3. Problem Statement
This term's problem is to design an MTBE plant that produces
2000 tons MTBE per day.
INTRODUCTION
MTBE is a gasoline additive used to increase octane number that is
produced from methanol and isobutylene. MTBE is produced by a
liquid-phase reaction over a catalyst. The reaction is between
isobutene and methanol as follows:
(CH3)2C=CH2 + CH3OH (CH3)3C-O-CH3
4. Problem Statement
INTRODUCTION
The isobutene and propane are inert. The conversion is 95%
and the selectivity is one.
The reactor
30 bar and 90 °C
,
Pure Methanol
Mixture :
-40% isobutylene
-55% isobutane
-5% propane
MTBE
2000 ton/day
5.
6. INTRODUCTION
MTBE SYNTHSIS
- Raw Material
- Properties and Thermodynamics
MTBE PROCESSES
- Process Description
- Process Flow Diagram (PFD)
- Uses and Alternatives
- Safety
Outlines
7. INTRODUCTION
MTBE is a chemical compound with molecular formula C5H12O.
It has been used since 1979 when it was first added to gasoline
to replace lead as an anti-knock agent and to boost octane.
MTBE oxygenate has achieved a great economic importance in
recent years as a gasoline additive because of its ability to
enhance the octane value of unleaded motor gasoline while
increasing the oxygen content.
MTBE is produced by the reaction of isobutylene and methanol
in the presence of a cation exchange resin catalyst Amberlyst 15.
MTBE known as methyl tertiary butyl ether
8. MTBE is also used in organic chemistry as a relatively inexpensive
solvent with properties comparable to diethyl ether but with a higher
boiling point and lower solubility in water.
It is also used medically to dissolve gallstones.
INTRODUCTION
MTBE known as methyl tertiary butyl ether
10. RAW MATERIAL
METHANOL known as methyl alcohol
its molecular formula is CH3OH.
Methanol was formerly produced by the destructive
distillation of wood.
The modern method of preparing methanol is based on the
direct combination of carbon monoxide gas and hydrogen in
the presence of a catalyst.
Most methanol is produced from the methane which is
found in natural gas.
11. RAW MATERIAL
METHANOL known as methyl alcohol
Pure methanol is an important material in chemical synthesis.
Methanol is a colorless liquid, completely miscible with water
and organic solvents and is very hydroscopic. It boils at 64.96°
C (148.93° F) and solidifies at -93.9° C (-137° F).
It forms explosive mixtures with air and burns with a
nonluminous flame. It is a violent poison; drinking mixtures
containing methanol has caused many cases of blindness or
death. Methanol has a settled odor.
12. RAW MATERIAL
Isobutylene known as 2-methylpropene with a formula C4H8
It is called olefin because it contains a four-carbon branched
alkene.
It is colarless gas and on of the important hydrocarbon in
industrial.
Isobutylene is used as an intermediate in the production of a
variety of products.
It is reacted with methanol and ethanol in the manufacture of
the gasoline oxygenates methyl tert-butyl ether (MTBE) and
ethyl tert-butyl ether (ETBE), respectively. Alkylation with
butane produces isooctane, another fuel additive.
13. RAW MATERIAL
Propane It is molecular formula C3H8
Propane is a colorless, flammable gas at atmospheric
pressure and normal temperatures.
It has a natural gas odor and is soluble in ether, alcohol and
slightly soluble in water.
Typical uses include vehicle fuel, home heating, and
refrigerant gas.
