Due to the recent boom in shale gas
production, aromatics production
using direct nonoxidative methane dehydroaromatization (DHA) is being
investigated extensively. However, due to rapid coke formation, catalysts
in the nonoxidative methane DHA reactors get deactivated, which is
one of the critical issues for the commercial success of the methane
DHA process. In this paper, a model for catalyst deactivation is developed.
Rate models for other DHA reactions are developed by considering the
decrease in the catalyst activity with time. Due to the very fast
coke formation rate on the fresh catalyst, there is coke formation
immediately upon the introduction of the feed. Therefore, an algorithm
is developed for estimation of the initial state of the reactor and
the kinetic parameters by coupling an iterative direct substitution
approach with an optimization approach. Transient experimental data
from an in-house reactor are first reconciled and then used for developing
the kinetic model including the coke formation model. Using the rate
model, a dynamic, heterogeneous, multiscale reactor model with embedded
heating is developed. The model couples the catalyst pellet level
model with a reactor level model. Impacts of temperature, L/D ratio,
and scheduling of reactors on variability in conversion and yield
with time are studied.