Effect of H2O/SiO2 Molar Ratio on Direct Synthesis of ZSM-5 from Bangka's Kaolin Without Pretreatment

Abstract

The influence of the molar ratio H2O/SiO2 in the synthesis directly from Bangka Belitung's Kaolin has been studied by performing synthesis of ZSM-5 with a variation of the molar ratio H2O/SiO2 is different at 15, 25, 30, and 35. Weighing 3.980 g Bangka's kaolin are added other material so obtained molar composition 10Na2O: 120SiO2: 2Al2O3: 1800-4200H2O, and 1% of silicalite seed, subsequent hydrothermal proccess of 175°C for 24 hours. The result of solids were analyzed by X-ray diffraction (XRD) and Fourier Transform Infrared (FTIR) and SEM EDX to analyzed morphology of ZSM-5 crystal. The synthesis of ZSM-5 was directly optimum with molar ratio H2O/SiO2 of 30 having the highest cristalinity and largest crystal size of 59.44% and 3.795 µm, respectively.

Full text

Hamzah Fansuri , Ani Iryani
Department of Chemistry, Faculty of Science, Institut Teknologi Sepuluh Nopember (ITS), Kampus ITS Sukolilo, Surabaya 60111, Indonesia
Wahyu Erizky Shahbihi , Eko Santoso ,
Hartanto et al. / Malaysian Journal of Fundamental and Applied Sciences Vol. 13, No. 4 (2017) 817-820
817
Effect of H2O/SiO2 molar ratio on direct synthesis of ZSM-5 from
Bangka’s kaolin without pretreatment
Djoko Hartantoa,*, Rendy Muhamad Iqbala,
a,b
a
b
Department of Chemistry, Pakuan University, Bogor, Indonesia
*
Corresponding author: djokohar@its.ac.id
Article history
Received 17 November 2017
Accepted 20 December 2017
Graphical abstract
Abstract
The influence of the molar ratio H2O/SiO2
in the synthesis directly from Bangka Belitung’s Kaolin has
been studied by performing synthesis of ZSM-5 with a variation of the molar ratio H2O/SiO2 is
different at 15, 25, 30, and 35. Weighing 3.980 g Bangka’s kaolin are added other material so
obtained molar composition 10Na2O: 120SiO2: 2Al 2O3: 1800-4200H2O, and 1% of silicalite seed,
subsequent hydrothermal proccess of 175°C for 24 hours. The result of solids were analyzed by X-
ray diffraction (XRD) and Fourier Transform Infrared (FTIR) and SEM EDX to analyzed morphology
of ZSM-5 crystal. The synthesis of ZSM-5 was directly optimum with molar ratio H2O/SiO2 of 30
having the highest cristalinity and largest crystal size of 59.44% and 3.795 µm, respectively.
Keywords: Kaolin, direct synthesis, ZSM-5, hydrothermal, zeolite
© 2017 Penerbit UTM Press. All rights reserved
INTRODUCTION
Zeolite is aluminosilicat crystal that have pore and 3D framework,
Based on their framework, International Zeolite Association (IZA)
reported that zeolite have 218 framework (Kovo et al, 2009). Different
type of zeolite framework has different application and properties.
Zeolite has many utilizate on industrial area, it has many
advantages compared with others mineral because it has a uniform and
regularity pore, strength acid site, and some type of zeolite has good
thermal stability (Sun et al, 2007). Many researchers use zeolite as
adsorben, ion exchanger, molecular siever and catalyst. Zeolite also has
ability to solve waste water problem like active sludge material (Soraya
et al, 2012). Beside natural zeolite, zeolite synthetic also developed by
many researcher.
