By
Chris Heflin
Rachael Houk
Mike Jones
NANO-POROUS MEMBANES IN GAS
PROCESSING
A theoretical analysis of non-chemical separation of hydrogen sulfide from methane by nano-porous
membranes using capillary condensations from Chemical Engineering and Processing
INTRODUCTION

Natural Gas as it comes out of
ground needs to have H2S
removed before further processing
Starting levels can be high (>5%)
 For US pipelines, limit is 4 ppm

Traditionally done through chemical means
 One alternative is to use a nano-porous
membrane to achieve a physical separation

Image Source: http://chemistry.about.com/od/factsstructures/ig/Chemical-Structures---H/Hydrogen-Sulfide.htm
CONVENTIONAL H2S SEPARATION

Traditional methods
 Wash
with MEA, DEA, or other amines
 Use an oxide adsorbent

Disadvantages
 Consumes
these chemicals
 Added hazards due to additional chemical at site
AMINE WASH SEPARATION



Removes H2S, CO2, and
mercaptans
Need a lot of
equipment
Need both heating and
cooling utilities
Image from http://en.wikipedia.org/wiki/Amine_gas_treating
OXIDE ADSORBENT
Excellent separation achieved
 Can have significant pressure drop
 Need high temperatures
 Use iron oxide or zinc oxide

Image from http://www.cwaller.de/sorbents.htm
CRITERIA FOR A GOOD MEMBRANE
Good selectivity in allowing H2S through and
not CH4, only a small amount of CH4 dissolved
in liquid H2S phase
 Minimal pressure drop in bulk phase

MECHANISM
Bulk Phase
H
2
S
CH4
CH4
Permeate
CH4
CH4
H
2
S
H
2
S
Nano-porous
membrane
CH4
H
2
S
F
L
O
W
CH4
Not to scale
NANO-POROUOS MEMBRANES
Images from www.mdpi.com/1996-1944/3/1/165/ag
sites.google.com/.../home/MAIN_NANO_2.jpg
www3.interscience.wiley.com/.../ncontent
TEMPERATURE VS PERMEABILITY
SEPARATION FACTOR
Where
x = mole fraction in the pore
 y = mole fraction in the bulk

TEMPERATURE VS SEPARATION
So, How Are Nanoporous
Membranes Made?
SELF-ORDERING ELECTROCHEMICAL PROCESS

A schematic diagram showing
pore formation by
electrochemical self-ordering
Scheme of electrochemical
cell for anodization and
corresponding
electrochemical reactions.
Scheme of pore formation,
which includes several steps:
A.
B.
(I)
(II)
(III)
(IV)
C.
the formation of oxide layer
on metal surface;
local field distributions
caused by surface
fluctuations;
the initiation of pore growth
by field-enhanced
dissolution; and
the pore growth in steadystate condition
Typical current density curve
obtained with anodization
showing these stages
CYCLIC ANODIZATION
New development by Dr. Ducas Losic of the
University of South Australia
 A series of fabrication protocols to precisely
control their most critical parameters, including
pore diameters, pore geometry and surface
chemistry

CONCLUSION
H2S separation is necessary: traditional
methods are ok, but nano-porous membranes
could do better
 The H2S condenses and flows through the
membrane to separate; this depends on
temperature and pressure
 Membranes can be made through self-ordering
electrochemical process and cyclic anodazition

FURTHER RESEARCH
Gas mixtures of more than just methane and
hydrogen sulfide, like actual natural gas
 Optimized temperature and pressure
 Better manufacturing techniques, particularly
for large scale production
 Try a pilot plant scale testing

