Direct biogas reforming to turquoise H2 and carbon material in a catalytic fluidised-bed reactor

Abstract

The conversion of methane or natural gas into turquoise H₂ and carbon represents a promising pathway towards decarbonised energy. The pyrolysis of biogas (mainly a mixture of methane and CO₂) is considered to be a negative carbon-emission technology, as the carbon source comes from biomass and the carbon is captured in solid form. In addition, the presence of CO₂ in the gas mixture enables the dry reforming of methane into syngas. In this study, we show that direct biogas conversion in a fluidised catalytic reactor can produce a syngas whose composition meets the requirements for methanol synthesis or for liquid hydrocarbon production via the Fischer–Tropsch process. Confirmed by thermodynamic analysis, we show that the reaction proceeds at temperatures above 900 °C to produce carbon materials, whereas at lower temperatures the carbon is converted to CO by the Boudouard reaction. At 950 °C, very high methane and CO₂ conversions are achieved (>90% and 99%, respectively), accompanied by high hydrogen yield (>90%) and the sequestration of carbon into a turbostratic structure. We believe that the direct catalytic reforming of biogas in a fluidised bed, when combined in series with an FTS process, could allow the production of liquid fuels with no need for costly gas separation units, in particular those implemented for CO₂ capture.