1. Petrochemical Processes
Chapter 4
Petrochemical Processes
Dr Salam Al-Dawery

2. Petrochemicals are oil derived chemicals, are the major raw materials (building blocks) for the chemical industry

3. Main Categories of Petrochemical Products
Olefins
Aromatics
Synthesis gas

4. Lower Alkenes (Olefins)
The major part of Olefins are the ethylene and propylene are the basic source in preparation of several industrial chemicals and plastic products.
Butadiene is used to prepare synthetic rubber

5. Aromatics
Benzene, toluene and xylenes are major components of aromatic chemicals.
Aromatic petrochemicals are used in manufacturing of secondary products like synthetic detergents, polyurethanes, plastic and synthetic fibers.

6. Synthesis Gas
Synthesis gas comprises of carbon monoxide and hydrogen which basically used to produced ammonia and methanol.
Ammonia and methanol are further used to produce other chemical and synthetic substances.

7. Building block Chemicals (Base Chemicals)
Ethylene
Propylene
Butadiene (1,3)
Benzene
Toulene
Xylenes
Ammonia
Methanol
85% of the organic chemicals are produced from base chemicals

8. Ethylene, Propylene, 1.3-Butadiene & BTX,
Petrochemicals-The Origin
CRUDE OIL
REFINARY
FEEDSTOCKS
Gas, Naphtha, Gas Oil, Kerosene
PETROCHEMICAL
INDUSTRY
BASIC CHEMICALS
Ethylene, Propylene, 1.3-Butadiene & BTX,
PETROCHEMICALS
PE,PP,PVC,PS,PBR,MEG,LAB,ACN, AF, PTA, PHA, MA,CPL

9. Petrochemicals from Ethylene

10. Petrochemicals from Propylene

11. Petrochemicals from Butadiene
Polybutadiene
Rubber
PBR
Styrene-Butadiene
Rubber SBR
Acrylonitrile-
Butadiene
-Styrene ABS
Adiponitrile
ADN
Specialty
Polymers /
Chemicals

12. Petrochemicals from Benzene

13. Petrochemicals from Toluene
Benzene
Xylenes
Specialty/
Functionalized
chemicals

14. Petrochemicals from Xylenes
O-Xylene
m-Xylene
p-Xylene
Phthalic anhydride
Terephthalic acid
PTA
Iso-phthalic acid
Plasticizers
PET
Polyesters

15. Lower alkenes from oil Chemical industry uses
- 10% of available petroleum and natural gas as feed
- 5% as fuel
Produced from
steam cracking of various refinery streams.
dehydrogenation reactions.
Example: Lower alkenes or olefins an important feed for products such as LDPP or HDPP.

16. Lower alkenes from oil
(CH2=CH-CH=CH2)
C5 olefins

17. Steam Cracking: Industrial Process
A mixture of HC and steam are passed through tubes inside a furnace
Heating occurs by convection and radiation
Considerable heat input at a high temperature level
Limited HC partial pressure
Very short residence times (<1 s)
Rapid quench of product to preserve composition otherwise pyrolysis takes place

18. Steam cracking
Steam cracking is a thermal cracking in the presence of steam, yielding a complex product mixture ranging from hydrogen to fuel oil
A key process in the oil and petrochemical industry

19. A Simplified flow scheme of a steam cracker

20. Dehydrogenation
Related to catalytic dehydrogenation, where an alkane losses hydrogen at high temperatures to produce alkene

21. Dehydrogenation
Recently, the demand for propenes and butenes has been increasing.
Direct production for these specific alkenes received special attention
Selectively dehydrogenate the specific alkane (ie propane to form propylene)
Alkane dehyrogenation is highly endothermic

22. Dehydrogenation Variables in these processes include:
Type of catalyst used
Reactor design
Method of heat supply
Method for catalyst regeneration

