ABDALLAH ALHARABAH

INTRODUCTION

Problem Statement 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

Problem Statement Problem Statement

INTRODUCTION

The isobutene and propane are inert. The conversion is 95% and the selectivity is one.

The reactor30 bar and 90 °C

,Pure Methanol

Mixture :-40% isobutylene-55% isobutane-5% propane

MTBE 2000 ton/day

INTRODUCTION

MTBE SYNTHSIS - Raw Material - Properties and Thermodynamics

MTBE PROCESSES - Process Description - Process Flow Diagram (PFD) - Uses and Alternatives - Safety

Outlines

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.

known as methyl tertiary butyl ether

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.

INTRODUCTIONknown as methyl tertiary butyl ether

Raw Material

RAW MATERIALknown 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.

RAW MATERIALknown 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.

RAW MATERIALknown 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.

RAW MATERIALIt 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.

Properties and Thermodynamics

Properties and Thermodynamics

known as methyl tertiary butyl ether

MTBE properties

Molecular weight (g/mole) 88.15

Boiling Temperature ( °C) 54

Specific gravity 0.74

Water solubility (mg/L) 50000

Vapor pressure (mm Hg) 251

Henry's Law 1.5E-3

Latent heat of vaporization (Cal/g) 81.7

Specific heat (Cal/g.°C) 0.51

Properties and Thermodynamics

known as methyl alcohol with a formula CH3OH

Methanol propertiesMolecular weight (g/mole) 32.04

Boiling Temperature (°C ) 65

Melting pint (°C ) -97.7Relative Density 0.79Specific gravity 0.8Water solubility (mg/L) infinityVapor pressure (mm Hg) 122Heat of Formation (MJ/kmol) 201.3-

Gibbs Free Energy -162.62Tc (K) 512.6Pc (bar) 81Vc ( m³/kmol) 0.118Density ( kg/m³) 791Heat of Vaporization (kJ/kmol) 35278

Henry's Law 1.1E-4

Properties and Thermodynamics

known as methyl alcohol with a formula CH3OH

Butenes properties isobutylene 1-butene

Molecular weight (g/mole) 56.11 56.107Boiling Temperature (°C ) -6.9 -6.3

Melting pint (°C ) -140.3 -185.4Specific gravity 0.59 1.998Water solubility (mg/ml) insoluble 0.085Vapor pressure ( kPa) 268.8 268Flash point (°c) -76 -79

Tc (°c) -144.7 146.4

Pc (atm) 39.48 40.2

Vc ( cm³/mol) 239 -

Density ( g/cm³) gas 0.5879 2.72(kg/m³)

Latent Heat of Vaporization (cal/g)

94.3 390 (kj/kg)

Specific heat (kj/kg.k) 1.487 0.083 (kj/mol.k)

Properties and Thermodynamics

It is molecular formula C3H8

Properties and Thermodynamics

Propane propertiesMolecular weight (g/mole) 44.1Boiling Temperature (°C ) -42.09

Melting pint (°C ) -187.6Specific gravity 1.5503Water solubility (mg/ml) 0.07Vapor pressure (psig) 109Viscosity (centipoise) 0.008029Gibbs Free Energy -162.62Tc (°F) 206.2Pc (psia) 617.4Density ( kg/m³) gas 1.83 Density ( kg/m³) liquid 507.7Heat of Vaporization (cal/g) 101.76Specific heat (cal/g.°c) 0.3885

Process Description

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

 

 M

eth

anol R

ecy

cle

Colu

mn

MTB

E C

olu

mn

MTBE Reacto

r

 MethanolScrubber

Waste stream

Butene waste stream

Process Description

The Butenes stream contains 40% isobutylene, 55% isobutene and and 5% light gases mainly propane

Methanol

Butenes

Water

MTBE

 

 M

eth

anol R

ecy

cle

Colu

mn

MTB

E C

olu

mn

MTBE Reacto

r

 MethanolScrubber

Waste stream

Butene waste stream

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

 

 M

eth

anol R

ecy

cle

Colu

mn

MTB

E C

olu

mn

MTBE Reacto

r

 MethanolScrubber

Waste stream

Butene waste stream

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

 

 M

eth

anol R

ecy

cle

Colu

mn

MTB

E C

olu

mn

MTBE Reacto

r

 MethanolScrubber

Waste stream

Butene waste stream

Process Flow Diagram (PFD)

1

5

3

4

8

11

6

7

1 0

1 2

9

2

processwater

m ethanol

butenes

R-901

T-902

T-903

T-901

butenewaste stream

wastewater

M TB E

Figure 1 : P rocess F low D iagram for M TBE P roduction

R-901MTBEReactor

T-901MTBEColumn

T-902MethanolScrubber

T-903MethanolRecycleColumn

Process Flow Diagram

Process Flow Diagram

Kinetic Data and Uses

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

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

Safety

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

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

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