Cuprous oxide metallic phase

Acrolein and Acrylic Acid. Acrolein and acrylic acid are manufactured by the direct catalytic air oxidation of propylene. In a related process called ammoxida-tion, heterogeneous oxidation of propylene by oxygen in the presence of ammonia yields acrylonitrile (see Section 9.5.3). Similar catalysts based mainly on metal oxides of Mo and Sb are used in all three transformations. A wide array of single-phase systems such as bismuth molybdate or uranyl antimonate and multicomponent catalysts, such as iron oxide-antimony oxide or bismuth oxide-molybdenum oxide with other metal ions (Ce, Co, Ni), may be employed.939 The first commercial process to produce acrolein through the oxidation of propylene, however, was developed by Shell applying cuprous oxide on Si-C catalyst in the presence of I2 promoter. 

The metal catalyzed reaction with ammonia or amines likely proceeds by the SNAr mechanism. This reaction, with phase-transfer catalysis, has been used to synthesize triarylamines. Copper ion catalysts (especially cuprous oxide or iodide) also permit the Gabriel synthesis (10-41) to be applied to aromatic substrates. Aryl bromides or iodides are refluxed with potassium phthalimide and... 

Bur] Burylev, B.P., Romanov, V.D., Tsemekhman, L.Sh., Mechev, V.V., Vaysburd, S.E., The Distribution of Iron Group Metals of the Between Copper and Cuprous Oxide , Russ. Metall, (5), 60-63 (1976), translated fiom/zv. Akad. NaukSSSR, Met., 5,75-77 (1976) (Experimental, Phase Relations, 9)... 

With the supply of large amounts of propane in the 1950s the search began to find a system for its direct oxidation with molecular oxygen to yield acrolein. Attempts with cuprous oxide marked the beginning of the technical development of alkene oxidation in the gas phase by metal oxide catalysts [22]. But this system showed weak points in the conversion (20%) [23,24] and in the selectivity, with the consequence that most of the propane added had to be recycled and many side products had to be removed. The development and introduction of the bismuth molybdate/bismuth phosphomolybdate system (Sohio, 1957) as a catalyst [25-27] and the following application for propane... 

A mixture of silicon and cuprous chloride granules is heated in a slow stream of inert gas. Cuprous chloride is thus reduced to metallic copper and SiC gas. The copper produced is in an active state and forms an alloy, the so-called t)-phase, with the silicon. This phase is far more active than the alloy prepared by the conventional method of reducing copper oxide by hydrogen and then alloying the copper with silicon. The NCL process uses ferrosilicon instead of pure silicon, because it is much cheaper. Also, the presence of iron in general is reported to add stability to the ii-phase (Lobusevich et al., 1976). This phase catalyzes the reaction between silicon and methyl chloride. Thus we have here a solid-solid reaction to give the catalyst followed by a gas-solid reaction to give the final products. The entire scheme may be represented as... 

There were also unique corrosion problems associated with foam cleaning by using air as the gas phase. When air was used, a cyclical type corrosion process could occur. In the presence of an iron oxide deposit and an acidic foam, the ferric ion would spend on base metal to become reduced to the ferrous ion. Exposure to the oxidant air, present as the gaseous phase of foam, regenerated the ferrous ion to the ferric ion and the corrosion process was repeated. If recycle of the foam cleaning was attempted, the corrosion could become quite severe. The same type of cyclical process could occur in the presence of cupric copper. Cupric copper would reduce on admiralty metal and form the cuprous ion. In the presence of air, the cuprous would be regenerated into the cupric ion for a repetition of the corrosion process. Equations (4)-(7) show the corrosive processes. 

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