Optimal Process Flow

OPTIMAL PROCESS FLOW

PRODUCTS : OPTIMAL OLEFINS (MALAYSIA) SDN BHD Products

Capacity (kTa)

Market Applications

Ethylene

600

Feedstock for Olefins Derivatives, Polyethylene and Ethylene Oxide Glycol

Propylene

95

Butanol and Derivatives

Pyrolysis Gasoline

35

Aromatics

OPTIMAL GLYCOLS (MALAYSIA) SDN BHD Products

Capacity (kTa)

Market Applications

Mono-Ethylene Glycol

365

Resins for Fibers and PET containers/bottles, Antifreeze as well as Electronic applications

Di-Ethylene Glycol

20

Unsaturated Polyester Resins (used for fiberglass) and Brake Fluid Formulation

Re-Distilled Ethylene

140

Derivatives

Oxide

OPTIMAL CHEMICALS (MALAYSIA) SDN BHD Products

Capacity (kTa)

Market Applications

A. Performance Chemicals Ethanolamines

75

Personal Care Products, Electronics, Taurine and Glyphosate

Gas Treating Fluids

10

Oil & Gas Processing

25

Detergents, Household, Industrial &

(UCARSOL™ Solvents) Nonyl Phenol Ethoxylates

Institutional Cleaners and Emulsion

(TERGITOL™

Polymerization

surfactants) Octyl Phenol Ethoxylates

5

Specialty Surfactants, Paints and Emulsion Polymerization

(TRITON™ surfactants) Polyalkylene Glycol

10

(UCON™ Fluids)

Metal Quenchants, Hydraulic Fluids, Compressor Lubricants and Metalworking Fluids

Polyethylene Glycol

15

(CARBOWAX™)

Pharmaceuticals, Cosmetics and Personal Care Products

B. Chemicals Brake Fluids DOT-3

3

Automotive Brake Fluids

140

Butyl Derivatives for Solvents, Paints &

(UCON ™ E-360) Butanol / Iso butanol

Inks, Coatings and Adhesives Butyl Acetate

50

Paint, Printing Ink, Leather and Coating markets

Butyl Glycol Ethers (CELLOSOLVE ™ &

60

Coatings, Hard Surface Cleaners and Electronics

CARBITOL™ Butyl Glycol Ethers)

Production ETHYLENE Ethylene is produced in the petrochemical industry by steam cracking. In this process, gaseous or light liquid hydrocarbons are heated to 750–950 °C, inducing numerous free radical reactions followed by immediate quench to freeze the reactions. This process converts large hydrocarbons into smaller ones and introduces unsaturation. Ethylene is separated from the resulting complex mixture by repeated compression and distillation. In a related process used in oil refineries, high molecular weight hydrocarbons are cracked

over zeolite catalysts. Heavier feedstocks, such as naphtha and gas oils require at least two "quench towers" downstream of the cracking furnaces to recirculate pyrolysisderived gasoline and process water. When cracking a mixture of ethane and propane, only one water quench tower is required.[9] The areas of an ethylene plant are: 1. 2. 3. 4. 5. 6. 7. 8. 9.

steam cracking furnaces; primary and secondary heat recovery with quench; a dilution steam recycle system between the furnaces and the quench system; primary compression of the cracked gas (3 stages of compression); hydrogen sulfide and carbon dioxide removal (acid gas removal); secondary compression (1 or 2 stages); drying of the cracked gas; cryogenic treatment; all of the cold cracked gas stream goes to the demethanizer tower. The overhead stream from the demethanizer tower consists of all the hydrogen and methane that was in the cracked gas stream. Different methods of cryogenically treating this overhead stream results in the separation of the hydrogen and the methane. This usually involves liquid methane at a temperature around −250 °F (−156.7 °C). Complete recovery of all the methane is critical to the economical operation of an ethylene plant. Often one or two Turboexpanders are used for Methane recovery from the demethanizer overhead stream. 10. the bottom stream from the demethanizer tower goes to the deethanizer tower. The overhead stream from the deethanizer tower consists of all the C2,'s that were in the cracked gas stream. The C2's then go to a C2 splitter. The product ethylene is taken from the overhead of the tower and the ethane coming from the bottom of the splitter is recycled to the furnaces to be cracked again; 11. the bottom stream from the deethanizer tower goes to the depropanizer tower. The overhead stream from the depropanizer tower consists of all the C3's that were in the cracked gas stream. Prior to sending the C3's to the C3 splitter this stream is hydrogenated in order to react out the methylacetylene and propadiene. Then this stream is sent to the C3 splitter. The overhead stream from the C3 splitter is product propylene and the bottom stream from the C3 splitter is propane which can be sent back to the furnaces for cracking or used as fuel. 12. The bottom stream from the depropanizer tower is fed to the debutanizer tower. The overhead stream from the debutanizer is all of the C4's that was in the cracked gas stream. The bottom stream from the debutanizer consists of everything in the cracked gas stream that is C5 or heavier. This could be called a light pyrolysis gasoline.[9] Since the production of ethylene is energy intensive, much effort has been dedicated recovering heat from the gas leaving the furnaces. Most of the energy recovered from the cracked gas is used to make high pressure (1200 psig) steam. This steam is in turn used to drive the turbines for compressing cracked gas, the propylene refrigeration compressor, and the ethylene refrigeration compressor. An ethylene plant, once running, does not need

