Direct conversion of rice husk into hydrogen and sodium silicate via alkaline thermal treatment with low‐CO ₂ emission

Abstract This study presents a novel single‐step method for producing sodium silicate and high‐purity hydrogen from rice husk biomass with reduced CO 2 emission using alkaline thermal treatment (ATT). Conventional methods extract amorphous silica from rice husk through an energy‐intensive, CO 2 ‐emitting process, followed by a separate reaction with sodium carbonate to synthesize sodium silicate. In contrast, the proposed method eliminates this additional step by directly generating sodium silicate while simultaneously producing hydrogen, ensuring a reduced carbon‐emission process. ATT enables interconnected reactions, including in‐situ CO 2 capture, enabling decarbonized hydrogen production as an energy carrier and sodium silicate for high‐value applications. The use of NaOH promotes hydrogen generation at lower temperatures while capturing CO 2 as solid carbonates, distinguishing this process from conventional gasification. Additionally, sodium carbonates formed in situ react with SiO 2 in rice husk ash, enabling direct sodium silicate synthesis. Experimental results demonstrate that ATT at 950°C, with a rice husk‐to‐NaOH ratio of 1:3 and 1.9 g of SiO 2 , yields up to 5.1 g of sodium silicate and 51 mmol of hydrogen per gram of rice husk, with reduced CO 2 emission. Optimizing reaction conditions through elemental analysis enhances hydrogen yield and improves sodium silicate synthesis, highlighting the sustainability of this approach.