Surface chemical modifications induced on high surface area graphite and carbon nanofibers using different oxidation and functionalization treatments

Dongil, Ana Belén; Bachiller‐Baeza, B.; Guerrero-Ruı́z, A.; Rodrı́guez-Ramos, I.; Martı́nez-Alonso, A.; Tascón, J.M.D.

doi:10.1016/j.jcis.2010.11.066

Cited by 114 publications

(56 citation statements)

References 34 publications

(41 reference statements)

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“…Considering the infrared spectra and the absence of any peak on the N 1s region, a tentative assignation of the peaks according to literature can be as follows. Peak A would be ascribed to oxygen in CeO 2 and/or NiO [36,37]; peak B, to defective oxygen as oxygen atoms in the vicinity of Ni and Ce vacancies [38], although it might also include the contribution of the ceria hydroxyls and remaining oxygen groups [39], and peak C to oxygen in bridgetype Ce-O-Na or Ni-O-Na [35], although it could also include the contribution of adsorbed water [40]. between Ni species and the sodium promoter.…”

Section: Characterizationmentioning

confidence: 99%

Promoter effect of sodium in graphene-supported Ni and Ni–CeO2 catalyst for the low-temperature WGS reaction

Dongil

Pastor‐Pérez

Sepúlveda-Escribano

et al. 2015

Applied Catalysis A: General

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Graphical abstract Highlights-Graphene-supported Ni and Ni-CeO 2 catalysts have been studied.-Metal dispersion depends on the presence of ceria and on the precipitating agent, NaOH or urea.-The graphene support strongly interacts with the ceria promoter.-The presence of sodium increases the catalytic activity, mainly in the presence of ceria. AbstractThe low temperature water-gas shift (WGS) reaction has been studied over NiCeO 2 /Graphene and Ni/Graphene. The catalysts were prepared with 5 wt% Ni and 20 wt% CeO 2 loadings, by deposition-precipitation employing sodium hydroxide and urea as precipitating agents. The materials were characterized by TEM, powder X-ray diffraction, Raman spectroscopy, H 2 -temperature-programmed reduction and X-ray photoelectron spectroscopy (XPS). The characterization and the reaction results indicated that the interaction between the active species and the support is higher than with activated carbon, and this hinders the reducibility of ceria and thus the catalytic performance. On the other hand, the presence of residual sodium in samples prepared by precipitation with NaOH facilitated the reduction of ceria. The catalytic activity was highly improved in the presence of sodium, what can be explained on the basis of an associative reaction mechanism which is favored over Ni-O-Na entities.

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Section: Characterizationmentioning

confidence: 99%

Promoter effect of sodium in graphene-supported Ni and Ni–CeO2 catalyst for the low-temperature WGS reaction

Dongil

Pastor‐Pérez

Sepúlveda-Escribano

et al. 2015

Applied Catalysis A: General

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“…It is well known that the treatment of CNT with HNO 3 introduces a high proportion of oxygen groups that evolve as CO 2 (carboxyl, anhydride and lactone groups) and CO (phenolic, carbonyl, quinine and anhydride groups) upon heating the sample. It can be assumed that below 723 K most of the weight loss is due to CO 2 whereas at temperature above 723 K the mass loss is mainly due to CO and, accordingly, the concentration of oxygen can be estimated [19]. The values, in Table 1, show that the parent supports, CNT and MG, displayed a very low concentration of oxygen.…”

Section: Support Characterizationmentioning

confidence: 99%

Ir supported over carbon materials for the selective hydrogenation of chloronitrobenzenes

