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Propylene, Propylene Oxide and Isopropanol

Propylene often referred as the crown prince of petrochemicals is superficially similar to ethylene but there are many differences in both production and uses. Propylene is used in many of the world’s largest and fastest growing synthetic materials and thermoplastics. The demand of propylene has increased rapidly during the last twenty years and primarily driven by polypropylene demand . Product profile of propylene is given in Table M-VII 6.1.

According to SRI consulting 2010 global production and consumption of propylene in 2009 was both approximately 71 million tones with capacity utilization of 78.5%. Global propylene consumption is forecast to average growth of around 5.1% per year from 2009 to 2014 and 3.5% per year from 2014-19. Consumption of refinery grade propylene made up 9% of total consumption in 2009, chemical grade 23% and polymer grade 68%. Refinery grade propylene is consumed mainly for production of cumene and isopropyl alcohol. Chemical grade propylene mostly goes into oxo alcohol, propylene oxide and acrylonitrile. 

Table M-VII 6.1: Product Profile of Propylene 

 

Product

Uses

Miscellaneous

chemicals

1 butanol, 2-ethyl hexanol, Allyl chloride, Epichlorohydrin

Polymer

Polypropylene,, Polyacrylamide, nylon 66, acrylic sheets

Propylene oxide

Polyether-polyols, glycol ethers, isopropyl amines, propylene carbamate, surfactants

Propylene glycol

Unsaturated polyester resins, food additives, cellophane, paints and coating, plasticisers, functional fluids, antifreeze, tobacco treatment

Acrylonitrile

Acrylic fiber, acrylic acid, acrylates, methyl methacrylates, adiponitrile

Isopropanol

Acetone, cosmetics, solvents, pharmaceuticals, isopropyl acetate

Polyols

Polyurethane and Polyester

 
Sources of Propylene 
 
Propylene is a byproduct of steam crackers and varying amount of olefins is produced from steam crackers depending on the type of feedstock. Other sources of propylene may be recovery of propylene from FCC light ends, Propane dehydrogenation, Metathesis. Some of the major processes for production of propylene is given in Table M-VII 6.2.Typical Composition of FCC Gas Stream is given in Table M-VII 6.3.
 
Table M-VII 6.2: Propylene Production Technologies
 

 

Technology

Process

Licensor

Olefin

conversion

technology

This process involves production of propylene from ethylene and 2-butenes in a fixed bed metathesis reactor containing proprietary catalyst, which promotes reaction of ethylene and 2-butene to form propylene and simultaneously isomerises 1-butene to 2-butene.

ABB Lumus

Global

Superflex

Process

The process uses a fluidised bed catalytic reactor system using proprietary catalyst which converts low value feedstock to predominantly propylene and ethylene products. Low value light hydrocarbon streams from ethylene plant and refineries can be used, e.g. C4 and Colefin rich stream from ethylene plants, FCC naphtha, C4 stream, thermally cracked naphtha from visbreakers or cokers.

Kellogg Brown &

Root, Inc.

Propylur

Process

This process produces propylene beside ethylene from low value rich feeds ranging from C4-C8 from ethylene plant and refineries in a fixed bed reactor using proprietary catalyst. The process offers high selectivity towards propylene.

Lurgi Oel

Gas Chemie

GmbH

UOP Oleflex

Process

This process produces polymer grade propylene from propane and the process consist of a reactor, catalyst regeneration section and product separation and fractionation section. The process uses platinum catalyst (DeH-12 catalyst).

UOP LLC

UOP/Hydro MTO Process

This process converts crude methanol (produced from synthesis gas using natural gas) to ethylene and propylene and can be operated either a maximum ethylene or a maximum propylene production mode using MTO-100 silicoaluminophosphate synthetic molecular sieve based catalyst. The process utilizes fluidised bed reactor and regenerator.

UOP LLC and Hydro Norway

Methanol to propylene (MTP) Technology

This process produces propylene through methanol route

using natural gas. In this process propylene is produced in two steps. First methanol is converted to dimethyl ether in reactor followed by reaction of methanol/DME in second reactor. Methanol can be produced from methane from conventional method.

