ISOMERIZARION, ANKYLATION, POLYMERIZATION

HANOI UNIVERSITY OF SCIENCE AND TECHNOLOGY ISOMERIZARION, ANKYLATION, POLYMERIZATION Student: Pham Van Quan - 20153044 Dinh Xuan Viet - 20154340 Table of Contents 1|Page Preface Chapter 1: PRODUCT BLENDING Chapter 2: ISOMERIZATION 2.1 Introduction 2.2 Catalyst 2.2.1 Liquid 2.2.2 Solid c 2.2.3 Bio-fu 2.3 The mechanism 2.4 Process variables 2.5 Isomerization unit in Dung Quat refinery factory Chapter 3: ANKYLATION 3.1 Introduction 3.2 Catalyst 3.3 The mechanism 3.4 Ankylation 3.5 Process vari Chapter 4: POLYMERIZATION 4.1 Introduction 4.2 Catalyst and 4.3 Catalyst an 4.4 Process vari 4.5 Polymerizat Conclusion References 2|Page 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]  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 3|Page  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 4|Page Chapter 1: PRODUCT BLENDING Refining processes 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] 5|Page 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 6|Page In this essay we will discuss about three processes: isomerization, ankylation and polymerization 7|Page 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 AlCl 3, be activated by HCl Nowsday, AlBr3 and AlBr3 + SbCl3 combination are being used The advantage of this new o catalyst is that it is highly active, at 93 C, it almost converts n-paraffin to iparaffin 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: o BeO: Converts xyclohexene to metylxyclopentene at 450 C o Cr2O3: Converts hexadiene-1,5 to hexadien-2,4 at 225-250 C o ThO2: Isomerize Olefin at 395-440 C 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 8|Page 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 o (AlCl3) at 80-100 C 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 9|Page 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 10 | P a g e 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 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: 11 | P a g e 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 12 | P a g e Butamer process has been the production of iC4 for the conversion of C and C4 refinery olefins to high octane alkylate A more recent demand for Ic 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-C are recycled as appropriate to achieve essentially 100 percent conversion of the feed butanes to MTBE 13 | P a g e 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 (C 4H10, 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 H 2SO4 and make side reactions easily occur And iso-butane harly solute in H 2SO4, HF so we need to agitate strongly + AlCl3 + HCl catalyst O This catalyst allows reaction occurs at low temperature (-15 to 25 C), easy to produce and very few side products +BF3+HF O The reaction on this catalyst can be operated at high temperature (40 to 45 C), 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 14 | P a g e For high selectivity, we choose the ratio between i-prafin and olefin is 5:1 or o higher, the temperature is adjusted from -15 to 45 C 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 2-butene to form C8 carbonium ions capable of reacting with isobutane to form C paraffins and tertiary-butyl ions These tertiary-butyl ions then react with other 2-butene 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 15 | P a g e reaction is highly exothermic, with the liberation of 124,000 to 140,000 Btu per barrel (929 MJ/m3) of isobutane reacting 16 | P a g e 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 17 | P a g e 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, 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 18 | P a g e of the fresh feed and externally recycled isobutane in the reactor Contact time for hydrofluoric acid alkylation ranges from to 25 and for sulfuric acid alkylation from to 40 19 | P a g e 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 H 3PO4 and H3PO4 / carrier is usually used Nowsdays, in industry we use solid catalyst like Al 2O3, o aluminosilicat, zeolite The reaction occurs at 150 to 200 C 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 20 | P a g e 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 : 10C2H4 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 C 12 to C35 and easily separate through capillary of zeolite o This process is operated at high temperature 120 to 300 C 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 o In industry the temperature is controlled from 170 to 225 C 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 21 | P a g e 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 22 | P a g e 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 23 | P a g e References James H.Gary, Glenn E.Handwerk, Mark J.Kaiser, Petroleum Refining Technology and economics, 2004 Mohamed Fahim, Taher Al-Sahhaf, Amal Elkilani, Fundamentals of Petroleum Refining, 2009 Robert A.Meyers, Handbook of Petroleum Refining Processes, 2003 GS.TS Đinh Thị Ngọ, PGS.TS Nguyễn Khánh Diệu Hồng, Hóa học dầu mỏ khí, 2017 24 | P a g e ... 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. .. 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... operated at 25-28 at 21 | P a g e 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