Zeolite Socony Mobil-5 (ZSM-5) is a type of zeolite that have pore
channel on it’s structure. Oil refinery and petrochemical industry use
ZSM-5 as catalyst. In catalyst area, ZSM-5 called as heterogenous
catalyst that have Brǿnsted a n d L e w i s site. ZSM-5 us e as catalyst for
many reaction such as isomerisation, alkilation, catalytic cracking,
epocsidation, hydrolisis, etc (Kovo et al, 2009). ZSM-5 can synthesized
from raw material which has high contain of silica and alumina, such
as kaolin (Wang et al, 2007 ; Hartanto et al, 2016), fly ash (Feng et al,
2009), rice husk (Prasetyoko et al, 2012), serpentin (Dong et al, 2003),
and smektit (Abdmeziem et al, 1994). Synthesis of ZSM-5 from
metakaolin as alumina source and silicate acid as silica source have
been studied, activation kaolin at temperature from 600°C to 1100°C to
form metakaolin ( P an et al, 2014). But, transformation to metakaolin
need high temperature and increase cost of production. The utilizate
source of silica and alumina from natural resource will decrease cost of
synthesis and also temperature calcined.
Generally, ZSM-5 synthesized by hydrothermal from silica
precusor, alumina, metal cation, and organic template. Conventional
synthesis of zeolite using organic template like TPA+ (Petushkov et al,
2011), utilization of tetrapropilamonium (TPA+) has many problem
such as difficult to degradation, high cost, and need of higher
temperature to release the template (Dey et al, 2013). The high
temperature of calcined might able to destroyed zeolite structure and
decreasing crystalinity of ZSM-5. So, another promising way to
synthesis of ZSM-5 is direct synthesis. Kim et al reported to direct
synthesis of ZSM-5 with two step, first is nucleation at 190°C and
continuesly by crystalization at 150-165°C (Kim et al, 2004). The
advantages of direct synthesis is low calcined temperature, no treatment
for source of silica and alumina (Kaolin). Synthesis of Zeolite use
kaolin as source was reported by many researcher. Direct synthesis also
use addition of ZSM-5 seed, after condensation and polymerisation
reaction, percusor will form zeolite as well as their seed (Xue et al,
2012).
Direct synthesis of ZSM-5 without organic template was influenced
by some factor like temperature, Si/Al molar ratio, and also H
2
O/SiO
2
molar ratio. Generally, the higher temperature increase crystalinity, but
every material has their limit. After optimum temperature, crystalinity
of ZSM-5 would decrease, its caused higher temperature could broke
zeolite structure (Dey et al, 2013 ;Hartanto et al, 2016). Another factor
which influenced were H
2
O/SiO
2
molar ratio. The amount of SiO
2
can
controlled by addition of LUDOX as silica source and water play
important thing in hydrothermal synthesis, its as place to crystal
growth. But, if amount of water too much, proccess of synthesis would
disturb by increasing amount of Na
+
and OH
-
on proccess reaction. Its
would disturb crystal formation and the product would has low
crystalinity. In this study foccus to find optimum H
2
O/SiO
2
molar ratio
on ZSM-5 crystal formation.
EXPERIMENTAL
Materials
NaOH (Merck, 99%), LUDOX (Aldrich, 30 wt% of Si), Bangka
Belitung’s Kaolin (45,86% of SiO
2
and 22% of Al
2
O3), ZSM-5 seed or
Silicalite seed, and aquademineralization.
RESEARCH ARTICLE
a
aa

Hartanto et al. / Malaysian Journal of Fundamental and Applied Sciences Vol. 13, No. 4 (2017) 817-820
818
Synthesis of zeolite socony mobil-5 (ZSM-5)
In this research, ZSM-5 synthesized without organic template with
different variation of H
2
O/SiO
2
molar ratio : 15, 25, 30, and 35. The
synthesis pathway follow a method was reported by Prasetyoko et al
with 10Na
2
O:120SiO
2
:2Al
2
O
3
:1800H
2
O. 0.8 g of NaOH solute with
water (Prasetyoko et al, 2012). Then, Kaolin added into NaOH solution
under constant stirring until form white mixture. LUDOX was added
into mixture and stirring during 8 hour (speed 400 rpm). The mixture
left undisturbed condition during 12 hours at room temperature (aging).
