Polypropylene pyrolysis

A. Marcilla, A. Gdmez, J. A. Reyes-Labarta, A. Giner, and F. Hemdndez, Kinetic study of polypropylene pyrolysis using ZSM-5 and an eqnilibrium finid catalytic cracking catalyst, J. Anal. Appl. Pyrolysis, 68-69, 467 (2003). 

Numerous studies were done for polypropylene pyrolysis [81-98], etc. Also, the kinetics of polypropylene pyrolysis has been studied in detail in an inert atmosphere, in the presence of catalysts or in the presence of other materials such as wood [46, 99-101]. 

Fig. 3.2. Diagram illustrating the formation of volatile polypropylene pyrolysis products as a result of rupture of certain bonds. 1 = propane 2 = isobutane 3 = 2-methylpentane 4 = 2,4-dimethylpentane 5 = 2,4-dimethylheptane 6 = 2,4,6-trimethylheptane 7 = 2,4,6-trimethylnonane. Reprinted with permission from ref. 18.

Chung et al. [23] have investigated the effects of NaOH concentration and reaction lime on the mineralogical structure of zeolites synthesized by hydrothermal treatment of fly ash with NaOH solution. It has been reported that the effect of these zeolites on the pyrolysis behavior of low density polyethylene and polypropylene can be delineated in terms of recovery and distribution of boiling points of liquid pyrolysis products. It appears that the fly ash derived zeolites are not effective for low density polyethylene (LDPE) pyrolysis but slightly effective for polypropylene pyrolysis. 

Propjiene [115-07-17, CH2CH=CH2, is perhaps the oldest petrochemical feedstock and is one of the principal light olefins (1) (see Feedstocks). It is used widely as an alkylation (qv) or polymer—ga soline feedstock for octane improvement (see Gasoline and other motor fuels). In addition, large quantities of propylene are used ia plastics as polypropylene, and ia chemicals, eg, acrylonitrile (qv), propylene oxide (qv), 2-propanol, and cumene (qv) (see Olefin POLYMERS,polypropylene Propyl ALCOHOLS). Propylene is produced primarily as a by-product of petroleum (qv) refining and of ethylene (qv) production by steam pyrolysis. 

Polypropylene contains Irganox 1076 antioxidant. b Commercial cal-cium stearate contains both stearate and palmitate. After Lattimer [37]. Reprinted from Journal of Analytical and Applied Pyrolysis, Vol. 26, R. P. Lattimer, pp. 65-92, Copyright (1993), with permission from Elsevier. 

The two polymer substrates investigated as part of the study of DBDPO mixtures were polypropylene (PP) and linear high density polyethylene (HDPE). while both PP and HDPE decompose by similar random chain scission, radical mechanisms, chain transfer occurs much more teadily during the pyrolysis of PP because of the presence of the tertiary hydrogens. In addition, only primary chain end radicals are formed when the HDPE chain cleaves homolytically. Therefore, a comparison of the PP/DBDPO and the HDPE/DBDPO mixtures volatile product distributions was undertaken. 

L. Ballice, Classification of volatile products evolved during temperature-programmed co-pyrolysis of low-density polyethylene (LDPE) with polypropylene (PP). Fuel, 81(9),1233-1240 (2002). 

L. Ballice and R. Reimerta, Classification of volatile products from the temperature-programmed pyrolysis of polypropylene (PP), atactic-polypropylene (APP) and thermogravimetrically derived kinetics of pyrolysis. Chem. Eng. Process., 41(4), 289-296 (2002). 

The condensed phase mechanism was explained taking into account the decrease of the pyrolysis rate of polypropylene BiCl3 could catalyze the condensation between chloroparaffin and polypropylene by addition to chain end double bonds (Equation 4.25) formed either in reaction (Equation 4.22) or in chain scission occurring during volatilization of polypropylene 31... 

Bockhorn, H., Homung, A., Homung, U., and Schwaller, D. Kinetic study on the thermal degradation of polypropylene and polyethylene. Journal of Analytical and Applied Pyrolysis 1999 48 17. 

High-temperatnre pyrolysis and cracking of waste thermoplastic polymers, such as polyethylene, polypropylene and polystyrene is an environmentally acceptable method of recycling. These type of processes embrace both thermal pyrolysis and cracking, catalytic cracking and hydrocracking in the presence of hydrogen. Mainly polyethylene, polypropylene and polystyrene are used as the feedstock for pyrolysis since they have no heteroatom content and the liquid products are theoretically free of sulfur. 

Y. Sakata, M. A. Uddin and A. Muto, Degradation of polyethylene and polypropylene into fuel oil by using sohd acid and non-acid catalysts, J. Anal. Appl. Pyrolysis, 51, 135-155 (1999). 

G. Audiso, A. Silvani, P. L. Beltrame and P. Camiti, Catalytic thermal degradation of polymers degradation of polypropylene, J. Anal. Appl. Pyrolysis 1, 83-90 (1984). 

Y. Uemichi, Y. Makino and T. Kanazuka. Degradation of polypropylene to aromatic hydrocarbons over Pt- and Fe-containing activated carbon catalysts. Journal of Analytical and Applied Pyrolysis, 16, 229-238 (1989). 

The following section reviews the literature data summarizing the behaviour during carbonization of five individual polymers, i.e. polyethylene (PE), polypropylene (PP), polystyrene (PS), polyvinyl chloride (PVC) and polyethylene terephthalate (PET). Eor each polymer, results will first be presented for flash pyrolysis then for slow pyrolysis by the isothermal and dynamic methods. 

By slow pyrolysis, the dynamic method is more appropriate to estimate the decomposition interval for the polypropylene decomposition. Table 10.11 indicates the temperature interval for the decomposition of the PP defined between the temperatures and... 

The carbonization of polypropylene is similar to that of polyethylene. During slow pyrolysis of polypropylene and for a temperature increase from 400 to 700°C, the yield in the liquid phase remains higher than 80% with a very small increase in the yield of gas phase (less than 20%). On the other hand, in flash pyrolysis of polypropylene, an increase of temperature from 550 to 700°C leads to a decrease of the yield in the liquid phase down to 40% with an increase of the gas phase up to 60%. As presented for PE (see Section 2.1), Sawagushi et al. [21] present the results of steam gasification of PP in a fixed bed reactor (Figure 10.8). 

Table 11.3 shows the yield of gas, oil/wax and char from the fixed bed pyrolysis of the main polyalkene plastics, polyethylene and polypropylene, found in municipal solid waste [7-15], Table 11.4 shows the gas, oil/wax and char from the pyrolysis of other plastics [7-9, 14-17], All of the plastics produced an oil/wax and gas and in some cases a char. The product yield related directly to the type of plastic, the reactor type... 

Figure 11.4 Fourier transform infrared spectra of the waxes derived from the pyrolysis of high-density polyethylene, low-density polyethylene and polypropylene...

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