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

Özkan, Gülay; Şahbudak, Başak; Özkan, Göksel

doi:10.1016/j.ijhydene.2018.11.198

Cited by 19 publications

(6 citation statements)

References 16 publications

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“…Therefore, the precursors of filamentous coke formation under these conditions are CH 4 (by decomposition reaction, eq ) and CO (by Boudouard reaction, eq ). This origin of the filamentous coke is well established in the literature ,, and explains the maximum coke content obtained for an intermediate value of space-time (Figure ) since the yields of CH 4 and CO are maximum (Figure ). Further increase in space-time enhances both CH 4 reforming and WGS reaction, which promotes the formation of CO 2 , thus disfavoring the coke formation by Boudouard reaction.…”

Section: Discussion On Precursors Of Coke Formationsupporting

confidence: 81%

Origin and Nature of Coke in Ethanol Steam Reforming and Its Role in Deactivation of Ni/La₂O₃–αAl₂O₃ Catalyst

Montero

Remiro

Valle

et al. 2019

Ind. Eng. Chem. Res.

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Deactivation of Ni/La2O3–αAl2O3 catalyst in ethanol steam reforming (ESR) was studied in order to establish the optimal conditions for maximizing H2 production and achieving steady behavior. The ESR reactions were conducted in a fluidized bed reactor under the following operating conditions: 500–650 °C; space-time up to 0.35 gcatalyst h/gEtOH; and steam/ethanol (S/E) molar ratio in the feed, 3–9. The features of the deactivated catalysts and the nature and morphology of the coke deposited were analyzed by temperature-programmed oxidation, X-ray diffraction, scanning electron microscopy, and Raman spectroscopy. Catalyst deactivation was solely caused by coke deposition, especially by encapsulating coke, with acetaldehyde, ethylene, and ethanol being the main precursors, whose concentration was high for lower values of space-time. Conversely, the filamentous coke formed from CH4 and CO (with their highest concentration for intermediate values of space-time) had a much lower impact on deactivation. Owing to the effect of space-time on the extent of reactions leading to the formation of coke precursors, the Ni/La2O3–αAl2O3 catalyst stability was enhanced by increasing space-time. The increase in temperature and S/E ratio was also beneficial since both variables promoted coke gasification. Consequently, a steady H2 yield throughout 200 h reaction was attained at 600 °C, a space-time of 0.35 gcatalyst h/gEtOH, and S/E > 3.

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Section: Discussion On Precursors Of Coke Formationsupporting

confidence: 81%

Origin and Nature of Coke in Ethanol Steam Reforming and Its Role in Deactivation of Ni/La₂O₃–αAl₂O₃ Catalyst

Montero

Remiro

Valle

et al. 2019

Ind. Eng. Chem. Res.

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“…ESR is a complex reaction, in which the catalytic performance depends on many parameters such as the reaction conditions and the types of catalysts , , . The most important points are the improvements of ethanol conversion and hydrogen selectivity, leading to the highest yield of hydrogen.…”

Section: Discussionmentioning

confidence: 99%

“…Also, the increased space‐time leads to an increase in hydrogen yield due to a decrease in intermediates . Higher water‐to‐ethanol ratios (> 3) favor the ESR and the forward water‐gas shift reaction and avoid the formation of coke .…”

Section: Introductionmentioning

confidence: 99%

Effect of Supports and Promoters on the Performance of Ni‐Based Catalysts in Ethanol Steam Reforming

et al. 2020

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Ethanol steam reforming (ESR) is one of the potential processes to convert ethanol into valuable products. Hydrogen produced from ESR is considered as green energy for the future and can be an excellent alternative to fossil fuels with the aim of mitigating the greenhouse gas effect. The ESR process has been well studied, using transition metals as catalysts coupled with both acidic and basic oxides as supports. Among various reported transition metals, Ni is an inexpensive material with activity comparable to that of noble metals, showing promising ethanol conversion and hydrogen yields. Additionally, different promoters and supports were utilized to enhance the hydrogen yield and the catalyst stability. This review summarizes and discusses the influences of the supports and promoters of Ni‐based catalysts on the ESR process.

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“…[195] Thus, it is widely believed that the modification of oxide support should be an effective approach for the improvement of catalytic activity. The addition of various elements ranging from transition metal to alkaline earth metal and rare earth metal including Mg, [60,196] Zn, [197] Ca, [198][199][200] Cs, [201] La, [202] and K, [203][204][205] has been detail investigated recently years. They play an important role in influencing the dispersion, oxygen capacity and surface properties of supported catalysts.…”

Section: Performance Improvement From Oxide Support Modifiedmentioning

confidence: 99%

Recent Status in Catalyst Modification Strategies for Hydrogen Production from Ethanol Steam Reforming

2023

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Hydrogen as the most promising alternative energy vector to fossil stands out due to its highly energy density and zero pollution. Extending the hydrogen feedstock from hydrocarbons (e. g., methane) to biomass derived oxygen‐containing compounds (CH3OH, C2H5OH etc.) provides the opportunity for low environmental pollution as well as a promising sustainable energy economy. Recently, ethanol with less toxic and high calorific value than traditional fossil energy (coal, oil and natural gas) has garnered significant attention for ethanol steam reforming (ESR) to produce hydrogen, a key component in fuel cell cogeneration system. This paper reviews recent advances on the catalyst developing strategies including structural constitution control, oxide supports modification, surface topography control and bimetallic interactions, and further discusses the catalytic mechanisms, anti‐carbon deposition and sintering resistance strategies on the ethanol steam reforming (ESR) processes. Finally, the challenges and possible strategies for the development of high‐performance catalysts in terms of fundamental research have been discussed.

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

Cited by 19 publications

References 16 publications

Origin and Nature of Coke in Ethanol Steam Reforming and Its Role in Deactivation of Ni/La₂O₃–αAl₂O₃ Catalyst

Origin and Nature of Coke in Ethanol Steam Reforming and Its Role in Deactivation of Ni/La₂O₃–αAl₂O₃ Catalyst

Effect of Supports and Promoters on the Performance of Ni‐Based Catalysts in Ethanol Steam Reforming

Recent Status in Catalyst Modification Strategies for Hydrogen Production from Ethanol Steam Reforming

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

Cited by 19 publications

References 16 publications

Origin and Nature of Coke in Ethanol Steam Reforming and Its Role in Deactivation of Ni/La2O3–αAl2O3 Catalyst

Origin and Nature of Coke in Ethanol Steam Reforming and Its Role in Deactivation of Ni/La2O3–αAl2O3 Catalyst

Effect of Supports and Promoters on the Performance of Ni‐Based Catalysts in Ethanol Steam Reforming

Recent Status in Catalyst Modification Strategies for Hydrogen Production from Ethanol Steam Reforming

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Product

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Origin and Nature of Coke in Ethanol Steam Reforming and Its Role in Deactivation of Ni/La₂O₃–αAl₂O₃ Catalyst

Origin and Nature of Coke in Ethanol Steam Reforming and Its Role in Deactivation of Ni/La₂O₃–αAl₂O₃ Catalyst