Next step, 0.085 (1 wt%) Silicalite seed added into the mixture and
stiring for 30 minutes and then mixture moved into autoclave steel for
hydrothermal proccess. Hydrothermal proccess under close condition
at 175°C and the crystalization time is 24 hours. Solid product washed
with aquadem and drying at 110°C during 12 hour.
Characterization of ZSM-5
The product of synthesis characterized by XRD JOEL JDX 3530 to
determine crystal structure, Fourrier Transform Infrared (FTIR)
Shimadzu Instrument Spectrum One 8400S to analyze function group
on finger print area, and Scanning Electron Microscopy (SEM) FEI
Inspect S25 and Energy Disspersive X-Ray (EDX) EDAX AMETEX
to analyze morphology and compound of product, respectively.
Crystalinity of product also determine from difractogram, which
calculated using equation :
Cristalinity (%) : Intensity of sample/Intensity of ZSM-5
Commercil x 100% ( 1 )
RESULTS AND DISCUSSION
Direct synthesis of ZSM-5
Direct synthesis of ZSM-5 followed in this reaction (Xue et al,
2012) :
Kaolin
(s)
+ NaOH
(aq)
+ H
2
O
(l)
+ SiO
2 (aq)
ZSM-5
(s)
( 2 )
Reaction (Sun et al, 2007 ; Hartanto et al, 2016 ; Hartanto et al,
2016) use water as solvent and the condition was closed. In this
hydrothermal synthesis would form Al-O-Si or T-O-T (T = Al or Si) by
condentation reaction. After condentation reaction, its continuesly by
polimerisation reaction and framework would follow ZSM-5 seed, the
product will have same framework with ZSM-5 seed that followed
Mordenite Framework Inverted (MFI) or researcher called product as
ZSM-5.
Fig. 1 XRD Pattern of (a) Kaolin (b) ZSM-5 Seed (c) ZSM-5 Commercil,
ZSM-5 with H
2
O/SiO
2
molar ratio (d) 15 (e) 25 (f) 30 (g) 35
Diffractogram of ZSM-5
ZSM-5 characterized by XRD at 2ϴ between 5-40°. Diffractogram
of Bangka Belitung’s kaolin (Fig. 1a) shown narrow peak at 2ϴ : 12.32,
19.87, 20.34, 24.85, 26.61, 34.95, 35.40, 35.91, 38.97, and 39.22°. This
result match with kaolinit which has spesific peak at 2ϴ on 20.5° and
35-38.5°. Besides Kaolinit, Its possible Bangka Belitung’s kaolin
contain qwartz, iron, rutile, anatase, and also montmorilonite.
Diffractogram of ZSM-5 with molar ratio 35 (Fig. 1g) obtained
amorph phase, its sign with appearing of hump at 17-33°, if compared
with diffractogram of kaolin which has narrow peak, its indicate kaolin
was soluted to form amorphous silica after hydrothermal proccess.
Figure 1d-1f represent has same spesific peak with ZSM-5 comercil, It
indicate kaolin was transform to ZSM-5 which has Mordenite
Framework Invert (MFI) structure (Treacy et al, 2001 ; Hartanto et a l ,
2016) and narrow peak shown crystal of ZSM-5 was form
Crystalinity of ZSM-5 also studied and following equation 1 to
calculate it. Tabel 1 showed result of crystalinity of ZSM-5 with
different molar ratio.
Table 1 Crystalinity of ZSM-5 with different H2O/SiO2molar ratio
H2O/SiO2
Crystalinity %
15
25
30
35
49.88
55.49
59.44
8.52
Based on Table 1, the highest crystalinity is ZSM-5 with molar ratio
30 and its reach 59.44%. Crystalinity of ZSM-5 increase with
increasing amount of H2O, but it decrease on molar ratio is 35. Its
caused system of amorphous silica solution at high temperature should
form silica crystal which has good stability, so kaolin can’t transform
to ZSM-5 and the product has low crystalinity of ZSM-5 (Prasetyoko
et al, 2012).
