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This study examines the modeling of hydrocarbon pyrolysis in a Ni 0.27 Bi 0.73 molten metal alloy reactor. The model is executed in two stages. The first stage investigates the effect of the physical properties of the gas and molten liquid on the bubble-size distribution, and determines the Sauter mean bubble diameter in the Ni 0.27 Bi 0.73 column. In this stage, a population-balance-based model using the Euler−Euler approach is coupled with nonreactive computational fluid dynamics in the ANSYS Fluent V17.2 software package. After estimating the Sauter mean diameter, the next stage computes the overall decomposition kinetics of hydrocarbons (gas phase + melt interface) and couples them with an existing hydrodynamic model to determine the final H 2 output and selectivity. The Sauter mean diameter was found to increase with increasing superficial gas velocity (or flow rate), liquid density, surface tension, column diameter, and decrease with increasing liquid viscosity. The hydrogen selectivity improved when the model included the surface kinetics, and the hydrogen selectivity of higher hydrocarbons was comparable to (or even higher than) that of pure methane at 1000 °C.

The transportation sector is among the largest contributors to carbon dioxide (CO2) emissions and demands immediate action. Although electrification is a promising technology to decarbonize light-duty vehicles, it has limited potential when applied to heavy trucks due to their longer travel distances and weight constraints. Hence, possible mitigation pathways must be identified to lower trucks’ carbon footprint. In this work, we propose an onboard post-combustion capture and storage system on heavy-duty freight vehicles using two state-of-the-art metal-organic frameworks (MOFs) with high CO2 selectivity and high-storage-capacity, respectively. We selected KAUST-7 as the capturing material because of its high stability and selectivity toward CO2 even in humid conditions; while Al-soc-MOF-1 as a CO2 storing material for its high gravimetric and volumetric CO2 uptake between 10 and 50 bar. Our solution aimed to reduce heavy-duty vehicle CO2 emissions by at least 50% and achieve above 95% CO2 purity at the storage point. First, we measured and modeled KAUST-7’s thermodynamic and kinetic properties, then we simulated and optimized the process conditions for the carbon capture system in response to dynamic engine behavior. Additionally, we minimized the capture and storage mass, offering as result innovative methods to mitigate carbon emissions in the heavy-duty freight industry.

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