Model-based evaluation of piston reactor to produce hydrogen from methane via catalytic SMR and ATR routes

Piston reactor technology can enable process intensification for electrical and mechanical power conversion to chemical products. Previous work has investigated hydrogen production via partial oxidation of methane (POM) in piston reactors; however, other routes remain unexplored. This work aims to theoretically evaluate if catalytic steam methane reforming (SMR) and methane autothermal reforming (ATR) constitute promising routes for hydrogen production using piston reactor technology for typical parameters and conditions encountered in automotive internal combustion engines (ICE). Specifically, the aim is to use reactor modeling and consider process design aspects in the early stages of investigation to provide direction and justify the next research and development stages involving experimentation, while eliminating infeasible options from the further expensive analysis. The piston reactor is first modeled using a zero-dimensional thermodynamic single-zone piston model coupled with available steady-state kinetic models for these routes. This model-based analysis shows that the highly endothermic SMR reaction is not feasible at ICE conditions, leading to its elimination from further assessments and studies. Thermal coupling of an endothermic reaction with a side-exothermic reaction is a potential solution to drive thermodynamically limited endothermic reaction routes in the piston reactor. The reactor modeling revealed that operation become feasible by coupling SMR with POM in ATR-type scenarios and achieves process intensification compared to steady-state ATR reactors through a significantly higher hydrogen production per catalyst (287-fold increase) and similar methane conversion between 89% and 97% at significantly lowered intake feed temperature (reduced by 283 K). The implementation of ATR piston reactors into grey and blue hydrogen production process designs is explored to understand overall performance and economy of scale effects. The process design studies reveal that the piston reactor-based processes offer savings of approx. 20% in hydrogen production costs compared to conventional ATR processes considering identical plant sizes and natural gas prices. The hydrogen production study highlights the value of the implemented approach for quickly identifying promising directions for further detailed experimental and modeling studies during early-stage exploration.