<p>The carbonate industry is a high-emission process that generates large amounts of CO₂, whereas in-situ hydrogen-assisted pyrolysis is an effective technological strategy for reducing emissions. This study utilizes a kilogram-scale rotary kiln to simulate industrial-scale carbonate hydrogenation processes, taking the in-situ hydrogenation conversion of limestone as an example. By adjusting parameters such as the tilt angle, rotational speed, hydrogen flow rate and temperature of the rotary kiln, it was found that under conditions of 750&#xa0;°C, a hydrogen flow rate of 2&#xa0;L min^–1, a tilt angle of 2° and a rotational speed of 4&#xa0;rpm, the CO selectivity in the rotary kiln reached 95.2%. This resulted in a CO generation rate of 6.96 mmol min^–1 and a total limestone pyrolysis reaction rate of 7.32 mmol min^–1. This outperformed the traditional fixed-bed reactor, which achieved a rate of 0.73 mmol min^–1 under the same conditions. Furthermore, kilogram-scale CaCO₃ pyrolysis was achieved. Characterization techniques such as XRD, XPS, SEM, and TEM confirmed that the hydrogenation pyrolysis produced CaO with high crystallinity. Furthermore, TG-MS and In situ FT-IR analyses further demonstrated that the introduction of hydrogen alters the carbonate decomposition pathway, thus reducing the reaction temperature and improving CO selectivity. This work investigates the process of in-situ hydrogen refining of carbonates in the rotary kiln. In addition to enhancing reaction performance, the process aligns with the existing cement clinker production process, providing a feasible pathway for the industrial scale-up and engineering application of this technology.</p> Graphical Abstract <p>The hydrogen-assisted pyrolysis of limestone was carried out in a rotary kiln reactor under conditions close to industrial applications, successfully achieving large-scale co-production of quicklime and CO at low temperatures.</p> <p></p>