Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Pd-Pt”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

5 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Optimizing feed modulation for coupled methane and NO x conversion over Pd-Pt/Mn 0.5 Fe 2.5 O 4 /Al 2 O 3 monolith catalyst

Here the impacts of feed modulation (frequency, amplitude) and catalyst design (composition and architecture) parameters are reported for the conversion of methane and NO x over a dual-layer Pt+Pd/Al 2 O 3 + Mn 0.5 Fe 2.5 O 4 /Al 2 O 3 monolith. CH 4 and NO x conversion data show that the dual-layer catalyst outperforms single-layer samples having the same catalyst loadings, with and without spinel. Close proximity of the PGM and MFO functions in the mixed-layer catalyst lowers the CH 4 conversion at high temperature while separating the PGM and spinel layers with an intermediate Al 2 O 3 layer does not. Methane conversion enhancement is linked to its nonmonotonic dependence on O 2 . The performance gains are tied to a transient activity spike that occurs during the lean-to-rich feed transition when water is present in the feed. The transient spike is attributed to the removal of CO and H 2 products via reactions with stored O 2 in the spinel, eliminating inhibition of methane steam reforming.

03 NATURAL GAS↗
DOE OSTI2024

Direct propylene epoxidation via water activation over Pd-Pt electrocatalysts

Direct electrochemical propylene epoxidation by means of water-oxidation intermediates presents a sustainable alternative to existing routes that involve hazardous chlorine or peroxide reagents. Here, we report an oxidized palladium-platinum alloy catalyst (PdPtO x /C), which reaches a Faradaic efficiency of 66 ± 5% toward propylene epoxidation at 50 milliamperes per square centimeter at ambient temperature and pressure. Embedding platinum into the palladium oxide crystal structure stabilized oxidized platinum species, resulting in improved catalyst performance. The reaction kinetics suggest that epoxidation on PdPtO x /C proceeds through electrophilic attack by metal-bound peroxo intermediates. This work demonstrates an effective strategy for selective electrochemical oxygen-atom transfer from water, without mediators, for diverse oxygenation reactions.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Templated encapsulation of platinum-based catalysts promotes high-temperature stability to 1,100 °C

Stable catalysts are essential to address energy and environmental challenges, especially for applications in harsh environments (for example, high temperature, oxidizing atmosphere and steam). In such conditions, supported metal catalysts deactivate due to sintering-a process where initially small nanoparticles grow into larger ones with reduced active surface area-but strategies to stabilize them can lead to decreased performance. In this work, we report stable catalysts prepared through the encapsulation of platinum nanoparticles inside an alumina framework, which was formed by depositing an alumina precursor within a separately prepared porous organic framework impregnated with platinum nanoparticles. These catalysts do not sinter at 800 °C in the presence of oxygen and steam, conditions in which conventional catalysts sinter to a large extent, while showing similar reaction rates. Extending this approach to Pd-Pt bimetallic catalysts led to the small particle size being maintained at temperatures as high as 1,100 °C in air and 10% steam. This strategy can be broadly applied to other metal and metal oxides for applications where sintering is a major cause of material deactivation.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on PdPt by Materials Project

PtPd crystallizes in the trigonal R-3m space group. The structure is three-dimensional. there are two inequivalent Pt2- sites. In the first Pt2- site, Pt2- is bonded to six equivalent Pt2- and six Pd2+ atoms to form a mixture of edge, corner, and face-sharing PtPd6Pt6 cuboctahedra. All Pt–Pt bond lengths are 2.79 Å. All Pt–Pd bond lengths are 2.80 Å. In the second Pt2- site, Pt2- is bonded to ten equivalent Pt2- and six Pd2+ atoms to form PtPd6Pt10 cuboctahedra that share corners with twelve PtPd6Pt6 cuboctahedra, edges with sixteen PtPd6Pt6 cuboctahedra, and faces with sixteen equivalent PtPd6Pt10 cuboctahedra. There are a spread of Pt–Pt bond distances ranging from 2.79–5.58 Å. All Pt–Pd bond lengths are 2.80 Å. There are three inequivalent Pd2+ sites. In the first Pd2+ site, Pd2+ is bonded in a distorted hexagonal planar geometry to six equivalent Pt2- atoms. In the second Pd2+ site, Pd2+ is bonded in a distorted hexagonal planar geometry to six Pt2- atoms. In the third Pd2+ site, Pd2+ is bonded in a distorted hexagonal planar geometry to six Pt2- atoms. All Pd–Pt bond lengths are 2.80 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on PdPt3 by Materials Project

Pt3Pd is alpha La-derived structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. there are two inequivalent Pt+0.67- sites. In the first Pt+0.67- site, Pt+0.67- is bonded to eight Pt+0.67- and four equivalent Pd2+ atoms to form PtPd4Pt8 cuboctahedra that share corners with twelve equivalent PtPd4Pt8 cuboctahedra, edges with eight equivalent PdPt12 cuboctahedra, edges with sixteen PtPd4Pt8 cuboctahedra, faces with four equivalent PdPt12 cuboctahedra, and faces with fourteen PtPd4Pt8 cuboctahedra. All Pt–Pt bond lengths are 2.81 Å. All Pt–Pd bond lengths are 2.81 Å. In the second Pt+0.67- site, Pt+0.67- is bonded to eight equivalent Pt+0.67- and four equivalent Pd2+ atoms to form PtPd4Pt8 cuboctahedra that share corners with four equivalent PtPd4Pt8 cuboctahedra, corners with eight equivalent PdPt12 cuboctahedra, edges with twenty-four PtPd4Pt8 cuboctahedra, faces with six equivalent PdPt12 cuboctahedra, and faces with twelve PtPd4Pt8 cuboctahedra. All Pt–Pd bond lengths are 2.81 Å. Pd2+ is bonded to twelve Pt+0.67- atoms to form PdPt12 cuboctahedra that share corners with four equivalent PdPt12 cuboctahedra, corners with eight equivalent PtPd4Pt8 cuboctahedra, edges with eight equivalent PdPt12 cuboctahedra, edges with sixteen equivalent PtPd4Pt8 cuboctahedra, faces with four equivalent PdPt12 cuboctahedra, and faces with fourteen PtPd4Pt8 cuboctahedra.

36 MATERIALS SCIENCE↗