Anhydro Ethanol Bye Silica Gel

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    4th BIOMASS-ASIA WORKSHOP

    20 22, NOVEMBER 2007

    ANHYDROUS ETHANOL PRODUCTION

    SU SU HLAING

    LECTURER

    DEPARTMENT OF CHEMICAL ENGINEERING

    MANDALAY TECHNOLOGICAL UNIVERSITY

    MINISTRY OF SCIENCE AND TECHNOLOGY

    UNION OF MYANMAR

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    Objectives

    To prepare anhydrous ethanol with liquid phase adsorption

    process

    To investigate the adsorption of water on blue silica gel and

    to find the adsorption capacity of blue silica gel

    To determine the operating parameters for liquid phase

    adsorption process

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    What is Ethanol?

    product of the fermentation of starch and sugar

    clear colorless liquid with a characteristic, agreeable odor

    completely miscible with water and organic solventsapplications

    fuel

    chemical solvent

    cosmetics and pharmaceutical

    human consumption

    commercial alcohol 96% ethanol + 4% water

    anhydrous alcohol 99.5% ethanol + 0.5% water

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    How is anhydrous ethanol produced?

    by dehydration of commercial alcohol or industrial alcohol

    Technologies

    Extractive distillation

    Adsorption of water

    Azeotropic distillation

    Molecular sieve technology

    Pervaporation

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    Adsorption Process

    adsorption is essentially an attraction of adsorbate molecules to anadsorbent surface

    silica gel selectively adsorbs water to give anhydrous ethanol

    product (99.5% v/v) from commercial ethanol (96% v/v)the experimental technique is related to the various steps which

    must take place:

    preparation of blue silica gel packed columnoperating procedure

    application of feed sample to the packed bed

    flow of feed sample through the packed bed

    collection of separated sample (effluent sample)

    detection or identification of separated sample

    regeneration of spent silica gel (pink color)

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    Blue Silica Gel

    Chemical molecular formula SiO2.nH2O

    highly active adsorption material

    inert and compatible with any kind of materials, except for strong

    alkaline substances and hydrofluoric acid

    turning from blue to pink after adsorping moisture

    an infinite life in terms of the ability to adsorb or desorb moisture

    silica gel can be reconditioned and reused indefinitelyit is not recommended that blue silica gel be heated above 120C

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    Table 1. Properties of Blue Silica Gel

    Apparent or bulk density, g/cm3 0.1 0.8

    Specific gravity 2.1 2.3

    Average porosity, % 50 65Specific surface, cm2/g 2x106 7x106

    Average pore diameter, cm 4x10-7

    Pore volume, cm3/g 0.43

    Commercial gas velocity, cm/min 0.82 3.28

    Weight adsorption of water at break

    point, %

    10 20

    Weight of water at saturation, % 40

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    Experimental Works

    size reduction of blue silica gel

    batch study (determination of isotherm)

    column studies (dynamic method)

    gravity flow separation process with one packed

    columngravity flow separation process with two packed

    column

    separation processes with mobile phase pumping

    unit

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    Size Reduction of Blue Silica Gel

    Grinding

    the spherical silica gel was ground in a ball mill

    Screening

    screen analysis of the crushed particles was made

    with the aid of a laboratory test sieve shakerDrying

    the desired size of particleswas preconditioned in an oven

    at 110C for 12 hr

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    y = 2.6667x

    R2 = 0.9996

    0

    0.01

    0.02

    0.03

    0.04

    0.05

    0.06

    0 0.005 0.01 0.015 0.02 0.025

    C, g of adsorbate/ml of fluid

    q,go

    fadsorbate

    /g

    ofadsorben

    Figure 1. Adsorption Isotherm Curve

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    Feed Reservoir

    Adsorption Column

    Effluent Ethanol

    Sample Collector

    Figure 2. Gravity Flow Separation Process with One Packed Column

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    Feed Reservoir

    First Adsorption Column

    Second Adsorption Column

    Effluent Ethanol Sample Collector

    Figure 3. Gravity Flow Separation Process with Two PackedColumn

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    Feed Reservoir

    Pump

    Adsorption Column

    Effluent Ethanol Sample Collector

    Figure 4. Separation Process with Mobile Phase Pumping Unit by

    using One Packed Column

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    Conclusions

    the adsorption isotherm curve on silica gel fit with the linear

    isotherm

    Separation of water using small particle size silica gel gave betterseparation, however, a high pressure pump is needed.

    Water removal efficiency of the silica gel in this work is about 50%

    of the 96% ethanol is removed for one pass operation.

    In further work of separation with two columns in series is removed

    75% on initial water present in 96% ethanol.

    Separation process with mobile phase pumping unit by using three

    column in series produces anhydrous ethanol (99.5% v/v) by

    removing 87.5% of initial water present in commercial ethanol.

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