ISOMERIZARION, ANKYLATION, POLYMERIZATION

HANOI UNIVERSITY OF SCIENCE AND TECHNOLOGY

ISOMERIZARION, ANKYLATION,
POLYMERIZATION
Student: Pham Van Quan - 20153044
Dinh Xuan Viet - 20154340

Table of Contents
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Preface

3

Chapter 1: PRODUCT BLENDING

5

Chapter 2: ISOMERIZATION

8

2.1 Introduction

8

2.2 Catalyst

8

2.2.1 Liquid catalyst

8

2.2.2 Solid catalyst

8

2.2.3 Bio-funtional catalyst

8

2.3 The mechanism

9

2.4 Process variables

10

2.5 Isomerization unit in Dung Quat refinery factory

11

Chapter 3: ANKYLATION

14

3.1 Introduction

14

3.2 Catalyst

14

3.3 The mechanism

14

3.4 Ankylation feedstock

17

3.5 Process variables

17

Chapter 4: POLYMERIZATION

20

4.1 Introduction

20

4.2 Catalyst and mechanism of polymerization to form gasoline

20

4.3 Catalyst and mechanism of polymerization to form diesel

21

4.4 Process variables

21

4.5 Polymerization feedstock

22

Conclusion

23

References

24

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Preface
Petroleum refining processes are the chemical enginering processes and other
facilities used in petroleum refineries (also referred to as oil refineries) to transform crude

oil into useful products such as liquefied petroleum gas (LPG), gasoline, kerosen, jet
fuel, diesel oil and fuel oils.
Petroleum refineries are very large industrial complexes that involve many different
processing units and auxiliary facilities such as utility units and storage tanks. Each refinery
has its own unique arrangement and combination of refining processes largely determined
by the refinery location, desired products and economic considerations.
Some modern petroleum refineries process as much as 800,000 to 900,000 barrels
(127,000 to 143,000 cubic meters)[1] per day of crude oil.
Processing units used in refineries[2]




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








Crude Oil Distillation unit: Distills the incoming crude oil into various fractions for
further processing in other units.
Vacuum distillationn unit: Further distills the residue oil from the bottom of the crude
oil distillation unit. The vacuum distillation is performed at a pressure well below
atmospheric pressure.
Naphtha hydrotreaterr unit: Uses hydrogen to desulfurize the naphtha fraction from the

crude oil distillation or other units within the refinery.
Catalytic reforming unit: Converts the desulfurized naphtha molecules into higheroctane molecules to produce reformate, which is a component of the end-product
gasoline or petrol.
Alkylation unit: Converts isobutane and butylenes into alkylate, which is a very highoctane component of the end-product gasoline or petrol.
Isomerization unit: Converts linear molecules such as normal pentane into higheroctane branched molecules for blending into the end-product gasoline. Also used to
convert linear normal butane into isobutane for use in the alkylation unit.
Distillate hydrotreater unit: Uses hydrogen to desulfurize some of the other distilled
fractions from the crude oil distillation unit (such as diesel oil).
Merox (mercaptan oxidizer) or similar units: Desulfurize LPG, kerosene or jet fuel by
oxidizing undesired mercaptans to organic disulfides.
Amine gas treater, Claus unit, and tail gas treatment for converting hydrogen
sulfide gas from the hydrotreaters into end-product elemental sulfur. The large majority
of the 64,000,000 metric tons of sulfur produced worldwide in 2005 was byproduct
sulfur from petroleum refining and natural gas processing plants.
Fluid catalytic cracking (FCC) unit: Upgrades the heavier, higher-boiling fractions
from the crude oil distillation by converting them into lighter and lower boiling, more
valuable products.
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
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

Hydrocracker unit: Uses hydrogen to upgrade heavier fractions from the crude oil
distillation and the vacuum distillation units into lighter, more valuable products.
Visbreaker unit upgrades heavy residual oils from the vacuum distillation unit by
thermally cracking them into lighter, more valuable reduced viscosity products.

