Boosting Carbonate Hydrogenation through In Situ Formation of the CaO/CaCO₃Interface

High-temperature calcination of carbonate minerals in energy-intensive industrial sectors is one of the greatest contributors to global carbon dioxide (CO₂) emissions. The hydrogenation of the most abundant carbonate minerals could potentially mitigate unavoidable CO₂emissions by converting them into value-added products, but progress has been hindered by a limited understanding of this process. Here, we aim to elucidate the underlying mechanism of self-induced direct hydrogenation of carbonates (DHC) to produce metal oxides and syngas at relatively lower temperature without using any catalysts. Various in situ technologies corroboratively illustrate H₂molecules can penetrate into CaCO₃to form multiple CaO/CaCO₃interfaces, resulting in porous CaO. The density functional theory calculations reveal the neighboring O and C sites at the active CaO/CaCO₃interface are responsible for the heterolytic dissociation of H₂, leading to the progressively self-induced DHC. An intrinsic microkinetic analysis by tracing the formation rate of the intermediate further verifies its self-induced catalytic characteristics. This subverts the consensus regarding the infeasible self-catalysis of stable ionic crystals. By lowering the temperature to 650 °C, 100% CaCO₃conversion is achieved with a CO selectivity of 91.8% in a packed bed reactor. Inspired by extensive applications of DHC to various carbonates, this innovative idea of treating carbonates as a White Carbon resource may pave a breakthrough pathway toward Carbon Neutrality in the industry.