Hydrogen cyanide Andrussow process

One caveat pertains to the platinum oxide transport model It does not appear to be able to explain the differences in metal weight loss during ammonia oxidation and hydrogen cyanide synthesis by the Andrussow process. In the Andrussow process a mixture of methane, ammonia, and air is used to maintain a high temperature (1200°C) while generating hydrogen cyanide. Alternative processes require energy input, because HCN synthesis is an endothermic reaction. Thus, in both ammonia oxidation and HCN synthesis, platinum or alloy... 

Approximately 80% of all hydrogen cyanide is manufactured by the reaction of air, ammonia, and natural gas over a platinum or platinum-rhodium catalyst at elevated temperature. The reaction is referred to as the Andrussow process. Hydrogen cyanide is also available as a by-product from aciylonitrile manufacture by ammoxidation (20%). 

Hydrogen cyanide is generally produced in industrial quantities by high temperature catalytic reaction between ammonia, methane, and air (the Andrussow process). The stoichiometry of the process is ... 

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... 

In hydrogen cyanide synthesis using the Andrussow process, air, methane, and ammonia are fed over 15 to 50 layers of noble metal gauze at 1050 to 1150°C at near atmospheric pressure. 

The scope of the review is therefore essentially related to the two industrially used processes, the nitric acid synthesis and the Andrussow hydrogen cyanide process. Both these processes have been in large-scale use for several decades but basic understanding of the relevant physics, chemistry, and engineering is still incomplete. 

Figure 4.1 Hydrogen cyanide via the Andrussow process. Source [7],...

Figure 4.1 is a flow diagram of the Andrussow process [7], To avoid the decomposition of methane and ammonia, the ratio of reactants must be carefully controlled. The products are cooled where care is taken to avoid the formation of azulmic acids, polymers formed by the reaction between hydrogen cyanide, ammonia, and water. The products go to a scrubbing tower where unconverted ammonia is absorbed in sulfuric acid. The product is then absorbed in water, stripped, and distilled to produce greater than 99% HCN [8]. Yields are 70 and 60% for methane and ammonia, respectively. 

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 ... 

This reaction was first reported by Andmssov (Andrussow) in 1927. It is primarily an industrial process used to manufacture hydrogen cyanide from methane, ammonia, and oxygen over a catalyst of 90% Pt-10% Rh in the form of a pad of woven screens at 1050-1100° C and 2 atm. Therefore, this reaction is known as Andrussow process. In this process, the catalytic gauze is 3-5 mm thick, and when the high gas velocities are employed, the contact times achieved are of the order of a few milliseconds. The effluent stream contains about 8% HCN and a number of byproducts such as hydrogen, CO, and C02. It was reported that in 1978 the output of hydrogen cyanide exceeded 600 million pounds in the United States alone. ... 

Hydrogen cyanide is produced industrially by thermolysis of formamide, or from methane and ammonia on platinum-rhodium catalysts (following a process developed by Leonid Andrussow (1896-1988) in 1927 at BASF in Ludwigs-hafen) (Fig. 5.196). 

Hazardous Product. The synthesis of hydrogen cyanide (HCN) is an example of a fast, high-temperature process that generates a hazardous gas. Researchers at the Institut fiir Microtechnik Mainz, Germany, aimed to develop a portable on-site, on-demand HCN-generating unit [1]. The Andrussow process was selected for generating HCN on the microscale. The reaction can be written as... 

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