Delayed coking and fluid coker units: Convert very heavy residual oils into endproduct petroleum coke as well as naphtha and diesel oil by-products.
The image[1] below is a schematic flow diagram of a typical petroleum refinery
that depicts the various refining processes and the flow of intermediate product streams
that occurs between the inlet crude oil feedstock and the final end-products.
The diagram depicts only one of the literally hundreds of different oil refinery
configurations. The diagram also does not include any of the usual refinery facilities
providing utilities such as steam, cooling water, and electric power as well as storage
tanks for crude oil feedstock and for intermediate products and end products.

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Chapter 1: PRODUCT BLENDING
Refining processes do not generally produce commercially usable products
directly, but rather semi-finished products which must be blended in order to meet
the specifications of the demanded products.
The main purpose of product blending is to find the best way of mixing
different intermediate products available from the refinery and some additives in
order to adjust the product specifications. For example, gasoline is produced by
blending a number of components that include alkylate, reformate, FCC gasoline
and an oxygenated additive such as methyl tertiary butyl ether (MTBE) to increase
the octane number. The final quality of the finished products is always checked by
laboratory tests before market distribution.
Gasolines are tested for octane number, Reid vapour pressure (RVP) and
volatility. Kerosenes are tested for flash point and volatility. Gas oils are tested for
diesel index, flash point, pour point and viscosity. Product qualities are predicted
through correlations that depend on the quantities and the properties of the blended
components.

In
this
chapter,
various mixing rules along with correlations are used to estimate the blend
properties such as specific gravity, RVP, viscosity, flash point, pour point,
cloud point and aniline point. The octane number for gasoline is correlated
with corrections based on aromatic and olefin content.
Blending property data for many refinery streams are given in Table below [1]

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Gasoline is typically a complex blend of many different refinery intermediate
streams. The most common refinery-produced components in the gasoline pool are:






FCC gasoline from the FCC unit - Good octane and vapor pressure, but often high
in sulfur and olefins
Reformate from the reformer - High octane and low vapor pressure, but high in
aromatics
Alkylate from the alkylation unit - Good octane and vapor pressure with no
aromatics, olefins, or sulfur
Isomerate from the isomerization unit - Moderately good octane, low aromatics,
and low sulfur, but high vapor pressure

Light straight run naphtha directly from the distillation tower - Low octane and
high vapor pressure

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In this essay we will discuss about three processes: isomerization, ankylation
and polymerization.

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Chapter 2: ISOMERIZATION
2.1 Introduction
Isomerization is the process in which light straight chain paraffins of low octane
numbers (C6, C5 and C4) are transformed with proper catalyst into branched chains
with the same carbon number and high octane numbers.
Specially, iso-butane is also a product of this process. This is an important
product because we can produce MTBE .
2.2 Catalyst
Catalyst for isomerization is acid catalyst and it can be dividied into three main
goups:
2.2.1 Liquid catalyst
We used to use Lewis catalyst like AlCl3, be activated by HCl. Nowsday, AlBr3
and AlBr3 + SbCl3 combination are being used. The advantage of this new catalyst
is that it is highly active, at 93oC, it almost converts n-paraffin to i-paraffin.

However, the disadvantages are that it quickly lose it’s activity, low selectivity and
easy to decomposition.
2.2.2 Solid catalyst
Some kind of solid catalyst:
BeO: Converts xyclohexene to metylxyclopentene at 450oC.
Cr2O3: Converts hexadiene-1,5 to hexadien-2,4 at 225-250oC
ThO2: Isomerize Olefin at 395-440oC
2.2.3 Bi-funtional catalyst
There are two types of isomerization catalysts: the standard Pt/chlorinated
alumina with high chlorine content, which is considered quite active, and
the Pt/zeolite catalyst.
+ Standard Isomerization Catalyst
This bi-functional nature catalyst consists of highly chlorinated alumina (8–15
w% Cl2) responsible for the acidic function of the catalyst. Platinum is deposited
(0.3–0.5 wt%) on the alumina matrix. Platinum in the presence of hydrogen will
prevent coke deposition, thus ensuring high catalyst activity. The reaction is

