HCN Synthesis Research Articles

Physics on plasma chemistry

In this paper, after a brief historical review of plasma chemistry, a short description of the different types of plasmas used, and of their means of production, we will present the plasma chemistry reactor with the problems of mixing the reactants with the plasma, the quenching and the catalysis. This is followed by a discussion of diagnostic techniques either on the plasma itself : spectroscopic measurement of temperature and population, laser fluorescence spectroscopy, gas velocity measurements and mass spectroscopy of ions ; or on the condensed materials injected into the plasma : velocity, surface temperature, population and diameters of the particles. For the reactions in homogeneous phase a brief summary on equilibrium and kinetics calculations is followed by an illustration of the application of this calculations with three examples : NO synthesis in a DC plasma jet, C2H2 and HCN synthesis in a HF plasma torch, organic compound synthesis with the O2 1 Δg metastable state produced in a HF low pressure plasma. For the reactions in heterogeneous phase, first we recall thermodynamic and transport properties of the plasma and then we deal with heat and mass transfer plasma particles. The applications described are first concerned with physical changes of solid materials in plasma : plasma spraying, spheroidisation, vaporisation, condensation and second chemical reactions.

PAДИAЦИOHHO-XИMИЧECКAЯ ФИКCAЦИЯ MOЛEКyЛЯPHOГO AЗOTA

The action of 340 kV electrons or γ- 60Co on gaseous mixtures of molecular nitrogen with various hydrocarbons give rise to radiation fixation of nitrogen. In all cases hydrocyanic acid is the main low molecular weight product of fixation. The radiation-chemical yield G(HCN) depends on the nature of the hydrocarbon and the ratio of components. the maximum G(HCN) values are obtained when the nitrogen/hydrocarbon ratio is 10:90. Most of the present experiments were carried out under an absolute pressure of 2 atm (200 kN m −2). The addition of inert gases to the mixtures increases G(HCN), which is 1⋅ for a mixture of 5 per cent CH 4, 5 per cent N 2 and 90 per cent Ar. Replacing nitrogen by air in the mixtures containing methane leads to a practically complete inhibition of HCN production due to interaction of methyl radicals and oxygen manifests the opposite effect in the case of mixtures of nitrogen with unsaturated hydrocarbons. Foe ethylene the maximum G(HCN) increases from 0⋅27 for ethylene-nitrogen mixtures to 0⋅48 for mixtures of ethylene and air. G(HCN) increases from 0c⋅23 to 1c⋅16 when passing from acetylene-nitrogen mixtures to acetylene-air mixtures; nitrogen-containing cuprene is not formed in the presence of oxygen. To elucidate a possible role of reactions of the methylene radical and atomic nitrogen, HCN synthesis in ketene-nitrogen mixtures has been studied. A maximum of G(HCN) = 1⋅6 is reached with 10 per cent of ketene. The addition of oxygen to the mixtures just slightly reduces G(HCN). The addition of small concentrations of N 2O to the mixtures of ethylene and nitrogen has the usual inhibition action. But when using N 2O as a nitrogen-containing component in the mixtures with ethylene, the maximum G(HCN) is three times larger that from C 2H 4−N 2 mixtures. It is 1⋅6 times smaller when replacing nitrogen by nitrous oxide in the mixtures with methane. Ammonia is also formed in hydrocarbon-nitrogen mixtures; G(NH 3) is comparable to G(HCN) for N 2−CH 4 mixtures. Acetonitrile ( G=0⋅6) and acrylonitrile ( G≈0⋅03) have been identified in CH 4N 2 mixtures irradiate under high pressures (50–75 atm = 5−7⋅5 MN m -2). Nitrogen-containing cuprene producedin C 2H 2–N 2 mixtures with high yield ( G ≈ 5) is more thermostable than usual cuprene and probably contains nitrogen in the form of various functional groups.

Characteristics of Pt-Rh gauze catalyst and kinetics of the HCN synthesis

Investigations were done on the HCN synthesis via the combustion of methane, air, and ammonia over Pt-Rh gauze catalyst. A pack of new catalyst required 60 to 80 hr to be fully activated. It could then maintain its economical life for several thousand hours. The relationships of catalyst activity with morphological change, crystal structure, surface area, and gauze impurities were defined. After external diffusion resistance was eliminated, maximum conversion of NH 3 to HCN was found at a certain contact time. During this period, the rate of HCN formation was approximately first order each with respect to NH 8 and CH 4.