Decomposition of gaseous ethyl acetate with spherical pellets of FePt/Al2O3 catalyst using a combustion method
Mayuko TSUNASHIMA1)，Noriyuki KITAORI1) *Abstract
The waste gases emitted from printing factories typically include volatile organic compounds (VOCs),
such as ethyl acetate. In general, VOCs are decomposed by catalyst combustion methods, in which
platinum catalysts are often employed. However, platinum is expensive and is a rare metal. In the present
study, the development of an inexpensive iron-based catalyst was successfully achieved. The performanceof the primitive iron catalyst was lower than the activity of commercially available platinum catalysts.
Thus, a trace amount of platinum was added to the iron-based catalysts to improve the performance.
Consequently, spherical pellets of the resulting Fe-Pt/Al2O3 catalyst exhibited optimal activity. Notably,
the cost of the material was reduced by approximately 90%.

Keywords：Iron oxide, Spherical aluminum oxide, Combustion catalysts, VOCs, Platinum
Received September 5, 2020; accepted February 9, 2021

1) Department of Chemical Science and Engineering, Tokyo National College of Technology, Kunugida-machi,
Hachiouji-shi, Tokyo, 193-0997, Japan* E-mail: kitaori@tokyo-ct.ac.jp

1

1 Introduction
As a consequence of extensive use of various
kinds of organic solvents, gases emitted by painting
and printing factories often include large amounts ofvolatile organic compounds (VOCs).1) Exposure to
VOCs, such as toluene and ethyl acetate, can havedetrimental effects on people’s health, and theemission of these chemicals typically produces
unpleasant smells.2-5) For this reason, theconcentrations of VOCs in industrial emissions are
regulated by law, and all factories must conduct
waste gas treatments to keep the levels of VOCs
below the specified standard concentrations.6-10)
Catalytic combustion methods are typically utilized
in printing plants for VOCs treatment.11-13) A
platinum-based catalyst in the presence of alumina
as a carrier is generally employed due to its goodoxidizing performance.14,15) However, it is widely
known that platinum is a rare and relatively
expensive metal. Accordingly, the fact that platinum
accounts for a significant amount of material costs
and leads to an increase in the price of the catalyst isa major issue.16-18) Therefore, the development of
catalysts using inexpensive metal and metal oxides
have been actively conducted.19-23) In this study, we
attempted to reduce the cost of VOCs combustion
catalysts by using iron. We selected iron instead of
platinum due to availability and low cost. The
performance of the iron-based catalyst wasevaluated by investigating ethyl acetate gas
decomposition reaction and comparing the activity
with a commercially available platinum catalyst. The
iron catalyst was prepared using a general
impregnation method. Initially, the developed
catalyst exhibited a lower decomposition
performance than the platinum catalyst.
Consequently, we examined a new method for the
production of a different iron-based catalyst. Thisapproach involved oxidizing iron by hydrogen
peroxide, followed by its attachment to an alumina
ball surface as FeOOH. The performance of thecatalyst produced by this method was somewhat
improved; however, remained lower than that of theplatinum catalyst. Since inadequate catalyst
performance was obtained using just iron, further
improvements were necessary. We subsequently
investigated addition of a small amount of platinum
to the iron catalyst. Ultimately, the performance ofthe catalyst-containing platinum exhibited activity
equivalent to that of a commercially available

platinum catalyst and importantly, the cost of thematerial was significantly reduced.

2 Experimental
2.1 Preparation of the iron-based catalyst
Fig. 1 shows the photographs of visualappearance of the iron-oxide catalyst and the ironoxyhydroxide catalyst. The iron catalysts wereprepared using two varying approaches. The firstincluded the synthesis of the iron-based catalyst
using a previously described impregnation
method.24) Spherical aluminum oxide with adiameter of 5 mm was used as a catalyst carrier(Nikki-Universal Co.). The carriers (alumina balls)
were immersed in a FeSO4 solution whose
concentration is 4.9wt.% and 11.7wt.% for 5 min.
Subsequently, the carriers were dried at 100 °C in adryer and baked at 500 °C in air, affording thedesired iron-oxide catalysts (see Fig. 1a). The
catalysts were prepared using two different a FeSO4
solution concentrations, i.e., 4.9wt.% and 11.7wt.%.

