5-7 OCTOBER

ISFR

2011

107

TOLEDO (SPAIN)

STEAM GASIFICATION OF EPOXY BOARD WITH TERNARY EUTECTICCARBONATESSZ. Zhang1, K. Yoshikawa1, H. Nakagome2, T. KAMO3
1Tokyo Institute of Technology, Frontier Research Center, 4259 G5-9 Nagatsuda, Midori-ku, Yokohama, 226-8502, Japan
2Chiba University, Facult of Engineering, 1-22 Yayoi-cho, Inage-ku, Chiba-shi, 263-8522, Japan
3National Institute of Advanced Industrial Science and Technology, 16-1 Onagawa, Tsukuba, 305-8569, Japane-mail:zhang.s.ad@m.titech.ac.jp

Abstract
Recovery of useful metals from end-of-life electric devices is important not only to lessen environmental burden, but also tosecure strategic materials essential to the electronic industry. Epoxy resins are common plastics applied on the metal parts,
which are hard to separate from metals cleanly. In this study, steam gasification of epoxy board with ternary eutectic
carbonates (Li2CO3, Na2CO3 and K2CO3) was carried out at 600-700 °C under the atmospheric pressure. Effects of theeutectic carbonates on epoxy board steam gasification were investigated. The experimental result indicated that the epoxy
board could be gasified rapidly with the main gas product of hydrogen, and the yield of tar as byproducts was much lower
than that in conventional gasification. It can be concluded that steam gasification at the presence of carbonate is an effective
method to recover useful metals from the end-of-life electric devices, and to convert plastics to hydrogen.

Keywords: epoxy board; steam gasification; ternary eutectic carbonates, end-of-life electric devices

1. Introduction
Recovery of useful metals from end-of-life electricdevices is important not only to lessen environmental
burden, but also to secure strategic materials essential tothe electronic industry. End-of-life electric devices (Ewastes) contain not only valuable metals, but also toxic
substances which will cause environment issues if
treated improperly [1], [2]. Technologies for recovering
those useful metals economically with minimum
environmental impact have been expected eagerly for
effective recycling of E-wastes. Epoxy resins are a kindof common plastics contained in E-wastes. In our study,
steam gasification of epoxy board was carried out under
the presence of eutectic carbonates composed of Li2CO3,
Na2CO3 and K2CO3 (LNK carbonate). Effects of the LNK
carbonate on epoxy board steam gasification wereinvestigated to convert plastics into hydrogen effectively
for recovering of useful metals.

sample feeder, the reactor (ID: 32 mm, L: 125 mm), theheater, the steam generator, the gaseous products
cooling system, and the gas analyzing system. The
carbonates were preloaded in the reactor vessel at thestart of the experiment. Nitrogen gas (40~100 cm3/min)and ultra pure water (0.2~1.3 g/min) were introduced intothe reactor after preheated. An epoxy sample (0.5 g) was
fed into the reactor through a tube after the temperatureof the reactor reached to the designated value (600700°C). Mixture of nitrogen gas and steam was injected
into molten carbonate to improve the efficiency ofphysical contact between the solid sample and themolten carbonate. Composition of the gaseous products
was analyzed by the rapid gas chromatography (VarianCP-4900) and the flow rate of the gas was measured byan integrating flow meter.

2. Materials and Methods
2.1 Samples
Glass fiber reinforced epoxy board (EL-3762, Hitachi
Chemical Company) was used as a model material of
epoxy resins, which widely used in electrical industry.
The low melting point eutectic LNK carbonate wasprepared by equal weight mixing of three carbonates(Lithium carbonate, sodium carbonate, and potassium
carbonate, obtained from Wako Pure ChemicalIndustries, Ltd.).
2.2 Experimental procedure
Schematic outline of the experimental apparatus isshown in Fig.1. The equipment was composed of theinteriores libro.indd 107

Fig.1. Experimental apparatus

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6th International Symposium on Feedstock Recycling of Polymeric Materials

3. Results and Discussion
Main gas products detected every five minutes by therapid GC were shown in Fig.2. Remarkable production ofcarbon dioxide that was formed from hydrolysis ofcarbonate was observed after beginning of steam
blowing into the molten carbonate. The main product,hydrogen, was detected when the epoxy sample wasintroduced after the carbon dioxide produced byhydrolysis of the carbonate had decreased small enoughto ignore. In addition, the trace amount of carbon
monoxide and methane were detected also.
C+2H20ಧ>CO2+2H2 (1)In the steam gasification, hydrogen and carbon dioxide
are produced as shown in the equation (1). However,production of carbon dioxide whose amount should be
half of hydrogen was not observed in our experiment. We
estimated that carbon dioxide derived from the steam
gasification reacted with hydroxide compounds in themolten carbonate. And then carbon dioxide wasproduced gradually from hydrolysis of the carbonate
again.

Fig.2. Main products detected by GC

Fig.3 shows the distribution of products in the steam
gasification of epoxy board with/without the ternary
eutectic carbonate. The percentages shown in this graphindicate the weight ratios of carbon contained in eachproduct to the carbon in the epoxy board. The amount of
produced carbon dioxide was calculated from that ofhydrogen by using the equation (1). Gaseous products
were observed mainly in the presence of the LNK
carbonate. These high yields of gaseous products
indicate that the carbonates promoted conversion of tar
into gas.
Fig.4 shows the Arrhenius plot of the rate of hydrogenformation in the steam gasification of epoxy board
with/without the ternary eutectic carbonate assuming thepseudo-first-order reaction. The reaction rate increased
with temperature. The activation energy of the reaction
with/without carbonate was 118.4kJ/mol or 159.6kJ/mol
respectively. The ternary eutectic carbonate is estimatedto have catalytic effect on this steam gasification,
because the activation energy with the carbonate wasslightly lower than that without carbonate.

Fig.4. Arrhenius plots for steam gasification with/withoutcarbonate mixture

4. Conclusions
The ternary eutectic carbonates (Li2CO3, Na2CO3 andK2CO3) accelerated steam gasification of the epoxy
board at 600-700°C under the atmospheric pressure.
Hydrogen was produced mainly and the yield of tar as
byproducts was much lower than that in conventional
gasification. We can conclude that steam gasification in
the presence of carbonates is an effective method torecover useful metals from the E-wastes, and to convert
plastics into hydrogen.

References

Fig.3. Product distribution in steam gasification
with/without carbonate mixture

interiores libro.indd 108[1] Brett H. Robinson. E-waste: An assessment ofglobal production and environmental impacts. Science of
the Total Environment 408 (2009) 183-191.
[2] Rolf widmer, Heidi Oswald-Krapf, et al. Global
perspectives on e-waste. Environmental impact
assessment review 25 (2005) 436-458.

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