradation of high density polyethylene over nanocrystalline HZSM-5 zeolite},
author = {José Francisco Mastral and César Berrueco and M Gea and Jesús Ceamanos},
doi = {10.1016/j.polymdegradstab.2006.06.009},
issn = {01413910},
year = {2006},
date = {2006-12-01},
journal = {Polymer Degradation and Stability},
volume = {91},
number = {12},
pages = {3330--3338},
publisher = {Elsevier},
abstract = {High density polyethylene (HDPE) was catalytically degraded using a laboratory fluidised bed reactor in order to obtain high yield of gas fractions at mild temperatures, between 350 and 550 °C. The catalyst used was nanocrystalline HZSM-5 zeolite. High yields of butenes (25%) were found in the gas fractions, which were composed mainly of olefins. Waxes were wholly composed of linear and branched paraffins, with components between C10 and C20. The effects of both temperature and polymer to catalyst ratio on the product yield were studied. Gas conversion was dramatically decreased when the operation temperature was low (below 450 °C) or when the polymer to catalyst ratio was greatly increased (9.2). Gas and wax compositions significantly altered over 500 °C, showing that a part of the HDPE was degraded thermally, increasing the olefin concentration in the waxes. The same variation was observed in the experiments carried out at high polymer to catalyst ratios, obtaining a 50% olefinic concentration in the waxes. The differences observed in product distributions can be attributed to both thermal and catalytic degradations. textcopyright 2006 Elsevier Ltd. All rights reserved.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
High density polyethylene (HDPE) was catalytically degraded using a laboratory fluidised bed reactor in order to obtain high yield of gas fractions at mild temperatures, between 350 and 550 °C. The catalyst used was nanocrystalline HZSM-5 zeolite. High yields of butenes (25%) were found in the gas fractions, which were composed mainly of olefins. Waxes were wholly composed of linear and branched paraffins, with components between C10 and C20. The effects of both temperature and polymer to catalyst ratio on the product yield were studied. Gas conversion was dramatically decreased when the operation temperature was low (below 450 °C) or when the polymer to catalyst ratio was greatly increased (9.2). Gas and wax compositions significantly altered over 500 °C, showing that a part of the HDPE was degraded thermally, increasing the olefin concentration in the waxes. The same variation was observed in the experiments carried out at high polymer to catalyst ratios, obtaining a 50% olefinic concentration in the waxes. The differences observed in product distributions can be attributed to both thermal and catalytic degradations. textcopyright 2006 Elsevier Ltd. All rights reserved.
Mastral, José Francisco; Berrueco, César; Ceamanos, Jesús
Pyrolysis of high-density polyethylene in free-fall reactors in series Artículo de revista
En: Energy and Fuels, vol. 20, no 4, pp. 1365–1371, 2006, ISSN: 08870624.
