Subsurface‐gesteuerte CO<sub>2</sub>‐Selektivität von PdZn‐Oberflächenlegierungen in der H<sub>2</sub>‐Erzeugung durch Methanoldampfreformierung

Rameshan, Christoph; Stadlmayr, Werner; Weilach, Christian; Penner, Simon; Lorenz, Harald; Hävecker, Michael; Blume, Raoul; Rocha, Túlio C. R.; Teschner, Detre; Knop‐Gericke, Axel; Schlögl, Robert; Memmel, N.; Zemlyanov, Dmitry; Rupprechter, Günther; Klötzer, Bernhard

doi:10.1002/ange.200905815

Cited by 21 publications

(11 citation statements)

References 16 publications

(14 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, despite enormous efforts to acquire supported PdZn intermetallic catalysts in a controllable fashion, there is a lack of convincing evidence about the key elementary steps associated with the intermetallic process; thus, mechanistic clarification and rational design of catalysts is hindered. Firstly, PdZn formation was investigated under ultrahigh‐vacuum conditions, based on some model systems, in which the interaction between deposited Zn layers and the single‐crystal Pd surface was studied at elevated temperatures in the absence of a gaseous atmosphere . According to the (sub)surface structural evolution of PdZn, determined by surface‐sensitive techniques, it was determined that the deposited Zn layer starts to diffuse into Pd (111) at about 350 K, followed by formation of a 1:1 PdZn multilayer intermetallic at about 500 K because of further diffusion of Zn into the Pd bulk.…”

Section: Figurementioning

confidence: 99%

“…The shared lattice plane (white lines in the HRTEM images, Figures e,f) of PdZn and PdH x phases were ascribed to PdH x (11‐1), indicating that the growth direction of PdZn was parallel to PdH x ⟨111⟩, as demonstrated by the atomic model in Figure S12. This is consistent with previous studies, which indicate that Zn atoms diffuse more readily into Pd for the formation of the PdZn structure on the Pd (111) plane than on the Pd (110) plane . Therefore, the PdH x structure was initially generated under H 2 atmosphere and acted as an intermediate during the phase transition.…”

Section: Figurementioning

confidence: 99%

See 1 more Smart Citation

Visualizing Formation of Intermetallic PdZn in a Palladium/Zinc Oxide Catalyst: Interfacial Fertilization by PdH_x

et al. 2019

View full text Add to dashboard Cite

Controllable synthesis of well‐defined supported intermetallic catalysts is desirable because of their unique properties in physical chemistry. To accurately pinpoint the evolution of such materials at an atomic‐scale, especially clarification of the initial state under a particular chemical environment, will facilitate rational design and optimal synthesis of such catalysts. The dynamic formation of a ZnO‐supported PdZn catalyst is presented, whereby detailed analyses of in situ transmission electron microscopy, electron energy‐loss spectroscopy, and in situ X‐ray diffraction are combined to form a nanoscale understanding of PdZn phase transitions under realistic catalytic conditions. Remarkably, introduction of atoms (H and Zn in sequence) into the Pd matrix was initially observed. The resultant PdHx is an intermediate phase in the intermetallic formation process. The evolution of PdHx in the PdZn catalyst initializes at the PdHx/ZnO interfaces, and proceeds along the PdHx ⟨111⟩ direction.

show abstract

Section: Figurementioning

confidence: 99%

Section: Figurementioning

confidence: 99%

Visualizing Formation of Intermetallic PdZn in a Palladium/Zinc Oxide Catalyst: Interfacial Fertilization by PdH_x

et al. 2019

View full text Add to dashboard Cite

show abstract

“…A low activation energy of ≈100 kJ mol −1 was determined by Arrhenius analysis, with a reaction onset temperature of ≈470 K. In comparison, the onset temperature of CuZn is ≈530 K with a similar activation energy . ZnPd showed an equally high reaction‐onset temperature of ≈540 K with a slightly higher activation energy of ≈116 kJ mol −1 . With regard to potential applications, the presented preparation technique is perfectly suitable for catalytic coatings (e.g., bimetallic coatings of ceramic monoliths for microreactors and microreformers), and can automatically form a highly active, highly selective, and very stable high‐surface‐area state by “selective corrosion” under MSR reaction conditions.…”

Section: Figurementioning

confidence: 99%

Boosting Hydrogen Production from Methanol and Water by in situ Activation of Bimetallic Cu−Zr Species

