Mtbe-prezentation.pptx

Supervised by: Dr. Adil H. Rashid Prepared by: Zainab Fadhil, Zainab Eyad, Asmaa Ali, and Shumus Kamil Academic Year 2018-2019

CHAPTER ONE INTRODUCTION

Methyl tertiary butyl ether (MTBE): • Methyl tert-butyl ether (also known as MTBE and tert-butyl methyl ether) is an organic compound with a structural formula (CH3)3COCH3. •

MTBE is a volatile, flammable, and colorless liquid that is moderately soluble in water. It has a minty odor unclearly reminiscent of diethyl ether, leading to unpleasant taste and odor in water

The chemical structure of MTBE

(CH3)3COCH3

Why we Choose MTBE in our Project????

 Gasoline standards throughout the world are continuing to move toward cleaner burning gasoline.  This includes mandating limits on aromatics, benzene, sulfur and distillation characteristics.  All of these changes must be met while maintaining or increasing gasoline octane number.

Some of the possible blend stocks that fulfill the abovementioned requirements are: Methanol(MeoH)

Alcohols

Ethanol(Etoh) Isopropyl alcohol (IPA)

Oxygenates

n-butanol (BuOH) Gasoline grade tbutanol (GTBA) Methyl tert-butyl ether (MTBE)

Alkylates

Tert-amyl methyl ether (TAME)

isomerate Iso-octane

Tert-hexyl methyl ether (THEME) Ethyl tert-butyl ether (ETBE)

Ethers

Tert-amyl ethyl ether (TAEE) Diisopropyl ether (DIPE)

 Oxygenates refer to oxygenated fuels and they are usually employed as gasoline additives to reduce carbon monoxide and soot produced during the burning of the fuel.  As for oxygenates, Methyl-Tert-Butyle-Ether (MTBE) became the single most widely used oxygenate for enhancing gasoline octane number, primarily for its superior blending characteristics and economics compared to other oxygenates such as ethanol , TAME and ETBE.  This gives a reason for the increasing demand for MTBE as a gasoline additive.

Production of MTBE in USA

Global MTBE Demand by Region (2014)

Physical Properties: The main physical properties of (MTBE) are illustrated in the following table.

Properties

Information

mp bp 0.36 mpa.s

Heat of vaporization(at bp) -314 kj\ mol Heat of combustion

-34.88 Mj/kg

Flash point (Abel-pensky) Ignition temperature Explosion limit in air

1.65- 8.4 %vol

Chemical Properties: Methyl tert-butyl ether (MTBE) is very stable under alkaline, neutral, and weakly acidic conditions.  In the presence of strong acids, it is cleaved to methanol and isobutene. Property

Explosion Limit

Information 1.65 to 8.4% in air

Ignition Henrys law temperatur constant at e 25C 224 C

5.87x10^-4 (atmm^3/mol)

Other

MTBE is unstable in acidic solution

Uses and Applications The most important uses of MTBE are:  MTBE is the most widely used fuel oxygenate, due to its combination of technical advantages and supply availability.  MTBE delivers high octane value at relatively low cost. In addition, MTBE offers low water solubility (compared to e.g. alcohols), low reactivity and relatively low volatility. These characteristics allow refiners to overcome handling problems in the fuel distribution system posed by alcohol oxygenates.  Another important reason for the widespread use of MTBE is feedstock flexibility thereby ensuring ready availability and reducing dependence on crude oil for the production of automotive fuels.

Production Methods Several Routes have been proposed to produce MTBE: MTBE from Tetr-Butyl Alcohol.

MTBE from a Mixture of Methanol and Isobutanol.

MTBE from a Mixture of Methanol and Isobutene.

Process Selection  Due to its high purity product, low cost, high conversion ratio, and ability to recycle & use of reactant material the production method of MTBE from Isobutene and Methanol has been selected.  The overall reaction stoichiometry for MTBE synthesis is quite simple: one mole of methanol is added to one mole of isobutylene.

 This etherification reaction is catalyzed

in an acidic medium.

 The reaction could be realized in an homogeneous reactor with the reactants being mixed with an acid to lower their pH.

