Performance of integrated multi-stage catalytic conversion of CO2 to solid carbon via RWGS–Boudouard coupling

Abstract

We report a structured, multi-stage catalytic system for converting CO₂ into solid carbon via the reverse water–gas shift (RWGS) reaction and carbon monoxide disproportionation. By spatially separating the reaction zones using spiral and hollow-tube catalysts, the system achieves high CO₂ conversion, suppresses methanation, and enables continuous carbon collection. Stable performance is maintained under continuous flow, and additional experiments confirm that RWGS occurs in situ within the carbon capture zone, supplying CO for downstream carbon formation. SEM and Raman analyses reveal that fibrous carbon structures are maintained throughout the reactor axis, with a gradual decrease in fiber diameter toward the downstream positions. Despite this morphological refinement, carbon productivity remains stable, demonstrating the durability and scalability of this CO₂-to-carbon platform for carbon-negative applications.