Partial oxidation of methanol over supported palladium catalysts

Cubeiro, M.L.; Fierro, J.L.G.

doi:10.1016/s0926-860x(97)00361-x

Cited by 189 publications

(85 citation statements)

References 29 publications

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“…The presence of Pd metal was evident in the XPS results and HRTEM, so the absence of this TPR peak was rather surprising. Nevertheless, this can be explained by the fact that the hydride could be decomposed once it was formed; therefore observation of the TPR decomposition peak could be masked by a major and positive peak due to the reduction of PdO as it was reported in other studies [39]. It was noted that the reduction of all of the PdZn/ZnO catalysts started at a similar low temperature range of 51-70 • C. These TPR peaks were undoubtedly attributed to the reduction of PdO [45,46].…”

Section: Study Of the Metal-support Interaction By Tpr Experimentsmentioning

confidence: 75%

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Ultraselective low temperature steam reforming of methanol over PdZn/ZnO catalysts—Influence of induced support defects on catalytic performance

Eblagon

Concepción

Silva

et al. 2014

Applied Catalysis B: Environmental

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The influence of the calcination atmosphere of ZnO precursor (Zn4(CO)3(OH)6·H2O) on the catalytic performance of a series of PdZn/ZnO catalysts was studied for production of H2 via low temperature (180 • C) direct methanol steam reforming (low temperature-MSR). The catalytic activity and selectivity of PdZn/ZnO were found to be strongly influenced by the calcination atmosphere of ZnO precursor and increased from oxidizing to reducing atmosphere, following the order (O2 < air < N2 < H2). As a result, a very active catalyst was obtained by simply supporting Pd on ZnO calcined in H2. Further evidence from XPS and TPR analysis indicated that calcination in reducing atmosphere gave rise to a significant increase in the concentration of oxygen vacancies on the surface of ZnO support. Thus, the superb performance of the best catalyst was attributed to the defect chemistry of ZnO support; mainly to the amount of oxygen vacancies present in the interface region, which act as additional active sites for water adsorption and subsequent activation. In addition, the formation of CO was drastically suppressed by replenishment of oxygen vacancies on ZnO support. Thus, it is clear that the abundance of specific active sites on PdZn/ZnO catalyst is strongly influenced by the preparation route of the ZnO support. Additionally, the PdZn alloy was discovered to be unstable under prolonged exposure to CO atmosphere and the stability test under methanol steam reforming conditions showed a 24% drop in conversion over 48 h testing period. This phenomena can have detrimental effect on the performance of this type of catalytic systems in continuous prolonged duty cycle time on-stream.

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Section: Study Of the Metal-support Interaction By Tpr Experimentsmentioning

confidence: 75%

“…In addition, the highest BE peak labelled Oc is associated with adsorbed OH groups on the surface of ZnO. These groups most likely originate from dissociation of adsorbed water on ZnO, which was produced during reduction of PdO [39].…”

Section: Xps Study Of Oxygen Vacancies In Zno Supportsmentioning

confidence: 99%

Ultraselective low temperature steam reforming of methanol over PdZn/ZnO catalysts—Influence of induced support defects on catalytic performance

Eblagon

Concepción

Silva

et al. 2014

Applied Catalysis B: Environmental

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“…This Kubelka-Munk/a.u. process is facilitated by metallic palladium, which simultaneously participates in the formation of PdZn alloys [3][4][5][28][29][30]. It is interesting that reduction of ZnO and thus formation of PdZn start at lower temperature in Pd/ ZnO-AOT sample.…”

Section: Resultsmentioning

confidence: 99%

Application of microemulsion method for development of methanol steam reforming Pd/ZnO catalysts

