Cobalt hydrotalcite for the steam reforming of ethanol with scarce carbon production

Espinal, Raúl; Taboada, Elena; Molins, Elı́es; Chimentão, R.J.; Medina, Françesc; Llorca, Jordi

doi:10.1039/c2ra00936f

Cited by 53 publications

(53 citation statements)

References 61 publications

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“…According to the d value, the shell structure was attributable to CoO and the core structure was attributable to Co metal. Recently, it was suggested that the oxidized cobalt (Co 2+ ) was an active species in ethanol steam reforming [29,31], although metallic cobalt (Co 0 ) is generally accepted as the active species [37,38]. Therefore, for Co/1K/␣-Al 2 O 3 , the CoO species might be the active catalytic site for ethanol steam reforming.…”

Section: Tem Measurementmentioning

confidence: 98%

“…Co 0 species is known as an active species for carbon nanotube and carbon nanofiber formations (i.e. coke formation) [31,39]. However, only few carbon nanotubes were detectable over Co/1K/␣-Al 2 O 3 , where the supported Co existed as Co 0 -CoO core-shell particles.…”

Section: Tem Measurementmentioning

confidence: 99%

“…is strongly desired. For suppressing coke and methane formation in ethanol steam reforming over Co-based catalyst, two solutions have been proposed: one is an addition of a second element [12,18,21,22,25,26,29]; another is changing catalytic support [22][23][24]30,31]. The Llorca group reported that Co/ZnO promoted with Fe, Mn, or Cr showed high activity for ethanol steam reforming, in which Co and these metals produced alloys [12,18,21].…”

Section: Introductionmentioning

confidence: 97%

“…Although the catalytic activity in ethanol steam reforming over Co-based catalysts has been traditionally assigned only to metallic Co 0 species [37,38], Co 0 species are known as an active species for carbon nanotubes and carbon nanofiber formation (coke formation) [31,39]. The Llorca group reported that Co 2+ species on hydrotalcite support was active for ethanol steam reforming [29,31]. Therefore, it was expected that the increase in Co 2+ species by K addition resulted not only in coke formation suppression but also in promoting the catalytic activity.…”

Section: Introductionmentioning

confidence: 99%

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Steam reforming of ethanol over K promoted Co catalyst

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Shimizu

Nakazawa

et al. 2015

Applied Catalysis A: General

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Section: Tem Measurementmentioning

confidence: 98%

Section: Tem Measurementmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Steam reforming of ethanol over K promoted Co catalyst

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Shimizu

Nakazawa

et al. 2015

Applied Catalysis A: General

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“…13 Llorca et al reported that the supported Co species on Co/hydrotalcite existed as Co 2+ species. 14,15 These reports suggested that cationic Co 2+ species (i.e. CoO) is a highly active species in ethanol steam reforming with scarce coke formation.…”

Section: ¹1mentioning

confidence: 99%

Coke Resistance of Sr-Hydroxyapatite Supported Co Catalyst for Ethanol Steam Reforming

2017

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Co/Sr-hydroxyapatite catalyst (Co/Sr 10 (PO 4 ) 6 (OH) 2 : Co/ Sr-P) shows high activity and low carbon formation on ethanol steam reforming. H 2 -TPR measurements revealed that the Co species supported on Co/Sr-P was reduced only slightly more than that on typical Co/α-Al 2 O 3 . XAFS measurements revealed that Co 2+ species was observed mainly on the Co/Sr-P catalyst after H 2 -reduction at reaction temperature of 823 K. Co 2+ , i.e. CoO particle, on Co/Sr-P catalyst plays an important role as an active site for ethanol steam reforming with high coke resistance.Keywords: Hydrogen production | Hydroxyapatite support | Coke resistanceBiomass-derived ethanol (bioethanol) is anticipated as an important renewable resource.1 Especially, direct production of hydrogen by ethanol steam reforming is being developed intensively as a highly efficient energy production process. 2,3Moreover, since ethanol steam reforming is an endothermic reaction, as shown in eq 1, the reformate has a higher heating value of about 1450.9 kJ mol ¹1 (1277.4 for ethanol ¦H c + 173.5) after ethanol steam reforming. Therefore, ethanol steam reforming might increase the exergy rate considerably. 4 The exergy rate is defined as the ratio of Gibbs free energy (potential useful work) over the combustion enthalpy (energy supplied). Development of highly active and selective catalysts for ethanol steam reforming has been pursued actively. Among transition-metal catalysts, Co-based catalysts have been used extensively because of their higher activity and lower cost than those of noble metal catalysts.511 However, catalyst deactivation by coke formation presents an important difficulty. Therefore, the suppression of coke formation is strongly desired. Two solutions have been proposed for suppressing coke formation in ethanol steam reforming over Co-based catalysts: addition of another element 8,1014 and controlling the catalytic support. 6,7,1416 Reportedly, the use of basic supports (CeO 2 , ZnO, Mg-Al hydrotalcite, perovskite oxides, etc.) can suppress formations of coke and by-products effectively. The substituted hydroxyapatite supports were prepared using a hydrothermal method according to a published procedure with some modifications. 2022 The crystalline structure was confirmed using powder X-ray diffractometry (XRD). These XRD patterns were attributed to each hydroxyapatite with a single phase (not shown). Samples of the prepared M-phosphate and M-vanadate hydroxyapatite (M = Ca and Sr) supports are designated as Ca-P, Sr-P, Ca-V, and Sr-V.The Co catalysts supported on the hydroxyapatite supports were prepared using an impregnation method. Co(NO 3 ) 2 ¢6H 2 O was used as a metal precursor. The Co loading amount was 5 wt %. The hydroxyapatite support was mixed with distilled water in vacuo at room temperature for 2 h using a rotary evaporator. Then aqueous solution of Co precursor was added and stirred for 2 h. The obtained solution was then evaporated under heating and stirring. Subsequently, the obtained powder was dried at 393 K overnigh...

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Sustainable Hydrogen Production by Ethanol Steam Reforming using a Partially Reduced Copper–Nickel Oxide Catalyst

et al. 2015

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Hydrogen production through the use of renewable raw materials and renewable energy is crucial for advancing its applications as an energy carrier. In this study, we fabricated a solid oxide solution of Cu and Ni within a confined pore space, followed by a partial reduction, to produce a highly efficient catalyst for ethanol steam reforming (ESR). At 300 °C, EtOH is completely converted, a H2 yield of approximately 5 mol per mol is achieved, and CO2 is the main carbon-containing product. This demonstrates that H2 production from bioethanol is an efficient and sustainable approach. Such a highly efficient ESR catalyst is attributed to the ability of the metal-oxide interface to facilitate the transformation of CHx adspecies from acetaldehyde decomposition into methoxy-like adspecies, which are reformed readily to produce H2 and consequently reduce CH4 formation.

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Cobalt hydrotalcite for the steam reforming of ethanol with scarce carbon production

Cited by 53 publications

References 61 publications

Steam reforming of ethanol over K promoted Co catalyst

Steam reforming of ethanol over K promoted Co catalyst

Coke Resistance of Sr-Hydroxyapatite Supported Co Catalyst for Ethanol Steam Reforming

Sustainable Hydrogen Production by Ethanol Steam Reforming using a Partially Reduced Copper–Nickel Oxide Catalyst

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