Fig. 1 The visual appearances of the iron-oxide catalyst(a) and the iron-oxyhydroxide catalyst(b)In the second approach, the alumina balls were
immersed in a FeSO4 solution, to which hydrogen
peroxide was added. The ionic iron species wereoxidized by hydrogen peroxide to form ironcompound on the surface of the alumina ball.
Following oxidation, the carriers were dried at
100 °C in a dryer (see Fig. 1b). The X-ray diffraction(XRD) pattern of iron compound on the catalyst
surface was recorded by the X-ray diffractometer(D8-Advance, Bruker). In addition, infrared (IR)
spectra of iron compounds on the catalyst surface
were recorded using the Fourier transformation
infrared spectrophotometer (FT/IR-4100typeA,
Jasco). The measured sample was prepared byscraping the outer surface of catalysts.
Furthermore, the catalysts were prepared by theaddition of a small amount of platinum to the assynthesized iron catalysts. The two types iron2

catalysts were immersed in a 0.1 g/L dinitrodiamine
platinum nitrate solution (Tanaka Kikinzoku Kogyo,
Japan) for 1 h. This resulted in the fixation of the
majority of the platinum species in the solution to thecatalysts. It is noteworthy that the platinum solution
concentration was 20-fold lower than the amount of
platinum required to produce a commercial catalyst(Nikki-Universal Co.). The commercially available
platinum catalyst was evaluated using X-ray
fluorescence analysis (Shimazu corporation, EDX7000). It was found that approximately 1.7–2.2 g ofplatinum was attached to 1 L of the carrier.
Subsequently, the immersed catalysts were dried at
approximately 100 °C in a dryer, affording two typesof Fe-Pt composite catalysts.
2.2 Evaluation of the catalytic activity
The evaluation of the catalyst performance foroxidative decomposition of gaseous VOCs was
carried out using ethyl acetate gas at a concentrationof 5000 ppm. The fixed bed reactor was used for theevaluation. The ethyl acetate gas was passed througha catalyst-containing heated furnace at a flow rate of
3 L/min. The air before and after passing through thecatalyst was analyzed by gas chromatography (GC).
The activity of a commercially available platinum
catalyst, i.e., the standard for the catalytic
performance, was assessed utilizing the same
experimental system. The catalyst performance
evaluation system is illustrated in Fig. 2. All piping
consisted of silicone hoses. The air drawn by thegas mixture of air and ethyl acetate at a concentrationof 5000 ppm was prepared by blowing dry air onto
ethyl acetate in a test tube. The catalyst with heightof 20 cm was in the quartz tube (a diameter of 26 mm
and length of 500 mm.), which was heated using aring furnace. The space velocity was approximately
424 /hr in the evaluation. The ethyl acetate gas was
passed through the heated catalyst in the quartz tube
from top to bottom. After passing through the sample,
the gas was exhausted and analyzed by GC. The
catalysts were heated at a temperature in the range of
250–400 °C. The concentration of gas was analyzed
5 times with the one temperature. The compositionand specific surface area of the catalysts were
measured by X-ray fluorescence analysis as well as
using Brunauer-Emmett-Teller (BET) methods,
respectively. Lastly, the surface structures wereobserved by scanning electron microscopy (SEM).
3 Result and discussion
3.1 Performance of the iron-oxide catalysts
The iron elemental content in the iron-oxide
catalysts was measured by X-ray fluorescenceanalysis. We determined that the iron elemental
content using the 11.7% FeSO4 solution was 0.441
mg/cm2, while the iron elemental content utilizing
the 4.9% FeSO4 solution was 0.245 mg/cm2. The
catalytic performance of the iron-oxide catalysts
under the oxidation conditions is shown in Table 1.
The ethyl acetate concentration after passing thecatalyst is a mean value of 5 times analyzes. The
catalyst activity was evaluated at 300 °C, 350 °C,
and 400 °C. Examination of the gas after passing
through the iron catalyst with the content of 0.441
mg/cm2 revealed that 1905 ppm of ethyl acetate was
detected at 300 °C, while at 350 °C, 70 ppm of thecompound was noted. It is noteworthy that no ethyl
acetate was detected at 400 °C; therefore, complete
decomposition was suspected. Moreover, analysis of
Table 1 Characteristics of the Fe/Al2O3 catalyst
Ethyl acetate concentration after
passing the catalyst(ppm)
Treatment temperature(℃)
300
350
400
0.441
1905
70
0
Baking at
500℃
0.245
2775
23
0
0.445
456
0
0
Additionof H2O2
0.270
487
63
0
Commercial platinum000
catalyst

