Propylene ammonoxidation

It is worth noting that HCN is also an important by-product of propylene ammonoxidation to acrylonitrile (the yield may be as large as 20% in relation to acrylonitrile). Other methods have been used in the past, for example, the conversion of nitrogen to cyanamide (NHj C=N) followed by a subsequent further hydrogenation to hydrogen cyanide, or the thermolysis of trimeihyl-amine obtained from niolasses. 

Ethylene oxidation 1.0-second contact time at 280°C, 1.0 atm Ethylene hydration 1800 hr space velocity at 300°C, 70 atm Propylene ammonoxidation, 20-second contact time at 400°C, 1 atm. 

Ammonoxidation. The contraction of two terms, ammonia and oxidation, ammonoxidation is a one-step process involving vapor phase, catalytic reaction of propylene with ammonia and the,oxygen portion of air to give acrylonitrile. The ammonoxidation reaction is carried out at about 800°F and 30 psi. 

Tlte method is now obsolete for the preparation of acrylonitriles as it has been replaced by the ammonoxidation processes of propylene. The catalyst is a solution of CU2CI3 in water containing HCI and an alkali chloride. Similarly, the addition of cyanogen chloride and acetylene is a copper catalyzed reaction. 

The catalytic gas-phase oxidation of olefins in the presence of ammonia on vanadium- or molybdenum-containing catalysts, so-called ammonoxidation, results in economic yields of the commercially important add nitriles, for example, acrylonitrile from propylene [1426]. Ammonoxidation of o-xylene yields phthalodinitrile in a single reaction step. 

This versatile monomer is produced by the catalytic ammonoxidation of propylene. A mixture of propylene, ammonia, and air in the volume ratio... 

A recently developed one-step ammonoxidation process to acrylonitrile developed by BP Chemicals uses propane instead of propylene feed [21]. Key to the feasibility of this lower cost option was the development of the new catalyst system, which is now at the commercial demonstration stage. Almost all the acrylonitrile production goes into synthetic polymers and copolymers mostly for applications as fibers, some for plastics applications, and a small percentage to elastomer markets (the nitrile rubbers). 

Today the most cost-effective processes are those based on propylene as the starting material. There are three major variations of propylene processes, the Distillers process [21-23], the Sohio process [24], and the DuPont process [25,26]. All three processes are based on the ammonoxidation of propylene. The Distillers process is carried out in two stages. In the first, propylene is oxidized in air to form acrolein and water. These intermediate products are allowed to react in the second stage with ammonia in the presence of molybdenum oxide and air to form crude acrylonitrile. The pure monomer is recovered by a series of azeotropic distillations. The Sohio process is carried out in just one stage. Ammonoxidation of propylene takes place in air at 2-3 atmospheric pressure and 425-510°C. With catalysts, such as concentrated bismuth phosphomolybdate or other oxides of molybdenum and cobalt, the reaction takes place with over 50% yield in a reaction time of only about 15 s. In the DuPont version of this process, the ammonoxidation is brought about with nitric oxide at 500°C using silver on silica catalyst. The chemistry of acrylonitrile monomer has been reviewed by a number of authors [27-30]. 

Ammonoxidation of propylene with ammonia and oxygen produces acrylonitrile, CH2=CHCN. Other acrylonitrile syntheses proceed from acetaldehyde and hydrogen cyanide via a-hydroxypropionitrile, or from ethylene oxide via ethylene cyanhydrin. 

By what is called ammonoxidation of propylene with ammonia and oxygen. This method is of increasing importance, because propylene is readily available from petrochemistry ... 

Acrylonitrile is produced today almost exclusively by ammonoxidation of propylene using the so-called Sohio process. Sohio stands for Standard Oil of Ohio, the first company to demonstrate successfully the process in 1960. The Sohio process reacts propylene, ammonia, and oxygen in a highly exothermic process (AH = —502 kj mol ) at 400-500 °C to acrylonitrile and water. The process uses a fluidized bed reactor to operate the reactor as isothermally as possible. The catalyst is a Fe-modified bismuth-phosphorous molybdate contact. The Sohio process has... 

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