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performed at low temperature at about 130 C (266 F) to improve the equilibrium
yield and to lower chlorine elution.
The standard isomerization catalyst is sensitive to impurities such as water and
sulphur traces which will poison the catalyst and lower its activity. For this reason,
the feed must be hydrotreated before isomerization. Furthermore, carbon
tetrachloride must be injected into the feed to activate the catalyst. The pressure of
the hydrogen in the reactor will result in the elution of chlorine from the catalyst as
hydrogen chloride. For all these reasons, the zeolite catalyst, which is resistant to

impurities, was developed.
+ Zeolite Catalyst
Zeolites are crystallized silico-aluminates that are used to give an acidic
function to the catalyst. Metallic particles of platinum are impregnated on
the surface of zeolites and act as hydrogen transfer centres. The zeolite
catalyst can resist impurities and does not require feed pretreatment, but it
does have lower activity and thus the reaction must be performed at a higher
temperature of 250 C (482 F). A comparison of the operating conditions
for the alumina and zeolite processes is shown in table below.

2.3 The mechanisms
Isomerization process in refining industry can be operated in both liquid and
vapor phase. However, the process in liquid phase with Friedel-Crafts catalyst
(AlCl3) at 80-100oC rarely is used. The process in vapot phase with solid catalyst
and bi-funtional catalyst at high temperature is much popular. Because of that, we’ll
consider the mechanism in this case.

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Isomerization by dual-functional catalysts is thought to operate through an
olefin intermediate. The formation of this intermediate is catalyzed by the metallic
component, which is assumed for this discussion to be platinum:

This reaction is, of course, reversible, and because these catalysts are used
under substantial hydrogen pressure, the equilibrium is far to the left. However, the
acid function (H+A ) of the catalyst consumes the olefin to form a carbonium ion
and thus permits more olefin to form despite the unfavorable equilibrium:

The usual rearrangement ensues:

The isoolefin is then formed

The isoparaffin is finally created by hydrogenation

2.4 Process variables
The degree of isomerization that occurs in the Butamer process is influenced
by the following process variables.

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Reactor Temperature
The reactor temperature is the main process control for the Butamer unit. An
increase in temperature increases the iC4 content of the product toward its
equilibrium value and slightly increases cracking of the feed to propane and lighter.
Liquid Hourly Space Velocity (LHSV)
An increase in LHSV tends to decrease the iC4 in the product at a constant
temperature when other conditions remain the same.
Hydrogen-to-Hydrocarbon Ratio (H2/HC)
The conversion of nC4 to iC4 is increased by reducing the H2/HC ratio;
however, the hydrogen effect is slight over the usual operating range. Significant
capital savings do result when the H2/HC ratio is low enough to eliminate the
recycle hydrogen compressor and product separator. UOP’s standard (and patented)
design calls for a H2/HC ratio of 0.03 molar and allows operation with once-through
hydrogen.

Pressure
Pressure has no effect on equilibrium and only a minor influence on the
conversion of normal butane to isobutane.
2.5 Isomerization unit in Dung Quat refinery factory
In Dung Quat refinery factory, UOP technology is being used.
The overall process-flow scheme for the Butamer system depends on the
specific application. Feed streams of about 30 percent or more iC4 are
advantageously enriched in C4 by charging the total feed to a deisobutanizer column.
Feeds that are already rich in nC4 are charged directly to the reactor section. A
simplified flow scheme is depicted blow:

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An nC4 concentrate, recovered as a deisobutanizer sidecut, is directed to the
reactor section, where it is combined with makeup hydrogen, heated, and charged
to the Butamer reactor. Reactor effluent is cooled and flows to a stabilizer
for removal of the small amount of light gas coproduct. Neither a recycle gas
compressor nor a product separator is required because only a slight excess of
hydrogen is used over that required to support the conversion reaction. Stabilizer
bottoms is returned to the deisobutanizer, where any iC4 present in the total feed or
produced in the isomerization reactor is recovered overhead.
Unconverted nC4 is recycled to the reactor section by way of the
deisobutanizer sidecut. The system is purged of pentane and heavier hydrocarbons,
which may be present in the feed, by withdrawing a small drag stream from the
deisobutanizer bottoms.
The Butamer process may also be incorporated into the design of new
alkylation plants or into the operation of existing alkylation units. For this type of

