Acrylonitrile, by ammoxidation

Production of acrylonitrile by ammoxidation of propylene (SOHIO process) ... 

Example 2.1 Acrylonitrile by Ammoxidation of Propylene Input/Output Analysis... 

Chapter 11 Acrylonitrile by Ammoxidation of Propene illustrates the synthesis of a flowsheet in which a difficult separation problem dominates. In addition, large energy consumption of both low- and high-temperature utilities is required. Various separation methods are involved from simple flash and gas absorption to extractive distillation for splitting azeotropic mixtures. The problem is tackled by an accurate thermodynamic analysis. Important energy saving can be detected. 

Thus, in ammonia synthesis, mixed oxide base catalysts allowed new progress towards operating conditions (lower pressure) approaching optimal thermodynamic conditions. Catalytic systems of the same type, with high weight productivity, achieved a decrease of up to 35 per cent in the size of the reactor for the synthesis of acrylonitrile by ammoxidation. Also worth mentioning is the vast development enjoyed as catalysis by artificial zeolites (molecular sieves). Their use as a precious metal support, or as a substitute for conventional silico-aluminaies. led to catalytic systems with much higher activity and selectivity in aromatic hydrocarbon conversion processes (xylene isomerization, toluene dismutation), in benzene alkylation, and even in the oxychlorination of ethane to vinyl chloride. 

Desulfurization of petroleum feedstock (FBR), catalytic cracking (MBR or FI BR), hydrodewaxing (FBR), steam reforming of methane or naphtha (FBR), water-gas shift (CO conversion) reaction (FBR-A), ammonia synthesis (FBR-A), methanol from synthesis gas (FBR), oxidation of sulfur dioxide (FBR-A), isomerization of xylenes (FBR-A), catalytic reforming of naphtha (FBR-A), reduction of nitrobenzene to aniline (FBR), butadiene from n-butanes (FBR-A), ethylbenzene by alkylation of benzene (FBR), dehydrogenation of ethylbenzene to styrene (FBR), methyl ethyl ketone from sec-butyl alcohol (by dehydrogenation) (FBR), formaldehyde from methanol (FBR), disproportionation of toluene (FBR-A), dehydration of ethanol (FBR-A), dimethylaniline from aniline and methanol (FBR), vinyl chloride from acetone (FBR), vinyl acetate from acetylene and acetic acid (FBR), phosgene from carbon monoxide (FBR), dichloroethane by oxichlorination of ethylene (FBR), oxidation of ethylene to ethylene oxide (FBR), oxidation of benzene to maleic anhydride (FBR), oxidation of toluene to benzaldehyde (FBR), phthalic anhydride from o-xylene (FBR), furane from butadiene (FBR), acrylonitrile by ammoxidation of propylene (FI BR)... 

The formation of acrylonitrile by ammoxidation occurs according to the following highly exothermic reaction ... 

Modeling of an Acrylonitrile Reactor [after Kunii and Levenspiel, 1969]. Design a fluidized bed reactor for the production of acrylonitrile by ammoxidation of propylene, with air as the oxidizing agent. The required production of acrylonitrile is 40,400 tons/year (count on approximately 8000 h or 340 days). The process achieves a 78 percent conversion of propylene at 400°C and atmospheric pressure. The rate constant of the reaction considered as a first-order process is k = 1.44 mVkg cat. h at 400°C. The volume fraction of propylene in the feed is 0.24. The catalyst used has a mean particle diameter dp = 51 p and the following size distribution ... 

Most, if not all, of the acetonitrile that was produced commercially in the United States in 1995 was isolated as a by-product from the manufacture of acrylonitrile by propylene ammoxidation. The amount of acetonitrile produced in an acrylonitrile plant depends on the ammoxidation catalyst that is used, but the ratio of acetonitrile acrylonitrile usually is ca 2—3 100. The acetonitrile is recovered as the water azeotrope, dried, and purified by distillation (28). U.S. capacity (1994) is ca 23,000 t/yr. 

Telescope the Process by Combining Stages. This has been done successfully in the conversion of propylene to acrylonitrile by direct ammoxidation rather than oxidation to acrolein followed by reaction with ammonia in a separate stage, as was described in the earlier patent literature. The oxychlorination of ethylene and HC1 directly to vinyl chloride monomer is another good example of the telescoping of stages to yield an economic process. 

Kurtz A process for making acrylonitrile by reacting hydrogen cyanide with acetylene in the presence of aqueous cuprous chloride. Invented by R Kurtz at I. G. Farbenindustrie in the 1940s. The process was widely used, but by 1970 had been abandoned in the United States in favor of the ammoxidation processes. 

Methacrylonitrile can be produced in the acrylonitrile plants by ammoxidation of isobutylene, which gives it the methyl group sticking out. 

Acrylonitrile. Acrylonitrile, an important monomer in numerous polymerization processes, is produced mainly from propylene by ammoxidation (see Section 9.5.3). In the traditional process, the major industrial route in the 1950s and 1960s, an aqueous solution of copper(I) chloride, NH4C1 and HC1 was reacted with acetylene and hydrogen cyanide 180 197... 

Most, if not all, of the acetonitrile produced commercially in the United States recently was isolated as a by-product from the manufacture of acrylonitrile by propylene ammoxidation. The acetonitrile is recovered as the water azeotrope, dried, and purified by distillation. 

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

H., Asahi-Japan, Process for producing acrylonitrile from propane by ammoxidation, USP 5973186, 1999... 

The crucial factor in the successful use of the fluidized-bed reactor for the synthesis of acrylonitrile by the ammoxidation of propenc (Sohio process) was... 

Although substantial amounts of hydrogen cyanide are produced and recovered as a byproduct from the manufacture of acrylonitrile by the ammoxidation of propylene, some hydrogen cyanide is also made on purpose from methane. Basically, two main approaches are available. ... 

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