 The use of a liquid acid requires, however, an additional separation step.  Eventually, the use of solid acidic catalysts easing the separation of the catalyst from the liquid phase and this led to the development of heterogeneous reactors.

CHAPTER TWO MATERIAL BALANCE

Flow sheet

BASIC CALCULATIONS  Production of Methyl-Tert-Butyl-Ether (MTBE) = 75,000 (ton/year)  Actual operating year = 350 day

 75,000(ton/year)*1000(Kg/ton)*(year/350 day)*(1day/24hr) = 8928.571(Kg/hr)  No. of moles of MTBE = wt / M.wt = 8928.571/88.15 = 101.2884(Kmol/hr)

Material Balance on Reactor MTBE i-C4

i-C4

N-C4

N-C4

CH3OH

1

H2O

Operating Conditions:

P = 1 Bar T = 90 °C Conversion = 97%

2

CH3OH H2O

The main equations applied in this section are:  No. of moles = wt. / M.wt  %conv.= ( reacted/input )  %excess of (CH3OH) = [(input–reacted)/reacted)] *100  Mole of unreacted=(input–reacted)  Total wt input=wt. (i-c4)+ wt.(N-c4)+wt. (CH3OH)+ wt. (H2O)  Total wt. output= wt. (i-c4)+wt. (N-c4) + wt. (CH3OH)+ wt. (H2O) +wt. (MTBE)  Total moles input = n (i-c4) + n (N-c4)+ n (CH3OH)+ n(H2O)  Total moles output= n(i-c4)+n(N-c4)+n(CH3OH) +n(H2O)+ n(MTBE)

Composition of the Input & Output Streams of the Reactor: Comp.

Stream 1 Stream 2 Stream 1 (Kmol/hr) (Kmol/hr) (Kg/hr)

Stream 2 (Kg/hr)

i-C4

104.421

3.1326

5858.749

175.7619

N-C4

85.43536

85.43536

4793.5219

4793.5219

CH3OH

111.41724

10.12884

3570.031

324.548

H2O

4.04765

4.04765

72.8577

72.8577

MTBE

101.2854

8928.571

Material Balance On Distillation (1) : MTBE i-C4

4

N-C4 CH3OH H2O

MTBE i-C4 N-C4

2

CH3OH MTBE

H2O

3

i-C4 N-C4 CH3OH H2O

Operating Conditions : P= 760 mm T= 120 °C

The main equations applied in this section are:

• Antoine equation 𝑩

𝑨−𝑻+𝑪

𝒑° = 𝟏𝟎 • The heavy and light component determine from Relative Volatility 𝛼=

𝐾𝑖 𝐾 𝑠𝑒𝑙𝑒𝑐𝑡

Kselect =MTBE 𝑲𝒊 = P sat. /P tot. Where: P °= the partial pressure of the component A, B, C are Antoine Coefficients α = Relative Volatility Ki = coefficient representing

Comp.

A

B

C

K

α

4.48

1

MTBE

5.096 708.69 179.9

3411

i-C4

6.84

923.1

240

18918 24.89 5.5

N-C4

6.84

926.1

240

18638

24.5

5.4

CH3OH

8.07

1574

238.8

4800

6.3

1.4

H2O

8.14

1810

244

1484.9

1.9

0.43

From the above Table: 1- MTBE and H2O are the heavy Keys. 2- CH3OH, i-C4, and N-C4 are the light Keys.

Composition of the Input & Output Streams of the Distillation Column (1): Comp.

MTBE i-C4 N-C4 CH3OH H2O

Stream 2 Stream4 Stream 3 (Kg/hr) (Kg/hr) (Kg/hr) 8928.5 89.285 8839.215 176 174.24 1.76 4792.7 4749.773 47.927 324 320.76 3.24 72.67 0.07267 91.943

Material Balance On Distillation (2) : i-C4 N-C4

5

CH3OH H2O

MTBE i-C4 N-C4

4

CH3OH

MTBE

H2O

i-C4

6

N-C4 CH3OH H2O

* The same procedure in Distillation Column (1) was applied in this Distillation Column.

