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STUDIES IN EXTRACTIVE AND AZEOTROPIC DISTILLATION SERIES

Study Number 3 - SEPARATION OF HYDROCARBONS

A summary of experimental results (in outline format) from a series of investigations of hard-to-separate hydrocarbon liquid binary mixtures

Dr. Lloyd Berg,

Chairman and Director of Research, Brix-Berg Company PLLC
Emeritus Department Head and Professor, Chemical Engineering Department, Montana State University
and

A. Terry Brix, President, Brix-Berg Company PLLC

Separations Studied:

Aliphatics - Saturated and Unsaturated

C6 1-hexene from hexane (Table 1)

C7 heptane from 1-heptene (Table 2)

C8 octane from 1-octene (Table 3)

1-octene from isomers (Table 4)

C10 1-decene from decane (Table 5)

Terpenes

a - phellandrene from 3-carene (Table 6)

menthane from cymene (Table 7)

 

Aromatic and Cyclic

benzene from non-aromatics (Table 8)

toluene from non-aromatics (Table 9)

cyclohexane from cyclohexene (Table 10)

 

Experimental:

For each hydrocarbon liquid pair, typically 100 to 200 different organic solvents were evaluated for potential as agents in extractive or azeotropic distillation. Tests consisted of determination of relative volatility - with and without agent - in an Othmer vapor-liquid equilibrium still.

In a number of cases (but not all), where favorable relative volatility was found in the Othmer still, a batch distillation test was conducted in a 3" diameter - 5.5 theoretical plate glass distillation column. All testing was conducted at atmospheric pressure at Bozeman MT.

Analyses were conducted by the author or his assistants using a Varian Gas Chromatograph equipped with a hydrocarbon column.

Results:

Following are a series of Tables summarizing the test series for each organic hydrocarbon separation studied in this work.

Table 1 - 1-hexene/hexane Separation

Separation

1-hexene from hexane

Method

Extractive Distillation

Relative Volatility - no agent

1.07

Effective Extractive agents found

20

Range of Relative Volatilities found with agents

1.18 to 1.35

Effective agent classes

Certain alcohols, esters, ketones

Agent Performance Examples

 

Agent

Relative Volatility

Notes

Isobutanol

1.18

1-hexene overhead
1-Hexanol

1.20

1-hexene overhead
Methyl amyl alcohol

1.25

1-hexene overhead
Butyl formate

1.20

1-hexene overhead
Hexyl acetate

1.27

1-hexene overhead
Hexyl formate

1.35

1-hexene overhead
2,6-Dimethyl-4-heptanone

1.25

1-hexene overhead
Propiophenone

1.30

1-hexene overhead

 

Table 2 - heptane/1-heptene Separation

Separation

Heptane from 1-heptene

Method

Extractive Distillation

Relative Volatility - no agent

1.10

Effective Extractive agents found

8

Range of Relative Volatilities found with agents

1.3 to 2.1

Effective agent classes

Ketones, alcohols, sulfoxide, amides

Agent Performance Examples

 

Agent

Relative Volatility

Notes

Ethyl butyrate

2.10

heptane overhead
5-Methyl-2-hexanone

1.30

heptane overhead
Di-nonyl phenol

1.35

heptane overhead
Diacetone alcohol

1.45

1-heptene overhead,

VLE still & 3" col. tests

Acetophenone

1.25

1-heptene overhead,

VLE still & 3" col. tests

Dimethylacetamide

1.35

1-heptene overhead,

VLE still & 3" col. tests

Dimethyl sulfoxide

1.58

1-heptene overhead,

VLE still & 3" col. tests

Table 3 - 1-octene/octane Separation

Separation

1-octene from octane

Method

Azeotropic Distillation

Relative Volatility - no agent

1.2

Effective Azeotropic agents found

5

Range of Relative Volatilities found with agents

1.5 to 1.9

Effective agent classes

Amide, ester, ether

Agent Performance Examples

 

Agent

Relative Volatility

Notes

Methyl acetate

1.5

1-octene overhead
Ethyl acetate

1.6

1-octene overhead
Dimethyl acetamide

1.5

1-octene overhead
Ethyl formate

1.9

octane overhead,

VLE and 3" col. test

t-Amyl methyl ether

1.8

octane overhead,

VLE and 3" col. test

Table 4 - octene/isomers Separation

Separation

Octene from isomers

Method

Extractive and Azeotropic Distillation

Relative Volatility - no agent

1.17

Effective agents found

22

Range of Relative Volatilities found with agents

1.25 to 3.0

Effective agent classes

AZ - ethers, esters, ED - alcohols, esters

Agent Performance Examples

 

Agent

Relative Volatility

Notes

Isophorone

1.45

ED - isomers overhead
Phenethyl alcohol

1.95

ED - isomers overhead
Ethyl valerate

3.0

ED - isomers overhead
t-Amyl methyl ether

2.1

AZ separation, VLE & 3" col. tests,

Isomers overhead

Isopropyl ether

1.75

AZ separation, isomers overhead
Isopropyl acetate

1.8

AZ separation,

isomers overhead

Methyl butyl ether

2.0

AZ separation,

isomers overhead

 

Table 5 - 1-decene/decane Separation

Separation

1-decene from decane

Method

Azeotropic Distillation

Relative Volatility - no agent

1.20

Effective Azeotropic agents found

7

Range of Relative Volatilities found with agents

1.25 to 1.65

Effective agent classes

Ester, ether

Agent Performance Examples

 

