Ammonia is emerging as a potential decarbonized H2energy
carrier when produced from renewable energy. The on-site production
of liquid ammonia from stranded renewable energy can solve the current
energy transportation challenges. The employment of microwave technology
can produce the desired ammonia product at milder conditions with
the supply of intermittent renewable energy sources. Our previous
studies have indicated that the Cs–Ru/CeO2catalyst
is a promising catalyst for microwave-driven ammonia synthesis. In
this study, the Cs–Ru/CeO2catalyst mechanically
mixed with carbon nanotubes (CNT) and chemically synthesized using
coprecipitation and a hydrothermal method is investigated systematically
at low temperatures and atmospheric pressure for microwave-assisted
ammonia synthesis. Additionally, the combination of two Ru-based catalysts
(Cs–Ru/CeO2and Cs–Ru/CNT) is studied as
well. Mechanical mixing of Cs–Ru/CeO2with CNT exhibited
superior activity as compared to the chemically synthesized Cs–Ru/CeO2-CNT catalyst. Besides the enhancement in dielectric property,
the probable synergistic effect leads to increased interfacial polarization
at the interface of the mechanically mixed catalyst, improving the
overall heating and ammonia production rate. Moreover, the combined
Ru-based catalyst also exhibited higher activity as compared to their
individual activity toward ammonia synthesis. Numerous characterization
techniques were performed, including thermal imaging camera and dielectric
measurements, to better understand microwave interaction with the
composite catalysts.