Performance of nano crystalline h zsm-5 as additive in fcc catalyst a review

IJRET: International Journal of Research in Engineering and Technology eISSN: 2319-1163 | pISSN: 2321-7308
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Volume: 03 Special Issue: 03 | May-2014 | NCRIET-2014, Available @ http://www.ijret.org 481
PERFORMANCE OF NANO CRYSTALLINE H-ZSM-5 AS ADDITIVE IN FCC CATALYST: A REVIEW Jitendra Kumar1, Chanchal Mewar2, Lekhraj Malviya3, Bharat Modhera4 1Chemical Engineering Department, Maulana Azad National Institute of Technology, Bhopal, India 2Chemical Engineering Department, Maulana Azad National Institute of Technology, Bhopal, India 3Chemical Engineering Department, Maulana Azad National Institute of Technology, Bhopal, India 4Chemical Engineering Department, Maulana Azad National Institute of Technology, Bhopal, India Abstract SiO2/Al2O3 ratios are different with ZSM-5 zeolites. The Changes to the compositions, poresizes, and morphology of the zeolite. Alkali-treatment compare are before and after the SiO2/Al2O3 ratios are influence with which the zeolites are synthesized. Alkali- treated ZSM-5 zeolites are produce higher yields of light olefins compared to untreated zeolites or alkali-treatment introduces mesopore. The zeolites are improves their catalytic cracking catalyst ability. The ZSM-5particle size has a strong effect on the changes in product yields. And also effect gas and gasoline compositions. And the performance of HZSM-5 zeolites of varying acidity and porosity were prepared under various synthesis conditions. In this paper discuss the effect of catalyst properties on the conversion of ethanol to gasoline reaction were investigated. Nano crystalline ZSM-5 catalyst has high acidity. The micro crystalline ZSM-5 also exhibited comparable acidity with nano zeolites, but gasoline yields is not higher due to the absence of mesopores in the catalyst. Keywords: Fluid catalytic cracking, ZSM-5, Nano crystalline, and Mesoporous.
-----------------------------------------------------------------------***----------------------------------------------------------------------- 1. INTRODUCTION Y-zeolite is the main constituent of FCC catalyst. ZSM-5 is used as additive with Y-zeolite in FCC process. ZSM-5 belongs to is pentasile zeolite family, primarily used for octane boosting or LPG maximization. It is a stable zeolite with alumina content below 10% and pores in the range of 5.5Ǻ diameter. ZSM-5 is responsible for higher olefins yield. There are two types of ZSM-5 additives are used. First type has higher cracking activity and produces higher yields of light olefins with reduced gasoline yield. Second type has less cracking activity; it tends to isomerizes straight chain molecules to branched hydrocarbons [1, 3]. The pore structure of an FCC catalyst determines the accessibility of feed molecules to active sites. Reaction takes place on catalytically active sites. There are two types of acid sites. Bronsted acid site donates protons and the Lewis acid site accepts electrons. Both zeolite and matrix in FCC catalyst contain acid sites. The site where most of the reaction takes place is Bronsted acid site. Lewis acid sites are ore in matrix materials. Extra frame work aluminum also result in Lewis acid site.
Cracking reaction is composite of many reactions. ZSM-5 zeolites have been used as catalysts that can increase the selectivity of olefins due to their large surface areas, as well as -defined micropores, and multi-dimensional of pores with molecular dimensions [1, 2]. Rownaghi et al. report that indicate the HZSM-5 catalyst with large pore volumes but small pore sizes and pore mouths, external active centers of surface areas and high populations, gives good stability but high selectivity to aromatics [3]. FCC process used and ZSM- 5 and HZSM-5 catalyst due to its high surface area, porous structure defined as well an acidic nature of pores [4]. However, the HZSM-5 catalyst sustains from low selectivity near about C5-C10 alkanes, further regeneration is requiring carbon deposition and high yields of aromatics. Ethanol to ethylene are process by Catalytic dehydration, and ethanol to propylene by disproportionate and some of the studies reported ethanol to aromatics in this direction, where the properties of ZSM-5 zeolite in particularly its structure Si/Al. It’s related to the catalyst acidity, performance of a vital role in representative the nature of the product [5- 7]. The greatly commercial additives usually pre-deactivated. High- temperature (750-850 °C) steam pretreatment is usually applied to the deactivated of ZSM-5 eventful in the commercial unit Octane increase. As ZSM-5 Catalyst is added, the yield will be effected of the gasoline yield is less and C3–C4 unsaturated. So far as typical acid function zeolitic catalyst of HZSM-5, the changes of ZSM-5 acidity caused by different ratio of Si/Al , the observed changes in octane number and product yields by chemical dealumination, or steam deactivation. 2. PHYSICO CHEMICAL CHARACT ERISTICS OF ZSM-5 ADDITIVE
A literature survey and in this paper are that the physic chemical characteristics of all of the ZSM-5 samples are given

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in below Table-1. The ratio of Si/Al, nominal from chemical
analysis, represents the structure ratio of Si/Al for the fresh
samples ZM-1 to ZM-6. The ratio Si/Al, particle size, acid site
number, surface area are shown for steamed samples at
various temperatures such as ZM-7 to ZM-12, in Table-1[3-
10]
Table-1: Chemical characteristics of all ZSM-5 samples
Fig. -1: SEM images of samples Zeolites (1) (a) and nano-
Zeolites (2) (b) [3-6].
