skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Modified Ni-Cu catalysts for ethanol steam reforming

Abstract

Three Ni-Cu catalysts, having different Cu content, supported on γ-alumina were synthesized by wet co-impregnation method, characterized and tested in the ethanol steam reforming (ESR) reaction. The catalysts were characterized for determination of: total surface area and porosity (N{sub 2} adsorption - desorption using BET and Dollimer Heal methods), Ni surface area (hydrogen chemisorption), crystallinity and Ni crystallites size (X-Ray Diffraction), type of catalytic active centers (Hydrogen Temperature Programmed Reduction). Total surface area and Ni crystallites size are not significantly influenced by the addition of Cu, while Ni surface area is drastically diminished by increasing of Cu concentration. Steam reforming experiments were performed at atmospheric pressure, temperature range 150-350°C, and ethanol - water molar ration of 1 at 30, using Ar as carrier gas. Ethanol conversion and hydrogen production increase by the addition of Cu. At 350°C there is a direct connection between hydrogen production and Cu concentration. Catalysts deactivation in 24h time on stream was studied by Transmission Electron Microscopy (TEM) and temperature-programmed reduction (TPR) on used catalysts. Coke deposition was observed at all studied temperatures; at 150°C amorphous carbon was evidenced, while at 350°C crystalline, filamentous carbon is formed.

Authors:
; ; ;  [1]; ;  [2];  [3]
  1. National Institute for Research and Development of Isotopic and Molecular Technologies, 65-103 Donath Street, 400293, Cluj-Napoca (Romania)
  2. Univ. Babes Bolyai, Fac. Chem. and Chem. Eng.,11 Arany Janos, 400028, Cluj-Napoca (Romania)
  3. 65-103 Donath Street (Romania)
Publication Date:
OSTI Identifier:
22257186
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 1565; Journal Issue: 1; Conference: PIM 2013: International conference on processes in isotopes and molecules, Cluj Napoca (Romania), 25-27 Sep 2013; Other Information: (c) 2013 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ADSORPTION; ALUMINIUM OXIDES; CARBON; CATALYSTS; CHEMISORPTION; DEPOSITION; DESORPTION; ETHANOL; HYDROGEN; HYDROGEN PRODUCTION; POROSITY; STREAMS; SURFACE AREA; TRANSMISSION ELECTRON MICROSCOPY; X-RAY DIFFRACTION

