Cyclic regeneration of Cu- and Ag-modified SiO2-based nanomaterials: impact of atmosphere on sulfur removal and hydrogen yield from heavy crude oil

• Regeneration atmosphere impacts sulfur removal and hydrogen production. • Oxidation shows best performance across 10 reuse cycles. • Gasification enables full sulfur conversion and high H 2 yield. • Pyrolysis forms metal sulfides, reducing catalytic activity. • Cu + /Ag 0 and their oxides are key to sulfur capture and H 2 generation. The main objective of this study is the evaluation of the regeneration dynamics of a bimetallic nanomaterial composed of Cu- and Ag-modified SiO 2 -based nanomaterials for coupled adsorptive desulfurization with hydrogen valorization. Specifically, it was examined how different regeneration atmospheres (oxidative, gasifying, and pyrolytic) affect sulfur removal efficiency, sulfur-to-gas conversion, and hydrogen production during cyclic reuse of the optimized material (SiAg1.5Cu1.4). Batch adsorption tests at a 1:20 adsorbent:crude oil ratio showed slight decrease in sulfur removal efficiency after ten regeneration cycles: 1.1 % (oxidation), 2.5 % (gasification), and 5.1 % (pyrolysis). Thermogravimetric analysis coupled with mass spectrometry (TGA-MS) revealed that complete conversion of the adsorbed sulfur species occurred before 10 min under oxidative and gasifying conditions. Pyrolysis led to a notable decline in sulfur conversion beyond the fifth cycle, attributed to catalyst poisoning by metal sulfides (Cu 2 S and Ag 2 S). Furthermore, hydrogen yield was closely linked to the oxidation states of the surface metals. Cu + and Ag 0 were critical for sulfur capture, while Cu 2+ and Ag 2+ (formed during oxidative and gasifying treatments) enhanced H 2 production. These results position oxidative and gasification atmospheres as superior strategies for maintaining sorbent activity and integrating hydrogen generation into the regeneration phase. This study advances the field by demonstrating a multifunctional regeneration route that simultaneously restores sorbent performance and produces hydrogen, thereby contributing to more sustainable oil upgrading processes.