Lurgi Oel

Gas Chemie

GmbH

C4

hydrogenation and Meta-4

Process

This process involves production of polymer grade propylene plus an isobutylene rich stream or MTBE by upgrading low value C4 stream pyrolysis C4 cuts or butene rich cut. The process steps involve - butadiene and C4 acetylenes selective hydrogenation and butadiene hydroisomerisation, isobutylene removal or MTBE production and metathesis step for conversion of butene and ethylene to propylene. The two main equilibrium reactions taking place are metathesis and isomerisation.

Axens,

Axens NA

Olefin Ultra TM

A new ultra high activity ZSM-5 additive that provides the highest activity has been developed by Davision catalysts.

 

KBR’s

MAXOFIN-3

TECHNOLOG

Y

KBR’s MAXOFIN process is based on fluidised bed cracking of gas oils and residue feeds using ZSM catalyst and proprietary MAXOFIN-3 catalyst additive. The process gives 15% or higher propylene yield from gas oil.

Kellogg Brown & Root, Inc.

 
 
Table M-VII 6.3: Typical Composition of FCC Gas Stream

 

Products

Yield weight (percent)

Dry gas (including ethylene)

12.7

Propane

6.5

Propylene

21.0

Butene

35.8

Catalytic Dehydrogenation 

Catalytic dehydrogenation of light paraffins is of increasing importance because of the growing demand of olefins such as propylene and isobutene and nbutenes. Propane dehydrogenation accounts for 2 percent of the total world propylene production. Some of the commercial processes available for dehydrogenation of propane and n-butane are :

  • Oleflex (UOP).
  • Catofin (ABB Lumus).
  • FBD-4 (Snamprogetti SPA).
  • Star (Phillips Petroleum Company).

              Catalytic dehydrogenation takes place at high temperature (6500C) using platinum based or chromium-alumina or Fe, Cr/Al2O3 as catalyst. Reactor effluent treatment for the separation of hydrogen, propylene, and propane is not simple and total investment is high. These production units can be installed only in areas where field propane is available at low costs. 

Methanol to Propylene:

This process produces propylene from natural gas via methanol by converting methanol to dimethyl ether in adiabatic reactor using high activity, high selectivity catalyst. The methanol, water, DME stream is then feed to series of MTP reactor where steam is added. The product stream is first processed for removal of traces of water, CO2 and DME, followed by further processing for yielding polymer grade propylene.  

Propylene Oxide, Propylene Glycol and Polyols 

Propylene oxide, propylene glycols and polyols are important derivatives of propylene. propylene oxide is used for the manufacture of propylene glycol and polyols. Major consumption of propylene oxide is manufacture of polyurethane and polyester resins. Propylene glycol find major application in the manufacture of unsaturated polyester resins, food additives, pharmaceuticals and personal care, tobacco humectants, cellophane, paints and coatings. Polyols major use is in the manufacture of polyurethane. 

Propylene Oxide

Various rote for making propylene oxide are There are two major processes for the manufacture of propylene oxide: Propylene chlorohydrin process and propylene oxidation process using peroxides.

Propylene Chlorohydrin Route: 

The chlorohydrination process consists of formation of propylene chlorohydrin by the reaction between hypochlorous acid and propylene. The propylene chlorohydrin is epoxidised to propylene oxide by a 10% solution of milk of lime or NaOH. Various steps involved are

  • Propylene hypochlorination: Propylene is reaxted with aquous chlorine resulting in the formation of propylene chlorohydrins. Unreacted propylene is recyled.
  • Neutralisation: Neutrialisation of propylene chlorohydrins containing hydrochloric acid which is formed during the process.
  • Dehydrochlorination: Reaction of propylene chlorohydrin with milk of lime or caustic soda to produce propylene oxide
  • Purification: Distillation of crude propylene oxide for separation heavy ends 

Reactions : 

Propylene, Propylene Oxide And Isopropanol (Part - 1) | Chemical Technology - Chemical Engineering

Propylene, Propylene Oxide And Isopropanol (Part - 1) | Chemical Technology - Chemical Engineering

Byproducts formed during the reaction are 1,2-dichloropropane and chlorinated di-isopropyl ether. Some of the disadvantages and major economic drawbacks of the process which led to the wide acceptability of epoxidation processes are use of costly chlorine, production of weak calcium chloride byproduct, and corrosion problem due to chlorine handling.

