This work deals with an efficient
two-step thermal upgrading process
for converting extra-heavy fuel oil to light olefins (ethylene, propylene,
and butenes) and fuels (gasoline and diesel fuel). In the first step,
mild thermal pretreatment was implemented at different temperatures
(360–440 °C) in the liquid phase to obtain a more suitable
feedstock for an olefin production unit. Thanks to this cost-effective
pretreatment, the upgraded feedstock demonstrated considerable flowability
and crackability compared to the initial fuel oil, making the subsequent
vapor-phase operation easier to handle at temperatures as high as
800 °C with no severe operational impediments. The quantitative 1H and 13C NMR studies shed light on the enhanced
features of the thermally treated feedstock toward lighter and more
valuable products. As a result, remarkable olefin production (74.7
or 55.1 wt % light olefins based on the upgraded or the original feedstock)
was accomplished in this two-step process. The process could be alternatively
stopped at the first stage for maximum liquid fuels (69.3 wt %) with
gasoline as the larger constituent. The detailed kinetic investigations
of the thermal decomposition of the feedstock using several reliable
approaches revealed that the activation energy predictions (42.3–272.9
kJ/mol) by the Kissinger–Akahira–Sunose method almost
perfectly matched the trend of a reference Starink model over the
whole range of conversion. All model-free methods correlated with
a coefficient of determination above 97.9%. Avrami’s theory
was further applied to determine the reaction order, and the values
were slightly smaller than those from a five-lump kinetic model of
the semibatch operation. However, the apparent activation barrier
in the reactor was in good correspondence with the range from the
microscale nonisothermal decomposition.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.