Catalytic
plasma-enhanced Fischer–Tropsch synthesis (FTS)
for gas-to-liquid conversion was investigated using a recently developed
novel nanostructured, hierarchically connected micro/meso-porous Co/SiO2 catalyst obtained through microwave irradiation-induced coassembly
of the catalyst and catalyst support precursors (Catalysts202010152). This catalyst
structure with its micron-scale morphological and chemical heterogeneity
is particularly suitable for catalytic plasma reactions. It is shown
that a dielectric barrier discharge (DBD) can promote FTS over the
catalysts at low temperatures and ambient pressure with 100% conversion
without any deactivation over a prolonged time scale (175 h in the
current study). In contrast to conventional FTS, the hydrogen conversion
is higher in plasma FTS, demonstrating that a DBD can promote FTS
for more methane and higher hydrocarbon formation. It is shown that
the catalyst is not fully reduced and is a mixture of CoO and Co.
Carbon deposition present due to incomplete heat treatment of the
catalyst to remove the organic coating on SiO2 support
results in catalyst deactivation, which can be eliminated by using
high catalyst reduction temperature. Furthermore, the catalytic activity
increases during the course of reaction due to the plasma-induced
morphological changes in the catalyst structure. In the absence of
a plasma, catalyst deactivation is very rapid, which is reversed by
burning carbon deposit using DBD plasma in oxygen atmosphere at 150
°C. The results indicate that it is possible to develop a new
sustainable, distributed FTS technology operating at low temperatures,
ambient pressure, and small scale by optimizing the catalyst property,
reactor design, and reaction parameters under plasma conditions.