Influence of Cs Promoter on Ethanol Steam-Reforming Selectivity of Pt/m-ZrO2 Catalysts at Low Temperature

The decarboxylation pathway in ethanol steam reforming ultimately favors higher selectivity to hydrogen over the decarbonylation mechanism. The addition of an optimized amount of Cs to Pt/m-ZrO2 catalysts increases the basicity and promotes the decarboxylation route, converting ethanol to mainly H2, CO2, and CH4 at low temperature with virtually no decarbonylation being detected. This offers the potential to feed the product stream into a conventional methane steam reformer for the production of hydrogen with higher selectivity. DRIFTS and the temperature-programmed reaction of ethanol steam reforming, as well as fixed bed catalyst testing, revealed that the addition of just 2.9% Cs was able to stave off decarbonylation almost completely by attenuating the metallic function. This occurs with a decrease in ethanol conversion of just 16% relative to the undoped catalyst. In comparison with our previous work with Na, this amount is—on an equivalent atomic basis—just 28% of the amount of Na that is required to achieve the same effect. Thus, Cs is a much more efficient promoter than Na in facilitating decarboxylation.

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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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Production of Hydrogen from Ethanol Using Pt/Hydrotalcite Catalysts Stabilized with Tungsten Oxides

Journal of New Materials for Electrochemical Systems ◽

10.14447/jnmes.v15i3.68 ◽

2012 ◽

Vol 15 (3) ◽

pp. 215-223 ◽

Cited By ~ 3

Author(s):

J.L. Contreras ◽

M.A. Ortiz ◽

R. Luna ◽

G.A. Fuentes ◽

M. Autié ◽

...

Keyword(s):

Crystal Structure ◽

Steam Reforming ◽

Fixed Bed ◽

Thermal Stabilization ◽

Fixed Bed Reactor ◽

Ethanol Steam Reforming ◽

Vis Spectroscopy ◽

Production Of Hydrogen ◽

Stabilization Effect ◽

Ethanol Steam

An stabilization effect of WOx over the Pt/hydrotalcite catalysts to produce H2 by ethanol steam reforming at low concentration was studied. The catalysts were characterized by N2 physisorption, X-ray diffraction, Infrared (IR), and UV-vis spectroscopy. The catalytic tests were made in a fixed bed reactor. The catalysts showed porous with the shape of parallel layers with a monomodal mesoporous distribution. By IR spectroscopy it was found superficial chemical such as: -OH, H2O, Al-OH, Mg-OH, and CO32-. The reaction products were; H2, CO2, CH3CHO, CH4 and C2H4. These catalysts did not produce CO and showed low selectivity to C2H4. By XRD we found that catalysts having Pt and the lowest W concentration showed the highest crystallinity and the highest stability during the reaction of ethanol steam reforming. A possible thermal stabilization effect of W in the hydrotalcite crystal structure leading to prevent the Pt sintering is proposed. By IR the hydrotalcite hydroxil groups coordinated with Mg and Al decreased by the presence of WOx. We found that catalysts with low W concentration and Pt having high crystallinity showed the highest stability after ethanol steam reforming. It could be a possible thermal stabilization effect of W in the hydrotalcite crystal structure leading to prevent the Pt sintering.

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Hydrogen Production by Ethanol Steam Reforming Over Cu and Ni Catalysts Supported on ZrO2 and Al2O3 Microspheres

Materials Science Forum ◽

10.4028/www.scientific.net/msf.591-593.734 ◽

2008 ◽

Vol 591-593 ◽

pp. 734-739 ◽

Cited By ~ 3

Author(s):

V.S. Bergamaschi ◽

F.M.S. Carvalho

Keyword(s):

Steam Reforming ◽

Fixed Bed ◽

Fixed Bed Reactor ◽

Feed Ratio ◽

Ni Catalyst ◽

Ethanol Conversion ◽

Ethanol Steam Reforming ◽

Hydrolysis Method ◽

Steam Reforming Of Ethanol ◽

Ethanol Steam

Ethanol reforming process to produce hydrogen rich-gas stream is performed using Cu/Ni catalyst supported on zirconia and alumina microspheres prepared by hydrolysis method. Theses catalysts were tested in a fixed-bed reactor system employing steam reforming of ethanol. The operating temperature was 550°C and water/ethanol feed ratio 3/1. Although all catalysts were very active for ethanol conversion and very selective towards the desired products, but that one supported on zirconia microspheres was produced slightly better results. The data reveal high activity of the Cu/Ni/ZrO2 catalyst for ethanol steam reforming and presented a good selectivity for H2.

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Production of hydrogen by ethanol steam reforming using Ni–Co-ex-hydrotalcite catalysts stabilized with tungsten oxides

International Journal of Hydrogen Energy ◽

10.1016/j.ijhydene.2020.11.143 ◽

2020 ◽

Author(s):

José L. Contreras ◽

Anabel Figueroa ◽

Beatriz Zeifert ◽

José Salmones ◽

Gustavo A. Fuentes ◽

...

Keyword(s):

Steam Reforming ◽

Ethanol Steam Reforming ◽

Tungsten Oxides ◽

Production Of Hydrogen ◽

Ethanol Steam

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Hydrogen Production from Ethanol Steam Reforming: Fixed Bed Reactor Design

International Journal of Chemical Reactor Engineering ◽

10.2202/1542-6580.1582 ◽

2008 ◽

Vol 6 (1) ◽

Cited By ~ 2

Author(s):

Pablo Giunta ◽

Norma Amadeo ◽

Miguel Laborde

Keyword(s):

Steam Reforming ◽

Flow Model ◽

Multicomponent Mixture ◽

Plug Flow ◽

Fixed Bed ◽

Fixed Bed Reactor ◽

Ethanol Steam Reforming ◽

Heterogeneous Model ◽

Ethanol Steam ◽

Hydrogen Stream

The aim of this work is to design an ethanol steam reformer to produce a hydrogen stream capable of feeding a 60 kW PEM fuel cell applying the plug flow model, considering the presence of the catalyst bed (heterogeneous model). The Dusty-Gas Model is employed for the catalyst, since it better predicts the fluxes of a multicomponent mixture. Moreover, this model has shown to be computationally more robust than the Fickian Model. A power law-type kinetics was used. Results showed that it is possible to carry out the ethanol steam reforming in a compact device (1.66 x 10 -5 to 5.27 x 10 -5 m3). It was also observed that this process is determined by heat transfer.

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