Professor Xijun Hu
Adsorption
References:
D.D. Do, “Adsorption Analysis: Equilibrium and Kinetics”,
0Imperial College Press, 1998.
R.T. Yang, “Gas Separation by Adsorption Processes”, Butterworths,
Boston, 1987.
D.M. Ruthven, “Principles of Adsorption and Adsorption
Processes”, John Wiley & Sons, New York, 1984.
In adsorption processes one or more components of a gas or liquid stream (adsorbate or solute) are adsorbed on the surface of a solid (adsorbent) and a separation is accomplished. 235
JEVE 5760 Advanced Physico-Chemical Treatment Processes
Professor Xijun Hu
Adsorbents
Good adsorbents should have
high surface area or micropore volume (for large adsorption capacity)
large pore network for the transport of molecules to the interior (for fast kinetics)
The porous solid must have small pore size (micropore) with a reasonable porosity to satisfy the first requirement and have a network of large pore size
(macropore) for the second requirement.
Micropore: d < 2 nm
Mesopore: 2 < d < 50 nm
Macropore: d > 50 nm
236
JEVE 5760 Advanced Physico-Chemical Treatment Processes
Adsorbent
Activated carbon Silica gel
Activated alumina Molecular sieve zeolites
Manufacturing method by thermal decomposition of coal, wood, vegetable shells, etc. by acid treatment of sodium silicate solution & then dried hydrated aluminum oxide is activated by heating to drive off the water porous crystalline aluminosilicate containing precisely uniform pores
Surface area (m2/g)
3002000
340800
200500
Professor Xijun Hu
Pore
Usage
diameter o (A )
10-60
Removal of organic vapors;
H2
purification
20-140 dehydrate gases & liquids; fractionate hydrocarbon 20-140 drying; gas JEVE 5760 Advanced Physico-Chemical Treatment Processes
Properties to characterize adsorbents:
Specific pore volume
References: D.D. Do, “Adsorption Analysis: Equilibrium and Kinetics”, 0Imperial College Press, 1998. R.T. Yang, “Gas Separation by Adsorption Processes”, Butterworths, Boston, 1987. D.M. Ruthven, “Principles of Adsorption and Adsorption Processes”, John Wiley & Sons, New York, 1984.