application, the inherent capabilities of the iC4 fractionation facilities in the
alkylation unit may be used to prepare a suitable Butamer feed with a high nC4
content and to recover unconverted nC4 for recycle. The major historical use of the
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Butamer process has been the production of iC4 for the conversion of C 3 and C4
refinery olefins to high octane alkylate. A more recent demand for Ic 4 has
developed in conjunction with the manufacture of methyl tertiary butyl ether
(MTBE), which is a high-octane gasoline blending component particularly useful in
reformulated gasolines. Isobutane is dehydrogenated to isobutylene and then made
into MTBE. Unconverted butenes and n-C4 are recycled as appropriate to achieve
essentially 100 percent conversion of the feed butanes to MTBE.

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Chapter 3: ANKYLATION
3.1 Introduction
Ankylation is the process add ankyl group to organic molecule, particularly
include two reactions:
-

-

Ankylate ankane to produce high octane gasoline. This is the main purpose of

refining technology. From vapor component like (C4H10, C4H8), we can produce
high octane gasoline (i-C8H18).
Ankylate aromatic. This reaction can be used to produce alkylbenzene which is
raw material for synthesis petroleum.

Although alkylation can take place at high temperatures and pressures without
catalysts, the only processes of commercial importance involve low-temperature
alkylation conducted in the presence of either sulfuric or hydrofluoric acid. The
reactions occurring in both processes are complex, and the product has a rather wide
boiling range. By proper choice of operating conditions, most of the product can be
made to fall within the gasoline boiling range, with motor octane numbers from 88
to 94 and research octane numbers from 94 to 99.
3.2 Catalyst
The catalyst in akylation process includes some kind below:
+ H2SO4, HF catalyst
If we use this catalyst, we’ll need to pay attention to the ratio olefin/iso-butane
to minimize olefin, because olefin solute in H2SO4 and make side reactions
easily occur. And iso-butane harly solute in H2SO4, HF so we need to agitate
strongly.
+ AlCl3 + HCl catalyst
This catalyst allows reaction occurs at low temperature (-15 to 25 OC), easy to
produce and very few side products.
+ BF3 + HF
The reaction on this catalyst can be operated at high temperature (40 to 45 OC),
but many side products.
+ Zeolit with high ratio Si/Al like: zeolite USY, zeolite β
3.3 The mechanism
Alkylate alkane is the most popular process to product ankylat. In some kinds
of alkanes there is iso-alkane which participates.

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For high selectivity, we choose the ratio between i-prafin and olefin is 5:1 or
higher, the temperature is adjusted from -15 to 45 oC and must strongly agitate.
The principal reactions that occur in alkylation are the combinations of olefins
with isoparaffins as follows:

Another significant reaction in propylene alkylation is the combination of
propylene with isobutane to form propane plus isobutylene. The isobutylene then
reacts with more isobutane to form 2,2,4-trimethylpentane (isooctane). The first step
involving the formation of propane is referred to as a hydrogen transfer reaction.
Research on catalyst modifiers is being conducted to promote this step because it
produces a higher octane alkylate than is obtained by formation of isoheptanes.
A number of theories have been advanced to explain the mechanisms of
catalytic alkylation, and these are discussed in detail by Gruse and Stevens [2]. The
one most widely accepted involves the formation of carbonium ions by transfer of
protons from the acid catalyst to olefin molecules, followed by combination with
isobutene to produce tertiary-butyl cations. The tertiary-butyl ion reacts with 2butene to form C8 carbonium ions capable of reacting with isobutane to form C8
paraffins and tertiary-butyl ions. These tertiary-butyl ions then react with other 2butene molecules to continue the chain. Figure 11.1 illustrates the above sequence
using sulfuric acid,2-butene, and isobutane as the example reaction. The alkylation
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reaction is highly exothermic, with the liberation of 124,000 to 140,000 Btu per
barrel (929 MJ/m3) of isobutane reacting .

