Noble metal

About: Noble metal is a research topic. Over the lifetime, 15113 publications have been published within this topic receiving 337947 citations.

Morphology-dependent performance of Co3O4 via facile and controllable synthesis for methane combustion

Abstract: Spinel type cobalt oxide (Co 3 O 4 ) nanocrystals were controllably synthesized with different morphologies (cubical, hexagonal and flower-like) via a facile hydrothermal method. The properties of the nanostructured Co 3 O 4 were characterized by XRD, SEM, TEM, HRTEM and XPS techniques. The performance of the catalysts in methane combustion was evaluated under lean methane atmosphere. Superior catalytic activities for methane combustion were observed over these oxides. The performances seemed to depend on their morphologies. The catalytic activities of flower-like Co 3 O 4 and hexagonal plate-like Co 3 O 4 were comparable to those of noble metal catalysts due to the preferred exposure of more active {111} crystal plane. In case of cubical Co 3 O 4 the {001} plane is the dominantly exposed crystal plane. The results may provide significant insights for the development of nanostructured metal oxide catalysts for the catalytic combustion of methane.

Promotion effects of potassium on the activity and selectivity of Pt/zeolite catalysts for reverse water gas shift reaction

Abstract: Catalytic hydrogenation of carbon dioxide to CO by reverse water gas shift reaction plays a vital role in the recycling of the abundant carbon source Here, the reaction over a series of zeolite L-supported platinum catalysts was systematically investigated to study the promoting role of potassium The results of activity tests showed that controlled addition of potassium promoter to Pt/L catalyst was beneficial for the catalytic activity and selectivity It was observed that cage encapsulation by zeolite pores could stabilize Pt nano-particles even at severe reaction conditions Furthermore, X-ray absorption near edge structure and X-ray photoelectron spectra results demonstrated that the chemical state of platinum was altered by the additional potassium promoter, providing evidence for the formation of Pt-O(OH)-K interfacial sites Thereafter, the Pt-O(OH)-K interfaces, acting as main active sites to adsorb CO2 and produce bridge-bonded formate intermediates, were identified by a set of in-situ diffuse reflectance Fourier transform infrared spectroscopy and microcalorimetry measurements This finding provides new insights into the use of a variety of zeolite as carriers for highly dispersed noble metal in catalytic CO2 reduction

Selective Hydrodeoxygenation of Guaiacol Catalyzed by Platinum Supported on Magnesium Oxide

Abstract: The conversion of guaiacol catalyzed by Pt/MgO in the presence of H2 was investigated with a flow reactor at 573 K and 140 kPa. Among the dozens of reaction products identified by gas chromatography (GC) and GC/mass spectrometry, the predominant ones were phenol, catechol, and (surprisingly) cyclopentanone, with others including methane, n-butane, butenes, n-pentane, and carbon monoxide. The predominant reactions were hydrodeoxygenation (with about 70 % of the guaiacol that was converted forming products that were reduced in oxygen). In contrast, when the catalyst incorporated an acidic support, Pt/γ-Al2O3, other reactions became kinetically significant, exemplified by transalkylation, and the selectivity to deoxygenated products was reduced to about half the value observed with Pt/MgO at guaiacol conversions in the range of about 6–20 %. Pt/MgO underwent deactivation less rapidly than Pt/γ-Al2O3, consistent with a lower rate of coke formation and with observations by scanning transmission electron microscopy showing that the average platinum cluster diameter, approximately 1–2 nm in each catalyst, did not change significantly during operation. The results point to the advantages of basic supports for noble metal hydrodeoxygenation catalysts. .