Hydrogen-treatment

The hydrogen treatment procedures, tensile, compression and torsion tests at fixed temperatures, transmission electron or optical microscopy at room temperature as well as X-ray diffraction measurements were detailed elsewhere All experiments were performed so as to compare properties of the same alloy, but modified using different treatment procedures. 

O.N. Senkov, I.O. Bashkin, S.S. Khasanov, and E.G. Ponyatovsky, Grain structure of titanium alloy VT20 after hydrogen treatment and deformation at moderate temperatures, Fiz. Met. Metallovedeniye, 76 128 (1993). 

The enantiomerically pure (/ )- and (iS )-ketones are prepared from the corresponding enantiomer of mandelic acid by catalytic hydrogenation, treatment of the resulting hexahydroman-delic acid with ethyllithium, and subsequent introduction of the silyl protecting group33. 

Wm. Haynes The nickel carbide formation has been reversed. That is,nickel carbide has been eliminated by hydrogen treatment in some of the laboratory tests at the Bureau of Mines, and catalyst activity has been restored that way. In the pilot plant, however, we have not been able to achieve any such regeneration of the catalyst. 

If an aliphatic amino group is to a COOR, CN, CHO, COR, and so on, and has an a hydrogen, treatment with nitrous acid gives not a diazonium salt, but a diazo compound Such diazo compounds can also be prepared, often more conveniently, by treatment of the substrate with isoamyl nitrite and a small amount of acid. Certain heterocyclic amines also give diazo compounds rather than diazonium salts. ... 

Fig. 1 Change of the acid sites on Co.Mo/Si02 AI2O3 with hydrogen treatment and the following outgassing.

It was argued by Saito et al. [509] that a hydrogen plasma treatment as used in the LBL technique causes chemical transport the a-Si H film deposited on the cathode prior to the hydrogen treatment is etched and transferred to the anode. Hence, in the hydrogen plasma silane-related molecules and radicals are present. In fact, material is deposited on the anode under the same conditions as in the case of high dilution of silane with hydrogen. 

The reaction of silica-supported bis(allyl)Rh complexes with PMe3 followed by hydrogen treatment leads to the synthesis of the surface SiO-RhH2(PMe3)4+ as the first example of a cationic organometallic complex attached to the silica surface by ion pairing. The counterion is presumed to be a siloxy group SiO- on the silica surface.276 277... 

The behavior of the isomeric dihydronaphthalenes emphasizes the importance of the relative stabilities of carbocation intermediates in ionic hydrogenations. Treatment of 1,2-dihydronaphthalene with Et3SiH/TFA at 50-60° gives a 90% yield of tetralin after one hour. Under the same conditions, the 1,4-dihydronaphthalene isomer gives less than 5% of tetralin after 70 hours.224 This difference in reactivity is clearly related to the relatively accessible benzylic cation formed upon protonation of the 1,2-isomer compared to the less stable secondary cation formed from the 1,4-isomer.224... 

Fig. 7. Arrhenius plot of the maximum hydrogen penetration depth in xm after a four hour hydrogenation treatment.

Liquid acid-catalyzed processes are mature technologies, which are not expected to undergo dramatic changes in the near future. Solid acid-catalyzed alkylation now has been developed to a point where the technology can compete with the existing processes. Catalyst regeneration by hydrogen treatment is the method of choice in all the process developments. Some of the process developments eliminate most if not all the drawbacks of the liquid acid processes. The verdict about whether solid acid-catalyzed processes will be applied in the near future will be determined primarily by economic issues. 

A working model for dendrimer thermolysis during calcination involves the PA-MAM dendrimer backbone initially reacting with oxygen (which may or may not be activated by a nanoparticle) in a relatively facile process to generate carboxylates and other surface species. Removal of carbonaceous species closely associated with the nanoparticle is required for complete activation of the catalyst. For Pt DENs, the surface carboxylates may be strongly adsorbed to the nanoparticle surface and extended O2 treatments are required for deep oxidation of the hydrocarbon to reach reasonably volatile species. Once formed, however, it appears that they can be removed more readily with a hydrogen treatment than with further oxidation. 

The NiO phase could be reduced to metallic Ni by hydrogen treatment (723 K, 1 h). The crystallite size of Ni metal (estimated from XRD pattern of the reduced sample) is similar to that of the NiO in the unreduced sample (e.g., for 7B, the Ni metal crystallite size is 8.2 nm). The textural characterization studies reveal that for the samples prepared by coprecipitation + digestion and hydrothermal synthesis (methods B and C) the pore sizes are in the mesopore range (2.9 to 6.8 nm) (Table 11.2). 

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