Revealing structure-activity relationships in chromium free high temperature shift catalysts promoted by earth abundant elements

2018-09-15
Zhu, Minghui
Yalcin, Ozgen
Wachs, Israel E.
Show full item record
Creative Commons License
This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.
41
views
0
downloads
Finding a replacement for the toxic hexavalent chromium oxide in commercial iron oxide-based high temperature water-gas shift (HT-WGS) catalyst is of current environmental concern. Previous studies in developing Cr-free catalysts mainly focus on ex-situ characterization on catalysts bulk structure. In the present study, CuO/MOx-Fe2O3 catalysts promoted by Si, Al, Cr or Mg were studied with XRD, in situ Raman, HS-LEIS, BET, transient (CO2)-O-16 -> (CO2)-O-18 isotopic switch, steady-state WGS 'activity test and CO-TPR to elucidate their structure-activity relationships. The Mg and Al are homogeneously distributed within both fresh and activated catalysts as texture promoters, while the Si exists as discrete SiO2 that is covered by iron oxides. During the HT-WGS reaction, the Mg promoter resulted in the poorest thermally stability and least amount of metal-metal oxide interface, and the Si promoter inhibited the reducibility of surface oxygen. Only the Al promoter was found to yield a catalyst that possessed similar catalyst structure, comparable thermostability and activity with the Cr-promoted catalyst. This work demonstrates the importance of in situ characterization to the rational design of Cr-free iron oxide based HT-WGS catalysts.
Process Chemistry and Technology, General Environmental Science, Catalysis
https://hdl.handle.net/11511/66262
APPLIED CATALYSIS B-ENVIRONMENTAL
Department of Chemical Engineering, Article

Suggestions

Nanoceria supported rhodium(0) nanoparticles as catalyst for hydrogen generation from methanolysis of ammonia borane
Ozhava, Derya; Özkar, Saim (Elsevier BV, 2018-12-05)
This work reports the preparation and catalytic use of nanoceria supported rhodium(0) nanoparticles, Rh(0)/nanoCeO(2), as catalyst for hydrogen generation from the methanolysis of ammonia borane. Rh(0)/nanoCeO(2) was in situ formed from the reduction of rhodium(II) octanoate on the surface of nanoceria during the catalytic methanolysis of ammonia borane at room temperature. The results of analysis using PXRD, TEM, STEM-EDS, XPS, SEM, SEM-EDX, N-2 adsorption-desorption and ICP-OES reveal that rhodium(0) nano...
Palladium(0) nanoparticles supported on polydopamine coated CoFe2O4 as highly active, magnetically isolable and reusable catalyst for hydrogen generation from the hydrolysis of ammonia borane
Manna, Joydev; Akbayrak, Serdar; Özkar, Saim (Elsevier BV, 2017-07-05)
Palladium(0) nanoparticles supported on cobalt ferrite (Pd degrees/CoFe2O4) are found to be highly active catalyst, providing an unprecedented catalytic activity with a turnover frequency of 290 min(-1) in hydrogen generation from the hydrolysis of ammonia borane at room temperature. However, the initial catalytic activity of Pd degrees/CoFe2O4 catalyst is not preserved after the reuse of the catalyst in hydrolytic dehydrogenation of ammonia borane. The stability of the catalyst is improved by using the pol...
Aqueous-phase hydrodechlorination of trichloroethylene over Pd-based swellable organically-modified silica (SOMS): Catalyst deactivation due to chloride anions
Çelik, Gökhan; Gunduz, Seval; Miller, Jeffrey T.; Edmiston, Paul L.; Ozkan, Umit S. (Elsevier BV, 2018-12-30)
Swellable-organically modified silica (SOMS) has been demonstrated to be an efficient catalyst scaffold for catalytic treatment of water contaminated with trichloroethylene (TCE). In this study, deactivation characteristics of Pd-incorporated SOMS for aqueous-phase hydrodechlorination (HDC) of TCE were investigated. Pd/SOMS catalysts were exposed to highly-concentrated chloride solutions (up to 1 M NaCl or 0.01 M HCl) to examine the deactivation resistant behavior of Pd/SOMS. The commonly used HDC catalyst ...
Rhodium(0) nanoparticles supported on nanosilica: Highly active and long lived catalyst in hydrogen generation from the methanolysis of ammonia borane
Ozhava, Derya; Özkar, Saim (Elsevier BV, 2016-02-01)
Nanosilica stabilized rhodium(0) nanoparticles (Rh(0)/nanoSiO(2)), in situ formed from the reduction of rhodium(II) octanoate impregnated on the surface of nanosilica, are active catalyst in hydrogen generation from the methanolysis of ammonia borane at room temperature. Monitoring the hydrogen evolution enables us to follow the kinetics of nanoparticles formation. The resulting sigmoidal kinetic curves are analyzed by using the 2-step mechanism of the slow, continuous nucleation and autocatalytic surface g...
Highly active, robust and reusable micro-/mesoporous TiN/Si3N4 nanocomposite-based catalysts for clean energy: Understanding the key role of TiN nanoclusters and amorphous Si3N4 matrix in the performance of the catalyst system
Lale, Abhijeet; Mallmann, Maira Debarba; Tada, Shotaro; Bruma, Alina; Özkar, Saim; Kumar, Ravi; Haneda, Masaaki; Machado, Ricardo Antonio Francisco; Iwamoto, Yuji; Demirci, Umit B.; Bernard, Samuel (Elsevier BV, 2020-09-05)
Herein, we developed a precursor approach toward the design of a titanium nitride (TiN)/silicon nitride (Si3N4) nanocomposite with an activated carbon monolith as a support matrix forming a highly micro-/mesoporous component to be used as a Pt support for the catalytic hydrolysis of sodium borohydride (NaBH4) as a model reaction. The experimental data demonstrated that the amorphous Si3N4 matrix, the strong Pt-TiN nanocluster interaction and the synergistic effects between the three components contributed t...
Citation Formats
M. Zhu, O. Yalcin, and I. E. Wachs, “Revealing structure-activity relationships in chromium free high temperature shift catalysts promoted by earth abundant elements,” APPLIED CATALYSIS B-ENVIRONMENTAL, pp. 205–212, 2018, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/66262.
METU IIS - Integrated Information Service open@metu.edu.tr