26. Synthesis Gas - Syngas1/2
A mixture of CO and H2 in varying ratios
Uses:
Refinery hydrotreating, hydrocracking
Ammonia
Alkenes
Methanol, higher alcohols
Aldehydes
Acids

27. Synthesis Gas - Syngas2/2
Produced from coal, natural gas, etc.
Major processes:
Steam reforming of NG or light HC in the presence of O2 or CO2
Partial oxidation of heavy HC with steam (H2O) and O2
Partial oxidation of coal (gasification) with steam (H2O) and O2
Raw materials depend on cost and availability

28. Steam reforming is used to describe the reaction of hydrocarbons with steam in the presence of a catalyst

29. Production of Syngas

30. Reactions to form Syngas
General reactions
(1) C + H2O→ CO + H2 (steam reforming, endothermic)
(2) C + ½ O2 → CO (partial oxidation, exothermic)
(3) CO + H2O ↔ CO2 + H2 (water gas shift)
NG as a feed:
(1) CH4 + H2O→ CO + 3H (steam reforming, endothermic)
(2) CO + H2O ↔ CO2 + H (water gas shift)
(3) CH4 + CO2 ↔2CO + 2H2
2CO ↔C + CO2
CH4 ↔C + 2H2
CH4 + ½ O2 → CO + H (partial oxidation)
(7) CH4 + 2O2 → CO2 + 2H2O
(8) CO + ½ O2 → CO2
(9) H2 + ½ O2 → H2O

31. Steam Reforming1/2 High temperatures
Nickel catalyst contained in tubes heated by a furnace
A mixture of NG and steam are passed through tubes inside a furnace. May contain tubes that are 7-12 m long with ID of mm
Heating occurs by convection and radiation
Feed pretreatment required a sulfur removal
Coke deposits can form that deactivate the catalyst and can block the furnace tubes, so excess steam is used to prevent coke deposit
Product is cooled in order to separate the condensed

32. Steam Reforming2/2

33. Ammonia synthesis1/2 Bulk Chemicals and Synthetic Fuels Derived from
Synthesis Gas
Ammonia synthesis1/2
A major product of the CPI
Early sources were natural, or byproduct of coke ovens
Major use in fertilizers (agricultural) and explosives
In 1909 Fritz Haber established the conditions under which nitrogen, N2(g), and hydrogen, H2(g), would combine using
medium temperature (~500oC)
very high pressure (~250 atmospheres, ~351kPa)
a catalyst such as: 1-a porous iron catalyst prepared by reducing
magnetite, Fe3O4) Osmium is a much better catalyst for the
reaction but is very expensive.
Requires a H2:N2 ratio of 3:1
N2 sources is air, H2 from Syngas
3H2+N2 ↔ 2NH3 DH= kJ/ml

34. Ammonia Synthesis2/2
See chapter 2 for process description

35. Uses of Ammonia Fertiliser Chemicals Explosives Fibres & Plastics
ammonium sulfate, (NH4)2SO4
ammonium phosphate, (NH4)3PO4
ammonium nitrate, NH4NO3
urea, (NH2)2CO
Chemicals
nitric acid, HNO3, which is used in making explosives such as TNT (2,4,6-trinitrotoluene),
nitroglycerine which is also used as a vasodilator (a substance that dilates blood vessels) and PETN (pentaerythritol nitrate).
sodium hydrogen carbonate (sodium bicarbonate), NaHCO3
sodium carbonate, Na2CO3
hydrogen cyanide (hydrocyanic acid), HCN
hydrazine, N2H4 (used in rocket propulsion systems)
Explosives
ammonium nitrate (NH4NO3)
Fibres & Plastics
nylon, -[(CH2)4-CO-NH-(CH2)6-NH-CO]-,and other polyamides
Refrigeration
used for making ice, large scale refrigeration plants, air-conditioning units in buildings and plants
Pharmaceutical
used in the manufacture of drugs such as sulfonamide which inhibit the growth and multiplication of bacteria that require p-aminobenzoic acid (PABA) for the biosynthesis of folic acids, anti-malarias and vitamins such as the B vitamins nicotinamide (niacinamide) and thiamine
Pulp & Paper
ammonium hydrogen sulfite, NH4HSO3, enables some hardwoods to be used
Mining & Metallurgy
used in nitriding (bright annealing) steel, used in zinc and nickel extraction
Cleaning

