Infiltrate Mesoporous Silica-Aluminosilicate Structure Improves Hydrogen Production via Methane Decomposition over a Nickel-Based Catalyst

High adsorption capacity of ammonia nitrogen on hexagonal porous aluminosilicate derived from solid-waste bagasse bottom ash

This study investigates the use of a hexagonal-porous aluminosilicate (HAS) adsorbent derived from bagasse bottom ash (BBA), an agricultural solid waste, for the adsorption of ammonia nitrogen (NH3-N)-a key water pollutant from agricultural and farming activities. Sodium silicate derived from BBA via the alkaline fusion method was employed, resulting in energy savings due to a synthesis temperature 1.53 times lower than that of commercial sodium silicate synthesis. The sol-gel method was utilized to successfully synthesize HAS featuring a high surface area and porosity using the sodium silicate prepared from BBA. However, an increase in aluminum content resulted in a decrease in surface area and hexagonal porosity. In performance tests, the HAS(5) adsorbent exhibited the most efficient NH3-N removal, outperforming other adsorbents by 4.54-25.19 times across all initial concentrations. This enhanced efficiency can be attributed to its numerous acidic surface sites, enabling the bonding of NH3-N molecules through monolayer adsorption on the HAS surface.

Effect of Calcination Temperature on Cu-Modified Ni Catalysts Supported on Mesocellular Silica for Methane Decomposition

Catalytic methane decomposition has been considered suitable for the green and sustainable production of high-purity H₂ to help reduce greenhouse gas emissions. This research developed a copper-modified nickel-supported mesocellular silica NiCu/MS(x) catalyst synthesized at different calcination temperatures to improve the activity and stability in the CH₄ decomposition reaction at 600 °C. Ni and Cu metals were loaded on a mesocellular silica (MS) support using a co-impregnation method and calcined at different temperatures (500, 600, 700, and 800 °C). The NiCu/MS(600) catalyst not only had the highest H₂ yield (32.78%), which was 1.47-3.87 times higher than those of the other NiCu/MS(x) catalysts, but also showed better stability during the reaction. Calcination at 600 °C helps improve the active nickel dispersion, the reducibility of the NiCu catalyst, and the interaction of the NiCu-MS support, leading to the formation of fishbone and platelet carbon nanofibers via a tip-growth mechanism, resulting in the NiCu metals remaining active during the reaction.

Catalytic Methane Decomposition to Carbon Nanostructures and COx-Free Hydrogen: A Mini-Review

Catalytic methane decomposition (CMD) is a highly promising approach for the rational production of relatively CO_x-free hydrogen and carbon nanostructures, which are both important in multidisciplinary catalytic applications, electronics, fuel cells, etc. Research on CMD has been expanding in recent years with more than 2000 studies in the last five years alone. It is therefore a daunting task to provide a timely update on recent advances in the CMD process, related catalysis, kinetics, and reaction products. This mini-review emphasizes recent studies on the CMD process investigating self-standing/supported metal-based catalysts (e.g., Fe, Ni, Co, and Cu), metal oxide supports (e.g., SiO₂, Al₂O₃, and TiO₂), and carbon-based catalysts (e.g., carbon blacks, carbon nanotubes, and activated carbons) alongside their parameters supported with various examples, schematics, and comparison tables. In addition, the review examines the effect of a catalyst’s shape and composition on CMD activity, stability, and products. It also attempts to bridge the gap between research and practical utilization of the CMD process and its future prospects.