Hydrogen Selectivity in the Steam Reforming of Alcohols

Cobalt catalysts supported on Y zeolite and mesoporized Y zeolite (Y-mod) have been studied in steam reforming of ethanol (SRE). Specifically, the effect of the mesoporosity and the acidity of the y zeolite as a support has been explored. Mesoporous were generated on Y zeolite by treatment with NH4F and the acidity was neutralized by Na incorporation. Four cobalt catalysts supported on Y zeolite have been prepared, two using Y zeolite without mesoporous (Co/Y, Co/Y-Na), and two using Y zeolite with mesoporous (Co/Y-mod and Co/Y-mod-Na). All catalysts showed a high activity, with ethanol conversion values close to 100%. The main differences were found in the distribution of the reaction products. Co/Y and Co/Y-mod catalysts showed high selectivity to ethylene and low hydrogen production, which was explained by their high acidity. On the contrary, neutralization of the acid sites could explain the higher hydrogen selectivity and the lower ethylene yields exhibited by the Co/Y-Na and Co/Y-mod-Na. In addition, the physicochemical characterization of these catalysts by XRD, BET surface area, temperature-programmed reduction (TPR), and TEM allowed to connect the presence of mesoporous with the formation of metallic cobalt particles with small size, high dispersion, and with high interaction with the zeolitic support, explaining the high reforming activity exhibited by the co/y-mod-Na sample as well as its higher hydrogen selectivity. It has been also observed that the formation of coke is affected by the presence of mesoporous and acidity. Both properties seem to have an opposite effect on the reforming catalyst, decreasing and increasing the coke deposition, respectively.

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Effect of molar ratio of water / ethanol on hydrogen selectivity in catalytic production of hydrogen using steam reforming of ethanol

International Journal of Hydrogen Energy ◽

10.1016/j.ijhydene.2018.11.198 ◽

2019 ◽

Vol 44 (20) ◽

pp. 9823-9829 ◽

Cited By ~ 6

Author(s):

Gülay Özkan ◽

Başak Şahbudak ◽

Göksel Özkan

Keyword(s):

Steam Reforming ◽

Molar Ratio ◽

Steam Reforming Of Ethanol ◽

Production Of Hydrogen ◽

Hydrogen Selectivity

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Promoting the Selectivity of Pt/m-ZrO2 Ethanol Steam Reforming Catalysts with K and Rb Dopants

Nanomaterials ◽

10.3390/nano11092233 ◽

2021 ◽

Vol 11 (9) ◽

pp. 2233

Author(s):

Michela Martinelli ◽

Richard Garcia ◽

Caleb D. Watson ◽

Donald C. Cronauer ◽

A. Jeremy Kropf ◽

...

Keyword(s):

Steam Reforming ◽

Ethanol Steam Reforming ◽

Catalyst Composition ◽

Reforming Catalysts ◽

Hydrogen Selectivity ◽

Temperature Programmed ◽

Diffuse Reflectance Infrared ◽

Temperature Programmed Reaction ◽

Ethanol Steam

The ethanol steam reforming reaction (ESR) was investigated on unpromoted and potassium- and rubidium-promoted monoclinic zirconia-supported platinum (Pt/m-ZrO2) catalysts. Evidence from in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) characterization indicates that ethanol dissociates to ethoxy species, which undergo oxidative dehydrogenation to acetate followed by acetate decomposition. The acetate decomposition pathway depends on catalyst composition. The decarboxylation pathway tends to produce higher overall hydrogen selectivity and is the most favored route at high alkali loading (2.55 wt.% K and higher or 4.25 wt.% Rb and higher). On the other hand, decarbonylation is a significant route for the undoped catalyst or when a low alkali loading (e.g., 0.85% K or 0.93% Rb) is used, thus lowering the overall H2 selectivity of the process. Results of in situ DRIFTS and the temperature-programmed reaction of ESR show that alkali doping promotes forward acetate decomposition while exposed metallic sites tend to facilitate decarbonylation. In previous work, 1.8 wt.% Na was found to hinder decarbonylation completely. Due to the fact that 1.8 wt.% Na is atomically equivalent to 3.1 wt.% K and 6.7 wt.% Rb, the results show that less K (2.55% K) or Rb (4.25% Rb) is needed to suppress decarbonylation; that is, more basic cations are more efficient promoters for improving the overall hydrogen selectivity of the ESR process.

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Catalytic Performance and Characterization of Ni-Co Bi-Metallic Catalysts in n-Decane Steam Reforming: Effects of Co Addition

Catalysts ◽

10.3390/catal8110518 ◽

2018 ◽

Vol 8 (11) ◽

pp. 518 ◽

Cited By ~ 3

Author(s):

Qinwei Yu ◽

Yi Jiao ◽

Weiqiang Wang ◽

Yongmei Du ◽

Chunying Li ◽

...