Oxidation Route using peroxide Compounds: In this process, propylene and peracetic acid (in ethyl acetate) which is produced by oxidation of acetaldehyde are reacted in a series of three specially designed reactors at 50-800C and 90-120 MPa pressure. The reaction products are fed to the stripper where a mixture of propylene and propylene oxide are obtained as top product while mixture of ethyl acetate and acetic acid is obtained as bottom product. Both mixtures are fed to two separated columns where separation of propylene oxide, ethyl acetate, acetic acid, and heavy end takes place. 

Reaction

Peroxide from acetaldehyde 

Propylene, Propylene Oxide And Isopropanol (Part - 1) | Chemical Technology - Chemical Engineering

Oxidation of propylene 

Propylene, Propylene Oxide And Isopropanol (Part - 1) | Chemical Technology - Chemical EngineeringPropylene, Propylene Oxide And Isopropanol (Part - 1) | Chemical Technology - Chemical Engineering

Propylene Glycol

Propylene glycol is made by hydrolysis of propylene oxide. The process steps involve are:

Reaction Section: Hydrolysis of propylene oxide resulting in formation of mono propylene glycols(MPG). Small amount of di propylene glycol (DPG) and tri propylene glycol (TPG) s are also formed

 Concentration Section: Concentration of glycol solution in multiple effect evaporator

Distillation Section: Separation of MPG,DIPG and TPG separated from MPG column. n series of distillation column where MPG is separated in first column.

Polyols 

Polyols are made by polymerization of propylene oxide/ethylene oxide using an proprietary catalysed chain starter. The process consist of  

  • Raw material Preparation: Preparation of chain starter and addition in reactor along with EO/PO 
  • Reaction: Polymerisation using catalysed cahin extender
  • Purification: Purification of raw polyol by neutralization 
The document Propylene, Propylene Oxide And Isopropanol (Part - 1) | Chemical Technology - Chemical Engineering is a part of the Chemical Engineering Course Chemical Technology.
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FAQs on Propylene, Propylene Oxide And Isopropanol (Part - 1) - Chemical Technology - Chemical Engineering

1. What is propylene and how is it produced?
Ans. Propylene is a colorless gas that is a byproduct of petroleum refining and natural gas processing. It can also be produced through the cracking of hydrocarbons, such as propane or naphtha, in a process known as steam cracking.
2. What is propylene oxide used for?
Ans. Propylene oxide is a versatile chemical compound used in various industries. It is primarily used as a raw material for the production of polyurethane foams, which are commonly found in furniture, mattresses, and insulation. It is also used in the manufacturing of solvents, detergents, and resins.
3. What are the main applications of isopropanol?
Ans. Isopropanol, also known as isopropyl alcohol, has numerous applications. It is commonly used as a solvent in the pharmaceutical, cosmetic, and personal care industries. It is also used as a cleaning agent, disinfectant, and antiseptic. Additionally, it is utilized in the production of printing inks, coatings, and electronic devices.
4. How is propylene oxide produced industrially?
Ans. Propylene oxide is typically produced through the oxidation of propylene using either the chlorohydrin process or the hydroperoxide process. In the chlorohydrin process, propylene reacts with chlorine to form propylene chlorohydrin, which is then treated with an alkali to produce propylene oxide. In the hydroperoxide process, propylene is reacted with hydrogen peroxide in the presence of a catalyst to directly produce propylene oxide.
5. What are the safety considerations when working with propylene oxide?
Ans. Propylene oxide is highly flammable and can form explosive mixtures with air. It is also a toxic substance and can cause irritation to the skin, eyes, and respiratory system. Proper safety measures, such as wearing protective clothing and respiratory equipment, should be followed when handling propylene oxide. Adequate ventilation and fire prevention measures should also be in place.
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