Acetic Acid Separation Methods Acetic Acid Separation Methods Supervisore: Prof. H. S. Ghaziaskar By: H. Rastegari

Contents  Acetic Acid Uses  Acetic Acid Production  Acetic Acid Separation methods  Conclusion  References 1

 In vinyl acetate monomer production  In acetic anhydride production  As solvent in production of terphetalic acid  As recrystalization solvent  In Silage  In production of various acetates such as:  Sodium acetate  Copper acetate  Aluminum acetate  Palladium acetate Acetic Acid Uses 2

Acetic Acid Production  Chemical processes for acetic acid production:  Reaction of methanol with carbon monoxide  Reaction of acetylene with water followed by air oxidation  Fermentation of ethanol  Butane oxidation 3

 Other chemical processes which produce acetic acid as a by-product:  Manufacture of cellulose esters  Reactions involving acetic anhydride  Synthesis of glyoxal from acetaldehyde and nitric acid  Wood distillate 4

 Problem Separating acetic acid from water 5

6 Separation Methods  Separation Involving Phase Changes: Simple Distillation Azeotropic Distillation Extractive Distillation Reactive Distillation  Separation involving membranes: Pervaporation Evapomeation Temperature Difference Evapomeation Electrodialysis Bipolar Membrane Electrodialysis

Simple Distillation  Physical separation process based on differences in volatilities 7

 Advantage Simple and easy to operate 8  Disadvantage Large energy consumption

Azeotropic Distillation  Distillation in the presence of entrainer 9

 Desirable properties for an azeotropic entrainer :  Heterogeneous azeotrope  Commercially available and inexpensive  Nontoxic  Chemically Stable  Noncorrosive  Low heat of vaporization The best entrainer is: The best entrainer is: Alkyl Acetate Alkyl Acetate 10

 Effective parameters for alkyl acetate selection  Azeotropic temperature  Azeotropic composition  Aqueous phase composition and entrainer pricing 11

 Advantage Improving the economics of the separation Improving the economics of the separation  Disadvantage Requiring large amount of entrainer Requiring large amount of entrainer 12

Extractive Distillation  Distillation in the presence of solvent 13

 Desirable properties for solvent:  Nonvolatile  High boiling point  Make large difference in volatility between components  Miscible with mixture and doesn´t form azeotropic mixture  Commercially available and inexpensive  Noncorrosive  Physically and chemically stable 14

The best solvent is: Trialkyl Amine Trialkyl Amine  Advantage Relatively little energy consumption Relatively little energy consumption  Disadvantage Need additional heat requirement on the column Some what larger plates 15

Reactive Distillation  Chemical separation method which combines simultaneous chemical reaction and multicomponent distillation in the same vessel 16

 Mechanism of reaction: First Step: Second Step: Third Step: 17

 Effect of various parameters on the acid conversion  Total feed flow rate Optimum value:192 mL/h  Mole ratio 18

 Reflux configuration  Feed position 19

Pervaporation (PV)  separation of liquid mixtures by partial vaporization through membrane 20

 Used membrane  Polydimethylsiloxane (PDMS)  Cross-linked polybutadiene  Silicalite-1 as adsorbent filler in PDMS membrane  Carbon molecular sieve in PDMS membrane  Silicalite-1(pure silica)  Ge-ZSM-5  Sn-ZSM-5 20

 Effective parameters on separation performance  Si/Sn  Temperature  Acid concentration  Disadvantage Shrinking and swelling of the membrane 21

Evapomeation(EV)  Vaporization of feed solution then permeation through polymeric membrane 22

 Effective parameters on separation performance  Temperature  Acid concentration  Disadvantage membrane condensation in high acid concentration membrane condensation in high acid concentration 23

Temperature Difference Evapomeation (TDEV)  Decreasing temperature in the membrane surroundingthan in the feed solution  Decreasing temperature in the membrane surrounding than in the feed solution 24

Electrodialysis (ED)  Ion transportation from one solution through ion- exchange membranes to another solution under the influence of an electric potential difference 25

 Application Concentrating acetic acid from water containing %1(w/w) acid to %10(w/w) 26

 Importance Make full use of our limited resources Protect our environment  Disadvantage Concentration efficiency up to %10 Low electric current efficiency (around %20) Low electric current efficiency (around %20) 27

Bipolar Membrane Electrodialysis (BME) 28

 Application Concentrating acetic acid from water containing %0.2(w/w) acid to %14(w/w) Concentrating acetic acid from water containing %0.2(w/w) acid to %14(w/w)  Disadvantage Low electric current efficiency (around %40) Low electric current efficiency (around %40) 29

Conclusion For high purity (%99.9) acetic acid Azeotropic Distillation For reasonably pure acetic acid Extractive Distillation For ester production Reactive Distillation For separation from solution containing % (5-15) acid PV 30

References [1] Garwin, L., Hutchisoni, K., E., Industrial And Engineering Chemistry 42(4), [2] Othmer, D., F., Industrial And Engineering Chemistry 27(3), [3] Lee, F., M., Wytcherley, R., W., Distillation, Academic Press, USA, [4] Chien, I., L., Kuo, C., L., Chemical Engineering Science 61, [5] Wang, S., J., Lee, C., J., Jang, S., S., Shieh, S., S., Process Control 18,

[ 6] Garwin, L., Haddad, P., O., Industrial And Engineering Chemistry 45(7), [7] Lei, Z., Li, C., Li, Y., Chen, B., Separation And Purification Technology 36, [8] Taylor, R., Krishna, R., Chemical Engineering Science 55, [9] Saha, B., Chopade, S., P., Mahajani, S., M., Catalysis Today 60, [10] Yu, L., Guo, Q., Hao, J., Jiang, W., Desalination 129, [11] Sun, W., Wang, X., Yang, J., Lu, J., Han, H., Zhang, Y., Wang, J., Membrane Science 335,

[12] Li, G., Kikuchi, E., Matsukata, M., Separation Purification Technology 32, [13] Toti, U., S., Kariduraganavar, M., Y., Soppimath, K., S., Aminabhavi, T., M., Applied Polymer Science 83, [14] Asman, G., Anl, O., Separation Science And Technology 41(6) [15] Asman, G., Sanli, O., Applied Polymer Science 100, [16] Chien, I., L., Zeng, K., L., Chao, H., Y., Liu, J., H., 2004.Chemical Engineering Science 59, [17] Kittur, A., A., Tambe, S., M., Kulkarni, S., S., Kariduraganavar, M., Y., Applied Polymer Science 94,

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Glyoxal: Acetic Acid Production

V HAC = (y HAC ) / (x HAC ) V H2O = (y H2O ) / (x H2O ) Dalton's Law: P H2O = (y H2O ) * p t Raoult's law: P H2O = (x H2O ) * p 0 H2O Simple Distillation

α = V H2O / V HAC Fenske Equation: (y H2O )/(1- y H2O ) = α n+1 (x H2O )/(1- x H2O )

Azeotropic Distillation

Extractive Distillation Solvent volume