@article{Mastral2006b,
title = {Pyrolysis of high-density polyethylene in free-fall reactors in series},
author = {José Francisco Mastral and César Berrueco and Jesús Ceamanos},
url = {https://pubs.acs.org/sharingguidelines},
doi = {10.1021/ef060007n},
issn = {08870624},
year = {2006},
date = {2006-07-01},
journal = {Energy and Fuels},
volume = {20},
number = {4},
pages = {1365--1371},
publisher = {American Chemical Society},
abstract = {Polyethylene pyrolysis has been studied analyzing the influence of temperature and residence time on the product distribution. The study was performed in an installation comprising two free-fall reactors in series, enabling the influence for both primary and secondary reactions to be studied separately. This also allows for the temperature to be increased in the second reaction zone, which is a parameter of great influence in the formation of aromatics. The use of reactors of different volume in the second zone also allows for the study of a broader range of residence times. The results obtained in the present work show qualitative trends similar to those obtained in other works of polyethylene pyrolysis in fluidized bed. At low temperatures, the main products obtained are solid waxes, while almost no aromatic compounds appear. The cracking rate increases with the rise in temperature, favoring the reaction of the heaviest fractions. Nevertheless, there are some differences. In general, ethylene, the direct product of the $beta$-scission of hydrocarbon chains, is the main compound in the gaseous fraction. The yields to methane and hydrogen increase as the temperature rises, with these being the final products of the degradation process and in the formation of aromatics. The production of aromatics and polycyclic aromatic hydrocarbons increases with the temperature and residence time. textcopyright 2006 American Chemical Society.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Polyethylene pyrolysis has been studied analyzing the influence of temperature and residence time on the product distribution. The study was performed in an installation comprising two free-fall reactors in series, enabling the influence for both primary and secondary reactions to be studied separately. This also allows for the temperature to be increased in the second reaction zone, which is a parameter of great influence in the formation of aromatics. The use of reactors of different volume in the second zone also allows for the study of a broader range of residence times. The results obtained in the present work show qualitative trends similar to those obtained in other works of polyethylene pyrolysis in fluidized bed. At low temperatures, the main products obtained are solid waxes, while almost no aromatic compounds appear. The cracking rate increases with the rise in temperature, favoring the reaction of the heaviest fractions. Nevertheless, there are some differences. In general, ethylene, the direct product of the $beta$-scission of hydrocarbon chains, is the main compound in the gaseous fraction. The yields to methane and hydrogen increase as the temperature rises, with these being the final products of the degradation process and in the formation of aromatics. The production of aromatics and polycyclic aromatic hydrocarbons increases with the temperature and residence time. textcopyright 2006 American Chemical Society.
2005
Berrueco, César; Esperanza, Ernesto; Mastral, José Francisco; Ceamanos, Jesús; García-Bacaicoa, Pedro
Pyrolysis of waste tyres in an atmospheric static-bed batch reactor: Analysis of the gases obtained Proceedings Article
En: Journal of Analytical and Applied Pyrolysis, pp. 245–253, Elsevier, 2005, ISSN: 01652370.
@inproceedings{Berrueco2005,
title = {Pyrolysis of waste tyres in an atmospheric static-bed batch reactor: Analysis of the gases obtained},
author = {César Berrueco and Ernesto Esperanza and José Francisco Mastral and Jesús Ceamanos and Pedro García-Bacaicoa},
doi = {10.1016/j.jaap.2004.10.007},
issn = {01652370},
year = {2005},
date = {2005-08-01},
booktitle = {Journal of Analytical and Applied Pyrolysis},
volume = {74},
number = {1-2},
pages = {245--253},
publisher = {Elsevier},
abstract = {Scrap tyre pyrolysis was studied under nitrogen atmospheric pressure in order to analyse temperature influence on the global yields and the gas composition. A static-bed batch reactor was used to pyrolyse 300 g of shredded scrap tyres at temperatures from 400 to 700 °C. The reactor was externally heated by means of electrical resistances, the heating rate being approximately 12 K min-1. Once the required system temperature was reached and stabilised, it was maintained for 4 h. The residence time of the gas in the reactor was calculated, with values falling between 1 and 1.5 min. Three phases were obtained after pyrolysis: solid (char), liquid (water and oils) and gas (light hydrocarbons, H2, CO and CO2). The product distribution and composition were studied as a function of the thermal treatment. Global yields were determined as follows: char, 47-63 wt.%, oils, 30-43 wt.%, and gas, 2.4-4.4 wt.%. It was observed that the liquid yield increases with temperature from 400 to 500 °C. However, from 500 °C on, this parameter remained almost constant. The solid yield followed an inverse trend to that observed for the liquid yield. On the other hand, the gas yield showed a slight continuous growth with temperatures ranging from 400 °C (2.4 wt.%) to 700 °C (4.4 wt.%). The gas phase was analysed off-line by gas chromatography. The main gases produced from the pyrolysis process were H 2, CO, CO2 and hydrocarbons: CH4, C 2H4, C3H6 and C4H 8. It was observed that the fraction of light gases (H2, CO, CO2 and CH4) was greater at higher temperatures. textcopyright 2004 Elsevier B.V. All rights reserved.},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