to import any steam to drive its steam turbines. A typical world scale ethylene plant (about 1.5 billion pounds of ethylene per year) uses a 45,000 horsepower (34,000 kW) cracked gas compressor, a 30,000 horsepower (22,000 kW) propylene compressor, and a 15,000 horsepower (11,000 kW) ethylene compressor. When starting an ethylene plant it is important to start the cooling systems in the proper order. The cooling systems consist of Cooling Tower Water (CTW); propylene refrigeration with four or five different levels or stages. Each level corresponds to a particular pressure and temperature; and three or four stages of ethylene regfrigeration. The CTW must be started first because the propylene system needs it to condense propylene and the ethylene refrigeration systems needs it to desuperheat high pressure ethylene. The propylene system must start next because the ethylene system needs high pressure propylene for desuperheating the high pressure ethylene stage and the low pressure propylene stage for condensing the high pressure ethylene. While the ethylene plant is running, the plant can continue to run for a time if the ethylene refrigeration compressor shuts down. However, if the propylene compressor shuts down the whole plant must be shut down immediately

ETHYLENE GLYCOL Ethylene glycol is produced from ethylene, via the intermediate ethylene oxide. Ethylene oxide reacts with water to produce ethylene glycol according to the chemical equation C2H4O + H2O → HOCH2CH2OH This reaction can be catalyzed by either acids or bases, or can occur at neutral pH under elevated temperatures. The highest yields of ethylene glycol occur at acidic or neutral pH with a large excess of water. Under these conditions, ethylene glycol yields of 90% can be achieved. The major byproducts are the ethylene glycol oligomers diethylene glycol, triethylene glycol, and tetraethylene glycol. This molecule has been observed in space.[2] EtHYLENE OXIDE Ethylene oxide is produced by oxidation of ethylene with oxygen at circa 250 °C over a catalyst comprising metallic silver supported on alumina[4]. Typically, promoters such as chloride are also included. Pressures used are in the region of 1-2MPa. The overall chemical equation is: 7 H2C=CH2 + 6 O2 → 6 C2H4O + 2 CO2 + 2 H2O The mechanism involves binding of ethylene and oxygen (O2) to the catalyst. Per molecule of oxygen, one atom is inserted into ethylene affording ethylene oxide. The

other oxygen atom remains strongly absorbed on the catalyst and must be burnt off before the next productive catalytic cycle can take place. This consumes one extra molecule of ethylene for every six molecules of ethylene oxide produced. The extra molecule of ethylene undergoes combustion to carbon dioxide and water presumably via acetaldehyde: 6 H2C=CH2 + 6 O2 → 6 C2H4O + 6 O (bound to catalyst) O (bound to catalyst) + H2C=CH2 → CH3CHO (bound to catalyst) CH3CHO (bound to catalyst) + 5 O (bound to catalyst) → 2 CO2 + 2 H2O Hence, the yield of the process is limited to 6/7 (85.7%). The yield under industrial conditions stands at 83-84%. The high yield is due to extensive research by big producers, driven by enormous cost savings potential: With approximately 15 million tonnes of ethylene oxide being produced annually[1] every percent of yield increase saves 95,500 tonnes of ethylene worth $67 million. Ethylene oxide can be produced in the laboratory by the action of an alkali hydroxide on ethylene chlorohydrin.[5] HOH2CCH2Cl + NaOH → C2H4O + NaCl + H2O PROPENE Propene is the raw material for the production of polypropylene, a versatile polymer widely used in several different grades for packaging. Most propene is polymerized using Ziegler-Natta catalysis, which produces isotactic polypropylene. Along with benzene, propene is a key feedstock in the cumene process, a reaction carried out on industrial scales to produce acetone and phenol. Propene is also used during the production of many other chemical products such as isopropanol (propan-2-ol), acrylonitrile, and propylene oxide (epoxypropane).[1] Oxosynthesis reactions The oxosynthesis process (also called hydroformylation) involves the reaction of syngas (CO and H2) with olefinic hydrocarbons to form an isomeric mixture of normal- and isoaldehydes. The basic oxosynthesis reaction is highly exothermic and is thermodynamically favorable at ambient pressures and low temperatures (Whyman, 1985). The reaction proceeds only in the presence of homogeneous metal carbonyl catalysts. One of the more important factors in oxosynthesis is the normal to branched isomeric ratio (n/i). The normal (straight chain) isomer is the desired product, as shown in the equation below. RCH=CH2 + CO + H2 → RCH2CH2CHO + R(CH3)CHCHO (normal) (branched)

