Nitrosamine Management in Aqueous Amines for Post-Combustion Carbon Capture.

276 Pages·2015·7.1 MB·English

by  Nathan Fine

Copyright
by
Nathan Andrew Fine
2015
The Dissertation Committee for Nathan Andrew Fine Certifies that this is the
approved version of the following dissertation:

Nitrosamine Management in Aqueous Amines for Post-Combustion
Carbon Capture

Committee:

Gary Rochelle Supervisor
David Allen
Eric Anslyn
Eric Chen
Benny Freeman
Eirik da Silva
Nitrosamine Management in Aqueous Amines for Post-Combustion
Carbon Capture

by
Nathan Andrew Fine, B.S. Ch.E.

Dissertation
Presented to the Faculty of the Graduate School of
The University of Texas at Austin
in Partial Fulfillment
of the Requirements
for the Degree of

Doctor of Philosophy

The University of Texas at Austin
May 2015
Dedication

To my parents,
Owen and Katy
for being proud of me along the way
Acknowledgements

First and foremost, I would like to thank you, Dr. Rochelle, for the intellectual
stimulation, support, and motivation you have provided me over my career at UT. I have
never met someone so patient but excitable. You are perfectly content to teach me for hours
on end about topics you have known for decades, yet you have an unquenchable thirst for
any new data and the theories that follow. Through camping trips, rappelling practice, and
mastermind games, I learned how well you balance work and play. I hope to take that
lesson to heart as I enter the workforce.
Maeve Cooney, you are one of the brightest spots in the ChemE building. Your
quick wit and cultured references often lose me, but I still enjoy our conversations as a
refreshing break from the science. I have enjoyed watching Cara, Olé, and Hanalei grow
up in your office, and I am thankful for the advice you gave me for training my own dog.
Thank you for editing all of my technical documents (except this one); I am a much better
writer because of your input.
The Rochelle group has a long and storied past. I am fortunate to be standing on
the shoulders of giants who graced these labs before I got here. Specifically your work,
Chen Shen, Sanjay Bishnoi, Marcus Hilliard, Andrew Sexton, Stephanie Freeman, and
Fred Closmann, has directly impacted my research. While I have not met some of you,
your legacy lives on through your detailed dissertations and well-designed experiments.
A big thanks to my mentors who initially taught me the ropes. Mandana
Ashouripashaki, Stuart Cohen, Peter Frailie, Alex Voice, Steven Fulk, Lynn Li, and Omkar
Namjoshi, you have all been instrumental in guiding my research and developing my skills.
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I applaud your patience with me even when I broke your apparatuses or asked truly stupid
questions.
I am so happy to have gone through this process with my rather large cohort, Tarun
Madan, Darshan Sachde, Brent Sherman, Yang Du, Matt Walters, and Paul Nielsen. I am
amazed at the knowledge we have amassed over these years and the skillsets we have honed
just through our weekly group meetings and lunches. A special thanks to Darshan for
reading my dissertation chapters and motivating me to stay on schedule.
I would like to acknowledge the next generation, Yu-Jeng Lin, Di Song, June Ding,
Yue Zhang, Kent Fischer, Matt Beaudry, and Ye Yuan. Your ambition is inspiring, and I
have enjoyed watching you develop your own research goals.
My undergraduate research assistants have been truly instrumental in the
completion of my research. Mark Goldman, Morgan Yung, and Virbin Sapkota are all
extremely intelligent and hard-working. I was very fortunate to have researchers who cared
about their project and would actively work to understand their role. It is no accident that
my most productive months were when I had them working with me full time.
I have had the pleasure of working with the most helpful and technically savvy
professionals I could ask for. Randy Rife and Jason Baborka have solved all of my
computer woes, Jim Smitherman and Butch Cunningham helped me machine parts and fix
electronics, and Adam Kennedy provided his glass-blowing expertise.
I am grateful to you, Drs. Paul Allen, Eric Anslyn, Eric Chen, Benny Freeman, and
Eirik da Silva for your service on my committee and your mentorship. Especially thank
you, Dr. Anslyn, for helping me come up with several decent chemistry mechanisms. Your
office visits were some of the most productive and inspirational half-hours of my entire
PhD career.
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Without the financial support of the Texas Carbon Management Program, the EPA
STAR, and the Thrust Celanese Fellowship, none of this research would be possible.
Finally and most importantly, I am forever indebted to my wife and best friend,
Aurora. You are the most compassionate, intelligent, and beautiful person I have ever met.
You are truly my favorite person, and I am ecstatic to be sharing this life with you. The
PhD process can be daunting, but these past four years building a home with you have been
the best years of my life. I am in shock at how much we have experienced and accomplished
here in Austin, and I cannot wait to see what we will do in Boulder.
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Nitrosamine Management in Aqueous Amines for Post-Combustion
Carbon Capture