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3.4 Ankylation feedstocks
Olefins and isobutane are used as alkylation unit feedstocks. The chief sources
of olefins are catalytic cracking and coking operations. Butenes and propene are the
most common olefins used, but pentenes (amylenes) are included in some cases.
Some refineries include pentenes in alkylation unit feed to lower the FCC gasoline
vapor pressure and reduce the bromine number in the final gasoline blend. The
alkylation of pentenes is also considered as a way to reduce the C5 olefin content
of final gasoline blends and reduce its effects on ozone production and visual
pollution in the atmosphere. Olefins can be produced by the dehydrogenation of
paraffins, and isobutane is cracked commercially to provide alkylation unit feed.
Hydrocrackers and catalytic crackers produce a great deal of the isobutane used in
alkylation, but it is also obtained from catalytic reformers, crude distillation, and
natural gas processing. In some cases, normal butane is isomerized to produce
additional isobutane for alkylation unit feed.
3.5 Process variables
The most important process variables are reaction temperature, acid strength,
isobutene concentration, and olefin space velocity. Changes in these variables affect
both product quality and yield.
Reaction temperature has a greater effect in sulfuric acid processes than in those
using hydrofluoric acid. Low temperatures mean higher quality, and the effect of
changing the sulfuric acid reactor temperature from 25 to 55°F (4 to 13°C) is to
decrease product octane from one to three numbers depending upon the efficiency
of mixing in the reactor. In hydrofluoric acid alkylation, increasing the reactor
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temperature from 60 to 125°F (16 to 52°C), degrades the alkylate quality about three
octane numbers .
In sulfuric acid alkylation, low temperatures cause the acid viscosity to become
so great that good mixing of the reactants and subsequent separation of the emulsion
is difficult. At temperatures above 70°F (21°C), polymerization of the olefins
becomes significant and yields are decreased. For these reasons, the normal sulfuric
acid reactor temperature is from 40 to 50°F (5 to 10°C) with a maximum of 70°F
(21°C) and a minimum of 30°F (1°C).
For hydrofluoric acid alkylation, temperature is less significant and reactor
temperatures are usually in the range of 70 to 100°F (21 to 38°C).
Acid strength has varying effects on alkylate quality depending on the effectiveness
of reactor mixing and the water content of the acid. In sulfuric acid alkylation,
the best quality and highest yields are obtained with acid strengths of 93 to 95% by
weight of acid, 1 to 2% water, and the remainder hydrocarbon diluents. The water
concentration in the acid lowers its catalytic activity about three to five times as
much as hydrocarbon diluents, thus an 88% acid containing 5% water is a much
less effective catalyst than the same strength acid containing 2% water. The poorer
the mixing in a reactor, the higher the acid strength necessary to keep acid dilution
down [6]. Increasing acid strength from 89 to 93% by weight increases alkylate
quality by one to two octane numbers.
In hydrofluoric acid alkylation, the highest octane number alkylate is attained
in the 86 to 90% by weight acidity range. Commercial operations usually have acid
concentrations between 83 and 92% hydrofluoric acid and contain less than 1%
water.
Isobutane concentration is generally expressed in terms of isobutane/olefin
ratio. High isobutane/olefin ratios increase octane number and yield, and reduce side

reactions and acid consumption. In industrial practice, the isobutane/olefin ratio on
reactor charge varies from 5:1 to 15:1. In reactors employing internal circulation to
augment the reactor feed ratio, internal ratios from 100:1 to 1000:1 are realized.
Olefin space velocity is defined as the volume of olefin charged per hour divided
by the volume of acid in the reactor. Lowering the olefin space velocity reduces the
amount of high-boiling hydrocarbons produced, increases the product octane, and
lowers acid consumption. Olefin space velocity is one way of expressing reaction
time; another is by using contact time. Contact time is defined as the residence time
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of the fresh feed and externally recycled isobutane in the reactor. Contact time for
hydrofluoric acid alkylation ranges from 5 to 25 min and for sulfuric acid alkylation
from 5 to 40 min.