Agent

Relative Volatility

Notes

Isobutanol

1.18

1-hexene overhead
1-Hexanol

1.20

1-hexene overhead
Methyl amyl alcohol

1.25

1-hexene overhead
Butyl formate

1.20

1-hexene overhead
Hexyl acetate

1.27

1-hexene overhead
Hexyl formate

1.35

1-hexene overhead
2,6-Dimethyl-4-heptanone

1.25

1-hexene overhead
Propiophenone

1.30

1-hexene overhead

Table 6 - a -phellandrene/3-carene Separation

Separation

a -phellandrene from 3-carene

Method

Azeotropic Distillation

Relative Volatility - no agent

1.05

Effective Azeotropic agents found

13

Range of Relative Volatilities found with agents

1.2 to 2.7

Effective agent classes

Aldehyde, ester, nitro-compounds

Agent Performance Examples

 

Agent

Relative Volatility

Notes

Methyl formate

1.7

Phellandrene overhead
Methyl caproate

2.7

Phellandrene overhead
Methyl amyl acetate

1.85

Phellandrene overhead - VLE and 3" col. tests
Acetal

2.0

Carene overhead
Nitroethane

1.3

Carene overhead
Nitromethane

1.5

Carene overhead
Ethyl acetate

1.25

Carene overhead

Table 7 - menthane/cymene Separation

Separation

p-menthane from p-cymene

Method

Azeotropic and Extractive Distillation

Relative Volatility - no agent

1.19

Effective agents found

35

Range of Relative Volatilities found with agents

1.3 to 3.9

Effective agent classes

Esters, alcohols, ethers

Agent Performance Examples

 

Agent

Relative Volatility

Notes

Methyl benzoate

1.64

ED - menthane overhead, VLE and 3" col. tests
Nonyl alcohol

1.8

ED - menthane overhead
Isobutyl heptyl ketone

1.4

ED - cymene overhead
Cyclododecanol

3.9

ED - cymene overhead
Isobutanol

2.4

AZ - menthane overhead, VLE and 3" col. tests
Diethylene glycol ethyl ether

3.8

AZ - menthane overhead
1-Pentanol

2.7

AZ - cymene overhead
Dipropylene glycol methyl ether

2.1

AZ - cymene overhead

 

Table 8 - benzene/cyclohexane

Separation

Benzene from cyclohexane

Method

Azeotropic and Extractive Distillation

Relative Volatility - no agent

1.02

Effective Azeotropic agents found

47

Range of Relative Volatilities found with agents

1.3 to 2.4

Effective agent classes

Sulfoxide, ester, phenols, cresols, ethers

Agent Performance Examples

 

Agent

Relative Volatility

Notes

Dimethylsulfoxide

175

ED - cyclohexane overhead
Methyl acetoacetate

2.0

ED - cyclohexane overhead
2-Furaldehyde

2.1

ED - cyclohexane overhead
3-Ethyl phenol

1.6

ED - cyclohexane overhead
Dimethoxy methane

1.78

AZ - cyclohexane overhead, VLE and 3" col. tests
Methyl acetate

2.4

AZ - cyclohexane overhead
2,2-Dimethoxy propane

1.65

AZ - benzene overhead
Methanol

1.6

AZ - cyclohexane overhead

Table 9 - toluene/methyl cyclohexane

Separation

Toluene from methyl cyclohexane

Method

Extractive Distillation

Relative Volatility - no agent

1.5

Effective Azeotropic agents found

16, plus mixes

Range of Relative Volatilities found with agents

2.0 to 4.1

Effective agent classes

Ketones, nitro-compounds, phenols, esters

Agent Performance Examples

 

Agent

Relative Volatility

Notes

Glycerol triacetate

2.85

Methylcyclohexane overhead
Phenol

2.95

Methylcyclohexane overhead
Furfural

3.35

Methylcyclohexane overhead
Acetophenone

2.68

Methylcyclohexane overhead
Dimethylformamide

3.6

Methylcyclohexane overhead
2-Nitrotoluene

2.55

Methylcyclohexane overhead
Triethylene glycol diacetate

3.1

Methylcyclohexane overhead
Maleic and phthalic anhydride/ glycerol triacetate mixture

4.1

Methylcyclohexane overhead,

VLE & 3" col. tests

Table 10 - cyclohexane/cyclohexene

Separation

Cyclohexane from cyclohexene

Method

Extractive and Azeotropic Distillation

Relative Volatility - no agent

1.07

Effective Azeotropic agents found

12 with mixes

Range of Relative Volatilities found with agents

1.3 to 2.3

Effective agent classes

Amides, n-alcohols, glycol ethers

Agent Performance Examples

 

Agent

Relative Volatility

Notes

Dimethylacetamide

1.3

ED - cyclohexane overhead
Dimethylacetamide + acetophenone

1.34

ED - cyclohexane overhead
Diacetone alcohol

1.23

ED - cyclohexane overhead, VLE & 3" col. tests
Propylene glycol methyl ether

1.25

ED - cyclohexane overhead
Ethanol

1.39

AZ - cyclohexane overhead
n-Propanol

1.43

AZ - cyclohexane overhead
n-Butanol

2.0

AZ - cyclohexane overhead
Ethylene glycol methyl ether

2.3

AZ - cyclohexane overhead

STUDIES IN EXTRACTIVE AND AZEOTROPIC DISTILLATION SERIES

 


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