E F F E C T O F C O E X I S T I NG M A T E R I A L S O N
S T E A M G AS I F I C A T I O N O F E - W A S T E
J. A. Salbidegoitia1, M.P. González-Marcos1, J.R. González-Velasco1, T. Bhaskar2, T. Kamo*3
1Chemical Engineering Department, Faculty of Science and Technology, University of Basque Country/E.H.U., 644, E-48080

Bilbao, Spain
2Thermo-Catalytic Processes Area (TPA), CSIR-Indian Institute of Petroleum (IIP), Dehradun 248005, Uttarakhand, India
3National Institute of Advanced Industrial Science and Technology (AIST), 16-1 Onogawa, Tsukuba, Ibaraki, 305-8569,

e-mail:Japan
tohru-kamo@aist.go.jp; Phone: +81298618427

Abstract
Steam gasification of tantalum electronic capacitors or phenolic boards in the presence of LNK ternary eutectic carbonates(Li2CO3, Na2CO3, and K2CO3) was carried out at 550-675ºC under atmospheric pressure to produce clean hydrogen. Ratesof hydrogen formation were accelerated in the presence of the metal contained in tantalum (Ta) capacitors as well as nickel
metal powder (-50+100 mesh). The results showed that nonsupported nickel metal or the metal contained in the connecting
terminals of electronic devices is effective to increase the rate of hydrogen production by steam gasification.

Keywords: tantalum capacitor; steam gasification; ternary eutectic carbonates, WEEE

1. Introduction
Recovery of valuable metals from waste electrical andelectronic equipment (WEEE) is important to reduce
landfill. Also, conversion of plastics contained in theelectronic devices to clean hydrogen by steam
gasification has been demonstrated to be feasible [1].
Phenolic resin/polymer is a widely used material for themanufacture of printed circuit boards. A tantalum (Ta)capacitor is a component on the PCBs of electronic
devices and it is composed mainly of tantalum, which isan essential material for manufacturing electronic
devices. Three different parts compose the capacitor:
terminal, sintered electrode and fireproof epoxy resin.
The terminal is made of iron, nickel, or copper. The innerpart of the capacitor is the sintered electrode and it ismostly composed by compacted Ta fine powder (90 wt.
%). It is covered by a fireproof epoxy resin with SiO2
powder to enhance its thermal durability [2].
In this work, steam gasification experiments of phenolicboards or Ta capacitors were carried out in the presenceof eutectic carbonates mixture (Li2CO3, Na2CO3, andK2CO3) to produce clean hydrogen fuel. The presence ofnickel, inherent in WEEE, is studied in order to determine
its catalytic effect in steam gasification.

2. Materials and Methods
2.1 Samples
Ta capacitors and phenolic boards (PL-1102, Sumitomo
Bakelite Co., Ltd.) are grinded (0.15 mm of particle size)
and used as samples for the thermogravimetric studies
or steam gasification experiments. The eutectic LNK
carbonate was prepared by mixing equal weights of threecarbonates (Lithium carbonate, sodium carbonate, andpotassium carbonate, supplied by Wako Pure ChemicalIndustries, Ltd.). Nickel powder (-50+100 mesh), with

99.7 % purity, was provided by ALFA AESAR.
2.2 Experimental procedure
2.2.1
Thermogravimetric studies
Thermogravimetric studies for phenolic boards were
performed in a Rigaku Thermoplus TG8120
thermobalance, in nitrogen and steam atmosphere.
Experiments for Ni (-50+100 mesh) and phenolic boards
plus 75% wt. Ni (-50+100 mesh) samples were also
carried out in order to study the behavior of the nickel
metal and its effect in the decomposition of phenolicboards under steam conditions. The heating ramp was
10ºC/min to reach 900ºC and a 50 ml/min of nitrogenflow was used for inert atmosphere. To obtain steam
conditions, the nitrogen flow is bubbled in water at 75ºC.
2.2.2
Steam gasification
A diagram of the process is presented in Fig. 1 and it
shows that the equipment was composed of the sample
feeder, the reactor (ID: 32 mm, L: 125 mm), the heater,
the steam generator and a cooling system. Compositionof the gas products was analyzed every 5 min by gas
chromatography (Varian CP-4900) and the gas flow rate
was measured by an integrating flow meter. LNK
carbonates (30 g) and nickel (1.5 g) were preloaded inFIC

GC

N2

Halogentrap
Feedermoisture
trap
Flow meter

Ice
coolerexhaustGas-liquid
separator

H2O
pump

Pre-heater

Tar productcarbonates
mixturePID thermocontroller

Fig. 1. Experimental diagram
7th International Symposium on Feedstock Recycling of Polymeric Materials (7th ISFR 2013)
New Delhi, India, 23-26 October 2013