Nathan Andrew Fine, Ph.D.
The University of Texas at Austin, 2015

Supervisor: Gary T. Rochelle

Nitrosamines are one of the largest environmental issues associated with amine
scrubbing. Nitrogen dioxide (NO ) is the primary precursor for nitrosamine formation. In
2
the amine scrubber, NO reacts with amine via a free-radical absorption mechanism,
2
forming an amine radical and nitrite. The overall liquid side mass transfer coefficient (k ’)
g
for NO at absorber conditions is 3*10-7 10*10-7, and >40*10-7 mol/m2 s Pa for 9 m
2 ,
monoethanolamine (MEA), 8 m piperazine (PZ) and 7 m methyldiethanolamine
(MDEA)/2 m PZ respectively; typical NO uptake in absorbers ranges from 73 % in MEA
2
to over 99 % in MDEA/PZ. The amine radical resulting from NO absorption can react
2
with NO to directly form nitrosamine; in PZ at absorber conditions, approximately 20 %
of the amine radical reacts with NO to form n-nitrosopiperazine (MNPZ). Nitrite from NO
2
absorption then cycles to the high temperature stripper where it can nitrosate a secondary
amine. Nitrosation at high temperature occurs through nitrite attack on the amine carbamic
acid. Primary amines may scavenge nitrite from solution, but typically react slower than
secondary amines. For example, N-(2-hydroxyethyl)glycine (HeGly), a common
secondary amine in degraded MEA, reacts five times faster than MEA. Tertiary amines
cannot form carbamates, so they are unable to competitively scavenge nitrite. After
nitrosation, the nitrosamine thermally decomposes in the stripper with a pseudo-first order
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nitrosamine decomposition rate constant. At 163 °C in 8 m PZ, MNPZ decomposes at
6.0*10-5 s-1, reaching steady-state in less than a week. Nitrosamines are relatively non-
volatile and thermally unstable at reclaiming conditions, allowing for efficient removal
through thermal reclaiming; less than 5 % of MNPZ would return to the circulating solvent
after thermally reclaiming PZ. Nitrosamines will accumulate to approximately 1 mM,
2 mM, and 21 mM in PZ, MEA, and MDEA/PZ respectively when the stripper is operated
at the maximum temperature and thermal reclaiming is used. Gaseous emissions of
nitrosamines will be below air quality regulations when scrubber nitrosamine is below
14 mM. If necessary, NO pre-scrubbing with sulfite/thiosulfate or triethanolamine can
2
lower nitrosamine by an order of magnitude with no net cost to the carbon capture system.
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Table of Contents
List of Tables ....................................................................................................... xvi
List of Figures ...................................................................................................... xix
Chapter 1: Introduction ............................................................................................1
1.1 Amine Scrubbing for Carbon Capture ......................................................1
1.2 Nitrosamines in Amine Scrubbing ............................................................3
1.3 Research Scope .........................................................................................5
Chapter 2: Methods ..................................................................................................9
2.1 Analytical Methods ...................................................................................9
2.1.1 Anion Analysis..............................................................................9
2.1.2 Cation Chromatography ..............................................................11
2.1.3 Individual Nitrosamine Analysis ................................................12
2.1.4 NHeGly and NHEEDA Quantification .......................................15
2.1.5 Total Nitrosamine Analysis ........................................................17
2.1.6 Total Aldehyde and Hemiaminal Analysis .................................21
2.1.7 High Resolution Mass Spectrometry ..........................................24
2.1.8 Total Inorganic Carbon Analysis ................................................25
2.1.9 Total Alkalinity and pH Analysis ...............................................25
2.1.10 Nitrogen Monoxide and Nitrogen Dioxide Analysis ................26
2.2 Experimental Methods ............................................................................27
2.2.1 Thermal Cylinder ........................................................................27
2.2.2 Wetted Wall Column Apparatus .................................................29
2.2.3 High Gas Flow Apparatus ...........................................................31
2.2.4 Hydrogen Peroxide Addition ......................................................33
2.2.5 Thermal Reclaimer......................................................................35
Chapter 3: Absorption of Nitrogen Oxides in Aqueous Amines ...........................37
3.1 Previous Research on NOx Absorption ...................................................37
3.1.1 NOx Absorption into Aqueous Solutions ....................................37
3.1.2 Nitrosamine Formation from NOx Absorption ...........................39
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