Thermochemical Aspects of the Conversion of the Gaseous System CO2-N2-H2O into a Solid Mixture of Amino Acids

Abstract

Conversion of the gaseous mixture CO₂(g)+N₂(g)+H₂O(g) to a solid amino acid condensate in an electric discharge plasma has high efficiency of the energy transfer from the different plasma components into chemical processes. The basic activation process is activation of the N₂ metastable electronic state, followed by formation of NCO* and ON-NCO free-radicals and generation of many reactive radicals. These radicals help to overcome the high activation energy of thermal dissociation of N₂ to N (950 kJ=9.846 eV).

The major product is a statistical polycondensate containing the amino acids: arginine, lysine, histidine, methionine, glycine, alanine, serine and aspartic acid. This information was obtained by comparing the IR spectra of the products with reference IR absorption spectra of pure components. Identification of the individual amino acids in the solid product was performed by HPLC, when samples were dissolved using 6 M HCl applied at 100°C for 24 h. Properties of the condensate were estimated using thermogravimetric analysis. Small amounts of oxamidato complexes and oligo pyrrole structures are formed on the electrode surface giving the surface catalytic properties. The gas cleaning process has practical applicability (production of useful fertilizers, reduction of the CO₂ concentration in the atmosphere) and may also contribute to explanation of the origin of life on Earth.