Supported
Oxidationamount ofmethod2Fe(mg/cm )Fig. 2 The fixed bed reactor system for evaluation of
catalytic activity

pump was passed through silica gel to produce dry
air exhibiting the relative humidity of 2–5%. A test3the gas after passing through the iron catalyst withthe content of 0.245 mg/cm2 showed that 2775 ppmof ethyl acetate was noted at 300 °C, 23 ppm at
350 °C, and 2 ppm at 400 °C. Thus, thedecomposition performance of ethyl acetate
increased with increasing furnace temperature. In
addition, the activity of the iron catalyst deposited
with the content of 0.441 mg/cm2 to decompose
ethyl acetate was higher than that at the catalyst withthe content of 0.245 mg/cm2. Hence, we establishedthat during the decomposition of ethyl acetate, theperformance of the catalyst was enhanced with anincrease in the iron content.
It was determined that the commerciallyavailable platinum catalyst completely decomposed
ethyl acetate at 300 °C. On the other hand, ironcatalysts require a temperature of 400 °C or higher.
To improve the performance of the iron catalyst, we
attempted to alter the method of oxidizing iron.
3.2 Changes in the catalytic activity followinghydrogen peroxide oxidation
The performance of the iron catalyst, in which
the iron was oxidized using hydrogen peroxide to
produce iron oxyhydroxide on the catalyst surface isshown in Table 1. To compare the performance of theiron-oxyhydroxide catalyst with the iron-oxide
catalyst, a sample of the former was prepared, andthe amount of supported iron was measured by Xray fluorescence analysis. It was found that theamount of iron in both types of catalysts was nearly
the same. When the content of the iron element was
0.445 mg/cm2, 456 ppm of ethyl acetate was detected
after passing through catalysts at 300 °C. No ethyl
acetate was detected at 350 °C or 400 °C. When thedeposition amount of iron on the catalyst surface was
at 0.270 mg/cm2, 487 ppm of ethyl acetate was
detected at 300 °C, whereas at 350 °C, 63 ppm wasnoted. Moreover, at 400 °C, no ethyl acetate was
detected. Similarly to the case of iron-oxide catalysts,
the decomposition of ethyl acetate increased withincreasing the processing temperature of the electric
furnace. In addition, the catalyst oxidation capacityof ethyl acetate improved with increasing ironcontent. The comparison of the performance of ironcatalysts prepared using two different oxidation
methods revealed that the activity of the catalyst
oxidized employing hydrogen peroxide was superior.
According to Fig. 2b, the iron compound
prepared by the second approach is yellowish
brown.25-28) For that reason, this iron compound isFig. 3 X-ray diffraction pattern of the Fe compound
coated on the iron-oxyhydroxide catalyst surface

