Acrylonitrile other processes

The propylene-based process developed by Sohio was able to displace all other commercial production technologies because of its substantial advantage in overall production costs, primarily due to lower raw material costs. Raw material costs less by-product credits account for about 60% of the total acrylonitrile production cost for a world-scale plant. The process has remained economically advantaged over other process technologies since the first commercial plant in 1960 because of the higher acrylonitrile yields resulting from the introduction of improved commercial catalysts. Reported per-pass conversions of propylene to acrylonitrile have increased from about 65% to over 80% (28,68—70). 

Essentially all the ammonium sulfate fertilizer used in the United States is by-product material. By-product from the acid scmbbing of coke oven gas is one source. A larger source is as by-product ammonium sulfate solution from the production of caprolactam (qv) and acrylonitrile, (qv) which are synthetic fiber intermediates. A third but lesser source is from the ammoniation of spent sulfuric acid from other processes. In the recovery of by-product crystals from each of these sources, the crystallization usually is carried out in steam-heated sa turator—crystallizers. Characteristically, crystallizer product is of a particle size about 90% finer than 16 mesh (ca 1 mm dia), which is too small for satisfactory dry blending with granular fertilizer materials. Crystals of this size are suitable, however, as a feed material to mixed fertilizer granulation plants, and this is the main fertilizer outlet for by-product ammonium sulfate. 

Although allylie oxidation , yielding products like acrolein and acrylonitrile, is the most important and successful partial oxidation reaction, several other processes are of interest. Table 3 represents a summary of the nature of the various processes and the main partial oxidation products. 

ACRYLONITRILE. [CAS 107-13-1], Today over 90% of the approximately 4,000.000 metric tons of acrylonitrile (also called aciylic acid nitrile, propylene nitrile, vinyl cyanide, and propenoic acid nitrile) produced worldwide each year use the Soldo-developed ammoxidation process. Acrylonitrile is among the top 50 chemicals producedin the United States as aresult of the tremendous growth m its use as a starting material for a wide range of chemical and polymer products. Acrylic fibers remain the largest use of acrylonitrile other significant uses are in resins and nitrile elastomers and as an intermediate in the production of adiponitnle and acrylamide. 

Co-product and by-product AS production depends on the process that is used to make the primary product - as shown in Table 12.3. Small amounts of AS may also be recovered in other processes such as acrylonitrile, acrylamide, formic acid, hydrogen cyanide, hydroquinone and p-aminophenol, and from the neutralization of sulfuric acid used to make clays and catalysts for catalytic cracking242. 

Ammonium sulfate is a coproduct in the production of synthetic-fiber intermediates, such as caprolactam, acrylonitrile, and methyl methacrylate, and in the production of formic acid and acrylamide. The recovery of ammonium sulfate form these syntheses has gained importance in the last thirty years. Almost all of the 2.8 megatons of ammonium sulfate produced annually is used as fertilizer. In industrial countries, ammonium sulfate is almost always a coproduct or by-product in other processes and can only be sold as fertilizer, mostly in developing countries. In Ihese couniries, its low nitrogen content makes the transportation cost per unit of nitrogen higher than for other nitrogen fertilizers. 

Derivation Addition of ammonia to (3-propiolac-tone, other processes based on the reaction of ammonia with acrylonitrile, etc. 

Ammonium sulfate can be produced by the following processes direct reaction between ammonia and sulfuric acid (crystalline form), reaction of ammonia with calcium sulfate in the presence of C02, and from the byproduct of other processes such as caprolactam and acrylonitrile. 

As Scheme 1 illustrates, part of the proposed catalytic cycle involves intermediate A which can either trap H20 (route I) to release the amide and regenerate the catalyst, or become inactive by product coordination (route II). A positive note involves the regioselectivity of the catalyst as only the C=N position is hydrated when bifunctional substrates, such as acrylonitrile, are used. At 75 °C, CH2=CHC(0)NH2 was produced exclusively with no detectable amounts of HOCH2CH2C=N and (N=CCH2CH2)20, which are drawbacks of other processes [66]. 

