CO2-Fixierung auf der frühen Erde mittels präbiotischer Katalysatoren

Peters, Sophia (2023): CO2-Fixierung auf der frühen Erde mittels präbiotischer Katalysatoren: ein neuer Erklärungsansatz für den Ursprung der organischen Materie als ersten Schritt für die Entstehung des Lebens. Dissertation, LMU München: Fakultät für Chemie und Pharmazie

Abstract

In this work, a completely new scenario for the formation of the first organic matter was developed and experimentally tested. Industrial heterogeneous catalytic processes served as models (Haber-Bosch synthesis and Fischer-Tropsch synthesis). In autoclave experiments, chemical processes were initiated between gases available in the Earth's atmosphere (carbon dioxide, hydrogen/water, ammonia) using a prebiotic catalyst consisting of a metal source (meteorite and volcanic ash) and a mineral from the early Earth. The resulting products were then separated, analyzed, and evaluated by GC-MS. As main products methanol, ethanol, acetaldehyde and formaldehyde and in smaller amounts n-alkanes and iso-alkanes could be detected. It was impressively demonstrated that the reaction proceeded even under various conditions (temperatures of 150 − 300 ◦C, reaction times of 3-38 d, pressures of 9-45 bar, including CO2:H2 ratios of 1:20 to 9:1), metal sources (two iron meteorites, a stony meteorite, and volcanic ash), and minerals (silica gel, montmorillonite, diopside, olivine, and hydroxyapatite). For the preparation of nitrogenous conditions, ammonia or urea were added to the scenario described above and the resulting products were determined via UHPLC/qTOF (ESI). Not only the masses of the substance classes of amides, alcohol-amides, alcohol-nitriles, carboxylic acid-amides, but also numerous unsaturated compounds rich in nitrogen or oxygen were detected. A general mechanism of CO2 fixation could be established by the formed classes of substances as well as the detected urotropins and purines. As in the experiments without a nitrogen source, similar classes of substances were always formed under variable conditions, but in different distributions and yields, as expected. The experiments show that already on the early Earth CO2 could be bound under different conditions. This process is likely to have been remarkably efficient. According to calculations, this reaction could produce organic matter on a scale equivalent to today's biomass over a period of an estimated ≈100 million years. Such a development and the resulting wide range of products could mark the starting point for the emergence of life.

• Dokumententyp: Dissertationen (Dissertation, LMU München)
• Themengebiete: 500 Naturwissenschaften und Mathematik ; 500 Naturwissenschaften und Mathematik > 540 Chemie
• Fakultäten: Fakultät für Chemie und Pharmazie
• Sprache der Hochschulschrift: Deutsch
• Datum der mündlichen Prüfung: 12. Mai 2023
• 1. Bericht­erstatter:in: Trapp, Oliver