Usually a 1:1 H2 to CO syngas mixture is required for oxosynthesis. The overall reaction rate has first-order dependence on the hydrogen partial pressure and inverse-first order dependence on CO partial pressure making the reaction rate essentially independent of total pressure (Pruett, 1979). Higher CO partial pressures are usually required, however, to maintain the stability of the metal carbonyl catalysts. The reaction is also first order in olefin and metal concentration at the higher CO partial pressures. The first step in the oxosynthesis process is to remove the CO from the organometallic catalyst making the catalyst deficient in electrons. The double bond in the olefin attaches to the metal atom at this site (the M-H bond) resulting in an alkyl metal carbonyl complex. A CO molecule is then inserted into the complex at the C-M bond followed by insertion of hydrogen at the same point to yield an aldehyde. The general reaction mechanism is shown in figure 2 (Whyman, 1985).

Oxosynthesis catalysts Oxosynthesis generally uses soluble cobalt or rhodium catalysts. Three complimentary catalytic hydroformylation processes have been developed and commercialized. The choice of catalyst depends of the particular starting olefin or desired product.

The first hydroformylation catalysts were cobalt carbonyls, specifically, HCo(CO)4 in equilibrium with Co2(CO)8. Cobalt metals and most cobalt salts will form cobalt carbonyl under hydroformylation conditions. The cobalt catalyzes both double bond isomerization and oxosynthesis. Undesired competing side reactions such as the direct hydrogenation of the starting olefin and the condensation of product aldehydes to high boiling products are generally avoided in the Co-catalyzed process. For cobalt carbonyl catalysts, a normal to branched isomeric ratio (n/i) of 4:1 can be achieved with catalyst concentrations of 0.1-1% metal/olefin at 200-300 atm and 110-200°C with a 1:1 H2/CO ratio. Lower process temperatures and higher CO partial pressures favor the formation of the straight chain isomer, however, the overall conversion efficiency decreases. Cobalt carbonyl catalysts are not very stable at high temperatures and tend to deposit on reactor walls decreasing their activity and reducing recovery of the catalyst. Phosphine-modified cobalt catalysts were developed by Shell Oil Company in the 1960’s, and are used for the production of higher (detergent range) alcohols. The addition of a phosphine ligand to Co results in a trialkylphosphine-substituted cobalt carbonyl catalyst [HCo(CO)3P(n-C4H9)3]. It shows high selectivity for straight-chain aldehydes (n/i = 7:1) and has improved thermal stability compared to the unsubstituted cobalt catalysts. The improved thermal stability allows for lower process pressures but higher process temperatures (50-100 atm and 160-200°C with H2:CO = 1). Even though this catalyst has improved thermal stability, it has a lower hydroformylation activity than cobalt carbonyl catalysts, hence the higher reaction temperature. The higher temperatures

also increase the competing olefin hydrogenation reaction. Shell has optimized the process to produce detergent range alcohols (C11-C14) in a single step by capitalizing on the conversion of terminal olefins to alcohols by hydrogenating the aldehyde hydroformylation products. A high n/i ratio results from increased isomerization rates concurrently with hydroformylation. Phosphine-modified rhodium catalysts are composed of triphenylphosphine rhodium (HRh(CO)(PPh3)3). These catalysts function under significantly lower operating pressures and temperatures (7-25 atm; 60-120°C; n/i ratio of 8-12:1) and demonstrate increased selectivity to linear products compared to other oxosynthesis catalysts. Rhbased catalysts are used mainly for the hydroformylation of lower olefins (e.g., propylene to butyraldehyde) and are typically not used for higher olefins because of their thermal instability at the high distillation temperatures required to separate the product and the catalyst. Rh-based hydroformylation catalysts are also expensive relative to other catalysts, and the availability of rhodium is low. The high cost of rhodium, however, is offset by lower equipment costs, increased activity, and higher selectivity and efficiency. The development of water-soluble Rh-based catalysts avoids some of these issues. Rhone-Poulenc commercialized an oxo process based on a water-soluble Rh catalyst in 1984 (Billig, 2000). Catalyst lifetimes are significantly reduced by poisoning from strong acids, HCN, organosulfur, H2S, COS, O2, and dienes (Bahrmann, 2000).

Butyl acetate Butyl acetates are commonly manufactured by the esterification of a butanol isomer and acetic acid with the catalytic presence of sulfuric acid. [1]