Composition of the Input & Output Streams of the Distillation Column (2): Comp.

MTBE i-C4 N-C4 CH3OH H2O

Stream 4 (Kg/hr)

Stream 5 (Kg/hr)

89.285 174.24 4749.773 320.76 0.07267

0 172.4976 4627.325 317.552 0.000726

Stream 6 (Kg/hr) 89.285 1.7424 47.4477 3.2076 0.07194

Material Balance on Absorber H2O

i-c4 N-c4 H2O CH3OH

9

8

i-C4 N-C4 CH3OH

5

7

H2O CH3OH

The main Equations applied in this section are: (L/G) act. = (L/G) theo. * 1.5

(L/G) theo. = 0.4588 L act. = G * 0.6882 𝒇𝒍𝒐𝒘 𝒓𝒂𝒕𝒆 𝒊−𝒄𝟒 𝒇𝒍𝒐𝒘 𝒓𝒂𝒕𝒆 𝒏−𝒄𝟒 G=( + ) 𝑴.𝑾𝒕 𝑴.𝑾𝒕 PA= H*XA XA = (0-1) H = Hanary constant=0.28851 Y = [PA/ (PA-PT)] PT = 760 mmHg

Composition of the Input & Output Streams of the Absorber : Comp.

Stream 5 (Kg/hr)

Stream 9 (Kg/hr)

Stream 8 (Kg/hr)

Stream 7 (Kg/hr)

i-C4

172.42

0

172.42

0

N-C4

4697.325

0

4697.325

0

CH3OH

317.552

0

3.1755

314.376

H2O

0.000762

936

0

693.000762

Material Balance on Stripper CH3OH H2O

CH3OH H2O

CH3OH H2O

10

11

7

9

H2O

Composition of the Input & Output Streams

of the Stripper:

Comp.

Stream 7 (Kg/hr)

Stream 11 Stream 10 (Kg/hr) (Kg/hr)

Stream 9 (Kg/hr)

CH3OH

315

0

311.232

3.1437

H2O

693

315

6.28

622.4

Material Balance on Knock Out i-C4 N-C4

14

6

i-C4 N-C4 CH3OH MTBE H2O

CH3OH MTBE H2O

13

Composition of the Input & Output Streams of the Knock out:

Comp.

Stream(6)

Stream(14)

( Kg/hr)

(Kg/hr)

Stream(13) (Kg/hr)

MTBE

89.285

_______

89.285

i-C4

1.7424

1.7424

_______

N-C4

47.447

47.447

_______

CH3OH

3.2076

_______

0.07194

H2O

0.017194

_______

3.2076

Material Balance on Decanter

MTBE

14 CH3OH

13

MTBE H2O

CH3OH H2O

15

Composition of the Input & Output Streams of the Decanter: Comp.

Stream

Stream

Stream

(13)

(14)

(15)

(Kg/hr)

(Kg/ hr)

(Kg/hr)

H2O

0.07194

_____

0.07194

MTBE

82.285

82.285

_______

CH3OH

3.2076

_____

3.2076

Material Balance on Mixer (2)

CH3OH H2O

i-C4 n-C4

12

16 10

15

CH3OH H2O 17 i-C4 n-C4 CH3OH H2O

CH3OH H2O

Composition of the Input & Output Streams of the Mixer (2): Comp. Stream 16

Stream 10

Stream 17

Stream 15

Stream 12

i-C4

0

0

1.74

0

1.7424

N-C4

0

0

47.49

0

47.447

3564.8

0.07194

0

72

3.2076

0

CH3OH

3251.6 311.232

H2O

65.65

6.28

Material Balance on Mixer (1)

i-C4 N-C4

18

1

17 i-C4 N-C4 CH3OH H2O

i-C4 N-C4 CH3OH H2O

Composition of the Input & Output Streams of the Mixer (1): Stream 18 (Kg/hr)

Stream17 (Kg/hr)

Stream 1 (Kg/hr)

i-C4

18084.4

1.74

18096

N-C4

5270

47.49

5270

CH3OH

0

3564.8

3564.8

H2O

0

72

72

Comp.

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