CFD study of a multiphase reactor for methane pyrolysis: investigation of soot deposition in a thermal and a catalytic process

Methane pyrolysis is a single-step technology for the production of turquoise hydrogen and carbon. This reaction represents an attractive technology to promote the shift towards a hydrogen-based economy and to reduce greenhouse gas emissions of oil and gas extraction activities, since the carbonaceous part of the hydrocarbon is transformed into a solid, much easier to store than a gas. At laboratory scale, it is extremely challenging to perform experiments on pyrolytic processes, due to temperature requirements (above 950 °C and long residence time required for non catalytic methane pyrolysis) and long experimental runs. In this framework, computational fluid dynamics (CFD) represents an excellent tool to support experimental studies to investigate underlying phenomena. This study aims to assess the physical and chemical phenomena of pyrolytic processes conducted in a reactor, ranging from heat transport phenomena up to the description of the reactive flow involved in the thermal decomposition of methane in a laboratory-sized quartz tubular reactor. The numerical simulations aim to support understanding how a thermal and a thermal-catalytic process occur when running a packed bed of carbon black (CB) pellets. Additionally, the present study evaluates the impact of various parameters and aspects, including the effect of the temperature field and soot deposition in the reactor.