Scrap tyre pyrolysis was studied under nitrogen atmospheric pressure in order to analyse temperature influence on the global yields and the gas composition. A static-bed batch reactor was used to pyrolyse 300 g of shredded scrap tyres at temperatures from 400 to 700 °C. The reactor was externally heated by means of electrical resistances, the heating rate being approximately 12 K min-1. Once the required system temperature was reached and stabilised, it was maintained for 4 h. The residence time of the gas in the reactor was calculated, with values falling between 1 and 1.5 min. Three phases were obtained after pyrolysis: solid (char), liquid (water and oils) and gas (light hydrocarbons, H2, CO and CO2). The product distribution and composition were studied as a function of the thermal treatment. Global yields were determined as follows: char, 47-63 wt.%, oils, 30-43 wt.%, and gas, 2.4-4.4 wt.%. It was observed that the liquid yield increases with temperature from 400 to 500 °C. However, from 500 °C on, this parameter remained almost constant. The solid yield followed an inverse trend to that observed for the liquid yield. On the other hand, the gas yield showed a slight continuous growth with temperatures ranging from 400 °C (2.4 wt.%) to 700 °C (4.4 wt.%). The gas phase was analysed off-line by gas chromatography. The main gases produced from the pyrolysis process were H 2, CO, CO2 and hydrocarbons: CH4, C 2H4, C3H6 and C4H 8. It was observed that the fraction of light gases (H2, CO, CO2 and CH4) was greater at higher temperatures. textcopyright 2004 Elsevier B.V. All rights reserved.
2004
Berrueco, César; Ceamanos, Jesús; Esperanza, Ernesto; Mastral, José Francisco
Experimental study of co-pyrolysis of polyethylene/sawdust mixtures Artículo de revista
En: Thermal Science, vol. 8, no 2, pp. 65–80, 2004, ISSN: 0354-9836.
@article{Berrueco2004,
title = {Experimental study of co-pyrolysis of polyethylene/sawdust mixtures},
author = {César Berrueco and Jesús Ceamanos and Ernesto Esperanza and José Francisco Mastral},
doi = {10.2298/tsci0402065b},
issn = {0354-9836},
year = {2004},
date = {2004-01-01},
journal = {Thermal Science},
volume = {8},
number = {2},
pages = {65--80},
publisher = {National Library of Serbia},
abstract = {A study of the behavior of the thermal decomposition of mixtures of biomass and thermoplastics, such as polyethylene, is of interest for processes for the thermal recovery of industrial and urban wastes such as pyrolysis or gasification. No solid residue is formed during the thermal degradation of pure polyethylene. However, the addition of biomass,which generates char, can vary the product distribution and increase the heating value of the gas obtained. A study of the thermal degradation of pine sawdust, polyethylene and mixtures of polyethylene and pine sawdust has been carried out in a fluidised bed reactor. Experiments were carried out at five different temperatures: 640, 685, 730, 780, and 850 textordmasculineC. The yields and composition of the derived oil, wax, and gas were determined. The addition of polyethylene increases the gas production and decreases theproduction of waxes and liquids for the different temperatures tested. The main gases produced from the co-pyrolysis process were, at low temperatures, carbon monoxide, ethylene, carbon dioxide, propylene, butadiene, methane and pentadiene, while at high temperatures the gas composition changed drastically, the main components being carbon monoxide (more than 33 wt.%), ethylene, methane, benzene and hydrogen. The analysis of the liquid fraction shows a decrease of the concentration of oxygenated and aliphatic compounds.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
A study of the behavior of the thermal decomposition of mixtures of biomass and thermoplastics, such as polyethylene, is of interest for processes for the thermal recovery of industrial and urban wastes such as pyrolysis or gasification. No solid residue is formed during the thermal degradation of pure polyethylene. However, the addition of biomass,which generates char, can vary the product distribution and increase the heating value of the gas obtained. A study of the thermal degradation of pine sawdust, polyethylene and mixtures of polyethylene and pine sawdust has been carried out in a fluidised bed reactor. Experiments were carried out at five different temperatures: 640, 685, 730, 780, and 850 textordmasculineC. The yields and composition of the derived oil, wax, and gas were determined. The addition of polyethylene increases the gas production and decreases theproduction of waxes and liquids for the different temperatures tested. The main gases produced from the co-pyrolysis process were, at low temperatures, carbon monoxide, ethylene, carbon dioxide, propylene, butadiene, methane and pentadiene, while at high temperatures the gas composition changed drastically, the main components being carbon monoxide (more than 33 wt.%), ethylene, methane, benzene and hydrogen. The analysis of the liquid fraction shows a decrease of the concentration of oxygenated and aliphatic compounds.
