Natural Gas Pyrolysis in a Liquid Metal Bubble Column Reaction System—Part II: Pyrolysis Experiments and Discussion

Abstract

This contribution presents the results of continued investigations on the production of hydrogen by means of pyrolysis in a liquid metal bubble column reactor, as developed at the Karlsruhe Institute of Technology in recent years. Part I of this contribution described the motivation and the methodology of this study, as well as a significant scale-up, and discussed its results for pure methane pyrolysis. Here in part II, two additional experimental campaigns with methane–ethane mixtures (MEMs) and high-calorific natural gas (nGH) will be presented and discussed for the first time, using the up-scaled liquid metal bubble column reactor. It could be proven that an MEM as the feed gas led to an increase in methane conversion at low temperatures, which is consistent with the literature data. The nGH pyrolysis confirms this trend and also results in a significant rise in methane conversion compared to pure methane pyrolysis. Furthermore, the nGH pyrolysis leads to an increased methane conversion even at higher temperatures compared to MEM pyrolysis. Additionally, both MEM and nGH pyrolysis also showed a shift in the formation of by-products toward lower temperatures.

Technology Development for the Pyrolysis of Hydrocarbons in Liquid Metal

“…This is due to the presence of ethane in natural gas. This effect and potential reasons are described and discussed in more detail in [10]. This experimental result demonstrates that a successful transition from laboratory to industrial scale is possible without reducing the efficiency of the process being developed.…”

“…One important result of these studies is shown in Fig. 2 [10]. The methane to hydrogen yield in experiments using pure methane and high caloric natural gas (molar fraction: 98.2 % methane, 1.71 % ethane, 0.07 % propane, another components 0.02 %) as a process feedstock is compared in the diagram for otherwise similar process conditions.…”

“…The process is currently under investigation and the results including the selectivity of the entire process will be published in detail in a separate publication in the near future. The hydrogen selectivity of the methane pyrolysis process at various process parameters has also been considered in [8,10]. In general, only small amounts of by-products (ethane, ethene) have been detected in the product gas in previous studies.…”

“…Figure2. Temperature-dependent methane to hydrogen yield for pure methane (PM) compared to natural gas (nGH) as reactants at different superficial gas velocities (SGV)[10].…”