Research Project: Amonyaktan Hidrojen Üretimi için Rutenyum Bazlı Katalizörlerle Alternatif Ucuz Nikel Bazlı Katalizörlerin Geliştirilmesi
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Contributors
Funders
ID
TB.00175
Authors
Uzun, Alper
Faculty Member
Publications
Tuning structural characteristics of red mud by simple treatments
(Elsevier, 2016)
Soyer-Uzun, Sezen
Department of Chemical and Biological Engineering
KUTEM (Koç University Tüpraş Energy Center)
Yes
Öztulum, Samira Fatma Kurtoğlu
Red mud (RM) is a hazardous waste produced vastly by aluminum industry worldwide. Because of its rich metal oxide content, it has potential to be utilized in various applications, such as ceramics production, construction, and catalysis. Here, we investigated the structural modification of RM by simple acid treatments using HCl and H2SO4 at different molarities, and at different digestion temperatures followed by calcinations at various temperatures. Structures before and after these treatments were characterized in deep detail by combining electron microscopy, diffraction, and spectroscopy complemented by thermal analysis and mass spectrometry to elucidate any changes in morphology, structure, and chemical composition introduced by these treatments. Results showed that acid treatments tremendously affect chemical composition; for instance, amount of Fe2O3 changes from 37 to 46 wt%, while that of minor components, such as Na2O, varies from approximately 9 wt% to trace amounts. Moreover, data also illustrated that high acid digestion temperature (220 degrees C) leads to significant improvements in surface area, from 17 m(2)/g to values exceeding 200 m(2)/g. Results presented here provide a guideline for modifying RM by simple treatments to tune its structural characteristics, potentially offering opportunities for its utilization as cost effective and environmentally friendly solutions to various applications.
Modifying the structure of red mud by simple treatments for high and stable performance in cox-free hydrogen production from ammonia
(Elsevier , 2018)
Soyer-Uzun, Sezen
Department of Chemical and Biological Engineering
KUTEM (Koç University Tüpraş Energy Center)
KUYTAM (Koç University Surface Science and Technology Center)
Yes
Red mud (RM) modified by various treatments was used as a catalyst for ammonia decomposition. Catalytic activity measurements performed at 500 degrees C and differential conversions illustrated that the rate increases with a decrease in the size of Fe3Ny nano particles formed during activation in NH3 flow. Measurements at 700 degrees C showed that a catalyst prepared by digesting RM in 6 M HCl followed by calcination at 900 degrees C provides a stable ammonia conversion of 98.8 +/- 0.5% for more than 70 h at a space velocity of 120 000 cm(3) NH3 h(-1) at. This rate is premier among all iron-based catalysts in terms of both activity and stability and even on par with the performance of other non-noble metal catalysts. Detailed characterization indicated Fe3Ny species readily available on the surface as the active species. Results provided here enable the utilization of RM as an environmentally-friendly, highly efficient, and almost cost-free catalyst for COx-free hydrogen production.
COx-free hydrogen production from ammonia decomposition over sepiolite-supported nickel catalysts
(Elsevier , 2018)
Soyer-Uzun, Sezen
Department of Chemical and Biological Engineering
KUTEM (Koç University Tüpraş Energy Center)
KUYTAM (Koç University Surface Science and Technology Center)
Yes
Sepiolite, a clay mineral, was utilized as a support for nickel-based catalysts for COx-free hydrogen production from ammonia decomposition. First, the physical and chemical properties of sepiolite were changed by calcining it at temperatures varying from 500 to 1000 degrees C, then nickel was impregnated on these calcined supports and tested for ammonia decomposition at various temperatures following reduction at 650 degrees C. Results indicated that even though the catalysts contained almost the same amount of nickel, they showed different hydrogen production performance. Detailed characterization of the catalysts before and after reaction illustrated that the support obtained by calcining sepiolite at 700 degrees C shows good basic properties with a high surface area offering a high degree of nickel dispersion. These properties lead to promising hydrogen production rates which are on par, if not higher, than most of the nickel-based catalysts prepared on supports, which are either not cheap or require tedious preparation procedures.
Red mud as an efficient, stable, and costfree catalyst for COx-free hydrogen production from ammonia
(Nature Publishing Group (NPG), 2016)
Kurtoğlu, Samira Fatma
Department of Chemical and Biological Engineering
Yes
Uzun, Alper
College of Engineering
Red mud, one of the mostly produced industrial wastes, was converted into a catalyst with exceptionally high and stable performance for hydrogen production from ammonia. Results showed that iron species produced after reduction of the HCl digested red mud were converted into epsilon-Fe2N during the induction period of ammonia decomposition reaction at 700 degrees C. The catalytic performance measurements indicated that the modified red mud catalyst provides a record high hydrogen production rate for a non-noble metal catalyst at this temperature. For instance, stable hydrogen production rates were measured as 72 and 196 mmol H-2 min(-1) g(cat)(-1) for the corresponding space velocities of 72 000 and 240 000 cm(3) NH3 h(-1) g(cat)(-1), respectively, at 700 degrees C. These results offer opportunities to utilize one of the key hazardous industrial wastes as an eco-friendly, efficient, stable, and almost cost-free catalyst for COx-free hydrogen production from ammonia decomposition.