Group of post graduate students have made a system to remaove carbondioxide and moisture from biogas production. It is reusable. Checkout the presentation to get the idea how to prepare it. For further information can contact.

1. SEPARATION OF CO2 AND H2O
FROM BIOGAS BY ADSORPTION PROCESS
Presented by:
EN-15 Minza Mumtaz
EN-18 Samira Saad
EN-20 Sarmad Ali
EN-21 Bushra Majeed
EN-24 Aiman Fatima
EN-26 Munaizza Asghar
NED University of Engineering & Technology
Department of Environmental Engineering
(M. Engineering-Weekend Program)
EN-515 AIR POLLUTION AND CONTROL
Course Instructor:
Dr. Mehmood Ali
Associate Professor

2. TABLE OF CONTENT
o Scope
o Introduction
o Biogas; Its production and advantages
o Adsorption and its types
o Adsorbents and its types
o Preparation of activated carbon
o Designing and fabrication of adsorption bed
o Result and discussion

3. SCOPE
To remove carbon dioxide and moisture content
from biogas, prepared in lab by adsorption
method. Adsorption bed is designed on lab
scale basis for this purpose.

4. METHODS OF SEPARATION
Carbon dioxide, moisture and other gases are
considered to be impurities, if mixed with
methane because it decreases its heating
value.
CO2 and H2O (moisture can be separated
through various methods, some are:
o Membrane separation
o Physical and chemical absorption
o Physical and chemical adsorption
We have selected physical adsorption because it is
easy process, non-toxic, can be regenerated and
cost effective.

5. This is the adsorption bed
which has two portion:
o The inlet portion consists of
activated carbon
o The outlet portion consists
of synthetic zeolite.
PROCESS OVERVIEW

6. BIOGAS
PRODUCTION AND
ITS ADVANTAGES

7. Biogas is the mixture of gases
produced by the breakdown of
organic matter in the absence
of oxygen.
o It is a Clean & Renewable
Energy Source.
o Primarily consisting of
methane and carbon dioxide
BIOGAS

8. BIOGAS
During the process, organic material is decomposed by
microbial organisms in the absence of oxygen and turned
predominantly into methane (CH4), which has a calorific
value of 9.97 kWh/m³.
The methane content of the biogas generated varies from
50 volume% to 70 volume%, depending on the feedstock.
The remaining part of the gas consists largely of CO2, of
which 30 volume% to 45 volume% is contained in the
biogas.
In addition, raw biogas contains small amounts of water
(H2O), oxygen (O2), hydrogen sulphide (H2S), ammonia
(NH3) and other trace gases.

9. BIOGAS PRODUCTION IN LAB
o Biogas was produced in lab scale 6
biogas digesters.
o Different kinds of biomass like cow
dunk, natural herbs and more were
used to generate biogas in anaerobic
condition.
o Methane gas was produced with other
impurities like CO2, H2O and others,
which was need to be removed from
methane (CH4) to increase the heatin
g value of methane gas.

10. ADVANTAGES OF BIOGAS

11. ADSORPTION AND
ITS TYPES

12. ADSORPTION
o Surface phenomenon
o The material which is to be adsorbed,
gets trapped on the surface of adsorbent
o Adsorbate:
Substance that is adsorbed.
Example H2, N2, and CO2 gases.
o Adsorbent:
Surface of a substance on which
adsorbate adsorbs
like Charcoal, Silica gel, Alumina

13. TYPES OF ADSORPTION
1) Physical adsorption (Physisorption)
2) Chemical adsorption (chemisorption)

14. Why Physical adsorption?
Characteristics
o The physical adsorption occurs readily at low temperature.
o Porous substances are better adsorbents as an increased surface
area promotes adsorption.
o Does not require energy for activation.
o This adsorption is a multi-layered process.

15. ADSORBENTS
AND ITS TYPES

16. ADSORBENTS
Adsorbents are those material which
are used to trap atoms or molecules,
which needs to be separated

17. TYPES OF ADSORBENTS
NATURAL ADSORBENTS
Natural material Agricultural waste
 Wood
 coal
 peat
 clay
 chitin
 clay
 Natural zeolites
 Shells, hulls , stones from fruits
and nuts
 Sawdust
 Corncob waste
 Sunflower stalks
 straws
 Sugar cane bagasse
SYNTHETIC ADSORBENTS
Strong adsorbent Intermediate adsorbent
Activated alumina
Activated carbon
Polymer and resin
Molecular sieve
Synthetic zeolites
Calcium carbonate
Calcium phosphate
Slaked lime
Silica gel
Selection criteria of adsorbent
• Selectivity
• Capacity
• Regeneration
• Chemical and thermal stability
• Cost

18. ADSORBENTS (we used)
ACTIVATED CARBON
Activated carbon, also called activated charcoal, is a
form of carbon processed to have small, low-volume
pores that increase the surface area available for
adsorption or chemical reactions.
SYNTHETIC ZEOLITES
Zeolites are crystalline, micro-porous, hydrated
aluminosilicates that are built from an indefinitely
extending three dimensional network of [SiO4]4- and
[AlO4]4- tetrahedral linked with each other by sharing
of oxygen atom.