2003
Mastral, José Francisco; Esperanza, Ernesto; Berrueco, César; Juste, Marta; Ceamanos, Jesús
Fluidized bed thermal degradation products of HDPE in an inert atmosphere and in air-nitrogen mixtures Artículo de revista
En: Journal of Analytical and Applied Pyrolysis, vol. 70, no 1, pp. 1–17, 2003, ISSN: 01652370.
@article{Mastral2003,
title = {Fluidized bed thermal degradation products of HDPE in an inert atmosphere and in air-nitrogen mixtures},
author = {José Francisco Mastral and Ernesto Esperanza and César Berrueco and Marta Juste and Jesús Ceamanos},
doi = {10.1016/S0165-2370(02)00068-2},
issn = {01652370},
year = {2003},
date = {2003-10-01},
journal = {Journal of Analytical and Applied Pyrolysis},
volume = {70},
number = {1},
pages = {1--17},
publisher = {Elsevier},
abstract = {Different processes involving thermal decomposition such as incineration, pyrolysis, gasification or co-combustion are becoming important for energy generation using plastic wastes as combustible materials. The thermal degradation of the material, the product distribution and consequently the economics of the process are strongly influenced by the experimental conditions used. In this work, the thermal degradation of high-density polyethylene (HDPE) has been carried out using a fluidized bed reactor under different temperature conditions. Two types of experiments have been performed, pyrolysis experiments, in which nitrogen has been used as inert gas, and gasification experiments, meaning that the thermal decomposition has been carried out in a nitrogen-air mixture with low oxygen concentration. The influence of the operating parameters on the product distribution and gas composition has been investigated using GC and MS/GC for the analysis of the gas, wax and oil fractions obtained. The results obtained show a widely differing product yield in both processes. The main objective of the paper is a comparison of pyrolysis and gasification in terms of the generation of products of high heating value, and the energy requirements for the thermal degradation and production of residues and polyaromatic compounds. An optimum interval of operation temperatures is suggested in order to obtain high yield to gases of high heating values and low yield to PAHs. textcopyright 2002 Elsevier B.V. All rights reserved.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Different processes involving thermal decomposition such as incineration, pyrolysis, gasification or co-combustion are becoming important for energy generation using plastic wastes as combustible materials. The thermal degradation of the material, the product distribution and consequently the economics of the process are strongly influenced by the experimental conditions used. In this work, the thermal degradation of high-density polyethylene (HDPE) has been carried out using a fluidized bed reactor under different temperature conditions. Two types of experiments have been performed, pyrolysis experiments, in which nitrogen has been used as inert gas, and gasification experiments, meaning that the thermal decomposition has been carried out in a nitrogen-air mixture with low oxygen concentration. The influence of the operating parameters on the product distribution and gas composition has been investigated using GC and MS/GC for the analysis of the gas, wax and oil fractions obtained. The results obtained show a widely differing product yield in both processes. The main objective of the paper is a comparison of pyrolysis and gasification in terms of the generation of products of high heating value, and the energy requirements for the thermal degradation and production of residues and polyaromatic compounds. An optimum interval of operation temperatures is suggested in order to obtain high yield to gases of high heating values and low yield to PAHs. textcopyright 2002 Elsevier B.V. All rights reserved.