SEPURAN® Green
Membrane technology
for upgrading biogas efficiently

Gas separation with SEPURAN®
Evonik, the creative industrial group from Germany, is one of the world leaders inspecialty chemicals. As a technology leader in high-performance polymers, we offer
hollow-fiber membranes for efficient and energy-saving gas separation. The first
product of the SEPURAN® product family is SEPURAN® Green for biogas upgrading.

2Benefits

Applications• Lower energy consumption• No auxiliary materials such as wateror sorbents required• No emissions into the environment• Separation at ambient temperature• Low space requirements• Continuous separation process• Simple, modular setup• Flexible and easily expanded• Very high selectivity• Extraction of methane• Upgrading of process gases• Nitrogen generation• Upgrading of H2• Helium recovery

Relative permeation rates of various gases

HOHeH

COO

FastN

Mode of operation of a membrane cartridge for gas separation

CHPermeate
Feed

Retentate

Slow
Hollow ﬁber membranes

How does membrane-based
separation work?
Gas separation membranes work on theprinciple of selective permeation througha membrane surface. The driving force
for permeation of the gas through themembrane is the difference between thepartial pressures of the gas on the retentate side (the interior of the hollow fiber)
and the permeate side (the exterior of thehollow fiber).

The greater this difference, the higher
the proportion of the gas that permeates
through the membrane. In a separation,such as between carbon dioxide andmethane, permeation of carbon dioxidethrough the membrane is much faster
while methane is retained within.
The permeation rate of each gas depends
on its solubility in the membrane material
and on the diffusion rate. Gases that havehigher solubility and smaller molecularsize permeate the membrane faster thanlarger, less soluble gases. The ratio of thetransport speeds of two gases is called
selectivity.
The higher the selectivity, the higher
the energy efficiency of the resulting
membrane process. Different membranematerials have different separation properties. The driving force required for theseparation is obtained through a partialpressure gradient.

3

Our product –The SEPURAN® Green cartridge
The SEPURAN® product family includes membrane systems for gas separationin various applications. The SEPURAN® Green cartridge is specially designed forbiogas upgrading.
The SEPURAN® Green membrane cartridge consists of several thousand hollow
fibers manufactured from high-performancepolymers and bundled in a stainless steel
vessel. The ends are embedded in a resin.
The membrane cartridge is contained ina closed housing unit.
The membrane system can now withstanda gas mixture under pressure.

4

Many membrane systems can be connected
together in series as desired, depending on
the application and the size of the system.
The simple, easy-to-handle set-up takes
up less space in the upgrading plant.
Thanks to the excellent selectivity ofthe membranes, the continuous separation
process results in very high energy
efficiency.

Cartridge housing
SEPURAN® Green cartridges are contained in specially developed housings.
The housings are available in different variants to match local requirements.

These stainless steel vessels for theSEPURAN® Green cartridges are manufactured by external partners, taking
individual national requirements intoconsideration.
This offers plant engineering companies
the advantage of being able to adapt
the pressure housings to local pressure
regulations. Housings for pressure up to40 bara are available.

Benefits of the cartridge system• Low weight• Quick and economic membrane
replacement• Flexibility for housing designs• Cost benefits in current expenses

5

Biomass fromorganic waste

Biomass from(liquid) manure

Biomass fromrenewable resources

Biogas plant

SEPURAN® Greenfor biogas upgrading
The SEPURAN® product family includes membrane systems for gas
separation for various applications. Thanks to its high CO2 over CH4 selectivity,
SEPURAN® Green is well suited for biogas upgrading.

6Production of biogas

Selectivity of SEPURAN® Green

Biogas is formed by fermentation in whichmicroorganisms anaerobically decompose
biomass. Crude biogas contains 55–65%
methane, 30–45% carbon dioxide, andtrace gases such as hydrogen sulfide. After appropriate pretreatment and subsequent upgrading with SEPURAN® Green,
the biomethane so produced is fed into
the natural gas grid, providing consumers
with eco-friendly, carbon-neutral gas.

Membrane-based upgrading of biogas
exploits the differences in the permeabilities of gases through the membranes.
SEPURAN® Green membranes have thehighest selectivity and provide a superior
technology for processing of crude biogas.

Filling station

Combined heat andpower plantUpgradingNatural gas grid

Gas separation

Distribution

Technical background

Benefits

The selectivity of the membranes is
process-stable, even at higher pressures
which are typical in the processing of crude
biogas.

• Reduced operating costs• Low investment• Simple to operate• Low space requirements andshort installation times• Can be used flexibly and inmodular fashion• No chemicals required• No additional drying stepThis is where Evonik’s membranes distinguish themselves from other availablemembranes.
The innovative technology was first
demonstrated and tested at an existing
biogas plant in Neukirchen an der Vöckla,
Austria and has since become establishedon the market.

