Methane Pyrolysis on Complex Melts: Reactive Separation for Hydrogen and Carbon

Utilization of low cost natural gas may be limited someday by society’s desire to reduce carbon dioxide emissions. The value of the resource as a fuel and source of hydrogen may be preserved by either capturing and storing the carbon oxides or avoiding their production altogether. Methane pyrolysis has long been utilized as a means of producing hydrogen from methane. If high value carbon products are desired for the carbon black market, plasma-based systems show promise to produce low pressure hydrogen and valuable carbon black. The high production costs can be supported by the value of the carbon product. Lower costs of production are possible using previously demonstrated molten metal-based processes whereby high-pressure hydrogen may be produced together with separable solid carbon which may be sold until the markets become saturated then readily and permanently disposed of. Results of investigations of methane pyrolysis in multiphase reacting systems containing molten metals and/or molten salts will be presented. Fundamentals of C-H bond activation on melt surfaces will be discussed for metals and salts and distinctions made as to how the subsequent reaction pathways can produce different types of carbons ranging from graphitic to disordered. Specific compositions of molten metal alloys and mixed molten salts will be discussed which have particularly high activities for pyrolysis and produce different types of carbon products. The practical problem of producing a commercially acceptable carbon product will be discussed along with the heat transfer and materials of construction challenges.