Metals andsolid residue

the reactor vessel at the start of an experiment. N2 gas(40 cm3/min) and ultra pure water (0.26 ml/min) wereintroduced into the reactor after a preheating treatment at
500ºC. Phenolic boards or Ta capacitors (0.5 g) were fed
to the reactor after the reactor temperature reached theset value (550, 600 and 675ºC). The mixture of N2 gas
and steam was injected into LNK molten carbonates toimprove the efficiency of physical contact between thesolid sample and the LNK molten carbonates.

obtained for steam gasification of phenolic boards are
similar than those obtained in previous studies [1].
Regarding steam gasification of Ta capacitors, theactivation energy in the presence of LNK carbonates was
88.5 kJ/mol. These experimental results indicate thatmetals contained in WEEE have a catalytic role for steam
gasification of plastic components and can improve theyield of hydrogen production on steam gasification ofWEEE.

3. Results and Discussion

0Ni (-50+100)(H2O)

100

550 (30 g LNK)550R (30 g LNK+1.5 g Ni)

ln(h) [mmol min-1]

The thermogravimetric profiles of phenol boards areshown in Fig. 2, where a one-step degradation can beseen to take place around 200ºC for phenolic boards ininert or steam conditions, and char corresponding to 30%
of initial phenol board remained above 600ºC. However,in the presence of nickel metal, phenolic board reacted
completely by steam gasification. Nickel metal (-50+100mesh) and terminal metal samples had no significant
weight loss in the same conditions. Thus, these resultssuggest that the presence of nickel metal particles canimprove steam gasification of phenolic boards above 600ºC.

600 (30 g LNK)
600 (30 g LNK+1.5 g Ni)
675 (30 g LNK)
675 (30 g LNK+1.5 g Ni)-2-3-4-5

45

95

145

time [min]Fig 3. Hydrogen production from steam gasification ofphenolic board-1

80

550 (30 g LNK)
Phenolic board+75%Ni(H2O)

60

600 (30 g LNK)

-2675 (30 g LNK)
40
Phenolic board(N2)Phenolic board(H2O)

20200

400

600
800
Temperature (ºC)

1000

1200

Fig. 2. TG profiles of the samples
Steam gasification of Ta capacitors and phenolic boards
is described by: C + 2H2O  CO2 + 2H2(1)H2 and CO2 were the main products, but traces of CH4
and CO were also detected. The results obtained inprevious studies showed that steam gasification ofphenolic board in the presence of LNK carbonates
mixtures was complete. In this work, the results for steam
gasification of phenolic boards and Ta capacitors at 550,
600 and 675ºC are presented in Fig. 3 and Fig. 4,respectively. Hydrogen production by steam gasificationof phenolic boards and Ta capacitors increased withtemperature. In the presence of 1.5 g of nickel in LNK
carbonates mixture, higher rate of hydrogen production
was observed. The experimental results indicate thatnickel powder accelerated hydrogen production in thesteam gasification of phenolic boards.
The activation energy for steam gasification of phenolicboards in the presence of LNK carbonates wascalculated as 146 kJ/mol. However, when steam
gasification of the same sample took place in thepresence of both LNK carbonates and nickel metal, theactivation energy decreased to 131 kJ/mol. The values

ln(h) [mmol min -1]

Weight (%)-1-3-4-5-515

time [min]3555

Fig 4. Hydrogen production from steam gasification ofTa capacitor

4. Conclusions
The results showed that nickel metal particles improvehydrogen production rate for steam gasification of WEEEin the presence of LNK carbonates mixture. It can beconcluded that metal scrap can act as a cheap andvaluable catalyst for WEEE degradation which can beeasily recovered after the process.

Acknowledgements
The authors want to thank the Basque Government (BFI2010-150) and the Spanish Ministry for Science andInnovation (CTQ2010-17277) for their economicalsupport.

References[1] S. Zhang, K. Yoshikawa, H. Nakagome and T. Kamo.
Applied Energy 101 (2013) 815-821.

7th International Symposium on Feedstock Recycling of Polymeric Materials (7th ISFR 2013)
New Delhi, India, 23-26 October 2013

[2] K. Mineta & T. H. Okabe. Journal of Physics andChemistry of Solids 66 (2005) 318-321.

7th International Symposium on Feedstock Recycling of Polymeric Materials (7th ISFR 2013)
New Delhi, India, 23-26 October 2013