adsorption engineering：吸附工程.ppt

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Aerosol & Particulate Research Lab
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Adsorption
Physical vs chemical adsorption
Sorbent materials
Mechanism
Isotherm
Effects of humidity
Fixed-bed systems
Regeneration
Rotary bed and fluidized bed systems
Pressure drop
Reading: Chap. 12
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Aerosol & Particulate Research Lab
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Definition
The concentration of gases, liquids or dissolved substances (adsorbate) on the surface of solids (adsorbent)
Physical Adsorption (van der Waals adsorption):
weak bonding of gas molecules to the solid;
exothermic (~ Kcal/mole);
reversible
Chemisorption:
chemical bonding by reaction;
exothermic (10 Kcal/mole);
irreversible
Q: Examples in your daily life?
Physical vs Chemical
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Aerosol & Particulate Research Lab
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Sorbent Materials
Activated Carbon
Activated Alumina
Air Pollution Engineering Manual., 1992
Silica Gel
Molecular Sieves (zeolite)
Polar and Non-polar adsorbents
Q: If an activated carbon granule is a solid particle with
1 mm diameter, what is the specific surface area (r = g/cm3)?
Properties of Activated Carbon
Bulk Density
22-34 lb/ft3
Heat Capacity
- BTU/lboF
Pore Volume
- cm3/g
Surface Area
600-1600 m2/g
Average Pore Diameter
15-25 Å
Regeneration Temperature
(Steaming)
100-140 oC
Maximum Allowable
Temperature
150 oC

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Aerosol & Particulate Research Lab
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OH
OH
heating
H2O
H2O
hydrophilic
OH
OH
O
hydrophobic
H2O
Q: What if it is heated over 250 oC?
Properties of Silica Gel
Bulk Density
44-56 lb/ft3
Heat Capacity
- BTU/lboF
Pore Volume
cm3/g
Surface Area
750 m2/g
Average Pore Diameter
22 Å
Regeneration Temperature
120-250 oC
Maximum Allowable Temperature
400 oC
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Aerosol & Particulate Research Lab
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Crystalline zeolite
Uniform pores to selectively separate compounds by size & shape
Air Pollution Engineering Manual., 1992
Properties of