Infrared spectrum of ZSM-5
Synthesize product characterized by FTIR to analyze functional
group at finger print area. Figure 2 exhibit infrared spectrum from
Kaolin, ZSM-5 seed, and also the synthesis product. Infrared spectrum
of kaolin on Fig 2a showed spesific peak at 429, 468, 540, 697, 757,
789, 917, 1031, and 1108 cm-1. Chandrasekar et al reported peak of
kaolin, the wavenumber of 540 cm-1 indicate vibration of Al-O, 789 and
914 cm-1 represent of vibration (Al-O)-H, 430, 693, 752, 794, 1035,
1096, and 1114 cm-1 exhibit vibration of Si-O bonding on SiO2 (Treacy
et al, 2001). The wavenumber of 1115 and 1008 cm-1 obtained by
stretching vibration from Si-O, the peak of 795 and 755 cm-1 shown
vibration of Si-O-Si , 755 and 697 cm-1 is vibration of Al-O-H, 469 and
430 cm-1 indicate vibration of Si-O (Treacy et al, 2001). Figure 2
represent peak of kaolin at 429, 468, 697, 757, 917, 1031, and 1108 cm-
1 did not appear on infrared spectrum of ZSM-5. Its indicate the bonding
of kaolin have break and start to form new bond.
Infrared spectrum of ZSM-5 with different ratio shown in Fig 2(c-
f), On spectrum appear 5 peak at 453, 545, 792, 1092 and 1222 cm-1.
Based on previous research, ZSM-5 has 5 spesific peak at 1221 and
1102 cm-1 from stretching asymmetric vibration of T-O-T, 796 cm-1
obtained by stretching symmetric vibration of T-O-T, 546 cm-1 showed
framework vibration on pentacil ring and its characteristic of zeolite
structure which has MFI type (Hartanto et al, 2016), and 450 cm-1
exhibit bending vibration from T-O-T bonding, where T is Si or Al. Ali
et al reported that peak of 1090 cm-1 represent stretching asymmetric
bending from SiO4 tetrahedral, 545 cm-1 showed external bonding from
tetrahedral with framework and 455 cm-1 represent bending vibration of
Si-O bonding (Ali et al, 2003). Peak at 1224 cm-1 exhibit a pore that
have three dimention channel (Dong et al, 2003), its caused by external
stretching asymmetric vibration of TO4 ( Ali et al, 2003 ; Hartanto et
al, 2016) . Based on data, it can concluded that the synthesize product
is ZSM-5.
Based on Fig 2(c-f), peak of ZSM-5 at 543 cm-1 from sampel with
molar ratio 15 has lowest transmintance and molar ratio 30 has highest
transmintance value.

Hartanto et al. / Malaysian Journal of Fundamental and Applied Sciences Vol. 13, No. 4 (2017) 817-820
819
Fig. 2 Infrared spectrum of (a) Kaolin (b) ZSM-5 Seed, ZSM-5 with
H2O/SiO2 molar ratio (c) 15 (d) 25 (e) 30 (f) 35
Fig. 3 Morphology of ZSM-5 with H2O/SiO2 molar ratio (a) 15 (b) 25 (c)
30
Morphology of ZSM-5
The observation of morphology ZSM-5 using Scanning Electron
Microscopy(SEM). Morphology of ZSM-5 with different molar ratio
shown by fig 3 (a-c). ZSM-5 with H2O/SiO2 molar ratio 15 shown
aggregation of crystal, and shape of crystal has irregularity. For ZSM-
5 with molar ratio 25 and 30 exhibit uniformity of crystal shape. Based
on figure, the shape of crystal is hexagonal prism.
