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48 2. Adsorption, Ion Exchange, and Catalysis

Table 2.9

Representative commercial gas-phase adsorption separations
Gas bulk separations Adsorbent
(adsorbate concentration in the feed 10% wt.)
N 2 /O 2 Zeolite
O 2 /N 2 e v Carbon molecular sie
H 2 O/ethanol Zeolite
CO, CH 4 ,C O 2 ,N 2 ,N H 3 /H 2 Zeolite, acti ated carbon v
Acetone/vent streams Activated carbon
C2H4/vent streams Activated carbon
ications Gas purif Adsorbent
(adsorbate concentration in the feed 3% wt.)

H 2 O/olefin-containing cracked gas, natural gas, Silica, alumina, zeolite
air, synthesis gas
SO 2 /vent streams Zeolite
CO 2 /C 2 H 4 , natural gas Zeolite
Organics/vent streams Activated carbon and others
Sulfur compounds/natural gas, hydrogen, liquef ied Zeolite
petroleum gas (LPG)
Solvents/air Activated carbon
Odors/air Activated carbon
NO x /N 2 Zeolite

As any process, adsorption has both some advantages and disadv antages:

age Advants
• v high remoal efficiency
• enables remoal of refractory and/or toxic organic compounds v
• possibility of compounds recoery (preferably with zeolites) v
• simple installation and maintenance
• capability of systems for fully automatic operation
• a large variety of adsorbents a ailable v

Disadvantages
• adsorbents deteriorate in capacity gradually
• particulates in the feed can cause problems
• high content of macromolecular compounds decreases efy and may cause irre- f icienc
versible blockage of acti e sites v
• risk of bed fires in the OC abatement V
• spent adsorbent has to be regenerated (high energy consumption) or disposed (causing
waste)
• relatively high capital cost