Keyword(s):

Steam Reforming ◽

Energy Dispersive Spectrometer ◽

Coke Deposition ◽

Morphological Properties ◽

Temperature Programmed Reduction ◽

N2 Adsorption ◽

High Hydrogen ◽

Hydrogen Selectivity ◽

Temperature Programmed ◽

Adsorption Desorption

Co-Ni bi-metallic catalysts supported on Ce-Al2O3 (CA) were prepared with different Co ratios, and the catalytic behaviors were assessed in the n-decane steam reforming reaction with the purpose of obtaining high H2 yield with lower inactivation by carbon deposition. Physicochemical characteristics studies, involving N2 adsorption-desorption, X-ray diffraction (XRD), H2-temperature-programmed reduction (H2-TPR), NH3 temperature programmed reduction (NH3-TPD), SEM-energy dispersive spectrometer (EDS), and transmission electron microscope (TEM)/HRTEM, were performed to reveal the textural, structural and morphological properties of the catalysts. Activity test indicated that the addition of moderate Co can improve the hydrogen selectivity and anti-coking ability compared with the mono-Ni/Ce-Al2O3 contrast catalyst. In addition, 12% Co showed the best catalytic activity in the series Co-Ni/Ce-Al2O3 catalysts. The results of catalysts characterizations of XRD and N2 adsorption-desorption manifesting the metal-support interactions were significantly enhanced, and there was obvious synergistic effect between Ni and Co. Moreover, the introduction of 12% Co and 6% Ni did not exceed the monolayer saturation capacity of the Ce-Al2O3 support. Finally, 6 h stability test for the optimal catalyst 12%Co-Ni/Ce-Al2O3 demonstrated that the catalyst has good long-term stability to provide high hydrogen selectivity, as well as good resistance to coke deposition.

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Steam-reforming of ethanol for hydrogen production

Chemical Papers ◽

10.2478/s11696-010-0100-0 ◽

2011 ◽

Vol 65 (3) ◽

Cited By ~ 83

Author(s):

Ahmed Bshish ◽

Zahira Yaakob ◽

Binitha Narayanan ◽

Resmi Ramakrishnan ◽

Ali Ebshish

Keyword(s):

Hydrogen Production ◽

Steam Reforming ◽

Molar Ratio ◽

Ethanol Conversion ◽

Impregnation Method ◽

Reaction Conditions ◽

Oxide Supports ◽

Steam Reforming Of Ethanol ◽

Production Of Hydrogen ◽

Hydrogen Selectivity

AbstractProduction of hydrogen by steam-reforming of ethanol has been performed using different catalytic systems. The present review focuses on various catalyst systems used for this purpose. The activity of catalysts depends on several factors such as the nature of the active metal catalyst and the catalyst support, the precursor used, the method adopted for catalyst preparation, and the presence of promoters as well as reaction conditions like the water-to-ethanol molar ratio, temperature, and space velocity. Among the active metals used to date for hydrogen production from ethanol, promoted-Ni is found to be a suitable choice in terms of the activity of the resulting catalyst. Cu is the most commonly used promoter with nickel-based catalysts to overcome the inactivity of nickel in the water-gas shift reaction. γ-Al2O3 support has been preferred by many researchers because of its ability to withstand reaction conditions. However, γ-Al2O3, being acidic, possesses the disadvantage of favouring ethanol dehydration to ethylene which is considered to be a source of carbon deposit found on the catalyst. To overcome this difficulty and to obtain the long-term catalyst stability, basic oxide supports such as CeO2, MgO, La2O3, etc. are mixed with alumina which neutralises the acidic sites. Most of the catalysts which can provide higher ethanol conversion and hydrogen selectivity were prepared by a combination of impregnation method and sol-gel method. High temperature and high water-to-ethanol molar ratio are two important factors in increasing the ethanol conversion and hydrogen selectivity, whereas an increase in pressure can adversely affect hydrogen production.

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Effect of metal composition on hydrogen selectivity in steam reforming of methanol over catalysts prepared from amorphous alloys

Applied Catalysis A General ◽

10.1016/s0926-860x(01)00641-x ◽

2001 ◽

Vol 218 (1-2) ◽

pp. 189-195 ◽

Cited By ~ 33

Author(s):

Takeshige Takahashi ◽

Makoto Inoue ◽

Takami Kai

Keyword(s):

Steam Reforming ◽

Amorphous Alloys ◽

Steam Reforming Of Methanol ◽

Metal Composition ◽

Hydrogen Selectivity

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Hydrogen Production from Ethanol Steam Reforming Using Ce- and La- Modified Mesoporous MCM-41 Supported Nickel-Based Catalysts

International Journal of Chemical Reactor Engineering ◽

10.1515/ijcre-2018-0212 ◽

2019 ◽

Vol 17 (8) ◽

Author(s):

Lida Rahmanzadeh ◽

Majid Taghizadeh

Keyword(s):

Hydrogen Production ◽

Steam Reforming ◽

Fixed Bed ◽

Fixed Bed Reactor ◽

Ethanol Conversion ◽

Steam Reforming Of Ethanol ◽

Hydrogen Selectivity ◽

Temperature Programmed ◽

Adsorption Desorption ◽

Mcm 41

Abstract Mesoporous MCM-41 containing different amounts of nickel (10, 15 and 20 wt%) and Ce and/or La promoters were prepared by hydrothermal and wet-impregnation methods. The catalysts were characterized by means of temperature-programmed reduction (TPR), X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), N2 adsorption-desorption, Fourier transform infrared (FT-IR) spectroscopy, and thermogravimetric (TGA) analyses. Then, the catalysts were tested for hydrogen production via steam reforming of ethanol in a fixed bed reactor. Hydrogen selectivity and ethanol conversion over Ni/MCM-41 catalyst were 69.6 % and 94 %, respectively. The best catalytic results were obtained with Ce-Ni/MCM-41 catalyst, i. e. 94 % ethanol conversion and 76.5 % hydrogen selectivity. These results remained constant about 90 h time on stream and ethanol conversion decreased to 87 % after 120 h.

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