Fig.-2: Absorption spectra of sample Zeolites (1) in Ultra
Violate region before (a) and after (b) calcinations in air at
Tmax = 250 0C. The d–d transitions of Fe in the parent sample
Z (1) are depicted in the top[5-15].
ZSM-5are takes two samples Zeolite and ZA greatly of the
surface and volume conform to zeolitic micropore but in nano
sample a large share of surface, namely the super micropore as
well as mesopore. This is also evident from the surface area
and pore volume of samples given in Table 1, where sample
Nano Zeolite exhibits higher values of external surface area,
total surface area, micropore area as well as total pore volume
compared to the corresponding micro crystalline Zeolite and
ZA samples. The volume in pores of various diameters given
in the table further indicates the perking order of porosity in
Nano Zeolite. The phenomenon of decrease in crystal size of
ZSM-5 should not influence the acidic nature of the sample, as
acidity is the inherent property of zeolite that is governed by
the framework Si/Al composition of the zeolite [13]. But, our
earlier studies on zeolite synthesis could not result in the
production of same acidity having nano zeolite and Z samples.
A special attention is given in the present study to synthesize
the samples having the similar Si/Al and acidity patterns. The
TPD patterns of the nano zeolites and Z samples shown that
indeed reveal the comparable acidity patterns of these two
samples which are differ in crystal size but having same value
of Si/Al ratios. Thus, in the present study, the crystal size of
ZSM-5 is successfully brought down from micro level to the
nano level, without affecting its acidity. These samples
allowed us to elucidate the role of additional porosity of nano
zeolite on the ethanol to gasoline reaction.
3. SYNTHESIS OF NANO ZSM-5 SAMPLE
In this synthesis Tetra ethylorthosilicate was used as silica
source. Al was added slowly to pre cooled TPAOH solution
Sample
Pretreatment
Si/Al ratio
(C.A.)a
Surface area
(m2/g. SP BET)b
No. of acid site
(mmol of NH3/g of Zeolite, TPD)
Particle size
Total Weak Strong (μm, SEM)
ZM-1 Fresh 12.5 431 1.15 0.55 0.60 10-15
ZM-2 Fresh 25 476 1.05 0.51 0.54 0.5-2
ZM-3 Fresh 35 448 0.70 0.34 0.36 10-30
ZM-4 Fresh >1000 430 0.07 0.07 0 10-15
ZM-5 Fresh 28 437 0.89 0.42 0.47 0.5-2
ZM-6 Fresh 41 439 0.68 0.34 0.34 0.5-2
ZM-7 Steamed, 660 0C 26 393 0.21 0.14 0.07 0.5-2
ZM-8 Steamed, 730 0C 27 395 0.11 0.07 0.04 0.5-2
ZM-9 Steamed, 790 0C 27 396 0.09 0.07 0.2 0.5-2
ZM-10 Steamed, 790 0C 42 420 0.08 0.06 0.02 0.5-2
ZM-11 Steamed, 790 0C 36 425 0.08 0.08 0 10-30
ZM-12 Steamed, 790 0C >1000 432 0.02 0.02 0 10-15

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and TEOS was added drop wise. And adding after all the
constituent the solution was left to hydrolyze at room
temperature for 41 h. The gel obtained was heated at 800C to
evaporate water and ethanol formed during the hydrolysis to
obtain a concentrated gel. The gel concentration charged with
Teflon lines autoclave for hydro thermal synthesis of zeolites
and nano zeolite. This process performed was taken at
duration of 48 h and 1700C. Hydrothermal treatment, in this
paper case for steamed samples. summery, the NH3 TPD
curves of the fresh H-ZSM-5 samples consist are two peaks
with temperature between 170oC and 210 °C for the first peak
and temperature between 430°C and 440 °C for the second
peak. These correspond to weak and strong acid sites,
respectively. For the fresh samples, the strong acid sites are
ore in matrix materials and certain to - OH groups of skeletal
aluminum. Extra frame work aluminum also result in Lewis
acid site. The relatively strong Bronsted acidity of H-ZSM-5
in this figure-3 shown:
Fig.-3: X- ray diffraction patterns of zeolites[5].