Over 500 different a-amino acids have now been synthesized or isolated. About 20 of them form the main components of proteins (see also Chapter 30). a-Amino acids are commerically obtained by fermentation of glucose (arg, asp, gin, glu, his, ile, lys, pro, val, thr) or glycine (ser), or enzymatic attack on aspartic acid (ala) or fumaric acid (asp), by hydrolysis, for example, of casein or sugar beet waste (arg, cys, his, hyp, leu, tyr), by transformation of ornithine (arg) or glutamic acid (gin), or, alternatively, by complete synthesis from aldehydes using the Strecker synthesis (ala, gly, leu, met, phe, thr, trp, val), from acrylonitrile (gly, lys), or from caprolactam (lys). The racemates are obtained by total synthesis, but L-amino acids are produced by all the other processes. The racemates are separated and the D-isomers produced are again racemized. 

In this chapter we shall consider first the largest-scale industrial process, the Monsanto hydrodimerization of acrylonitrile to adiponitrile, and then go on to discuss the other processes presently used or likely to be introduced in the near future. 

Recovery From Industrial Byproduct Liquors — Byproduct units have been installed in many countries for producing ammonium sulfate from the waste streams of caprolactam, acrylonitrile, and certain other processes. In such cases, the waste liquor should normally contain at least 35% of ammonium sulfate in... 

Process Chemistry. Much of the early work on propane ammoxidation had centered on the development of catalysts that can operate under process conditions similar to those currently used for the propylene-based process. The intent is simply to replace propylene with propane as the feedstock and change the catalyst with little or no major alteration in reactors or other process equipment. As in the case of propylene ammoxidation, a solid catalyst is used to kinetically direct the vapor phase reaction to the desired partial oxidation product, namely, acrylonitrile. Also like propylene ammoxidation, the major by-products of the reaction are CO and CO2 along with acetonitrile and HCN. 

There are other processes in which potential exists to reduce hydrogen consumption. For example, in the ammoxidation of propene to acrylonitrile (Equation 10.3), ammonia produced from hydrogen and nitrogen is used ... 

PROPENE The major use of propene is in the produc tion of polypropylene Two other propene derived organic chemicals acrylonitrile and propylene oxide are also starting materials for polymer synthesis Acrylonitrile is used to make acrylic fibers (see Table 6 5) and propylene oxide is one component in the preparation of polyurethane polymers Cumene itself has no direct uses but rather serves as the starting material in a process that yields two valuable indus trial chemicals acetone and phenol... 

The heat of hydration is approximately —70 kj /mol (—17 kcal/mol). This process usually produces no waste streams, but if the acrylonitrile feed contains other nitrile impurities, they will be converted to the corresponding amides. Another reaction that is prone to take place is the hydrolysis of acrylamide to acryhc acid and ammonia. However, this impurity can usually be kept at very low concentrations. American Cyanamid uses a similar process ia both the United States and Europe, which provides for their own needs and for sales to the merchant market. 

Although some very minor manufacturers of acryhc acid may still use hydrolysis of acrylonitrile (see below), essentially all other plants woddwide use the propylene oxidation process. 

Acrylonitrile copolymeri2es readily with many electron-donor monomers other than styrene. Hundreds of acrylonitrile copolymers have been reported, and a comprehensive listing of reactivity ratios for acrylonitrile copolymeri2ations is readily available (34,102). Copolymeri2ation mitigates the undesirable properties of acrylonitrile homopolymer, such as poor thermal stabiUty and poor processabiUty. At the same time, desirable attributes such as rigidity, chemical resistance, and excellent barrier properties are iacorporated iato melt-processable resias. 

Poly(vinyhdene chloride) (PVDC) film has exceUent barrier properties, among the best of the common films (see Barrier polymers). It is formulated and processed into a flexible film with cling and tacky properties that make it a useful wrap for leftovers and other household uses. As a component in coatings or laminates it provides barrier properties to other film stmctures. The vinyUdene chloride is copolymerized with vinyl chloride, alkyl acrylates, and acrylonitrile to get the optimum processibUity and end use properties (see Vinylidene chloride monomer and polymers). 

A third source of initiator for emulsion polymerisation is hydroxyl radicals created by y-radiation of water. A review of radiation-induced emulsion polymerisation detailed efforts to use y-radiation to produce styrene, acrylonitrile, methyl methacrylate, and other similar polymers (60). The economics of y-radiation processes are claimed to compare favorably with conventional techniques although worldwide iadustrial appHcation of y-radiation processes has yet to occur. Use of y-radiation has been made for laboratory study because radical generation can be turned on and off quickly and at various rates (61). 

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