Specifications acrylonitrile production

In the recovery section, the effluent vapor from the reactor is scrubbed to recover the organics. Non-condensables may be vented or incinerated depending on local regulations. In the purification section, hydrogen cyanide, water and impurities are separated from the crude acrylonitrile in a series of fractionation steps to produce acrylonitrile product that meets specification. Hydrogen cyanide (HCN) may be recovered as a byproduct or incinerated. 

The combination of durability and clarity and the ability to tailor molecules relatively easily to specific applications have made acryflc esters prime candidates for numerous and diverse applications. At normal temperatures the polyacrylates are soft polymers and therefore tend to find use in applications that require flexibility or extensibility. However, the ease of copolymerizing the softer acrylates with the harder methacrylates, styrene, acrylonitrile, and vinyl acetate, allows the manufacture of products that range from soft mbbers to hard nonfilm-forming polymers. 

Standard test methods for chemical analysis have been developed and pubUshed (74). Included is the determination of commonly found chemicals associated with acrylonitrile and physical properties of acrylonitrile that are critical to the quaUty of the product (75—77). These include determination of color and chemical analyses for HCN, quiaone inhibitor, and water. Specifications appear in Table 10. 

Synthetic. The main types of elastomeric polymers commercially available in latex form from emulsion polymerization are butadiene—styrene, butadiene—acrylonitrile, and chloroprene (neoprene). There are also a number of specialty latices that contain polymers that are basically variations of the above polymers, eg, those to which a third monomer has been added to provide a polymer that performs a specific function. The most important of these are products that contain either a basic, eg, vinylpyridine, or an acidic monomer, eg, methacrylic acid. These latices are specifically designed for tire cord solutioning, papercoating, and carpet back-sizing. 

Acetonitrile and hydrogen cyanide are hy-products that may he recovered for sale. Acetonitrile (CH3CN) is a high polarity aprotic solvent used in DNA synthesizers, high performance liquid chromatography (HPLC), and electrochemistry. It is an important solvent for extracting butadiene from C4 streams. Table 8-1 shows the specifications of acrylonitrile, HCN, and acetonitrile. ... 

There is a test that can detect acrylonitrile in blood. In addition, the major breakdown products of acrylonitrile by the body (termed metabolites) can be measured in urine. Some breakdown products that can be measured are specific to acrylonitrile. However, one breakdown product of the body (cyanide) that is commonly measured is not specific to acrylonitrile exposure, and the results can be affected by cigarette smoking. Because special equipment is needed, these tests cannot be performed routinely in your doctor s office. There is not enough information at present to use the results of such tests to predict the nature or severity of any health effects that may result from exposure to acrylonitrile. Further information on how acrylonitrile can be measured in exposed humans is presented in Chapters 2 and 6. 

Extension of the Kunii-Levenspiel bubbling-bed model for first-order reactions to complex systems is of practical significance, since most of the processes conducted in fluidized-bed reactors involve such systems. Thus, the yield or selectivity to a desired product is a primary design issue which should be considered. As described in Chapter 5, reactions may occur in series or parallel, or a combination of both. Specific examples include the production of acrylonitrile from propylene, in which other nitriles may be formed, oxidation of butadiene and butene to produce maleic anhydride and other oxidation products, and the production of phthalic anhydride from naphthalene, in which phthalic anhydride may undergo further oxidation. 

During this work we have studied the structure of products obtained from the polymerization of a mixture of butadiene and an acrylic monomer on a PVC latex. More particularly we have studied polymers by fractionation in solution and we describe this here for the specific case of systems of PVC-butadiene acrylonitrile. 

The water-free acrylonitrile is obtained as bottoms in the column C-4. Water leaves in top as a binary azeotrope, followed by decantation and reflux of organic phase. The water phase also removes some light impurities. The final product meets closely the specifications indicated in Table 11.1. Since heavy impurities inevitably appear, a final vacuum distillation of acrylonitrile is performed in practice before shipping. 

Acrylics. Manufacturers of acrylic fibers have not generally published or confirmed the chemical composition of their fibers (116). Acrylic fiber will generally contain 85-94% acrylonitrile the balance is made up of comonomers having a specific function, such as to provide dye affinity for specific dye classes or to regulate diffusion of dye into the fiber. A list of typical comonomers has been published (116). Acrylic fibers may also contain heat (117) and light stabilizers (116). They may also contain a delustrant such as titanium dioxide. Some products contain optical brightening agents. These materials probably never exceed 4r-5% of the total composition. The cross-sectional shapes of the fibers vary (116). 

The commercial importance of spin finishes can be realized from the sheer volume of synthetic fibers produced. For the year 2000, the production figures of the three major synthetic fibers, e.g., polyester, polyamide (nylon), and poly(acrylonitrile) were approximately 18, 4, and 3 million tons, respectively (51). If spin finishes are applied at 0.25-0.5% level, the annual requirement of these finishes will be in the range of 70-140 thousand tons. This has given rise to industries that supply spin-finish components and completely formulated spin finishes for specific applications (52). An experimental nonproprietory spin finish formulation supplied to TRI/Princeton by Henkel Corp. follows ... 

---