Influence of process parameters on direct solar-thermal hydrogen and graphite production via methane pyrolysis
Mostafa Abuseada, R. Mitchell Spearrin, Timothy S. Fisher
Abstract
Current hydrogen and carbon production technologies emit massive amounts of CO2 that threaten Earth's climate stability. Here, a new solar-thermal methane pyrolysis process involving flow through a fibrous carbon medium to produce hydrogen gas and high-value graphitic carbon product is presented and experimentally quantified. A 10 kWe solar simulator is used to instigate the methane decomposition reaction with direct irradiation in a custom solar reactor. From localized solar heating of fibrous medium, the process reaches steady-state thermal and chemical operation from room temperature within the first minute of irradiation. Additionally, no measurable carbon deposition occurs outside the fibrous medium, leaving the graphitic product in a form readily extractable from the solar reactor. Parametric variations of methane inlet flow rate (10–2000 sccm), solar power (0.92–2.49 kW) and peak flux (1.3–3.5 MW/m2), operating pressure (1.33–40 kPa), and medium thickness (0.36–9.6 mm) are presented, with methane conversion varying from 22% to 96%.