et al. 2015

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In the present work we have studied the effect of carbon supports with different graphitic character (carbon nanotubes, mesoporous graphite and activated carbon) on the catalytic performance of iridium nanoparticles on the liquid phase chemoselective hydrogenation of para-chloronitrobenzene at room temperature. The effect of the oxygen groups was also evaluated by oxidizing a portion of the carbon nanotubes. The Raman and XRD spectra showed that the mesoporous graphite displayed the strongest graphitic character. The characterization of the catalysts by HR-TEM, XPS and TPR-H2, showed that the catalysts had similar particle size and that the catalysts prepared over the previously oxidized support, Ir/CNTox, was not fully reduced. The activity and selectivity achieved with the catalyst Ir/CNT was the best among the samples and the presence of irdium oxide on Ir/CNTox diminished the yield to p-chloroaniline, being the worse catalyst. The reactivity of different isomers was also studied over Ir/CNT and it followed the order m > o > p. This is a previous version of the article published in Catalysis Today. 2015Today. , 249: 72-78. doi:10.1016Today. /j.cattod.2014 Highlights -Ir catalysts supported on carbon materials with different graphitic character.-The effect of oxygen groups in carbon nanotubes has been evaluated.-Ir/CNT shows the best catalytic performance in p-chloronitrobenzene hydrogenation.-The reactivity of different isomers on Ir/CNT was m > o > p. AbstractIn the present work we have studied the effect of carbon supports with different graphitic character (carbon nanotubes, mesoporous graphite and activated carbon) on the catalytic performance of iridium nanoparticles on the liquid phase chemoselective hydrogenation of para-chloronitrobenzene at room temperature. The effect of the oxygen groups was also evaluated by oxidizing a portion of the carbon nanotubes. TheRaman and XRD spectra showed that the mesoporous graphite displayed the strongest graphitic character. The characterization of the catalysts by HR-TEM, XPS and TPR-H 2 , showed that the catalysts had similar particle size and that the catalysts prepared over the previously oxidized support, Ir/CNTox, was not fully reduced. The activity and selectivity achieved with the catalyst Ir/CNT was the best among the samples and the presence of irdium oxide on Ir/CNTox diminished the yield to p-chloroaniline, *Manuscript Click here to view linked References being the worse catalyst. The reactivity of different isomers was also studied over Ir/CNT and it followed the order m > o > p.

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“…These fibers possess a stacked-cup morphology with a hollow core through the length of the fiber and also present a jagged outer surface with "round heads" or "loop" structures which connect several layers [34,35]. Commercial carbon nanofibers Pyrograph III, PR24-PS (CNFs-PS S BET = 36 m 2 /g), are pyrolitically stripped carbon fiber at 1373 K, and therefore, less graphitized than CNF-HHT.…”

Section: Methodsmentioning

confidence: 99%

“…However, when the catalytic activity is expressed as ethanol micromoles converted per second and per square meter it is seen that the CNF-HHT and MWCNT-ox samples present the highest values. The studies by Raman spectroscopy [35,44,45] indicate that the intensity ratio of D to G bands (I D /I G ), which can be related to the degree of the graphitic disorder, is lower for these two samples ( Table 2). This suggests that basic surface sites can be related with graphitic structures which are active and selective for the acetaldehyde formation.…”

Section: Catalytic Activitymentioning

confidence: 97%

Bioethanol Transformations Over Active Surface Sites Generated on Carbon Nanotubes or Carbon Nanofibers Materials

Almohalla¹,

Morales²,

Asedegbega–Nieto³

et al. 2014

TOCATJ

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Catalytic bioethanol transformations over carbon nanomaterials (nanofibers and nanotubes) have been evaluated at atmospheric pressure and in the temperature range of 473-773 K. The pristine carbon materials were compared with these samples after surface modification by introducing sulfonic groups. The specific activity for ethanol dehydrogenation, yielding acetaldehyde, increases with the surface graphitization degree for these materials. This suggests that some basic sites can be related with specific surface graphitic structures or with the conjugated basic sites produced after removing acidic oxygen surface groups. Concerning the dehydration reaction over sulfonated samples, it is observed that catalytic activities are related with the amount of incorporated sulfur species, as detected by the evolution of SO 2 in the Temperature programmed Desorption (TPD) as well as by the analysis of sulfur by X-Ray Photoelectron Spectroscopy (XPS).

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Surface chemical modifications induced on high surface area graphite and carbon nanofibers using different oxidation and functionalization treatments

Cited by 114 publications

References 34 publications

Promoter effect of sodium in graphene-supported Ni and Ni–CeO2 catalyst for the low-temperature WGS reaction

Promoter effect of sodium in graphene-supported Ni and Ni–CeO2 catalyst for the low-temperature WGS reaction

Ir supported over carbon materials for the selective hydrogenation of chloronitrobenzenes

Bioethanol Transformations Over Active Surface Sites Generated on Carbon Nanotubes or Carbon Nanofibers Materials

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