Fig-4: SEM of zeolite samples for morphology and crystal
size A = Nano Zeolite catalyst, B = Zeolite catalyst, C = ZA
catalyst [3].
Recent literature survey that According Liang Zhao, Jinsen
Gao to gives report that the ZSM-5 zeolites are typical twin
hexahedrons with perfect crystalline surfaces and highly
ordered structures. However, the morphologies of the zeolites
were changed after alkali-treatment. In this paper Literature
survey that these changes were SiO2/Al2O3 ratio of 38
observed using SEM techniques for the zeolite sample, several
large pores appeared on the zeolite's surface. A portion of the
structure had also crash down, ZSM-5 sample with a
SiO2/Al2O3 ratio of 50 several uniformly sized small pores
prepared, and relatively complete crystal
Table-2:- Surface area and pore volume
Sample Si/Al
Ratio
BET surface
area
(m2/g)
Micropore (20Ǻ)
Area
(m2)
External surface
area
(m2)
Total pore volume
(cm3/g)
Micro pore
volume (cm3/g)
Z 30 346 256 90 0.176 0.102
NZ 30 461 323 138 0.385 0.132
ZA 100 330 245 92 0.172 0.100
Volume (cm3/g) in pores of various diameters (Ȧ)
<10A 10-20
Ǻ
20-100
Ǻ
100-200
Ǻ
200-
500 Ǻ
>500Ǻ
Z 0.126 0.013 0.0143 0.0039 0.0079 0.0105
NZ 0.163 0.026 0.0176 0.0097 0.0220 0.1464
ZA 0.125 0.013 0.0135 0.0036 0.0072 0.0096

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structure of the zeolite was potted. The silicon species had
been removed properly. As for the zeolite samples with
SiO2/Al2O3 ratios of 150 and 360, their morphologies were
minimally changed after alkali-treatment, indicating that only
a small quantity of silicon species had been removed from the
zeolite structure[3-10]. Morphological changes to the zeolites
for use the amount of silicon species lost was too minimal.
The dispersion of zeolite particles was also greatly improved
after alkali-treatment [16]. Research on the alkali-treatment of
zeolites with different SiO2/Al2O3 ratios under the same
treatment conditions has shown that SiO2/Al2O3 ratios exert
great influences on the structural properties of zeolites. The
surface area and total pore volume of mesopores increased
with decreasing SiO2/Al2O3 ratios. However, that lower
SiO2/Al2O3 ratios produce better results. The SiO2/Al2O3 ratio
also has an effect on the catalytic performance of zeolites.
Fig.-5: Tends in gasoline distribution A = at 450 0C, B = at
500 0C [1-16]
.
All the three samples are observed in a very low background
signal and sharp reflections indicating good crystalline.
Fig.-6: Effect of reaction temperature on HT reaction over
various catalysts A = NZ catalyst,B = Z catalyst[3-10].
The SEM of the samples are the presence of about 30 nm
range crystallites in Nano zeolite, against micro meter range
crystals in Zeolite and ZA samples. The Nano Zeolite sample
shows mesoporosity and this is evident in the
adsorption/desorption isotherm. The hysteresis loop of Nano
Zeolite appeared at high relative pressure and reflects inter-crystalline
voids in the packing of the smaller crystals [12-15].
Normal ZSM-5 samples are most of the surface and volume
corresponding to zeolitic micropore. But nano zeolite sample
is a large share of surface compared to the corresponding
micro crystalline Zeolite and ZA samples. The volume in
pores for various diameters is given in Table-2. The volume in
pores indicates the order of porosity in nanozeolite [14].
4. CONCLUSIONS
The total numbers of ZSM-5 acid sides with nano zeolite in
fluid catalytic cracking process increase production in increase
porosity, as measured by TPD of ammonia. The performance
of ZSM-5 as the FCC catalyst with a additives in gas oil
cracking that a direct and smooth correlates between the
product yield and the total acidity of the ZSM-5 and the
aluminum content. The temperature of hydrothermal
deactivation of fresh sample is straight forward in FCC
process. And this paper result that nano zeolite and HZSM-5
zeolites with varying acidity with FCC catalyst. Zeolites are
high acid density and mesoporosity in HZSM-5 based
catalysts for the effective production of high octane gasoline
and diffusion reactions as exhibited by nano zeolite.
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