2:45 PM - 3:00 PM
[PPS09-05] Reaction efficiency of hydrogen and carbon monoxide on an amorphous substrate of Mg-Fe-bearing silicate
Keywords:Fischer-Tropsch reaction, Surface reaction, Solar nebula
Previous studies performed experiments at higher-temperature (>573 K) and pressure (~1 atm) than the expected conditions in the solar nebula [2-5]. In case of actual environment in the early nebula, the temperature and pressure should be below 500 K and lower than 102 Pa, respectively. It is not obvious that the results of the reaction experiments are able to extrapolate to the actual early nebula environment, because we still do not fully understand the fundamentals of catalytic reactions. To determine the chemical reaction rates at lower temperature and pressure, we prepared an experimental system, which was originally designed and constructed based on a new concept to conduct catalytic experiments on a substrate simulated dust surfaces at relatively low- temperature (50-750 K) and pressure conditions (lower than 103 Pa). The temperatures of the cold head and substrate are measured using a silicon diode and a thermocouple, respectively.
Initially, we used substrates of iron, nickel and iron-nickel alloys with 1 % or 10 % of Ni contents and detected formation of methane, water and carbon dioxide by FTT, Water-gas shift and Boudouard reactions in a wider temperature range under a mixture gas of hydrogen and carbon dioxide with a ratio of roughly 2:1. The efficiency for methane and water formations by FTT reaction is 5 × 10-11 s-1 at 750 K for instance. In this presentation, in addition to concluding results for metallic substrate, we will focus on our recent results performed using an amorphous substrate of magnesium-iron-bearing silicate, which was prepared by a RF sputtering method in Institute for Planetary Materials, Okayama University.
Acknowledgment: This work was supported by a grant-in-aid for Scientific Research on Innovative Areas "Evolution of molecules in space from interstellar clouds to proto-planetary nebulae" supported by the Ministry of Education, Culture, Sports, Science and Technology, Japan (25108003).
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