![]() This work provides a new perspective for efficient precious metal utilization under demanding catalytic conditions. Along with other experimental evidence, this leads to the finding that the single-atom Pt is the true catalytic site for the oxidation of CO and C 3H 6 in the widely-used Pt/La-Al 2O 3 material system. Intriguingly, with or without the barium additives and/or sintered platinum particles in the catalysts, the intrinsic activity per Pt atom stays intact. ![]() By implementing this improved formulation, the atomically dispersed Pt on alumina retains the original full dispersion even after 650 ☌ hydrothermal aging. SFC combines the advantages of GC and HPLC thanks to the superior properties of supercritical fluids. Boundless vets and curates high-quality, openly licensed content from around the Internet. As a natural next step, the Ba-Ox- species more » were introduced to specifically stabilize the single-atom Pt on the La-stabilized alumina support. Supercritical fluid chromatography is one of the most important column chromatography methods after gas chromatography (GC) and high-performance liquid chromatography (HPLC). This diagram indicates the supercritical fluid region of CO 2. Unfortunately, the La dopants in alumina support will not hinder the sintering of the active Pt1(II)-Ox- species. On a widely used La-stabilized alumina support, we find that the atomically dispersed Pt 1(II)-O x- species, rather than the much more visible large metal particles, are the actual catalytic sites for the CO and C 3H 6 oxidation reactions. Using fully dispersed precious metal atoms to deliver the catalysis remains an elusive goal. Pt/alumina), where the scarce metal atoms easily become wasted as sintered nanoparticles. The picture on the left shows that the dipole orienta. High-temperature operations present a substantial challenge for developing industrial-capable precious metal catalysts (e.g. of supercritical fluids in polymer synthesis has been the subject of several recent reviews. As a free fluid or dissolved in silicate minerals, supercritical water greatly influences the structure. We found that these results show the promise of supercritical fluid deposition as a scalable means of synthesizing highly active supported metal catalysts that offer efficient utilization of precious = clusters of high reducibility that improve the chemical activity of the oxide-metal interfaces at which the WGS reaction takes place. Water, the fluid of life at ambient pressure (P) and temperature (T), is mostly present under supercritical conditions in the Earth’s crust and mantle ( 1 ): that is, above the vapor-liquid critical point (647 K and 221 MPa). The term ‘supercritical fluid extraction’ is generally applied to the use of supercritical carbon dioxide, neat or with entrainers (co-solvents). The high activity was attributed to the significant fraction of platinum/ceria interfacial contact. Reaction rate measurements showed that the catalyst was more active for water-gas shift, with reaction rates per mass of platinum that exceeded most literature values for water-gas shift reaction on Pt-CeO x catalysts. The ceria-containing catalyst that was not pretreated exhibited a more uniform particle size, and the Pt particles were encapsulated in crystalline ceria. Pretreatment of the alumina-supported ceria in hydrogen prior to the deposition of the platinum precursor resulted in more platinum nucleated on ceria than non-pretreated alumina-supported ceria but varied in both particle size and structure. Analysis of the catalysts by high resolution scanning transmission electron microscopy indicated that platinum was present in the form of highly dispersed metal nanoparticles. image analysis and light scattering techniques. The organometallic precursor, platinum(II) acetylacetonate, was deposited from solution in supercritical carbon dioxide. Encapsulation and co-precipitation processes with supercritical fluids: Fundamentals and applications. Wågberg and C.Alumina-supported platinum catalysts, both with and without ceria, were prepared by supercritical fluid deposition and evaluated for activity for water-gas shift reaction. Nanoparticle formation of organic compounds with retained biological activityĬ. Investigation of different particle sizes on superhydrophobic surfaces made by rapid expansion of supercritical solution with in-situ laser diffraction (RESS-LD) Pressurised hot water extraction with on-line particle formation by supercritical fluid technology Towards superhydrophobic coatings made by non-fluorinated polymers sprayed from a supercritical solution. Superhydrophobic polymeric coatings produced by rapid expansion of supercritical solutions combined with electrostatic deposition (RESS-ED) Wågbergĭevelopment of a semicontinuous spray process for the production of superhydrophobic coatings from supercritical carbon dioxide solutions
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