Zinc oxide ethylene hydrogenation

Over zinc oxide it is clear that only a limited number of sites are capable of type I hydrogen adsorption. This adsorption on a Zn—O pair site is rapid with a half-time of less than 1 min hence, it is fast enough so that H2-D2 equilibration (half-time 8 min) can readily occur via type I adsorption. If the active sites were clustered, one might expect the reaction of ethylene with H2-D2 mixtures to yield results similar to those obtained for the corresponding reaction with butyne-2 over palladium That is, despite the clean dideutero addition of deuterium to ethylene, the eth-... 

Krumpolc, M. and Malek, J., Esterification of benzenecarboxylic acids with ethylene glycol, III. Kinetics of esterification of 2-hydroxyethyl hydrogen terephthalate with ethylene glycol catalyzed by zinc oxide, Makromol. Chem., 168, 119-129 (1973). 

Fig. 1. Arrhenius plots for hydrogenation rate of ethylene over nickel on doped zinc oxide.

Experiments intended to demonstrate the hoped-for connections between radiation damage and catalytic activity were begun at the Oak Ridge National Laboratory in 1950 (8). They showed an unmistakable effect of y-rays upon the catal3d ic activity of zinc oxide for the hydrogenation of ethylene. Tentative explanations for the observations were advanced, and the principal ways in which radiation could be used in the study of catalysts were described (9). 

Zinc oxide has been a favorite substance for studies of catalysis by semiconductors and was chosen because of its semiconducting properties for the first experiments on catalysts with y-rays (9). These experiments were successful in demonstrating an unquestionable effect of irradiation upon catalytic activity, a slow reduction in the rate of ethylene hydrogenation at 0°. 

There is a similar opportunity for a threshold experiment with zinc oxide. There is evidence that the destruction of activity for ethylene hydrogenation is an effect of atom displacement, and this could be established by bombardment at a series of controlled energies. 

The chief product is primary phosphine, which is liberated in a hydrogen-filled apparatus by slowly heating to boiling in a stream of hydrogen and pouring the boiling hquid into cold water. The oil which separates is primary phosphine and is dried over potassium hydroxide. (2) Ethylene dibromide, phosphonium iodide and zinc oxide are heated for six hours at 160° C. (3) One gram-atom of white phosphorus... 

Ethanol steam reforming catalysts were developed by Men et al. [24]. Nickel, rhodium and ruthenium catalysts on different carrier materials such as alumina, silica, magnesia and zinc oxide were tested at a S/C ratio of 1.5 and WHSV 90 Lh g J in the temperature range 400-600 °C. All the monometallic catalysts were mainly selective for acetaldehyde and ethylene. Over the rhodium catalyst, a reaction temperature of 600 °C was required to achieve 80% hydrogen selectivity. 

Salts of neodecanoic acid have been used in the preparation of supported catalysts, such as silver neodecanoate for the preparation of ethylene oxide catalysts (119), and the nickel soap in the preparation of a hydrogenation catalyst (120). Metal neodecanoates, such as magnesium, lead, calcium, and zinc, are used to improve the adherence of plasticized poly(vinyl butyral) sheet to safety glass in car windshields (121). Platinum complexes using neodecanoic acid have been studied for antitumor activity (122). Neodecanoic acid and its esters are used in cosmetics as emoUients, emulsifiers, and solubilizers (77,123,124). Zinc or copper salts of neoacids are used as preservatives for wood (125). 

Dehalogenation of monochlorotoluenes can be readily effected with hydrogen and noble metal catalysts (34). Conversion of -chlorotoluene to Ncyanotoluene is accompHshed by reaction with tetraethyl ammonium cyanide and zero-valent Group (VIII) metal complexes, such as those of nickel or palladium (35). The reaction proceeds by initial oxidative addition of the aryl haHde to the zerovalent metal complex, followed by attack of cyanide ion on the metal and reductive elimination of the aryl cyanide. Methylstyrene is prepared from -chlorotoluene by a vinylation reaction using ethylene as the reagent and a catalyst derived from zinc, a triarylphosphine, and a nickel salt (36). 

With Acyl Halides, Hydrogen Halides, and Metallic Halides. Ethylene oxide reacts with acetyl chloride at slightly elevated temperatures in the presence of hydrogen chloride to give the acetate of ethylene chlorohydrin (70). Hydrogen haUdes react to form the corresponding halohydrins (71). Aqueous solutions of ethylene oxide and a metallic haUde can result in the precipitation of the metal hydroxide (72,73). The haUdes of aluminum, chromium, iron, thorium, and zinc in dilute solution react with ethylene oxide to form sols or gels of the metal oxide hydrates and ethylene halohydrin (74). 

Violent reactions have occurred between ozone and many chemicals, a small selection being acetylene, alkenes, dialkyl zincs, benzene/rubber solution, bromine, carbon monoxide and ethylene, diethyl ether, hydrogen bromide, and nitrogen oxide. 

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