At sufficiently high temperature - well above 1000 °C for high conversion rates - and moderate heat input, methane decomposes into its components: Solid elemental carbon and gaseous hydrogen are formed. However, in conventional gas-phase reactors the carbon is deposited on the heated walls in a solid layer that blocks the reactor within a short time. In the context of the project presented here, the reactor vessel is filled with molten metal as a heat transfer medium. Methane gas is continuously introduced from below into this liquid metal bubble column, which is kept at up to 1200 °C, and rises therein as a swarm of bubbles. The gas very quickly reaches the reaction temperature, so that the pyrolysis reaction takes place. At the upper end of the liquid, the bubble opens and releases the gaseous hydrogen and the carbon. The latter precipitates as a microgranular powder that can be transported very easily, for example in gas-borne form. Due to the difference in density between the metals used, the carbon powder remains on the liquid surface and is discharged with the gas flow. It can be further processed in many ways, and analyses of its industrial use in lightweight construction materials, batteries, etc. have been started.<br/>In several test series with different temperatures, flow rates, additional materials in the reactor, etc., we demonstrated the possibility of continuous implementation of the process on a laboratory scale. Among other things, tricky corrosion issues had to be clarified - tin is highly corrosive to almost any material at temperatures beyond 1000 °C. A stable and spatially variable temperature structure had to be developed that avoid the formation of by-products. Conversion rates up to 79 % have been achieved.<br/>The contribution will present the project, its major results and the current development path.

Pyrolysis of methane in a liquid metal bubble column reactor

ACS Spring Meeting 2021

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