A microwave-based system for hydrogen production by using CNT/rGO catalyst

Due to strict environmental requirements and problems related to fuel use and shortages, hydrogen energy has emerged as a pivotal clean energy carrier. However, conventional production methods are often energy- and carbon-intensive. In the present work, a novel approach for hydrogen production was investigated using a microwave-assisted pyrolysis system. A hydrogen generation system was utilized in which carbon-based catalyst beds composed of reduced graphene oxide (rGO), carbon nanotubes (CNTs), and their composites were evaluated. rGO was synthesized through a rapid microwave-assisted thermal reduction process, characterized by FESEM, EDS, and XRD analysis. The key contribution of this work lies in the custom-designed fixed-bed quartz reactor integrated inside a modified microwave cavity, which enabled a direct comparison of the catalytic and thermal performance of pure CNT, pure rGO, and hybrid CNT–rGO beds under identical operating conditions. It was found that CNT-based systems exhibited superior microwave absorption behavior, reaching temperatures above 1200 °C and achieving a stable propylene glycol conversion rate of over 90%, together with a hydrogen yield of approximately 38 vol%, thereby outperforming both rGO and hybrid CNT–rGO systems. These results highlight the enhanced catalytic efficiency of CNT-based catalysts, driven by their high electrical conductivity, dielectric loss factor, and morphology-driven microwave coupling. This system represents a significant step towards the industrial-scale production of hydrogen using microwave heating, offering an energy-efficient and sustainable solution for hydrogen generation. CNT, rGO, and CNT–rGO catalysts for hydrogen production under microwave heating Pure CNT beds achieved temperatures above 1200 °C due to superior microwave absorption and dielectric loss properties CNT catalysts delivered over 90% propylene glycol conversion and up to ~38 vol.% hydrogen yield The tubular morphology and high electrical conductivity of CNTs enhanced micro-hot spot formation and catalytic efficiency A scalable and energy-efficient pathway for sustainable hydrogen production via microwave-assisted pyrolysis