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Chapter 4: POLYMERIZATION
4.1 Introduction
The polymerization process combines propenes and butenes to produce higher
olefins with high-octane numbers (97 RON and 83 MON) for the gasoline pool. The
polymerization process was used extensively in the 1930s and 1940s, but it was
replaced to a large extent by the alkylation process after World War II. It has gained
favor after phasing out the addition of tetraethyl lead (TEL) to gasoline, and the
demand for unleaded gasoline has increased.

Otherwise, we can polymerize etilene to produce diesel.
4.2 Catalyst and mechanism of polymerization to form gasoline.
Like other process to form gasoline or component for bleding gasonline,
polymerization flows carbanion reaction, so catalyst is acids. H3PO4 and H3PO4 /
carrier is usually used. Nowsdays, in industry we use solid catalyst like Al2O3,
aluminosilicat, zeolite. The reaction occurs at 150 to 200oC and 50 to 80 at with two
step:

Other polymers are formed. A compound of many kind polymers like that will
help gasoline have better quality.
The strength of acid is important factor, so elements which affect the strength
of acid need to be cared.
If water quantity is beyond the boundary will draw lower strength of acid.
The presence of base like NH3 will poison catalyst.
The presence of Oxigen and butadiene in material also reduce the activity of
catalyst, because is is the reason for deposition of other compound on catalyst.
Gasoline from this process is polymerat with octane number approximately
97-RON and 83-MON.
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4.3 Catalyst and mechanism of polymerization to form diesel.
Nowsdays, finding new feedstock to synthesis diesel is a crucial demand. A
solution for this problem is oligomerization of ethylene – product from thermal
cracking.
The product of oligomerization is C10+ ankene and after hydrogenation of
ankene we have ankana corresponding which is precious component for fuel.
The reaction :

H2
10C2H4  C20H40  C20H42

The polymer we have after this process have high xetane number because of
it’s straight chain.
The catalyst for this process is Ni/Al2O3,SiO2 or zeolite. In fact, if catalyst is
Ni/zeolite X, the product is C12. If catalyst is Ni/zeolite Y the product is C12 to C35
and easily separate through capillary of zeolite.
This process is operated at high temperature 120 to 300 oC and about 35 bar.
4.4 Process variables
Tempreture
High temperature will increase speed of reaction, resultly increase the
covertion of reaction.
However, the increasation of temperature will deposit on catalyst and reduce
the activity and residence time of catalyst.
In industry the temperature is controlled from 170 to 225 oC.
Pressure
When process is operated in vapor phase, pressure strongly influences to time
reaction.
At high pressure, it will suspended phase and push polymers out of catalyst
and prevent the loss of catalyst activity. And if the pressure is too low, polymer will
deposit on the face of catalyst and reduced catalyst activity. In reality, this process
is operated at 25-28 at.
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The activity of catalyst

4.5 Polymerization feedstock
Propylene and butylene are used as feedstock unit for polymerization to
produce high octane number gasoline.
If produce diesel we use ethylene.
Material is removed S, N, O before polymerization to avoid empoison
catalyst and decrease the quality of product.

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Conclusion
Product blending plays a key role in preparing the refinery products for the
market to satisfy the product specifications and environmental regulations. The
objective of product blending is to assign all available blend components to satisfy
the product demand and specifications to minimize cost and maximize overall profit
.Almost all refinery products are blended for the optimal use of all of the
intermediate product streams for the most efficient and profitable conversion of
In sipte of the shortage of knowledge, we discussed three common processes
to product base component for product blending. In searching process we have
learned a lot of useful information in refinery industry.

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References
1. James H.Gary, Glenn E.Handwerk, Mark J.Kaiser, Petroleum Refining

Technology and economics, 2004
2. Mohamed Fahim, Taher Al-Sahhaf, Amal Elkilani, Fundamentals of Petroleum
Refining, 2009

3. Robert A.Meyers, Handbook of Petroleum Refining Processes, 2003
4. GS.TS. Đinh Thị Ngọ, PGS.TS Nguyễn Khánh Diệu Hồng, Hóa học dầu mỏ
và khí, 2017

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