Hydrogen Evolution from Hydrocarbon Pyrolysis in a Simulated Liquid Metal Bubble Reactor

The evolution of
hydrogen from methane decomposition in a liquid
metal bubble reactor (LMBR) has become a recent subject of interest;
this study examines a novel approach to hydrogen production from pyrolysis
of complex hydrocarbon fuels. Modeling hydrocarbon fuel decomposition
in an LMBR is executed in two stages of pyrolysis: First, primary
pyrolysis intermediates are simulated using a functional-group-based
kinetic model (FGMech). Then, a detailed high temperature mechanism
(AramcoMech 1.3 + KAUST PAH + 5 solid carbon chemistry) is applied
to simulate secondary pyrolysis of intermediates. The quantities of
major products of the secondary pyrolysis simulation (CH4, H2, Cs, C6H6) are approximated
by simplified regression equations. Further decomposition of smaller
hydrocarbons (until exiting the reactor) is simulated using a coupled
kinetic and hydrodynamics model that has been reported in the literature.
The mixing effects of bubble coalescence and breakup are investigated
in a comparative study on homogeneous and non-homogeneous reactors.
Finally, a qualitative relationship between H2 yield per
mass of fuel, functional group, and other factors such as temperature,
pressure, and residence time is analyzed. In general, the H/C ratio
and cyclic/aromatic content are the main features influencing total
conversion to H2.