Hexagonal prism of crystal confirm that product is ZSM-5, SEM
micrograph result support XRD and FTIR result. The shape of crystal
influenced by crystalinity of ZSM-5. The higher amount of crystalinity
will produce good hexagonal prism on SEM micrograph. Beside that,
uniformity of crystal shape also important to analyze. For more detail
shape and size of crystal, its shown by fig 4(a-c).
Fig 4 SEM Micrograph of ZSM-5 with H2O/SiO2 molar ratio (a) 15 (b) 25
(c) 30
Crystal size determined by SEM and the result shown by fig 4.
ZSM-5 with molar ratio 15 has lowest of crystal size with the value is
2.684 µm, crystal size of ZSM-5 with molar ratio 25 is 3.562 µm, and
ZSM-5 with molar ratio 30 has highest of crystal size and its value is
3.795 µm. Increasing of crystal size equals with increasing of
crystalinity of ZSM-5.
The increasing size of crystal at higher H2O/SiO2 molar ratio (15-
30), its caused on this condition could break percusor crystal and
hydrothermal synthesis was transformed percusor to ZSM-5. The
higher amount of H2O would increasing crystal size, H2O is place to
growth of crystal, increasing amount of water can increase crystal size.
But, the amount of water has their limit and if its amount too much, its
will decrease crystalinity.
Energy Disspersive X-Ray (EDX) result
EDX analysis has purpose to determine compound of ZSM-5
product, the result shown by Table 2. ZSM-5 contain Si, Al, Na, and O
with different percentage. The high compound of ZSM-5 product is
oxygen and its percentage reach 66.16% on ZSM-5 with molar ratio 25.
Si/Al ratio of ZSM-5 product also determined on Table and the result
(a)
(b)
(c)
(a)
(b)
(c)

Hartanto et al. / Malaysian Journal of Fundamental and Applied Sciences Vol. 13, No. 4 (2017) 817-820
820
shown generally Si/Al for ZSM-5 product is 11.23, 11.70, and 11.41
for ZSM-5 with molar ratio 15, 25, and 30, respectively.
Table 2 Compound of ZSM-5 with different H2O/SiO2molar ratio.
H2O/SiO2
Percentage %
Si
Al
Na
O
Si/Al
15
25
30
27.63
24.69
24.88
2.46
2.11
2.18
2.55
2.92
3.20
60.50
66.16
64.80
11.23
11.70
11.41
CONCLUSION
Bangka Belitung kaolin is promising natural resource as raw
material to synthesis of ZSM-5. Where, its can use for direct synthesis
and its product has different properties based on H2O/SiO2 molar ratio.
The highest crystalinity is ZSM-5 with molar ratio 30 with the value
59.44%, its followed by molar ratio 25, 15, 35 and its value is 55.49;
49.88; 8.52%, respectively. The spectrum of infrared shown spesific
peak at 1221 and 1102 cm-1 from stretching asymmetric vibration of T-
O-T, 796 cm-1 obtained by stretching symmetric vibration of T-O-T,
546 cm-1 shown framework vibration on pentacil ring, and 450 cm-1
exhibit bending vibration from T-O-T bonding, 545 cm-1 shown
external bonding from tetrahedral with framework and 455 cm-1 shown
bending vibration of Si-O bonding. Peak at 1224 cm-1 represent a pore
that have three dimention channel.
Observation of morphology from different H2O/SiO2 molar ratio
represent different shape of crystal. ZSM-5 with H2O/SiO2 molar ratio
30 has shape like hexagonal prism and its also has highest crystal size
with the value is 3.795 µm and followed by molar ratio 25 and 15 with
value is 3.562 and 2.684 µm, respectively. EDX result shown Si/Al
ratio for ZSM-5 with H2O/SiO2 molar ratio 15;25;30 is 11.23; 11.70;
11.41, respectively. From this work can concluded the optimum
H2O/SiO2 molar ratio on direct synthesis of ZSM-5 is 30.
ACKNOWLEDGEMENT
This work was financially supported by the Ministry of Research,
Technology and Higher Education of Indonesia under DRPM Grant.
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