7

SEPURAN® Greenin the biogas plant
Evonik has developed a biogas upgrading process that maximizes the performanceof the membranes. By judicious combination of SEPURAN® Green membranes,
methane of a purity higher than 99% can be obtained from the crude gas. The only
equipment needed is a compressor.

Benefits

The biogas leaves the biogas plant as a
mixture of CO2, methane, and the typicalby-products. It is ﬁrst desulfurized withactive carbon, ﬁltered, and pre-dried.
The pre-cleaned gas is then drawn in witha compressor, compressed to 10–20 bar,and upgraded in several membrane stages
to give biomethane and a CO2-rich oﬀ-gas
stream. The membrane-based upgrading
process delivers a consistently high qualityof biomethane that is up to 99% pure.
Further, the oﬀ-gas is very clean and contains signiﬁcantly less than 1% methane.
Almost all of the methane is thus obtainedin natural gas quality.

8• Low methane slip (loss) of <1%during upgrading• High methane yield of up to 99%,
which means maximum added value
for the operator• Highest energy eﬃciency for upgrading(<0.2 kWel/Nm3 crude  biogas,<0.4 kWel/Nm3 biomethane)• No additional ancillary materials such  
as water or sorbents (amines, glycols)  
are required, so no emissions into the  environment• Easily regulated for changes in ﬂow  
rate or composition• Following the upgrading process with  membranes, the biomethane is already  
dry and satisﬁes the dew-point
requirement for feeding into the grid
• Easily scalable; can be used for small  plants (10 Nm3/h) as well as large  
(>1000 Nm³/h)• Starting and stopping of the plant is  possible at short intervals, ensuring  
high ﬂexibility; therefore ideally suited  for operation of a biomethane ﬁlling  
station at the site
• Direct feeding (via a transmissionpipeline) into the natural gas grid is  possible without an additional
compressor

Evonik pilot plant

Our products and services

From 2011 to 2014 Evonik operated apilot plant in Neukirchen an der Vöckla,
Austria, to test the newly developed upgrading process with SEPURAN® Greenmembranes.

We offer SEPURAN® Green membrane
technology and develope superior processsolutions for your biogas separation requirements jointly with partners in plantengineering.

Crude biogas fromthe fermenter, approx.
53% methane,
47% CO2• SEPURAN® Green cartridges• Process design for membrane-based
biogas upgrading• We work in conjunction with knowledgeable plant-engineering companies
to oﬀer system solutions on the market.

Compressor
10 - 20 bar

Product stream
biomethane (>99%)
10 - 20 bar

Connection ofSEPURAN® Greenmembranes
Reverse stream

Oﬀ-gas, predominantly
CO2 with <1% methane

Gas content [%]Gas content remains stable in the long term

0100

200300

400

6000

6500

7000

7500

8000

8500

Time [h]   CH4 oﬀ -gas   CH4 product gas   CH4 in crude gas   CO2 in crude gas

9

SEPURAN® Green –Our references worldwide
Biogas upgrading facilities* with SEPURAN® GreenSize [Nm3/h]
Country

Quantity

Austria

3China2

Denmark

2France11

Germany13

Italy

1Japan1Korea2

Netherlands

6

Norway1Sweden

2Switzerland

8Thailand

2United Kingdom

23*Operating plants and plants under construction

101 - 199

200 - 499

500 - 999

> 1000Icknield Farm, Ipsden (Oxfordshire),
United Kingdom 350 Nm­­³/h11

® registered trademark
This information and any recommendations, technical or otherwise, are presented in good faith and believed to be correct as of the date prepared. Recipients of this information and recommendations must
make their own determination as to its suitability for
their purposes. In no event shall Evonik assume liability for damages or losses of any kind or nature thatresult from the use of or reliance upon this information and recommendations. EVONIK EXPRESSLYDISCLAIMS ANY REPRESENTATIONS AND WARRANTIES OF ANY KIND, WHETHER EXPRESS ORIMPLIED, AS TO THE ACCURACY, COMPLETENESS, NON-INFRINGEMENT, MERCHANTABILITY AND/OR FITNESS FOR A PARTICULAR PURPOSE (EVEN IF EVONIK IS AWARE OF SUCHPURPOSE) WITH RESPECT TO ANY INFORMATION AND RECOMMENDATIONS PROVIDED.
Reference to any trade names used by other companies is neither a recommendation nor an endorsement of the corresponding product, and does not imply that similar products could not be used. Evonikreserves the right to make any changes to the information and/or recommendations at any time, without prior or subsequent notice.

Evonik Fibres GmbH
Gewerbepark 44861 Schörfling
Austria
phone +43 7672 701-2891
fax +43 7672 96862
www.sepuran.com
sepuran@evonik.com