Fig. 4 The infrared spectra of the Fe compound coatedon the iron-oxyhydroxide catalyst surface

considered FeOOH. Fig. 3 shows the XRD patternof iron compound on the catalyst surface. It isconsidered the amorphous peaks at 2θ = 35.3°, 36°
originated from δ-FeOOH and β-FeOOH.29,30) Fig. 4
shows the IR spectra of the iron compound on the
catalyst surface. Two absorption band observed
around 705 and 847 cm-1 originated from βFeOOH.33) Furthermore, an absorption band
observed around 1125 cm-1 originated from δFeOOH.34) Considering these results from XRD
pattern and IR spectra, the iron compound on the
catalyst surface is identified the mixture of δ-FeOOH
and β-FeOOH. When heated above 250 °C, iron
oxyhydroxide (FeOOH) finally converts to ironoxide; therefore, heating does not change the ironcontent. However, the structure of the catalyst
surface was altered by thermal decomposition of iron
oxyhydroxide.
The SEM images of the two types of iron catalyst
surfaces are illustrated in Fig. 5. Based on the SEM
observation, the surface of the iron catalyst formedby baking at 500 °C was flat, while the surface of theiron catalyst oxidized with hydrogen peroxide wascomposed of numerous fine particles ofapproximately 0.1~0.5 µm and many pores of 1 µm.
To gain further insight, we subsequently
4

Table 2 Characteristics of the Fe-Pt/Al2O3 catalyst

Fig. 5 SEM images of the catalyst surface (a) heat-treatedat 500 °C in air and (b) oxidized with hydrogen peroxideFig. 6 Relationship between the platinum amount per unit
area measured by X-ray fluorescence analysis and thegross platinum mass attached to 1 L of alumina pellets

measured the BET specific surface area of thecatalysts. The specific surface area of the carriers(alumina balls) was 141 m2/g. And the specificsurface area of the heat-oxidized iron catalyst wasestablished at 145 m2/g, whereas the specific surface
area of the iron catalyst oxidized with hydrogen
peroxide was 171 m2/g. These results wereconsistent with the SEM observation. Thus, it isconsidered that the iron catalyst prepared fromoxyhydroxide exhibited a large specific surface area,
and thus the dispersion effect is high, which is anadvantageous property for catalytic reactions.35-37)
Furthermore Because of having many pores, contact
efficiency between the iron catalyst oxidized withhydrogen peroxide and reaction gas increased. Thus,
it is considered that the catalyst performance has
improved.38,39)
3.3 Improvement of the iron catalyst
performance by the addition of trace platinum
The Fe-Pt catalysts were obtained by adding asmall amount of platinum to the two types of ironcatalysts. The performance of the prepared catalysts
is shown in Table 2.

It was found that the Fe-Pt catalysts(impregnation method) prepared by the addition of
trace platinum completely decomposed ethyl acetate
at 300 °C (high iron content catalyst) and at 350 °C(low iron content catalyst). Furthermore, the Fe-Pt
catalyst obtained by adding trace platinum to theiron-oxyhydroxide catalyst decomposed ethyl
acetate at 250 °C, regardless of the Iron content.
Notably, the performance of this Fe-Pt catalyst was
shown to outperform the characteristics ofcommercially available platinum catalysts.
Moreover, the Fe-Pt catalyst prepared by theaddition of platinum to the iron-oxide catalyst
containing a large supported amount as well as thecatalyst obtained by adding platinum to the ironoxyhydroxide catalyst exhibited analogous
performance to the commercially available platinum
catalyst. We suspect that this is a consequence of theaddition of a small amount of platinum to the ironcatalyst, which promoted the catalytic activity ofiron. Platinum is known to display strong
dehydrogenating
effectsonhydrocarbon
40)
molecules. Thus, the presence of platinum resultsin dehydrogenation and activation of ethyl acetate.
Subsequently, iron catalyzes the decomposition of
ethyl acetate activated by platinum. Therefore, it isconsidered that the decomposition proceeds moreeasily using both catalysts than with iron alone. The
amount of the supported platinum was also measuredby X-ray fluorescence analysis. We determined thatthe platinum content of the commercially available
platinum catalyst was 0.333 mg/cm2, while theplatinum content of the Fe-Pt catalyst was in the5range of 0.014–0.016 mg/cm2.
The relationship between the platinum amount
per unit area measured by X-ray fluorescenceanalysis and the total platinum mass attached to 1 Lof spherical alumina pellets is demonstrated in Fig.
6. As it can be seen, the platinum content in the FePt catalyst at 0.014–0.016 mg/cm2 corresponds toapproximately 0.1 g of platinum attached to 1 L of
the alumina pellets. Furthermore, the platinum
content of this Fe-Pt catalyst is approximately 1/20
that of a commercially available platinum catalyst,
the catalytic performance is enhanced. Importantly,
the material costs were reduced by approximately
90%. Based on the results of our study, the cost of
the combustion catalyst was significantly reduced byutilizing the described catalytic system consisting ofiron and trace platinum.
4. Conclusion
The performance of the developed iron-based
catalysts was evaluated using ethyl acetate gas
decomposition reaction and compared with acommercially available platinum catalyst. The
activity of the iron-oxide catalyst obtained utilizing
a general impregnation method was lower than thatof the commercially available platinum catalyst.
Based on this result, we searched for a new approachfor producing a more efficient iron catalyst. The iron
was oxidized by hydrogen peroxide and attached toan alumina surface as FeOOH. The performance of
the iron-oxyhydroxide catalyst prepared in this way
considerably improved; however, it was not as highas the activity of commercially available platinum
catalysts. Since the catalyst performance using justiron was inadequate, it was necessary to makefurther improvements. Hence, we prepared Fe-Pt
catalysts by the addition of a very small amount of
platinum to the iron catalysts. As a result, it was
found that the catalyst performance was enhanced to
the level of commercially available platinum.
Ultimately, the mass of platinum used was reduced
to approximately 1/20 of that of commerciallyavailable platinum catalysts, and the overall cost of
the VOCs decomposition and combustion catalysts
was greatly reduced.

