Degussa process

The Degussa process, on the other hand, reacts ammonia with methane in absence of air using a platinum, aluminum-ruthenium ahoy as a catalyst at approximately 1200°C. The reaction produces hydrogen cyanide and hydrogen, and the yield is over 90%. The reaction is endothermic and requires 251 KJ/mol. 

In contrast, amino acid dehydrogenases comprise a well-known class of enzymes with industrial apphcations. An illustrative example is the Evonik (formerly Degussa) process for the synthesis of (S)-tert-leucine by reductive amination of trimethyl pyruvic acid (Scheme 6.12) [27]. The NADH cofactor is regenerated by coupling the reductive amination with FDH-catalyzed reduction of formate, which is added as the ammonium salt. 

Hydrogen cyanide is an important building block chemical for the synthesis of a variety of industrially important chemicals, such as 2 hydroxy-4 methylthiobutyric acid, adiponitrile, nitrilotriacetic acid, lactic acid, and methyl methacrylate. The primary commercial routes to hydrogen cyanide are the reaction of methane and ammonia under aerobic (Andrussow Process) or anaerobic conditions (Degussa Process), or the separation of hydrogen cyanide as a by-product of the ammoxidation of propylene < ) The ammoxidation of methanol could represent an attractive alternate route to HCN for a number of reasons. First, on a molar basis, the price of methanol has become close to that of methane as world methanol capacity has increased. However, an accurate long term pricing picture for these two raw... 

An alternative route for HCN formation, the Degussa process, is also discussed. Only methane and ammonia are used to form HCN. 

The most widespread efforts made towards the achievement of selective oxidation of alkanes are targeted on methane, a principal constituent of natural gas f 6-8]. Activation of the very stable C-H bond of methane is a particularly demanding problem. One example in which this has been achieved on industrial scales is the Degussa process [9], Methane is coupled to ammonia by heterogeneous catalysis in order to produce HCN, an important fundamental material for industrial chemistry. An unsolved problem is the selective oxidation of methane to methanol a reaction that would convert the methane gas into a transportable liquid. In nature, monooxygenases have evolved. These are able to activate molecular oxygen and to... 

The Degussa process (now owned by Dupont) starts from acrolein, which is hydrated in the presence of an acidic ion exchanger into 3-hydroxypropanal (3HP, Fig. 8.8 a). The latter is subsequently extracted into isobutyl alcohol and hydrogenated over a Ni catalyst [53]. The overall yield does not exceed 85%, due to competing water addition at the 2-position and ether formation in the initial step. It has been announced that Degussa will supply up 10 kt a-1 to Dupont until the fermentative process of the latter company (see below) comes on stream [54]. 

The second method is the pyrolysis of a methane-ammonia mixture (8) in the presence of Pt deposited inside a-alumina tubes. The yield is 80-85% based on Nllj and 90 - 91% based on CH4. Alumina participates in the formation of the actual catalyst (a Pt Al alloy). This method is also applied in industry (the Degussa process). 

An example of an acylase to perform a resolution is provided by the Degussa process to L-methionine (1). The racemic acetylmethionine (2) is prepared by a chemical synthesis. The acylase hydrolyses only the L-isomer (Fig. 2). The D-isomer is racemized by base and put back into the process stream (48). 

Production of Amino Acids Using Amino Acy loses the Degussa Process... 

Since the early 1980s this process has been scaled-up to a production level of many hundreds of tons per year. Scheme 16 shows the Degussa process for man-... 

Since the early 1980s this process has been scaled-up to a production level of hundreds of tons per year. Fig. 6 shows the Degussa process for manufacturing l-methionine, l-6 [9 a]. The biocatalyst is produced in bulk quantities and its operational stability is high hence this continuous EMR-acylase process demonstrates high efficiency, especially on a large-scale [9]. 

Figure 1A Mechanistic model for the Pt-catalysed HCN synthesis from CH4 and NH3 in the Degussa process.

The Degussa BMA (Blausaure-Methan-Ammoniak, or hydrocyanic acid-methane-ammonia) process also is used in the production of hydrogen cyanide from methane. The difference between the Andrussow process and the Degussa process is that the latter does not use air in the synthesis of hydrogen cyanide. The reaction is as follows ... 

The use of perpropionic add as an epoxidation agent for propylene has been proposed by BayeriDegussa, Interox (Carbochimique, laporte, Sofray) and Ugine Kuhlmann. The perpropionic add is produced by the oxidation of propionic add with hydrogen peroxide, in the presence of sulfuric acid. The propylene is epoxidized between 05 and 1.4.106 Pa absolute, at about 60 to 80°C, in the Bayer/Degussa process, which operates in the presence of benzene, and at 100°C in the Interox process, which uses 12-dichloropropane as a solvent. 

Figure 11.6 shows the scheme of alkylanthraquinone hydrogenation using the Degussa process. The reaction is carried out in a loop reactor by varying the diameter of the reactor tubes different reactant flow velocities are achievable. 

Variants of this breakdown process are also in use. In the Degussa process, for example,33 the beryl is fused with limestone before sulphuric acid breakdown, and the Joy-Windecker process similarly involves fusion with sodium carbonate before breakdown. The reaction mechanism in these cases is believed to be the conversion of the beryl into a complex silicate, followed by its decomposition with sulphuric acid, i.e. 

The German Degussa process, - operated during the Second World War, was essentially of this type, but Degussa tended to operate their cells simply with a sodium chloride-beryllium chloride melt. This necessitates a higher temperature and vapour losses, or alternatively working between two high beryllium chloride concentration limits, so that even at the end of electrolysis about 30 per cent of beryllium chloride is still present in the melt. 

At the current time, almost all HCN is produced on a large scale using one of two methods the Andrussow process or the Degussa process (see descriptions below). In addition to nylon manufacture, HCN is used for synthesis of many specialty chemicals. Companies, such as DuPont, currently supply the HCN for these processes via transport of HCN in... 

The Andrussow and Degussa processes account for almost all large-scale synthesis, which could also be scaled down for small-scale synthesis on-demand and on-site by end-users, thereby eliminating the risks associated with large-scale storage and transport. There are a number of options for achieving such on-site, on-demand syntheses ... 

Nicotinic acid is an important intermediate for pharmaceuticals and serves as a provitamin in food additives for animal feeding. It is produced by the Lonza process (involving oxidation of 2-methyl-5-ethyl pyridine using nitric acid) or by the Degussa process.The latter process involved hydrolysis of P-cyanopyridine, which in turn was produced by amminoxidation of P-picoline. A third process involving selective vapour phase oxidation of P-picoline catalysed by vanadium titanium oxide catalyst has also been described. ... 

Sol-gel processing is one of the methods that has been widely implemented for manufacturing three-dimensional nanoparticles, which can be used for polymer modification. In the 1950s the Degussa process (Eq. 1) became the method for preparation of nanoparticles based on Si02, Ti02 or AI2O3 [13]. 

The Degussa process for manufacturing gas black was developed in 1935 and is described by Buxbaum (1998). Oil vapour is carried in hydrogen, methane or coke-oven gas and combusted. Very fine particle sizes can be generated with the addition of air. 

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