Chromic oxide catalyst

High-density polyethylenes are formed from metal oxide initiation. These poly-ethylenes are stiffer, with much less branching. HDPE is used more in automotive applications due to this property. Phillips Petroleum uses a chromic oxide catalyst and Standard Oil of Indiana has developed a molybdenum oxide catalyst [5], These catalysts are not flammable, which presents an advantage over Ziegler-Natta. 

Subsequently, patents covering the conversion of synthesis gas to complex mixtures of organic oxygen compoimds, including methanol, were issued to BASF during 1913. This followed work by Mittasch and Schneider. Full-scale production of methanol was not attempted, however, imtil 1923. By that time high-pressure equipment had been in operation for several years in the new ammonia process. The methanol process was developed by Piers and the plant, built at Leima, used mixed zinc oxide-chromic oxide catalyst. The use of metallic iron for the internal parts of the reactor was avoided to prevent the formation of the volatile iron penlacarbonyl. The would have decomposed on the surface of the catalyst, to deposit finely divided iron metal, which in turn would have promoted the exothermic formation of methane. 

The industrial synthesis of methyl alcohol involves hydrogenation of carbon monoxide. Although this reaction has the favorable AH0 value of —28.4 kcal mole-1, it requires high pressures and high temperatures and a suitable catalyst excellent conversions are achieved using zinc oxide-chromic oxide as a catalyst ... 

An industrial method is briefly described in Ref 2, p945 Chromic oxide has been used in metallurgy, in manuf of soluble Cr salts, as a green pigment in manuf of glasses and ceramics and as a catalyst. C O -CuO catalysts are widely used, such as in manuf of methanol and in cyclizations of hydrocarbons (Refs 2 5). Its use in smoke -producing pyrotechnic compns is discussed under Chromium Compounds for Smoke Production, Chromic oxide, as well as Cr hydroxide, are parent compds of Chromites Refs l)Mellor 1 1 (1931), 176-85 2)Kirk Othmer 3 (1949), 944-5 3)Ullmann 5... 

The unsaturated 3a-acetoxy-17-formyl-16-etiocholen-lip-ol-18-one lip,18-lactol is hydrogenated in the presence of palladium catalyst to saturate the 16,17-double bond, and then saturated aldehyde are oxidized by treatment with chromic oxide in pyridine to give 3a-acetoxy-lip-ol-18-one-pregnane lip,18-lactone 17-carboxylic acid. 

Zelinskil and Levina studied the shift of double bonds when olefins were passed over oxide catalysts (446). Levina also established that in the presence of chromic oxide on alumina at 250° the triple bond in a 1-alkyne is shifted, giving a product one half of which consists of the corresponding 2-alkene and one-half of a 1,3-diene (206). She also reported migration of double bonds from side chains into the ring of naphthenes carrying unsaturated side chains. 

High-Density Polyethylene (HDPE). Polymerization of ethylene to polyethylenes is most often carried out at low temperature and pressure, using either the Ziegler aluminum triethyl plus titanium tetrachloride catalyst system, the Phillips chromic oxide plus silica plus alumina system, or more recently the newer metallocene single-site catalyst systems. 

These catalysts consist of the oxides of vanadium, chromium, molybdenum or tungsten deposited by co-precipitation or by impregnation on a silica or silica—alumina support. The catalysts require an activation process before use, and for those containing chromic oxide this consists of... 

For verification, dibenzenechromium bichromate [(C6H6)2Cr]2 Cr207 was prepared from the reaction of dibenzenechromium hydroxide and chromic oxide (CeHo)o CrOH CrOa. The resultant catalyst showed catalytic activity analogous to the original catalyst. 

Examples of supports modifying the properties of transition metal oxides have also appeared in the literature. Recent work points to iron oxide phases as important species in Fischer-Tropsch synthesis (3 ). Iron oxide supported on SiO2 (4 ) and TiO ( ) resist reduction under conditions in which bulk iron oxide easily reduces. Thus supported iron oxide catalysts are potentially interesting Fischer-Tropsch catalysts. The extensive studies on ethylene polymerization catalysts suggests that chromium (VI) species exist on a SiOp surface at temperatures above which bulk chromic anhydride (CrOg) decomposes ( ). 

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