Pawlonka

Gac

Greluk

et al. 2016

J Therm Anal Calorim

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Thermal decomposition of palladium acetylacetonate adsorbed on zinc oxide (ZnO), and the formation of palladium oxide (PdO) and palladium zinc alloy (PdZn) phases were studied. Two types of ZnO supports were prepared by the microemulsion method using different surfactants, i.e. hexadecyltrimethylammonium bromide (CTAB) and (Bis(2-ethylhexyl) sulfosuccinate sodium salt, AOT). The nanoparticles of ZnO synthesized in the presence of CTAB surfactant showed higher specific surface area, smaller crystallite size and more irregular shape. Palladium was loaded on the surface of obtained supports by the impregnation method from the acetone solution of palladium acetylacetonate. Thermogravimetric studies indicated that palladium precursor loaded on CTAB-modified ZnO support was less stable and simultaneously decomposed in broader range of temperatures. Slight differences between the forms of precursors adsorbed on the supports were demonstrated by the diffuse reflectance infrared Fourier transform spectroscopy studies. Thermal decomposition of palladium acetylacetonate precursors in the air led to the formation of PdO species. The influence of ZnO morphology on the metal-oxygen bonds strength in PdO and formation of active phases were observed. Strongly dispersed PdZn crystallites on ZnO supports were formed upon reduction at 350°C. Smaller crystallites of the size equal to 6.5 nm were detected in the Pd/ZnO-AOT catalysts.

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“…An impregnation method has been performed by the addition of supports into precursor suspensions of metal catalysts. 11,12 In a precipitation method, the PdZnO catalysts were prepared by the addition of a basic solution to a mixed aqueous solution of Pd and Zn salts. 13 PdZnO catalysts have also been prepared by heat treatment of physical mixtures of Pd and Zn powders.…”

Section: 9mentioning

confidence: 99%

Preparation of Palladium Catalysts by Pretreatment Steps in Electroless Plating toward Partial Oxidation of Methanol with Steam Reforming

Kobayashi

Tadaki

Takahashi

et al. 2006

J. Ceram. Soc. Japan

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ᠪҽ╫ɩɋȵ֭ᥴకᲦȡ᧸ǦǮɩɇɖʀɳȤոɛ‫ك‬ᕮ⋛ᕧტ‫ۀ‬අ Pd ╮ǽΰ⓯ ତአ↽ᨇ í ɿ‫ޗ‬ቆᗱ౪ɿ‫ڢ‬ᑼӡడଉ ɿ͑ʅᨇ ኇ‫ل‬গકগકрకકᮾ᳣ᲇ‫ك‬કకકଗფࢫ980-8579 ͜۞లԂ⊡ٚ∕ఫઆԂ⊡ 6-6-07 ଉ ᮸႒ᰓʄకᏡጋ࣠ᬬᮾ᳣ཀࢫ235-8501 ᑥᘛలᰚٚᄽ˛‫ڤ‬ᨊ A previously proposed method for depositing Ag nanoparticles on silica particles was extended to the preparation of ZnO-supported Pd PdZnO catalysts. The method presented in this work consists of two steps: 1 Sn 2ࢪ ions are adsorbed on the surfaces of ZnO particles, and 2 Pd 2ࢪ ions added are reduced by oxidization of Sn 2ࢪ to Sn 4ࢪ and simultaneously adsorbed on the surface. TEM observations revealed that Pd nanoparticles with an average size of 2-3 nm were formed on the 20 nm ZnO particles. The Pd nanoparticles were transformed into a Pd-Zn alloy by partial oxidation and steam reforming of methanol, and consequently the PdZnO attained CH 3 OH conversion efficiencies of 35-50ಚ at reaction temperatures of 310-370c C.

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Partial oxidation of methanol over supported palladium catalysts

Cited by 189 publications

References 29 publications

Ultraselective low temperature steam reforming of methanol over PdZn/ZnO catalysts—Influence of induced support defects on catalytic performance

Ultraselective low temperature steam reforming of methanol over PdZn/ZnO catalysts—Influence of induced support defects on catalytic performance

Application of microemulsion method for development of methanol steam reforming Pd/ZnO catalysts

Preparation of Palladium Catalysts by Pretreatment Steps in Electroless Plating toward Partial Oxidation of Methanol with Steam Reforming

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