Reaction between H2, CO, and H2S over Fe, Ni metal in the solar nebula: Experimental evidence for the formation of sulfur-bearing organic molecules and sulfides

Abstract

Detailed laboratory studies have been carried out in order to simulate the interaction between nanometer-sized kamacite metal particles and different gas mixtures consisting of H2:H2S (250:0.1), H2:CO (250:1), and H2:CO:H2S (250:1:0.1) under nebular-type conditions (5 x 10-4 atm and 473 K). Reaction of H2 + H2S with kamacite particles for 1000 h leads to the formation of pyrrhotite. Incorporation of CO into the gaseous reactant mixture results in the formation of both sulfide and carbide phases. At the same time, amorphous C is deposited onto the metal particles and organic molecules are evolved, namely hydrocarbons and thiols in the C1-C5 and C1-C2 range, respectively. Carbon deposition and production of organics are enhanced with respect to experiments performed with H2 + CO, where a carbide phase is formed. There is no evidence for the existence of S-poisoning effects on the metal-catalysed hydrogenation of CO through Fischer-Tropsch-type reactions in nebular environments. In fact, it is experimentally demonstrated that S-containing organic species could be synthesized by such reactions from nebular gas.