Pollution, 2008, 151, 362-367.
3) J. S. Kiurski, B. B. Marić, S. M. Aksentijević, I.
B. Oros, V. S. Kecić, and I. M. Kovačević,
Renewable
andSustainable
EnergyReviews,2013, 28, 224-231.
4) K. Jelena, M. Branislav, A. Dragan, M.
Aleksandra, G. Selena, O. Ivana, and K. Jelena,
Renewable and Sustainable Energy Reviews,
2012, 16, 660-667.
5) D. Ye, M. Klein, H. H. Chang, J. A. Sarnat, J.
A. Mulholland, E. S. Edgerton, A. Winquist, P.
E. Tolbert, and S. E. Sarnata, Epidemiology,
2017, 28, 197-206.
6) Y. Nishimura, The Surface Finishing Society ofJapan, 2005, 56, 594-600 . [in Japanese]
7) Y. Yonehara, Japan Society of Colour Material,
2017, 90, 122-126. [in Japanese]
8) W. H. Cheng, S. K. Hsu, M. S. Chou, Journalof Environmental Management, 2008,
88,1485-1494.
9) D. F. Zhao, A. Buchholz, R. Tillmann, E. Kleist,
C. Wu, F. Rubach, A. Kiendler-Scharr, Y.
Rudich, J. Wildt and Th. F. Mentel, Nature
Communications, 2017, 8, Article number:
14067.
10) K. Taguchi, J. Japan Association on Odor
Environment, 2004, 35, 135-138. [in Japanese]11) W. B. Li, J. X. Wang, and H. Gong, Catalysis
Today, 2009, 148, 81-87.
12) F. N. Aguero, B. P. Barbero, L. Gambaro, andL. E. Cadu´ s, Applied Catalysis B:
Environmental, 2009, 91, 108-112.
13) D. Delimaris and T. Ioannides, Applied
Catalysis B: Environmental, 2008, 84, 303-312.
14) T. Muroi, Materia Japan, 2001, 40, 206-209.
[in Japanese]
15) S. Somekawa, T. Hagiwara, K. Fujii, M.
Kojima, T. Shinoda, K. Takanabe, and K.
Domen, Applied Catalysis A: General, 2011,409-410, 209-214.
16) M. S. Kamal, S. A. Razzak and M. M. Hossain,
Atmospheric Environment, 2016, 140, 117-134.
17) X. H. Tai, C. W. Lai, J. C. Juan and K, M, Lee,
Nanomaterials for Air Remediation, Micro andNano Technologies, 2020, Chap. 7.
18) Clariant Corporation. Z. Dang, G. Cullen.
LOW COST OXDATION CATALYSIS FORVOCAND
HALOGENATED
VOCEMISSION CONTROL, U. S. patent
10,569,256. 2020-2-25.
19) D. A. Aguilera, A. Perez, R. Molina and S.
Moreno, Applied Catalysis B: Environmental,
2011, 104, 144-150.