36. Methanol Synthesis1/3 Bulk Chemicals and Synthetic Fuels Derived from
Synthesis Gas
Methanol Synthesis1/3
CO+ 2H2 ↔ CH3OH
CO2+3H2 ↔ CH3OH+H2O
Coupled by: CO+H2O ↔ CO2+H2
Second large scale process involving catalyst at high pressure and temperature
Catalyst selectivity is very important, as other products may form.
Cu/ZnO/Al2O3 catalysts are newer catalysts that enable lower pressure

37. Methanol
Methanol also known as methyl alcohol is a chemical with the formula CH3OH. It is the simplest alcohol and is light, volatile, colorless, flammable liquid.

38. Methanol Synthesis2/3
Equilibrium data:

39. Methanol Synthesis3/3 To distillation CO, CO2 & H2 from
steam reforming,

40. Application of Methanol
Chemical industry
Solvent (Octane booster as Methyl tert-butyl ether (MTBE))
Intermediate (i.e. Formaldehyde)
Energy source

41. Polymers & Polymerization
Sources of Polymers
Natural polymers since
prehistoric times are:
Wood
Rubber
Cellulose, rayon
First synthetic polymers:
Phenol formaldehyde resins
Used of polymers
Main component of food:
Starch, protein
Clothes:
Silk, cotton, polyester, nylon
Building materials
Wood, paints, PVC etc.

42. What is a “polymer”? Polymers
The terms polymer and monomer are part of our everyday speech.
Poly = many Mono = one
“Mer” is derived from the Greek meros, meaning “part.” So, a monomer is a “one part” and a polymer is a “many part.”

43. Polymers -R-R-R-R- Or –[R]n-
Constructed of monomer units connected by a covalent bond:
-R-R-R-R-
Or –[R]n-
R: a bi-functional entity not capable of separate existence
n: degree of polymerization DP
MW: molecular weight, obtained from the MW of the
monomer multiplied by n

44. Example: Polyethylene
Polyethylene is an example of a synthetic polymer.
Ethylene, derived from petroleum: is made to react with itself to form polyethylene.

45. Categories of Polymers1/2
Thermoplastic
Become flexible solids above a certain T
then become rigid again upon cooling below this T
flexible/rigid cycle can be repeated
When flexible it can be molded into shapes
Fibers can be drawn into strands, non fibers cannot
Thermoset resins
Network co-polymers that do not become flexible until the T is so high thermal decomposition takes place
Synthetic rubber
Deformed by small stresses but regain original shape

46. Categories of Polymers2/2

47. Engineered polymers High % growth
Special properties, replacements for metals, chemical inertness, etc. used in carpet and tire reinforcement.
Examples:
Acetal (poly-oxy-methylene POM)
Nylons (polyamides)
Polyethylene or poly-butylene terephthalate (PET or PBT)
Polycarbonate PC
Polyphenylene oxide PPO

48. Polymerization reactions
2 mechanisms: chain growth and step growth
Chain growth (or additional polymer)
Reaction occurs by successive addition of a monomer to the reactive end
Example, polymerization of a monomers such as ethylene, propylene, styrene, vinyl chloride
nCH2=CHX -(-CH2-CHX)n-
Where X can be H, CH3, C5H6 or Cl
Initiator or catalyst is required to start the chain growth reaction
High MW product is produced right away (during polymerization)
Polymerization is generally fast, irreversible and moderately to highly exothermic.

