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TOLEDO (SPAIN)PYROLYSIS REACTION OF POLYURETHANE FOAM AND EFFECT OF METALLICCOMPOUND FOR THERMAL DECOMPOSITION PRODUCTT. Suzuki, H. Yanase, O. Terakado and M. Hirasawa
Department of Materials Science and Engineering, Graduate School of Engineering, Nagoya University, Japane-mail: suzuki.toshimi@c.mbox.nagoya-u.ac.jp

Abstract
The effect of metal oxide (ZNO, Fe2O3, La2O3, Nd2O3) and metal chloride (ZnCl2, FeCl2, CuCl2, FeCl3) on polyurethane (PUR)
foam pyrolysis was studied with thermogravimetric analysis (TGA), gas chromatography-mass spectrometry (GC/MS)
analysis and ion meter. The addition of FeCl2, FeCl3 and CuCl2 decreased the weight loss temperature of PUR foam. On theother hand, the addition of ZnCl2 increased the temperature of the initial weight loss. The addition of metal chloride increased
gaseous products and carbonaceous residue. As for the nitrogen-containing pyrolysis products, the addition of metallic oxide
compounds increased ammonia production. This result indicates that the addition of metallic compounds is effective for asafe pyrolysis of PUR foam which avoids the emission of hazardous HCN and NOx.

Keywords: pyrolysis of polyurethane, metal oxides, metal chlorides, addition of metal compound

One of the greatest advantages of the pyrolysis
treatment is a significant volume reduction of polymeric
wastes. Therefore, pyrolysis of PUR foam is very
promising because of its low density. It is known that theproduction of PUR is about 1.5 weight percents inJapanese plastic industry, though the volumetric ratio
reaches ca. 30% (Data in 1991). Thus, the volume
reduction is a crucial issue in the management of waste
PUR foam.
Moreover, in the view of the energy consumption inthermal treatment, it is important to develop an efficientpyrolysis method. The utilization of metallic compounds
is an attractive option, because some of them are known
to act as catalysts that change the degradation behavior
of PUR and products distribution[1,2]. In this study, we
report the thermal decomposition behavior of PUR under
the presence of various metallic compounds.

2. Materials and Methods
The flexible and rigid types of PUR foam (Toyo rubber
Ind. Co., Ltd.) were used in the present study. The weightof the flexible PUR foam was about 200mg for pyrolysis
experiments and ca. 10 mg for TGA. The rigid PUR foam
was pulverized by cutter mill and the particle diameter
was less than 250μm. Density of flexible PUR foam was
4.5×10-2 g/cm3 and that of rigid foam was 5.2×10-1 g/cm3.
ZnO, Fe2O3, La2O3 and Nd2O3 were used as metaloxides. ZnCl2, FeCl2, CuCl2 and FeCl3 were used as
metal chlorides. The sample of PUR-chloride wasprepared by impregnation with acetone solution. The
sample of PUR-oxide was prepared by mechanicalmixing. The composition of [PUR foam]:[metalliccompound]=1:1 in weight ratio was examined.

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Thermal decomposition behavior was examined by TGA.
A sample was heated up to 800oC with the heating rateof 5oC/min under helium atmosphere.
Pyrolysis experiments were carried out in a horizontal
reactor under helium atmosphere at 800 oC. The
experimental set-up was similar to that described
elsewhere [3]. The collected gaseous and liquid products
were examined by GC/MS, and one of the important
nitrogen-containing products, i.e. ammonia, was captured
in a water trap. The NH4+ concentration was measured
by an ion-meter with NH4+-selective electrode.

3. Results and Discussion
Fig.1 shows the TGA results of flexible PUR foam withmetal chlorides. The addition of FeCl2, FeCl3 and CuCl2
decreased the temperature of the initial weight loss.
100
Mass % , W/W0 × 100

1. Introduction+ZnCl2+FeCl80+CuCl260+FeCl340200100pure200300

400 500 600
Temperature /oC700

800

Fig.1. TGA results of PUR foam with metal chloride
mixture under helium atmosphere. (heating rate = 5oC/min)

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6th International Symposium on Feedstock Recycling of Polymeric Materials

The addition of ZnCl2, on the other hand, increased theweight loss temperature of PUR foam. It is known thatthe cleavage of urethane linkage is responsible for theinitial decomposition of PUR [4]. The present results
suggest that metal compound affects the cleavage ofurethane linkage.
Fig.2 shows the GC/MS results of gaseous products ofpyrolysis of rigid PUR foam metal chloride. The additionof metal chlorides increased the yield of gaseousproducts. Significant increase in the case of iron chloride
is due to the carbothermic reduction of iron. Thus, theyield of gaseous products for the trivalent iron chloride ishigher than that for the divalent FeCl2. As for the tar andcarbonaceous residue, the yield of them was increasedby the addition of metal chloride. This can be ascribed to
the Lewis-acidic nature of the salts, which enhances thebridging of the decomposition polyurethane moieties.

rigid+Nd2O3
rigid+La2O3
rigid+Fe2O3rigid+ZnO
rigid+CuCl2
rigid+FeCl2rigid+ZnCl2
rigid-pureflexible+CuCl2
flexible+FeCl2
flexible+ZnCl2
flexible-pure0+FeCl3+CuCl2+FeCl2
pure01020304050

2.0

Fig.3. Yield of ammonia in pyrolysis of PUR foam-metallic
compound.

C3H8C3H6C2H6C2H4CO2CH4CO+ZnCl2

0.5
1.5
1.0
100 × WNH3/W0,polyurethane (wt%)

References

60

100 × Wproducts/W0,polyurethane (wt%)
Fig.2. GC/MS results of gaseous products from rigid PUR
foam pyrolysis with metal chloride.

[1] G. Moroi, J. Anal. Appl. Pyrolysis, 71 (2004) 485-500[2] G. Moroi, C.Ciobanu, E.Costea, N.Blba, I.Palamaru,Thermochimi. Acta, 291 (1997) 95-99[3] Y. Masuda O.Terakado M.Hirasawa Proceeding of
The 13th APCChE (2010) 10370[4] P. Carty, E.Metcalfe and S.White, Polymer, 33 (1992)
2704-2708[5] R. Font, A.Fullana, J.A.Caballero, L.Candela,A.Garcia, J. Anal. Appl. Pyrolysis, 58-59 (2001) 63-77

It has been reported that nitrogen-containing compounds,
such as hydrogen cyanide (HCN) and nitrogen oxide(NOx) are produced by pyrolysis of PUR [5]. Theemission control of these hazardous products is,therefore, of special importance.
Fig.3 shows the results of quantitative analysis ofammonia. The yield of ammonia is increased by theaddition of metallic compounds.

4. Conclusions
In this study, we examined pyrolysis reaction of flexible
and rigid PUR foam and effect of metallic compound forthermal decomposition product in inactive gas
atmosphere.
The addition of metal chloride changes the behavior atthe initial PUR degradation. These results suggest thatmetal compound affects the cleavage of urethane linkage.
The addition of metal chloride increases the yield ofgaseous products, tar and carbonaceous residue.
Furthermore, the addition of metallic compounds
increases the yield of ammonia products. Thus, theaddition of metallic compound is effective for a safe
pyrolysis of PUR foam which avoids the emission of
hazardous HCN and NOx.

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