References
1) G. Li, W. Wei, X. Shao, L. Nie, H. Wang, X.
Yan and R. Zhang, Journal of Environmental
Sciences, 2018, 67, 78-88.
2) M. Kampa and E. Castanas, Environmental
620) M. H. Castano, R. Molina, S. Moreno,
Molecular Catalysis, 2017, 443, 117-124.
21) D. Delinaris, T. Loannides, Applied Catalysis
B: Environmental, 2009, 89, 295-302.
22) X. Yang, X. Yu, M. Lin, X. Ma, M. Ge,
Catalysis Today, 2019, 327, 254-261.
23) S. Dissanayake, N. Wasalathanthri, A. S.
Amin, J. He, S. Poges, D. Tathnayake, S. L.
Suib, Applied Catalysis A: General, 2020, 590
Article number: 117366.
24) Y. Morioka, S. Okada, H. Kosugi, and J.
Kobayashi, The Chemical Society of Japan,
1989, 4,653-659 (1989). [in Japanese]25) A. Jagminas, K. Mazeika, J.Teklaitis, D.
Baltrunas, Applied Surface Science, 2010, 256,3993-3996.
26) R. B. Pujari, S. J. Patil, J. Park, A.
Shanmugasundaram, Journal of Power
Sources, 2019, 436, 226826.
27) R. Yu, J. Pee, Y. J. Kim, Journal of
Nanoscience and Nanotechnology, 2013, 13, 13.
28) X. Chen, Y. Jiang, C. Jiao, Journal ofHazardous Materials, 2014, 266, 114-121.
29) JCPDS ASTM Cards No. 13-87.
30) JCPDS ASTM Cards No. 18-639.
31) S. Nobuoka, T. Ando, Science of powder, 1966,
13, 286-289. [in Japanese]
32) S. Nobuoka, The journal of chemical industry,
1965, 68, 2311-2317. [in Japanese]33) K. Sato, T. Koike, M. Aoki, Japan Analyst,
1972, 21, 256-263. [in Japanese]34) T. Misawa, W. Suetaka, S. Shimodaira,
Journal of the Society of Materials Science,
Japan, 1970, 19,537-542. [in Japanese]35) A. T. Bell, Science, 2003, 299, 1688-1691.
36) J. C. S. Wu, Z. A. Lin, J. W. Pan, M. H Rei,
Applied Catalysis A: General, 2001, 219, 117124.
37) M. Morbidelli, A. Gavriilidis, A. Varma,
Catalyst Design: Optimal Distribution of
Catalyst in Pellets, Reactors, and Membranes,
2001, Cambridge University Press, 40-46.
38) R. Portela, V. E. Garcia-Sanchz, M. Villarroel,
S. B. Rasmussen, P. Avila, Applied Catalysis A:
General,2016, 510, 49-56.
39) Q. -H. Xia, K. Hidajat, S. Kawai, Ctalysis
Today, 2001, 68, 255-262 (2001).
40) E. Kikuti, Y. Imizu, K. Segawa, A. Tada, and
H. Hattori, Shinpan Atarashishokubaikagaku,
2013, Sankyo Shuppan, Tokyo, Chap. 1. [inJapanese]
41) L. Xinsheng, K. Olga, F. Robert, Applied

Catalysis A: General, 2002, 226, 293-303.
42) L. Lingling, M. Chenfang, W. Shaohuang, Y.
Shaoming, C. Feng, Y. Chenqing, Z.
Huanglong, Y. Donghong, Journal of
Electroanalytical Chemistry, 2020, 877,
114519.
43) C. Wei, K. Jaemin, S. Shouheng, C. Shaowei,
The Journal of Physical Chemistry C, 2008,
112, 3891-3898.

7