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.

The production of benzene, toluene, and xylene (BTX) is an energy-efficient subprocess that produces highly pure CH4 from shale gas by coaromatizing shale gas-derived C2H6 and C3H8; this method is considered a feasible option for replacing conventional cryogenic distillation. Moreover, a rationally designed proof-of-concept co-production of BTX and methanol production is proposed. Our proposed BTX production process from shale gas consists of multiple beds, each of which undergoes five sequential processes, including carburization, reaction, cooling, regeneration, and heating in a continuous cyclic mode. Also, the switching time of the reaction/regeneration process is optimized with fixed-bed reactor experiments, and the general algebraic modeling system was used to develop the corresponding nonlinear programming-optimized catalyst regeneration strategy. Our Mo/HZSM-5-based BTX production method enables continuous BTX production from shale gas and shows relatively high yield of BTX (10.0%) compared to conventional methane dehydroaromatization process (∼5%). Furthermore, the method leads to an increased amount of produced CH4 with a high BTX yield owing to the cracking of C2H6 and C3H8, thereby resulting in increased methanol production. Most importantly, the technoeconomic analysis revealed that the estimated minimum selling price of methanol production is approximately 0.321 $/kg methanol for 24.4% improved methanol production, which is comparable to that obtained with the current most mature methanol production process. The proposed process also lower CO2 emission compared to that of the conventional process. The results of this analysis support the feasibility of the integrated BTX and methanol production process for energy-efficient shale gas conversion into high-value products.

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.

The production of benzene, toluene, and xylene (BTX) is an energy-efficient subprocess that produces highly pure CH4 from shale gas by coaromatizing shale gas-derived C2H6 and C3H8; this method is considered a feasible option for replacing conventional cryogenic distillation. Moreover, a rationally designed proof-of-concept co-production of BTX and methanol production is proposed. Our proposed BTX production process from shale gas consists of multiple beds, each of which undergoes five sequential processes, including carburization, reaction, cooling, regeneration, and heating in a continuous cyclic mode. Also, the switching time of the reaction/regeneration process is optimized with fixed-bed reactor experiments, and the general algebraic modeling system was used to develop the corresponding nonlinear programming-optimized catalyst regeneration strategy. Our Mo/HZSM-5-based BTX production method enables continuous BTX production from shale gas and shows relatively high yield of BTX (10.0%) compared to conventional methane dehydroaromatization process (∼5%). Furthermore, the method leads to an increased amount of produced CH4 with a high BTX yield owing to the cracking of C2H6 and C3H8, thereby resulting in increased methanol production. Most importantly, the technoeconomic analysis revealed that the estimated minimum selling price of methanol production is approximately 0.321 $/kg methanol for 24.4% improved methanol production, which is comparable to that obtained with the current most mature methanol production process. The proposed process also lower CO2 emission compared to that of the conventional process. The results of this analysis support the feasibility of the integrated BTX and methanol production process for energy-efficient shale gas conversion into high-value products.

Carbon nanotubes (CNTs), having either metallic or semiconducting properties depending on their chirality, are advanced materials that can be used for different devices and materials (e.g., fuel cells, transistors, solar cells, reinforced materials, and medical materials) due to their excellent electrical conductivity, mechanical strength, and thermal conductivity. Single-walled CNTs (SWNTs) have received special attention due to their outstanding electrical and optical properties; however, the inability to selectively synthesize specific types of CNTs has been a major obstacle for their commercialization. Therefore, researchers have studied different methods for the separation of SWNTs based on their electrical and optical properties. Gel chromatography methods enable the large-scale separation of metallic/semiconducting (m/s) SWNTs and single-chirality SWNTs with specific bandgaps. The core principle of gel chromatography-based SWNT separation is the interaction between the SWNTs and gels, which depends on the unique electrical properties of the former. Controlled pore glass, silica gel, agarose-based gel, and allyl dextran-based gel have been exploited as mediums for gel chromatography. In this paper, the interaction between SWNTs and gels and the different gel chromatography-based SWNT separation technologies are introduced. This paper can serve as a reference for researchers who plan to separate SWNTs with gel chromatography.