Acrylonitrile manufacture

Amm oxida tion, a vapor-phase reaction of hydrocarbon with ammonia and oxygen (air) (eq. 2), can be used to produce hydrogen cyanide (HCN), acrylonitrile, acetonitrile (as a by-product of acrylonitrile manufacture), methacrylonitrile, hen onitrile, and toluinitnles from methane, propylene, butylene, toluene, and xylenes, respectively (4). 

Although acrylonitrile manufacture from propylene and ammonia was first patented in 1949 (30), it was not until 1959, when Sohio developed a catalyst capable of producing acrylonitrile with high selectivity, that commercial manufacture from propylene became economically viable (1). Production improvements over the past 30 years have stemmed largely from development of several generations of increasingly more efficient catalysts. These catalysts are multicomponent mixed metal oxides mostly based on bismuth—molybdenum oxide. Other types of catalysts that have been used commercially are based on iron—antimony oxide, uranium—antimony oxide, and tellurium-molybdenum oxide. 

The first U.S. plant for acrylonitrile manufacture used an ethylene cyanohydrin feedstock. This was the primary route for acrylonitrile manufacture until the acetylene-based process began to replace it in 1953 (40). Maximum use of ethylene cyanohydrin to produce acrylonitrile occurred in 1963. Acrylonitrile (qv) has not been produced by this route since 1970. 

The full cost of acrylonitrile manufacture based on methane was about 22)4/lb in 1960 (allowing 15% return). But the marginal cost—with no capital charges or overheads—was only 7 /lb. The full cost of propylene ammoxidation (with 15% return) was about 13-16ff/lb according to location. Thus, as soon as it was clear that ammoxidation was likely to... 

Hughes TW, Horn DA. 1977. Source assessment Acrylonitrile manufacture (air emissions). Research Triangle Park, NC U.S. Environmental Protection Agency, Office of Research and Development. EPA- 60V2-77-107j. NTIS No. PB-271969. 

The by-product of acrylonitrile manufacture, HCN, has its primary use in the manufacture of methyl methacrylate by reaction with acetone. This is covered later in this chapter, Section 4. 

Hydrogen cyanide is also available as a by-product from acrylonitrile manufacture by ammoxidation. 

Some convention is employed in the sources of AS, mainly for the benefit of statisticians, who try to follow developments in the AS business. AS that is obtained from caprolactam or acrylonitrile manufacture is normally referred to as co-product. On the other hand, AS that is produced from coke ovens, flue gas desulphurization, smelter tail gas, sewage treatment, gypsum, waste acid from methyl methacrylate and from other chemical processes is usually termed byproduct241. 

Figure 2.4 Input/output structure of the acrylonitrile manufacturing.

Table 2.7 Input/output material balance for acrylonitrile manufacturing.

The contemporary commercial reactors used for sulphide ore roasting, Ficher-Tropsch synthesis and acrylonitrile manufacture were routinely operated in the bubbling and turbulent fluidization regimes [56, 112]. 

Hydrogen cyanide is often obtained as a by-product of acrylonitrile manufacture (see Section 11.4). However, its availability by this method is steadily decreasing, in view of the improved yields of techniques for producing acrylonitrile and die faster growth of markets for methyl methacrylate. It is therefore produced by direct synthesis from hydrocarbons, according to three main schemes ... 

Since these reactions are themselves highly exothermic, it is found in practice that the total exothermidtY of acrylonitrile manufacture is higher than indicated by theory, and is as high as 650 to 670 kJ moL... 

Suggest a flowsheet to separate the reactor effluents from acrylonitrile manufacture (2C016 + 302 -I- 2NH, 2C3H3N + 6H2O). 

Non-noble metal 1% pollutants (presumably in air) 260 NR 20,000 hr-i Pollutant removal from acrylonitrile manufacture 47... 

ACN is produced as a by-product of acrylonitrile manufacture and its yield from the process is small. As a result its price can be very volatile. Many of its industrial uses involve mixtures with other solvents (e.g. toluene, isopropanol) that form binary... 

The reported demand for hydrogen cyanide in the U.S. A. is now over 550 kt per annum. Possibly one quarter is by-product from acrylonitrile manufacture the remainder is produced by the oxidation of methane/ ammonia mixtures over platinum at about 1100°C. The major use (40-45%) is in DuPont s adiponitrile production, with some 30-35% used for methyl methacrylate (MMA) (methyl 2-methylpropenoate) manufacture and 10% for sodium cyanide. 

Acrylonitrile manufacture probably contributes a major proportion of the (much smaller) demand in western Europe for MMA and NaCN production, though first-intent production is practised for example Degussa dehydrogenate methane/ammonia mixtures over platinum at 1200-1300°C. 

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