et al. 2016

Self Cite

View full text Add to dashboard Cite

Ab imetallic Cu/Cu 51 Zr 14 precatalyst,a ctivated in situ, for hydrogen generation from methanol and water providesv ery high CO 2 selectivity (> 99.9 %) and high H 2 yields. Referenced to the geometrics urface area of our model surface, highera ctivity of at least one order of magnitude was observed in comparison to supportedC u/ZrO 2 and Cu/ZnO/ZrO 2 catalysts. Evolution of structurala ctivation monitored by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and electron microscopy indicatest ransformation of the bimetallic Cu/Cu 51 Zr 14 precatalyst into an active, selective, and self-stabilizing state with coexistence of dispersed Cu and partially hydroxylated tetragonal ZrO 2 .The outstanding performance is assigned to the presence of ah igh interface-site concentration following in situ decompositiono ft he intermetallic compound. These actives ites result from the cooperation of Cu, responsible for methanol activation,a nd tetragonal ZrO 2 ,w hich activates the water by surface hydroxylation.Copper-based catalysts are widely used for technical applications in methanolc hemistry,w ell-known examples include methanol synthesis from syngasw ith an optimized CO/CO 2 ratio, hydrogenation/photoreduction of CO 2 to produce "renewable" methanol, and methanol steam reforming (MSR) as the reversal of the synthesis reactionf rom CO 2.[1] The ability to control product selectivity is ak ey criterion for technical usage. Therefore, to realize the efficient on-boardp roduction of clean hydrogen in, for example, automotive applications, the key targets for MSR are high CO 2 selectivity,l ow CO content,a nd maximum H 2 yield in the reformate.[2] With respect to the catalytic functiono fZ rO 2 in MSR, the simple addition of ZrO 2 to the conventionally used Cu/ZnO catalysts overcomes the inherent drawback of purely ZnO-based catalysts,t hat is, the poor sinterings tability.[2] Beneficial synergistic effectsf or methanol synthesis have also been described for Cu/Zn and the ternary Cu/Zn/Al system prepared by ac o-precipitation technique.[3]Synergistic Cu-ZrO 2 interactions have also been reported for Cu/ZrO 2 catalysts without ZnO, involving CuÀOÀZr bonds at the phase boundary. The Cu-ZrO 2 interactions are believed to play ac rucial role in steering the methanol reforming reaction to maximum CO 2 selectivity.[4] Specifically,ananocrystalline Cu/ tetragonal ZrO 2 catalyst synthesized by ap olymer templating technique [5] was reported to be more active, selective, and stable in MSR than the technical Cu/ZnO/Al 2 O 3 methanol synthesis catalyst.[6] Although the beneficial effects of the redox chemistry of Cu and the Cu 0 /Cu oxidized ratio at the interface has been suggesteda sa ni mportants electivity descriptor,a longside disorder and strain phenomena within the metallicC u phase, [2] ac ontradictingi nfluence hasa lso been reported. Both beneficial [4a, b] and adverse [4d] effectso ft he reducibility of Cu can be found in the literature. Nevertheless, any influence appears strongly connected to the quantity...

show abstract

“…[12] The presence of oxidized Zn in near-surface regions has been shown to be inevitably linked to a high CO 2 -selectivity in inverse model catalyst studies of near-surface intermetallic phases. [14][15][16] The knowledge transfer from these model systems to high-performance catalysts represents a great step towards understanding MSR.…”

Section: Matthias Friedrich Simon Penner Marc Heggen and Marc Armbmentioning

confidence: 99%

High CO₂ Selectivity in Methanol Steam Reforming through ZnPd/ZnO Teamwork

et al. 2013

Self Cite

View full text Add to dashboard Cite

show abstract

Subsurface‐gesteuerte CO₂‐Selektivität von PdZn‐Oberflächenlegierungen in der H₂‐Erzeugung durch Methanoldampfreformierung

Cited by 21 publications

References 16 publications

Visualizing Formation of Intermetallic PdZn in a Palladium/Zinc Oxide Catalyst: Interfacial Fertilization by PdH_x

Visualizing Formation of Intermetallic PdZn in a Palladium/Zinc Oxide Catalyst: Interfacial Fertilization by PdH_x

Boosting Hydrogen Production from Methanol and Water by in situ Activation of Bimetallic Cu−Zr Species

High CO₂ Selectivity in Methanol Steam Reforming through ZnPd/ZnO Teamwork

Contact Info

Product

Resources

About

Subsurface‐gesteuerte CO2‐Selektivität von PdZn‐Oberflächenlegierungen in der H2‐Erzeugung durch Methanoldampfreformierung

Cited by 21 publications

References 16 publications

Visualizing Formation of Intermetallic PdZn in a Palladium/Zinc Oxide Catalyst: Interfacial Fertilization by PdHx

Visualizing Formation of Intermetallic PdZn in a Palladium/Zinc Oxide Catalyst: Interfacial Fertilization by PdHx

Boosting Hydrogen Production from Methanol and Water by in situ Activation of Bimetallic Cu−Zr Species

High CO2 Selectivity in Methanol Steam Reforming through ZnPd/ZnO Teamwork

Contact Info

Product

Resources

About

Subsurface‐gesteuerte CO₂‐Selektivität von PdZn‐Oberflächenlegierungen in der H₂‐Erzeugung durch Methanoldampfreformierung

Visualizing Formation of Intermetallic PdZn in a Palladium/Zinc Oxide Catalyst: Interfacial Fertilization by PdH_x

Visualizing Formation of Intermetallic PdZn in a Palladium/Zinc Oxide Catalyst: Interfacial Fertilization by PdH_x

High CO₂ Selectivity in Methanol Steam Reforming through ZnPd/ZnO Teamwork