Nickel, chemisorption acetylene

A few measurements of the changes in magnetization of nickel resulting from the chemisorption of hydrogen, ethylene and acetylene have also been reported by Breeder and his co-workers lOSa, b). Their results and conclusions appear to be qualitatively in accord with those of Selwood. 

Ethylene and Acetylene. On nickel (111), both ethylene and acetylene are irreversibly chemisorbed neither can be thermally desorbed. We also find that trimethylphosphine cannot displace ethylene or acetylene from these surfaces. There have been suggestions that ethylene and acetylene are not present on the surface as molecules but as molecular fragments. Many ultra-high vacuum studies of ethylene and of acetylene chemisorption on nickel crystal planes have been reported. Most of these studies seem to implicate states in which C-H bond cleavage reactions have accompanied the basic chemisorption process (19). 

Chemisorption of hydrocarbons on various metals, such as nickel, platinum, copper, etc., was investigated in great detail (9, 90, 91, 92). Information on chemisorption of ethylene, acetylene and methane on various metals may be found in Trapnell s review (93). However, direct application of the relations obtained to metal oxide catalysts would scarcely be justifiable. As a rule, oxygen covers the whole surface of the metal, and chemisorption of hydrocarbons occurs either on a thin layer of the given metal oxide formed as an individual phase, or on oxygen that was sorbed on the surface and has filled the adjacent-to-surface layers. Thus data on chemisorption of hydrocarbons on oxides of these metals may be of use in the above cases. 

Other loose ends which I might have discussed are the missing asymmetric stretching band for carboxy-lates on reduced metals ( ), the reactive surface carbon which is produced by self hydrogenation of acetylene on nickel (9), and simultaneous infrared and magnetic studies of chemisorption (] ). In some cases termination of projects was due to reaching the limit of what we could effectively accomplish. In other cases it was due to a shortage of time because of the numerous worthwhile projects which were open to us in 1952. 

Abstract Gold and silver nanoparticles were obtained by in situ reduction with silicon hydride groups grafted to the mesoporous MCM-41 silica surface. Nickel-, eobalt-, and iron-containing silicas were synthesized by chemisorption of appropriate metal aeetylacetonates with following reduction in the acetylene atmosphere. Such metal-containing MCM-41 matrices have been applied for preparation of carbon nanostructures at pyrolytie deeomposition of acetylene. From transmission electron microscopy (TEM) data a lot of carbon nanotubes were formed, namely tubes with external diameter of 10-35 nm for Ni-, 42-84 nm for Co-, and 14—24 nm for Fe-eontaining silieas. In the metal absence on the silica surface low yield of nanotubes (up to 2%) was detected. 

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