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KIST team develop
high-efficiency and stable catalyst for extraction of hydrogen from
ammonia
07 April 2021
Ammonia has
recently emerged as a liquid storage and transport medium that has
shown promising stability for long-distance hydrogen transport. At 108
kg H2/m3, liquefied ammonia (NH3) can
store 50% more hydrogen than liquid hydrogen. When ammonia is
decomposed at high temperatures, only hydrogen and nitrogen gases are
produced, with minimal carbon dioxide emissions.
Because more
than 200 million tons of ammonia are currently produced annually for
industrial use around the globe, the infrastructure for its mass
storage and long-distance transport already exists and could simply be
re-purposed for hydrogen transport. However, the need for large
amounts of heat has thwarted the widespread adoption of ammonia for
use in hydrogen transport and storage.
The
decomposition reaction through which hydrogen is extracted from
ammonia can only proceed at high temperature—which requires high
energy input. A catalyst in the form of a solid powder can be added
during the decomposition reaction to lower the reaction temperature;
however, the existing ruthenium-metal-based catalysts are very
expensive and have low stability, thus requiring regular replacement.
Now,
researchers at the Korea Institute of Science and Technology (KIST)
led by Drs. Hyuntae Sohn and Changwon Yoon have
developed
a catalyst for hydrogen production
from ammonia decomposition that exhibits 2.5-times higher ammonia
decomposition performance than conventional commercial catalysts.
The results of this study were published in the journal Applied
Catalysis B: Environmental.
The catalyst
consists of ruthenium metal particles and zeolite strongly bound by
calcination under vacuum, resulting in the containment of
sub-nanometer and nanometer ruthenium metal particles in each pore of
the zeolite support.
A
schematic diagram of the catalytic structure for ammonia decomposition
developed by KIST researchers. Credit: Korea Institute of Science and
Technology (KIST)
This novel
catalyst achieves its efficiency while using only 40% of ruthenium
metal compared to existing catalysts. Because nanometer-sized (or
smaller) ruthenium metal particles are present and maintain their
stability during the ammonia decomposition process even at high
reaction temperatures, the use of the proposed catalyst can overcome
the problem of low stability, which has been significantly limiting
the commercialization of existing catalysts.
The developed catalyst has an advantageous structure in that the
nanometer-sized ruthenium metal particles are uniformly spread over
zeolite, a crystalline mineral. Thus, this catalyst has shown higher
performance and stability than previously reported catalysts and is
expected to facilitate the commercialization of the process for
high-purity hydrogen production from ammonia.Dr.
Hyuntae Sohn
The importance of large-capacity hydrogen transport based on ammonia
is rapidly increasing, with fierce competition among advanced
countries over the development and acquisition of related
technologies. The application of the proposed catalyst for
large-capacity hydrogen production via ammonia decomposition, which is
currently under research and development, will ultimately help the
commercialization of ammonia-derived hydrogen and the large-capacity
hydrogen transportation between countries.
—Dr. Changwon Yoon
This research was supported by the New & Renewable Energy Core
Technology Program of the Korea Institute of Energy Technology
Evaluation and Planning(KETEP), granted financial resources by the
Ministry of Trade, Industry & Energy (MOTIE).
Resources
·
Junyoung Cha, Taeho Lee, Yu-Jin Lee, Hyangsoo Jeong, Young Suk Jo,
Yongmin Kim, Suk Woo Nam, Jonghee Han, Ki Bong Lee, Chang Won Yoon,
Hyuntae Sohn (2021) “Highly monodisperse sub-nanometer and nanometer
Ru particles confined in alkali-exchanged zeolite Y for ammonia
decomposition,” Applied Catalysis B: Environmental, Volume 283
doi:
10.1016/j.apcatb.2020.119627
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