Citation Formats

Dan, M., Mihet, M., Almasan, V., Borodi, G., Katona, G., Muresan, L., and Lazar, M. D., E-mail: diana.lazar@itim-cj.ro. Modified Ni-Cu catalysts for ethanol steam reforming. United States: N. p., 2013. Web. doi:10.1063/1.4833729.
Dan, M., Mihet, M., Almasan, V., Borodi, G., Katona, G., Muresan, L., & Lazar, M. D., E-mail: diana.lazar@itim-cj.ro. Modified Ni-Cu catalysts for ethanol steam reforming. United States. doi:10.1063/1.4833729.
Dan, M., Mihet, M., Almasan, V., Borodi, G., Katona, G., Muresan, L., and Lazar, M. D., E-mail: diana.lazar@itim-cj.ro. 2013. "Modified Ni-Cu catalysts for ethanol steam reforming". United States. doi:10.1063/1.4833729.
@article{osti_22257186,
title = {Modified Ni-Cu catalysts for ethanol steam reforming},
author = {Dan, M. and Mihet, M. and Almasan, V. and Borodi, G. and Katona, G. and Muresan, L. and Lazar, M. D., E-mail: diana.lazar@itim-cj.ro},
abstractNote = {Three Ni-Cu catalysts, having different Cu content, supported on γ-alumina were synthesized by wet co-impregnation method, characterized and tested in the ethanol steam reforming (ESR) reaction. The catalysts were characterized for determination of: total surface area and porosity (N{sub 2} adsorption - desorption using BET and Dollimer Heal methods), Ni surface area (hydrogen chemisorption), crystallinity and Ni crystallites size (X-Ray Diffraction), type of catalytic active centers (Hydrogen Temperature Programmed Reduction). Total surface area and Ni crystallites size are not significantly influenced by the addition of Cu, while Ni surface area is drastically diminished by increasing of Cu concentration. Steam reforming experiments were performed at atmospheric pressure, temperature range 150-350°C, and ethanol - water molar ration of 1 at 30, using Ar as carrier gas. Ethanol conversion and hydrogen production increase by the addition of Cu. At 350°C there is a direct connection between hydrogen production and Cu concentration. Catalysts deactivation in 24h time on stream was studied by Transmission Electron Microscopy (TEM) and temperature-programmed reduction (TPR) on used catalysts. Coke deposition was observed at all studied temperatures; at 150°C amorphous carbon was evidenced, while at 350°C crystalline, filamentous carbon is formed.},
doi = {10.1063/1.4833729},
journal = {AIP Conference Proceedings},
number = 1,
volume = 1565,
place = {United States},
year = 2013,
month =
}
  • Supported Rh catalysts have been developed for selective H2 production at low temperatures. Ethanol dehydration is favorable over either acidic or basic supports such as γ-Al2O3 and MgAl2O4, while ethanol dehydrogenation is more favorable over neutral supports. A series of CeO2-ZrO2 supports with various CeO2/ZrO2 ratios were prepared by a co-precipitation method and Rh was impregnated on the as-synthesized support to achieve a strong metal to support interaction (SMSI). 2%Rh/Ce0.8Zr0.2O2 catalyst exhibited the highest H2 yield at 450oC among the various supported Rh catalysts evaluated in this study. This is mainly due to a favored reaction pathway via ethanol dehydrogenationmore » to form the acetaldehyde intermediate, and both the strong interaction between Rh and Ce0.8Zr0.2O2 and the high oxygen storage capacity of Ce0.8Zr0.2O2 which favors oxidation of acetaldehyde decomposition products« less
  • Rh/CeO2-ZrO2 catalysts with various CeO2/ZrO2 ratios have been applied to H2 production from ethanol steam reforming at low temperatures. The catalysts all deactivated with time on stream (TOS) at 350 C. The addition of 0.5% K has a beneficial effect on catalyst stability, while 5% K has a negative effect on catalytic activity. The catalyst could be regenerated considerably even at ambient temperature and could recover its initial activity after regeneration above 200 C with 1% O2. The results are most consistent with catalyst deactivation due to carbonaceous deposition on the catalyst.
  • Rapid deactivation of Rh/Ce0.8Zr0.2O2 catalysts in low temperature ethanol steam reforming was studied. A significant build-up of carbonaceous intermediate, instead of carbon deposit, was observed at a lower reaction temperature which was attributed to the rapid catalyst deactivation. Co-feed experiments indicated that acetone and ethylene caused more severe catalyst deactivation than other oxygenates such as acidic acid and acetaldehyde.
  • Hydrogen production was carried out via ethanol steam reforming over supported cobalt catalysts. Wet incipient impregnation method was used to support cobalt on ZrO2, CeO2 and CeZrO4 followed by pre-reduction with H2 up to 677 °C to attain supported cobalt catalysts. It was found that the non-noble metal based 10 wt % Co/CeZrO4 is an efficient catalyst to achieve ethanol conversion of 100% and hydrogen yield of 82% (4.9 mol H2/ mol ethanol) at 450 oC , which is superior to 0.5 wt % Rh/Al2O3. The pre-reduction process is required to activate supported cobalt catalysts for high H2 yield ofmore » ethanol steam reforming. In addition, support effect is found significant for cobalt during ethanol steam reforming. 10% Co/CeO2 gave high H2 selectivity while suffered low conversion due to the poor thermal stability. In contrast to CeO2, 10 wt % Co/ZrO2 achieved high conversion while suffered lower H2 yield due to the production of methane. The synergistic effect of ZrO2 and CeO2 to promote high ethanol conversion while suppress methanation was observed when CeZrO4 was used as a support for cobalt. This synergistic effect of CeZrO4 support leads to a high hydrogen yield at low temperature for 10 wt % Co/CeZrO4 catalyst. Under the high weight hourly space velocity (WHSV) of ethanol (2.5 h-1), the hydrogen yield over 10 wt % Co/CeZrO4 was found to gradually decrease to 70% of its initial value in 6 hours possibly due to the coke formation on the catalyst.« less
  • The catalytic activity of cobalt in the production of hydrogen via ethanol steam reforming has been investigated in its relation to the crystalline structure of metallic cobalt. At a reaction temperature of 350 8C, the specific hydrogen production rates show that hexagonal close-packed (hcp) cobalt possesses higher activity than face-centered cubic (fcc) cobalt. However, at typical reaction temperatures (400– 500 8C) for ethanol steam reforming, hcp cobalt is transformed to less active fcc cobalt, as confirmed by in situ X-ray diffractometry (XRD). The addition of CeO2 promoter (10 wt.%) stabilizes the hcp cobalt structure at reforming temperatures up to 600more » 8C. Moreover, during the pre-reduction process, CeO2 promoter prevents sintering during the transformation of Co3O4 to hcp cobalt. Both reforming experiments and in situ diffuse-reflectance infrared Fourier transform spectroscopy (DRIFTS) showed that the surface reactions were modified by CeO2 promoter on 10% Ce–Co (hcp) to give a lower CO selectivity and a higher H2 yield as compared with the unpromoted hcp Co.« less