Acrylonitrile synthesis

Because of the large price differential between propane and propylene, which has ranged from 155/t to 355 /1 between 1987 and 1989, a propane-based process may have the economic potential to displace propylene ammoxidation technology eventually. Methane, ethane, and butane, which are also less expensive than propylene, and acetonitrile have been disclosed as starting materials for acrylonitrile synthesis in several catalytic process schemes (66,67). 

Plants for the production of sodium cyanide from Andmssow process or from acrylonitrile synthesis by-product hydrogen cyanide are operating in the United States, Italy, Japan, the UK, and AustraUa. In Germany, sodium cyanide is produced from BMA hydrogen cyanide, and in AustraUa one plant uses Fluohmic process hydrogen cyanide. 

Solids blending Acrylonitrile synthesis Reduction of iron oxide Coal gasification... 

Figure 11.3 Sketch of the fluid-bed reactor for acrylonitrile synthesis.

Acrylonitrile and methacrylonitrile can be obtained from petro-chemical olefins [2] by the noncatalytic reactions of HCN with acetaldehyde, acetone (cyanohydrin is the intermediate in these processes) or oxiranes (Z-cyanoetltanol being the intermediate in the acrylonitrile synthesis from ethylene oxide). 

In conclusion, this overview demonstrates that the ammoxidation field is still a quite attractive area from both fundamental and commercial points of view. It also stresses that the same concepts and catalysts used for more known areas (such as acrylonitrile synthesis) could also be successfully appHed in the conversion of less-conventional molecules. 

The success of FCC encouraged applications of the fluidized catalyst reactor to other catalytic reactions. Successful applications can be found in fluid catalytic reforming, production of alkyl chloride by oxychlorina-tion, production of phthalic anhydride, acrylonitrile synthesis by ammox-idation, and production of maleic anhydride. 

More than 5 million tons of acrylonitrile are made annually. It is synthesized industrially by the gas-phase heterogeneous ammoxidation of propene. New catalysts based on Bi-Mo or V-Sb oxides may lead to manufacture of this important compound from propane. Although the new process has a considerably lower selectivity to acrylonitrile, the lower cost of the alkane makes it economically interesting (the propane method can cut at least 20 % from the production costs of the propene route). Nevertheless, increases in the selectivity of the catalysts, especially at higher conversions, will be necessary for this process to compete with the usual process of acrylonitrile synthesis [24]. 

Fluidized beds have been used extensively for physical operations (e.g., adsorption and heat exchanger), chemical synthesis (e.g., acrylonitrile synthesis and maleic anhydride synthesis), metallurgical and mineral processes (e.g., roasting of sulfide ores, resid hydro-treating, and reduction of iron oxide), and other applications, such as coal combustion and microorganism cultivation. 

In a study of acrylonitrile synthesis in a 0.5-m x 9-m reactor. Pell and Jordan [21] found a steady increase in conversion as the fines concentration was increased from 23% to 44%. The effect was more pronounced at a velocity of 0.38 m/sec than at 0.66 m/sec, and the optimum fines concentration was about 40%. A strong effect of size distribution was also demonstrated in the ozone decomposition tests of Sun and Grace [16]. For the same average particle size (60 /rm), a wide PSD gave significantly higher conversion than a narrow PSD, as shown in Figure 9.13. The study covered... 

The amoxidation of propylene is an important industrial process of acrylonitrile synthesis. One of the methods of acrylonitrile synthesis involves the reaction of propylene with ammonia and oxygen in the presence of a heterogeneous catalyst (bismuth molybdate containing compounds of Ni, Co, Fe, Sn, etc.) " " see equation (13.249). The amoxidation process is also carried out in the case of other compounds, for instance, 3-methylpyridine and / -xylene, which allows the preparation of nicotinic and terephthalic acids, respectively, after hydrolysis of the nitriles. 

Hydrogen cyanide is an essential chemical for the production of methacryhc esters, adipodinitrUe, and some technical important amino acids, such as L-methio-nine. Alongside the two mentioned synthetic routes from methane, considerable amounts of HCN are also formed as a side product of acrylonitrile synthesis using the Sohio process (Section 5.3.3.8). 

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