REFERENCES







http://en.wikipedia.org/wiki/Amine_gas_treating
http://www.chem.tamu.edu/class/majors/chem470/Synthesis_Gas.
html
http://www.thefuelman.com/Documents/H2S_removal.pdf
http://en.wikipedia.org/wiki/Hydrogen_sulfide
“Engineering of Nanomembranes for Emerging Applications” by Dr.
Ducas Losic http://www.azonano.com/details.asp?ArticleId=2445
“Simple and reliable technology for manufacturing metal-composite
nanomembranes with giant aspect ratio” by Jovan Matovića and
Zoran Jakšić http://www.sciencedirect.com
“Self-ordered nanopore and nanotube platforms for drug delivery
applications” by Dusan Losic & Spomenka Simovic
http://informahealthcare.com/doi/pdf/10.1517/17425240903300
857?cookieSet=1
Group S2 rebuttal
Chris Heflin
Rachael Houk
Mike Jones
• Data used showed amine needed to be replaced
slowly with a fresh stream because some of it
leaves in the tail gas stream
• No info available on the cost of the nano-porous
membrane to compare with traditional methods
• The presentation was right after Dr. Seminario did
a harsh critique of a previous presentation, so
there was reason to be nervous, but we should
have rehearsed more.
• Thanks for the feedback on the animation and
introduction. We’ll try to continue this
practice in our future presentations.
Group S1
Review of Nano Membranes for Gas
Separation
Group S1
Notes on Presentation
Positive Notes
• Good at answering
questions
• Separation animation was
helpful
• Summary of chemical
method was thorough and
educational
• Good analysis of research
and future development
needs
Group S1
Opportunities for Improvement
• Presentation was very short
– Could have included more
information and spent more
time on use and applications
– Lasted less than 15 minutes
• More eye contact during
presentation
• Cite sources on slides
– Could not have known due to
guidelines being presented
right before
Grade
• Slides (20/20)
– Informative, well designed
• Oral presentation (19/20)
– Good skills but needed more eye contact
• Graphics (18/20)
– Needed a few more pictures and diagrams
• Educational Value (20/20)
– Topic was well explained
• Group Analysis of Research (19/20)
– Needed a little more research on topic for thoroughness
• Overall (96/100)
Group S1
Group S3:
Michael Koetting
Bradford Lamb
James Kancewick



The presentation was informative and the
slides were generally well done.
Student questions were answered confidently
and in detail.
Presentation was not too detailed to be
understandable by the audience, yet still
detailed.



Speaking could have been more polished, with
more eye contact from some of the speakers
and less reading from slides/notes.
Some figures in the slideshow were not
explained, so they added very little to the
presentation.
Despite this, however, the presentation was
very good on the whole.
Group S4
Review of Nano Membranes
for Gas Separation
Scott Marwil
Danielle Miller
Joshua Moreno
Group S4
Things Done Well







Very good job with the illustrations and the
animations
The group did a good job of answering the classes
questions in a full and in-depth manner
The group members presenting knew the material and
did an good job relaying that knowledge onto the rest
of the class
The Group was very well spoken
They made good use of animations and pictures to
illustrate points
Their introduction was very thorough and well written
The material was presented in an interesting and
exciting way
Group S4
Things That Need Improvement


The overall presentation was a little on the short
side.
The group needs to develop a better introduction
to introduce the topic and background to the class
instead of just jumping to the heart of the
material so quickly
The Not-So-Good

Sometimes the slides contained a bit too much
information. They should try limit the amount of
information on the slides so they can draw
attention to the speaker.
Group S4
Group S5
Review of Nano Membranes for Gas
Separation
Pradip Rijal
Jason Savatsky
Trevor Seidel
Laura Young
Group S5
Presentation Review
• The groups power presentation and visuals
were very well done.
• They probably should have practiced the
presentation a little more. The oral
presentation was weak and unfocused.
• Their attire was appropriate for the occasion.
Group S5
Group S6
Review of Nano Membranes for Gas
Separation
John Baumhardt
Daniel Arnold
Michael Trevathan
Michael Tran
Review
• Slide layout was agreeable and pleasant to look at.
• The presentation was detailed and well thought out.
• The further research section is a little weak (the
natural gas composition could have included a
sample composition of “actual natural gas”
• The presentation overall was quite good, but the
presenters seemed a little nervous, and were reading
off of the slides.
Review of Information
• From a natural gas background, the disadvantages listed are
not valid. In an amine system, there are no chemicals stored
on site because there are very few reasons to change the
amine. Apart from wanting to try a more efficient amine,
standard amine reclamation (cleaning) can be performed to
regenerate the existing amine.
• Even without regeneration, amine lasts years in plants
without replacement.
• We would have liked a cost comparison of the nano-porous
membranes vs the traditional amine, to determine the
commercial viability of the membranes in gas plants.