Heterogeneous photosynthetic production of amino acids at platinum/titanium dioxide suspensions by near ultraviolet light

TLDR: In this article, the authors described the production of amino acids by xenon lamp irradiation of platinized TiOz powders (Pt/TiO), suspended in aqueous ammoniacal solutions saturated with methane.

Abstract: Studies of the previously reported production of amino acids (glycine, alanine, serine, aspartic acid, glutamic acid) from methane, ammonia, and water in contact with irradiated suspensions of Pt/TiO, were extended. Products were analyzed by LC, HPLC, and coupled GC/mass spectroscopy. Analysis of product mixtures also shows the presence of MeOH, EtOH, and CH3NH2 as products of the photoprocess. Experiments with nitrogen-15 labeled ammonia showed that the nitrogen in the amino acids originated with the N H 3 rather than from contaminants. Amino acids were also produced from the CH4-NH3-H20 mixture during decomposition of hydrogen peroxide at Pt foil. A mechanism for the reaction based on free-radical reactions initiated by hydroxyl radical produced at the irradiated catalyst is proposed. A previous communication from this laboratory' described the production of amino acids by xenon lamp irradiation of platinized TiOz powders (Pt/TiO,) suspended in aqueous ammoniacal solutions saturated with methane. The process apparently occurs by a photosynthetic (energetically uphill) reaction driven by the absorption of the near-ultraviolet (A e405 nm) radiation by the TiO,. These reaction conditions for amino acid formation from a simple reducing mixture are mild compared to previous methods for amino acid production that involved electrical discharge or very short wavelength radiation.2