Experimental study and mechanistic kinetic modeling for selective production of hydrogen via catalytic steam reforming of methanol

Patel, Sanjay; Pant, Kamal K.

doi:10.1016/j.ces.2007.01.044

Cited by 65 publications

(39 citation statements)

References 32 publications

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“…Among the many rate equations proposed previously, 21,22,[24][25][26][27][28][29] this equation resembles most closely that of Jiang et al, 22 who reported, however, no detectable CO among reaction products and ignored the role of WGS reactions in the catalytic sequence. Our proposed catalytic sequence (Scheme 1) requires only one type of site to account for all observations, without awkward proposals for sites in Cu/ZnO/Al 2 O 3 that desorb hydrogen and other sites that stabilize oxygenated intermediates.…”

Section: Sequence Of Elementarysupporting

confidence: 53%

“…As a result, we examine here the kinetics and mechanism of CH 3 OH reforming, specifically on Cu-based catalysts that form H 2 , CO 2 , and CO with high selectivity from CH 3 OH-H 2 O reactants. [20][21][22][23][24][25][26][27][28][29][30] CH 3 OH reforming mechanistic studies have reached diverse conclusions about kinetically relevant steps, which have included H-abstraction from molecularly adsorbed CH 3 OH by O-H bond cleavage, 24 H-abstraction from methoxides, 22,25,26 and the intermediate formation of formic acid from formaldehyde molecules derived from methoxides and its eventual decomposition; 29 these conclusions were based solely on comparisons between rate data and predicted rate equations. Even the kinetic dependence of reforming rates on reactant and products pressures remains unresolved (ref 26 and references therein).…”

Section: Introductionmentioning

confidence: 99%

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Isotopic and Kinetic Assessment of the Mechanism of CH₃OH−H₂O Catalysis on Supported Copper Clusters

Kim

Iglesia

2008

J. Phys. Chem. C

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This study provides kinetic and isotopic evidence for the identity and kinetic relevance of elementary steps in CH 3 OH-H 2 O reactions on monofunctional Cu-based catalysts. H 2 , CO 2 , and CO were the only products formed in these reactions, which proceed via kinetically relevant C-H bond activation in chemisorbed methoxides. All other elementary steps are in quasi-equilibrium, consistent with the effects of reactants and products on rates, with isotopic tracing and kinetic isotope evidence, and with the equilibrated nature of water gas shift reactions at all reaction conditions. Turnover rates increased with CH 3 OH pressure but did not depend on CO, CO 2 , or H 2 O concentrations. H 2 inhibited CH 3 OH-H 2 O reactions by decreasing the concentration of surface methoxide intermediates via quasi-equilibrated CH 3 OH dissociation steps. Isotopic scrambling was complete among hydroxyl groups in methanol and water, but undetectable among hydroxyl and methyl groups in methanol, consistent with quasi-equilibrated O-H activation and irreversible C-H activation steps. Deuterium substitution at methyl groups in methanol gave normal kinetic isotope effects, whereas substitution at hydroxyl groups in methanol or water led to weaker isotope effects consistent with their thermodynamic origin from quasi-equilibrated O-H activation steps. These mechanistic conclusions are consistent with detailed kinetic data on both large and small Cu clusters and with reforming pathways requiring only Cu surfaces to complete catalytic turnovers. CH 3 OH-H 2 O turnover rates increased weakly with Cu dispersion as Cu cluster size decreased from 30 to 5 nm, suggesting that these reactions are insensitive to structure when CH 3 OH-H 2 O reaction occurs on Cu via monofunctional pathways limited by H-abstraction from methoxide intermediates. This structure insensitivity may reflect the titration of low-coordination surfaces with strongly held and unreactive forms of adsorbed intermediates, causing turnovers to occur preferentially on low-index surfaces for clusters of varying size.

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Section: Sequence Of Elementarysupporting

confidence: 53%

Section: Introductionmentioning

confidence: 99%

Isotopic and Kinetic Assessment of the Mechanism of CH₃OH−H₂O Catalysis on Supported Copper Clusters

Kim

Iglesia

2008

J. Phys. Chem. C

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“…For example, Nakagaki developed a design method for methanol reformers by examining the reaction rates with Cu-Zn catalyst and reforming performance of a tube reactor [38]. Patel established a mechanistic kinetic model for methanol steam reforming over a Cu/ZnO/Al 2 O 3 catalyst, to predict the production rates of hydrogen, carbon dioxide and carbon monoxide for different operation conditions [39]. Hou investigated the performance of a non-isothermal solar reactor for methanol decomposition, obtained the reactor performance under different radiation intensity, beam incidence angle, and feed parameters [40].…”

Section: Technical Considerationsmentioning

confidence: 99%

Performance comparison of two low-CO 2 emission solar/methanol hybrid combined cycle power systems

Zhang

Lior

2015

Applied Energy

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“…However, these catalysts presented some inconveniences: high CO formation, low stability with time due to the tendency of copper sintering and their pyrophoric nature when they are exposed to oxidizing environments. The effects of CeO 2 and ZrO 2 on CuOeZnOeAl 2 O 3 catalysts have also been examined [14,19].…”

Section: Introductionmentioning

confidence: 99%

Activity and stability of a CuO/CeO2 catalyst for methanol steam reforming

Tonelli

Gorriz

Tarditi

et al. 2015

International Journal of Hydrogen Energy

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Experimental study and mechanistic kinetic modeling for selective production of hydrogen via catalytic steam reforming of methanol

Cited by 65 publications

References 32 publications

Isotopic and Kinetic Assessment of the Mechanism of CH₃OH−H₂O Catalysis on Supported Copper Clusters

Isotopic and Kinetic Assessment of the Mechanism of CH₃OH−H₂O Catalysis on Supported Copper Clusters

Performance comparison of two low-CO 2 emission solar/methanol hybrid combined cycle power systems

Activity and stability of a CuO/CeO2 catalyst for methanol steam reforming

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Experimental study and mechanistic kinetic modeling for selective production of hydrogen via catalytic steam reforming of methanol

Cited by 65 publications

References 32 publications

Isotopic and Kinetic Assessment of the Mechanism of CH3OH−H2O Catalysis on Supported Copper Clusters

Isotopic and Kinetic Assessment of the Mechanism of CH3OH−H2O Catalysis on Supported Copper Clusters

Performance comparison of two low-CO 2 emission solar/methanol hybrid combined cycle power systems

Activity and stability of a CuO/CeO2 catalyst for methanol steam reforming

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Product

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Isotopic and Kinetic Assessment of the Mechanism of CH₃OH−H₂O Catalysis on Supported Copper Clusters

Isotopic and Kinetic Assessment of the Mechanism of CH₃OH−H₂O Catalysis on Supported Copper Clusters