49. Step growth (or condensation polymerization)
Formed when monomers combine and split out water or some other simple substance.
Essentially a substitution reaction
Nylon is a condensation polymer.
High MW product is produced from the end of polymerization
Commodity Polymers
Polyethylene (PE)
Polypropylene (PP)
Polyvinylchloride (PVC)
Polystyrene (PS)

50. Polyethylenes1/2 Classification and properties
linear, unbranched polymers are more densely packed therefore more ordered
Side branches interfere with alignment of polymer chains
Density can be controlled by operating T, P, catalysts and co-monomers used
Example: LDPE is produced at high T and high P
– higher T results in more side reactions and branching, thus lower density
Polymer density is degree of crystallinity

51. Polyethylenes2/2

52. Applications

54. Production of LDPE1/3 Ethylene fed to reactor at high T, P No catalyst
Initiator can be used (oxygen, peroxide)
Ethylene behaves like a liquid and a solvent
CSTR or tubular reactor

55. Production of LDPE2/3
Using a tubular reactor: a long pipe heat exchanger with
m long, and cm ID
Reactants heated to K
Heat of polymerization means cooling is required by outer jackets, T is raised up to K
Conversions of 15-22%, so recycle stream is employed
Pressure cycling from 3000 to 2000 bar

56. Production of LDPE3/3
Dr Salam Al-Dawery

57. Production of HDPE1/2
There are many processes for production of HDPE such as:
Bulk polymerization
Polymer dissolves in the monomer
Solution polymerization
Polymer and monomer dissolve in HC solvent
Slurry polymerization
Catalyst-polymer particles suspended in HC
Fluidized bed polymerization
Catalyst-polymer particles fluidized in gaseous monomer
Catalytic processes for HDPE and LLDPE are similar

58. Production of HDPE2/2
Fluidized bed polymerization (gas phase polymerization) is the most flexible method

59. Solution polymerization of ethylene, using Ziegler-Natta catalysts59

60. Polymer recovery
Unless bulk polymerization, polymer must be separated from the solvent
Typical separation methods such as crystallization, distillation.
Precipitation can’t normally be used (as polymers are highly viscous).
Method for precipitation can be done by non solvent process such as: centrifugation, and removal of solvent by steam stripping can be used.

61. Exxon Mobile

62. Formaldehyde Resins
Is used in the production of two different but related classes of thermosets:
1- Phenoplast: is called phenolic resins which is produced by
condensation of phenol and formaldehyde.
2- Amenoplast: is prepared from condensation of urea (urea resin) and
formaldehyde

63. Phenolic Resins1/3
Phenolic resins (phenol-formaldehyde polymers), copolymers of phenol and formaldehyde, were the first fully synthetic polymers made. They were discovered in 1910 by Leo Baekeland and given the trade name Bakelite®.
Two processes, both involving step growth polymerization, are used for the manufacture of phenolic resins.
A one-stage resin may be obtained by using an alkaline catalyst , water, phenol and formaldehyde then heated to form linear, low-molecular-weight called the resol resins. See next slide
Acidification and further heating causes the curing process to give a highly cross-linked thermoset polymer (ie high molecular weight) called the resite.

64. Bakelite

65. Formaldehyde (H2C=O) Phenol (C6H5OH)
At ordinary temp, colorless gas with pungent suffocating odor
Relatively low cost, high purity and reactivity, used as chemical intermediate. It has become one of the world’s most important industrial and research chemicals
Phenol (C6H5OH)
White crystalline solid at room temp extracted from coal tar
Produce in large scale use as a precursor to many materials and useful compounds
Major uses involve its conversion to plastics
Key for building epoxies, Bakelite, nylon, detergents, drugs, herbicides and pharmaceuticals

66. Phenol-Formaldehyde Polymers (Bakelite)
Each formaldehyde molecule reacts with two phenol molecules to
eliminate water. The polymer is then formed.
Polymers of this type are used, in electrical equipment, because of the insulating and fire-resistant properties.

67. High crosslinking gives this type of phenolic resins its hardness, good thermal stability and chemical imperviousness
Resoles are major polymeric resin materials widely used for gluing and bonding building materials. Applications include exterior plywood, oriented strand boards, engineered laminated composites etc.