15. Properties and Thermodynamics
MTBE known as methyl tertiary butyl ether
MTBE properties
88.15
Molecular weight (g/mole)
54
Boiling Temperature ( °C)
0.74
Specific gravity
50000
Water solubility (mg/L)
251
Vapor pressure (mm Hg)
1.5E-3
Henry's Law
81.7
Latent heat of vaporization (Cal/g)
0.51
Specific heat (Cal/g.°C)
16. Properties and Thermodynamics
METHANOL known as methyl alcohol with a formula CH3OH
Liquid
Properties:
Viscosity:
a = 555.3 b = 260.6
where log(viscosity) =
a * ( 1/T - 1/b )
viscosity: mNs/m² T: °K
Vapor
Properties:
Heat capacity:
a = 21.152 b = 0.07092 c = 2.59E-05 d
= -2.85E-08
where Cp = a + b*T + c*T² + d*T³
Cp: kJ/kmol.K T: °K
Vapour pressure:
a = 18.5875 b = 3626.55 c = -34.29
where ln(P) = a - b/(T+c) P: mmHg6 to
91°C
17. Methanol properties
32.04
Molecular weight (g/mole)
65
Boiling Temperature (°C )
-97.7
Melting pint (°C )
0.79
Relative Density
0.8
Specific gravity
infinity
Water solubility (mg/L)
122
Vapor pressure (mm Hg)
201.3-
Heat of Formation (MJ/kmol)
-162.62
Gibbs Free Energy
512.6
Tc (K)
81
Pc (bar)
0.118
Vc ( m³/kmol)
791
Density ( kg/m³)
35278
Heat of Vaporization (kJ/kmol)
1.1E-4
Henry's Law
Properties and Thermodynamics
METHANOL known as methyl alcohol with a formula CH3OH
18. 1-butene
isobutylene
Butenes properties
56.107
56.11
Molecular weight (g/mole)
-6.3
-6.9
Boiling Temperature (°C )
-185.4
-140.3
Melting pint (°C )
1.998
0.59
Specific gravity
0.085
insoluble
Water solubility (mg/ml)
268
268.8
Vapor pressure ( kPa)
-79
-76
Flash point (°c)
146.4
-144.7
Tc (°c)
40.2
39.48
Pc (atm)
-
239
Vc ( cm³/mol)
2.72(kg/m³)
0.5879
Density ( g/cm³) gas
390 (kj/kg)
94.3
Latent Heat of Vaporization
(cal/g)
0.083 (kj/mol.k)
1.487
Specific heat (kj/kg.k)
Properties and Thermodynamics
Butenes
19. Propane It is molecular formula C3H8
Properties and Thermodynamics
Propane properties
44.1
Molecular weight (g/mole)
-42.09
Boiling Temperature (°C )
-187.6
Melting pint (°C )
1.5503
Specific gravity
0.07
Water solubility (mg/ml)
109
Vapor pressure (psig)
0.008029
Viscosity (centipoise)
-162.62
Gibbs Free Energy
206.2
Tc (°F)
617.4
Pc (psia)
1.83
Density ( kg/m³) gas
507.7
Density ( kg/m³) liquid
101.76
Heat of Vaporization (cal/g)
0.3885
Specific heat (cal/g.°c)
21. Process Description
(MTBE) is a gasoline additive used to increase octane number
that is produced from methanol and isobutylene.
Methanol is purchased but the isobutylene is obtained from the
isomerization and dehydrogenation of butane .
Methanol
Butenes
Water
MTBE
Methanol
Recycle
Column
MTBE
Column
MTBE
Reactor
Methanol
Scrubber
Waste
stream
Butene waste
stream
22. Process Description
The Butenes stream contains 40% isobutylene, 55% isobutene and
and 5% light gases mainly propane
Methanol
Butenes
Water
MTBE
Methanol
Recycle
Column
MTBE
Column
MTBE
Reactor
Methanol
Scrubber
Waste
stream
Butene waste
stream
23. Process Description
The MTBE produced is extracted from the reaction effluent via
distillation, while the unreacted methanol is absorbed by water
before it is separated from water via distillation. The recoverd
methanol is recycled back to the reactor.
Methanol
Butenes
Water
MTBE
Methanol
Recycle
Column
MTBE
Column
MTBE
Reactor
Methanol
Scrubber
Waste
stream
Butene waste
stream
24. Process Description
MTBE is produced by a liquid-phase reaction over a catalyst. The
reaction is between isobutylene and methanol as follows:
(CH3)2C=CH2 + CH3OH (CH3)3C-O-CH3
Methanol
Butenes
Water
MTBE
Methanol
Recycle
Column
MTBE
Column
MTBE
Reactor
Methanol
Scrubber
Waste
stream
Butene waste
stream
29. Process Flow Diagram
The catalyst used in this reaction is Amberlyst 15.
A kinetic model for the liquid phase reaction using
Amberlyst 15 as a catalyst is
30. MTBE has many properties that make it a good gasoline
component for technical and environmental reasons:
• MTBE can be used as fuel that can supplement the
supply of gasoline components.
• Its high octane rating makes it an ideal substitute for
other octane components, e.g. lead.
• It is an oxygenate, which can be used in the
formulation of cleaner-burning gasoline.
Uses
32. Safety is very important in the plant because any small mistakes will
cost money. For example:
in reactor we should have a jacket or coil to cool the reactor
because the reaction is exothermic and isothermal. If we don't have
cooler the reaction temperature with time will increase and that will
lead to break the catalyst and explosion.
Also in the distillation column limit the maximum height to 53 m
because of wind load and foundation considerations
Safety
33. Also we need to use spare pump because if the primary pump is not
working we don't have problem.
Moreover we need to use PID tuning to control the process
conditions like temperature and pressure.
Also some safety factors will required in the design's calculation to
avoid problems.
Safety
