71
Table 4 Commercially available biogas upgrading technologies
Method
type
Upgrading
technology
Principle
CH 4 purity [%] Reference
Physical
methods
Water physical
scrubbing
Biogas stream flows through a
counter flow water in a column.
CO 2 ’s higher solubility in water
makes the water absorb CO 2 , thus
enriching the CH 4 content of
biogas. The method required
biogas drying and water
regeneration to remove CO 2 by
desorption
96–98
Adnan et al.
[114], Bauer
et al. [116]
and Munoz
et al. [117]
Organic
solvent
scrubbing
The same as in the case of water
scrubbing, except for the use of
organic solvents (e.g.
polyethylene glycol) instead of
water. Cooling and heating of the
solvent are needed during the
procedure
96–98
Adnan et al.
[114] and
Bassani [115]
Pressure swing
adsorption
A water solution of amines (a
mixture of monoethanolamine or
di-methyl ethanol amine DEA and
piperazine) binds with CO 2
molecules in the biogas; then, the
amine solution is regenerated by a
stripper that releases CO 2 into the
atmosphere
>99
Adnan et al.
[114], An
et al. [118],
Augelleti et al.
[119] and
Bassani [115]
Membrane
separation
Dry or wet separation of biogas
components using selective
membranes (organic polymer
polyimide; inorganic zeolites,
silica; activated carbon
membranes, metallic-based
materials; mixed polymerceramic, polymer-carbon, etc.) as
a permeable material for CH 4 , N 2 ,
H 2 S, CO 2 , H 2 O
92–96
Bassani [115],
Bassani [111],
Bauer et al.
[116],
Harasimowicz
et al. [120]
and Khan
et al. [121]
Chemical
methods
Amine or
alkali/salt
chemical
scrubbing
Biogas-liquid mass transfer
principle in a countercurrent flow,
using absorbents such as mono-,
di-, triethanolamine, methyl
diethanolamine with a stripper
piperazine or alkali aqueous
solutions
99.9
Andriani et al.
[122] and
Munoz et al.
[117]
Methanation
(Sabatier
reaction)
Reaction of CO 2 with H 2 for
producing CH 4 and H20 (Sabatier
reaction), on selective catalysts
(nickel or heterogeneous
catalysts: copper-, iron-, zinc- or
ceria-based oxides), at
temperatures of ~500 °C and
pressure of 5–10 MPa
Adnan et al.
[114],
Klankermayer
et al. [123],
Sun et al.
[124] and
Wang et al. [9]
Biochemical Conversion of Residual Biomass: An Approach to Fuel Gas and Green…
Table 4 Commercially available biogas upgrading technologies
Method
type
Upgrading
technology
Principle
CH 4 purity [%] Reference
Physical
methods
Water physical
scrubbing
Biogas stream flows through a
counter flow water in a column.
CO 2 ’s higher solubility in water
makes the water absorb CO 2 , thus
enriching the CH 4 content of
biogas. The method required
biogas drying and water
regeneration to remove CO 2 by
desorption
96–98
Adnan et al.
[114], Bauer
et al. [116]
and Munoz
et al. [117]
Organic
solvent
scrubbing
The same as in the case of water
scrubbing, except for the use of
organic solvents (e.g.
polyethylene glycol) instead of
water. Cooling and heating of the
solvent are needed during the
procedure
96–98
Adnan et al.
[114] and
Bassani [115]
Pressure swing
adsorption
A water solution of amines (a
mixture of monoethanolamine or
di-methyl ethanol amine DEA and
piperazine) binds with CO 2
molecules in the biogas; then, the
amine solution is regenerated by a
stripper that releases CO 2 into the
atmosphere
>99
Adnan et al.
[114], An
et al. [118],
Augelleti et al.
[119] and
Bassani [115]
Membrane
separation
Dry or wet separation of biogas
components using selective
membranes (organic polymer
polyimide; inorganic zeolites,
silica; activated carbon
membranes, metallic-based
materials; mixed polymerceramic, polymer-carbon, etc.) as
a permeable material for CH 4 , N 2 ,
H 2 S, CO 2 , H 2 O
92–96
Bassani [115],
Bassani [111],
Bauer et al.
[116],
Harasimowicz
et al. [120]
and Khan
et al. [121]
Chemical
methods
Amine or
alkali/salt
chemical
scrubbing
Biogas-liquid mass transfer
principle in a countercurrent flow,
using absorbents such as mono-,
di-, triethanolamine, methyl
diethanolamine with a stripper
piperazine or alkali aqueous
solutions
99.9
Andriani et al.
[122] and
Munoz et al.
[117]
Methanation
(Sabatier
reaction)
Reaction of CO 2 with H 2 for
producing CH 4 and H20 (Sabatier
reaction), on selective catalysts
(nickel or heterogeneous
catalysts: copper-, iron-, zinc- or
ceria-based oxides), at
temperatures of ~500 °C and
pressure of 5–10 MPa
Adnan et al.
[114],
Klankermayer
et al. [123],
Sun et al.
[124] and
Wang et al. [9]
Biochemical Conversion of Residual Biomass: An Approach to Fuel Gas and Green…