68. Phenolic Resins2/3
The two stage process (Fig. 1) uses an acid catalyst and excess phenol to give a linear polymer (called novolac as shown next slide) that has no free methylol groups for crosslinking.
In a separate second part of this two-stage process, a cross-linking agent is added and further reaction occurs. In many instances, hexamethylenetetramine is used, which decomposes to formaldehyde and ammonia.
Other modifications in making phenolic polymers are the incorporation of cresols or resorcinol as the phenol (Fig. 1) and acetaldehyde or furfural as the phenol.

70. Phenolic Resins3/3

71. Industrial Application of Phenolic Formaldehyde (PF) Resins
Adhesives
Circuit boards
Paints
Laminates for building
Automobile parts
Ion exchange resins
Global production of phenol-formaldehyde
resins exceeded 5 billion pounds in 1997

72. Urea Resins1/2
Urea resins (urea formaldehyde polymers) are formed by the reaction of urea with formaldehyde (Fig. 1).
Monomethylolurea (HOH2CNHCONH2) and dimethylolurea ((HOH2CNHCONHCH2OH) are formed first under alkaline conditions. Continued reaction under acidic conditions gives a fairly linear, low-molecular-weight intermediate polymer.
A catalyst and controlled temperature are also needed and, since the amine may not be readily soluble in water or formalin at room temperature, it is necessary to heat it to about 80oC to obtain the methylol compounds for many amine-formaldehyde resins.
Heating for an extended period of time under acidic conditions will give a complex thermoset polymer of poorly defined structure including ring formation.

73. Urea Resins2/2

74. Formalin Plant (CH2O)

75. INTRODUCTION
Formalin is the aqueous form of formaldehyde produced mostly from methanol by an oxidation process.
Recently, the production volume of formaldehyde has grown rapidly thanks to the every-increasing demand in the manufacturing sector for resins including phenolic, urea, melamin, acetal and many additives.
Other additional application areas of formaldehyde include surface coating, leather tanning, bindery applications, laminates, insulation materials, etc.

76. 76

77. Processes
There are two processes known to produce formalin from methanol— methanol excess and air excess.
The basic difference between them is the catalyst applied.
1-The methanol excess process, called the silver process, employs silver as the catalyst,
2-The air excess process, called molybdenum process, uses metallic oxides of iron and molybdenum.
Second process, is considered a higher investment cost and more complicated operation than the silver process, the use the silver process is recommended

78. Process Description1/2
The evaporated methanol, filtrated air and steam are fed into the mixer where theses gases are mixed uniformly, and then sent to reactor.
Most of the methanol is converted into formaldehyde when the mixed gas passes through the catalyst.
The reacted gas is immediately quenched in the waste heat boiler integrated with the reactor. At the same time, the waste heat boiler recovers reaction heat to generate steam, which is effectively used as heat sources for the methanol evaporator and other heaters, and as steam supply for the mixer.
The reacted gas is introduced into the absorber where produced formaldehyde and residual methanol are absorbed by recycling formalin at the lower section of the absorber.

79. Process Description2/2
The vent gas from the absorber, containing about 20% of hydrogen, can be used as boiler fuel to generate steam and prevent air pollution.
The concentration of formalin produced in the absorber can be adjusted as required by regulating the treated water flow rate. The formic acid content in the raw formalin as produced from the absorber bottom is usually 60~150 ppm, but the lower formic acid content can be obtained by treating it through the ion-exchanger.
The product yield of the reaction is more than 91% (wt) and this process requires small utilities and the cost of catalyst is very low.

80. Process Flow Diagram

81. Applications Phenol Resin and Adhesives / Urea and Melamine Adhesives
Urea Resin / Melamine Resin / Hexamethylenetetramine
Pentaerythritol / Paraformaldehyde
Medicines and Agricultural Chemicals as antiseptic (disinfectant)