19. TYPES OF ZEOLITES
ZEOLITES TYPICAL OXIDE FORMULA
Zeolite A Na2O.Al2O3.2SiO2.4.5H2O
Zeolite X Na2O.Al2O3.2.5SiO2.6H2O
Zeolite Y Na2O.Al2O3.4.8SiO2.8.9H2O
We have selected synthetic zeolite of pore size 4A with basic
PH-11 because biogas which we have obtained is acidic in nature.

20. ADSORPTION CAPABILITIES
MODEL PORE DIAMETER
(ANGSTROM)
USAGE
3A 3 Desiccation of petroleum cracking gas and alkenes, selective
adsorption of H2O in insulated glass (IG) and polyurethane
4A 4 Adsorbed species include SO2, CO2, H2S, C2H4, C2H6, and C3H6.
Generally considered a universal drying agent in polar and nonpolar
media, separation of natural gas and alkenes, adsorption of water in
non-nitrogen sensitive polyurethane.
5A 5 Desiccation and purification of air; dehydration and desulfurization
of natural gas and liquid petroleum gas; oxygen and hydrogen
production by pressure swing adsorption process.
10X 10 High-efficient sorption, used in desiccation, decarburization, desulfu-
rization of gas and liquids and separation of aromatic hydrocarbon.
13X 13 Desiccation, desulfurization and purification of petroleum gas and
natural gas.

21. PREPARATION OF
ACTIVATED
CARBON IN LAB

22. ACTIVATED CARBON
o Micro pores
o Increase surface area for adsorption
o One gram of activated carbon has a surface area in excess
of 3,000 m2 (32,000 square feet) as determined by gas
adsorption.
o Filters with activated carbon are usually used for natural gas
purification to remove hydrocarbons, moisture and odor from
natural gas (methane).

23. PREPARATION OF ACTIVATED
CARBON IN LAB
1. Washed, dried
(exposure to
sunlight for 10
hours) and
peeled Coconut
fibers.
2. Fibrous part
was collected
by broken it in
to small fibers.
3. Burnt in the
furnace at 350°
C for an hour.
4. Obtained
charcoal was
sieved to get the
mean diameter
particles.

24. DESIGNING AND
FABRICATION
OF ADSORPTION
BED

25. DESIGNING
REACTOR 1 COW MANURE (25%) CONTROLLED PANICUM
(25%)
WATER (50%)
ASSUMPTIONS
Inlet moisture (H2O) concentration 35% (w/w)
Inlet Carbon dioxide (CO2) concentration 25% (w/w)
Inlet methane (CH4) concentration 40% (w/w)
Velocity of biogas 0.5 L/min
EXPERIMENTAL CONDITIONS
Adsorption temperature 25 ℃
Adsorption pressure 1 bar
BED DESIGN
Bed weight 40 grams activated carbon
25 grams synthetic zeolite
Bed length 8 inches
4 inches for activated carbon
4 inches of synthetic zeolite
Bed diameter 11/2 inches

26. FABRICATION OF
ADSORPTION BED
o For the fabrication of adsorption bed 8 inches long, PVC pipe of
schedule 40 with inner diameter 11/2 inches was used.
o In 8 inches pipe two portion of equal lengths were made, lower portion
which is the inlet was filled with 40 grams activated carbon, used for
moisture removal.
o The upper portion was filled with 25 grams of synthetic zeolite for
carbon dioxide removal.
o The upper and lower ends were sealed PVC air tight pipe caps.
o Connecting rubber pipe was fitted on both ends.
o At inlet side one ball valve was installed to control the flow of biogas.
o One pressure gauge at inlet side just after valve was connected in
order to get the inlet pressure of gas, before going into the bed.

28. EXPERIMENTAL PROCESS OF
ADSORPTION OF BIOGAS
o Reactor one is connected with one end of the compressor.
o The other end was connected with the rubber pipe of the adsorption
bed.
o The valve of the biogas reactor and the inlet valve of adsorber was
opened.
o As the compressor starts, the gas starts to flow through the compre-
ssor into the adsorber bed at 1 bar pressure.
o The gas passes through the activated carbon portion and then
synthetic zeolite portion.
o After that the biogas was collected in balloon, in order to know the
volume of biogas generated in a biogas reactor.

29. RESULTS AND DISCUSSION
RESULTS ON THE BASIS OF ASSUMPTIONS
Inlet H2O = 35 (w/w) Efficiency is in the range of 60-70%
Inlet CO2 = 25 (w/w) Efficiency more than 90%
These results are based on assumption, referred from
research paper, so it may vary from real values. But from
these results it can be concluded that the capacity of
activated carbon for moisture removal is low but it is cost
effective and easy to make. Activated carbon is more
reliable to remove hydrocarbons and odors. The efficiency
of zeolite is good and its capacity for the absorption of
carbon dioxide is high, more than 90%, because the volu
me collected in balloon was found to be 1550ml while the
maximum volume from different reactor was 2626ml from
reactor 6.

30. THANK
YOU

31. REFERENCES
o https://www.sciencedirect.com/topics/chemistry/biogas-production
o https://www.sciencedirect.com/science/article/abs/pii/S1750583607
00031X
o https://www.sciencedirect.com/topics/engineering/synthetic-zeolite
o https://www.sciencedirect.com/topics/earth-and-planetary-sciences
/activated-carbon
o https://www.sciencedirect.com/topics/earth-and-planetary-sciences
/activated-carbon
o https://www.pnas.org/content/96/7/3471