ON MECHANISMS OF INCREASING HCL DISSOCIATION DEGREE IN GLOW DISCHARGE PLASMA
Abstract
The influence of initial compositions of the binary HCl+Ar and HCl+O2 gas mixtures on the hydrogen chloride dissociation kinetics in low temperature gas discharge plasma was investigated. The experiments were carried out under the conditions of direct current glow discharge at constant total gas pressure (100 Pa) and discharge current (25 mA). The data on electro-physical plasma parameters and plasma composition were obtained by modeling procedure based on the simultaneous solution of Boltzmann kinetic equation and the equations of chemical kinetics for neutral and charged species in a steady-state approximation. It was found that an increase in the second component fraction in both gas mixtures results in the sufficient increase in the HCl dissociation degree (aHCl = 23–43% for 0–80% Ar and 23–90% for 0–80% O2), which is associated with different mechanisms. Particularly, in the HCl+Ar gas mixture, an effect of increasing aHCl is provided by an increase in the electron impact dissociation frequency due to the change in electro-physical plasma parameters, such as electron mean energy and electron density. For the HCl+O2 gas mixture, such mechanism is almost negligible because of the weak disturbances in both electron energy distribution and formation/decay balance for charged species in the combination of two molecular electronegative gases. At the same time, the HCl dissociation kinetics in this gas system appears to be strongly dependent on the gas-phase interactions with ground state of oxygen atoms O(3P), metastable atoms O(1D) and OH radicals. It was found that the rates of corresponding processes begin to exceed the HCl electron impact dissociation rate at 20% O2 in HCl+O2.
Forcitation:
Efremov A.M., Murin D.B., Belyaev S.V. On mechanisms of increasing hcl dissociation degree in glow discharge plasma. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2018. V. 61. N 7. P. 61-66
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