The Route from Green H2 Production through Bioethanol Reforming to CO2 Catalytic Conversion: A Review

A Model for the Flow Distribution in Dual Cell Density Monoliths

Monoliths are promising as catalytic structured supports due to their many operational advantages. Compared to pellets, monoliths offer low backpressure and good heat distribution, even at high flow rates. There is interest in the industry for improving temperature control in highly exothermic systems, such as the catalytic hydrogenation of CO2 for e-fuels synthesis. In this context, novel substrate shapes, such as non-homogeneous cell density monoliths, show good potential; however, to date, they have only been sparsely described. This work focuses on a dual cell density substrate and uses a computational model of a straight-channel monolith with two concentric regions to analyze its flow distribution. The central (core) and peripheral (ring) regions of the substrate differ in cell density in order to obtain a non-homogeneous cross-section. The model is validated against classical data in the literature and theoretical equations. Then, the flow fraction passing through each region of the substrate is registered. Several flow rates, core sizes and combinations of apparent permeabilities are tested. According to the results, the flow distribution depends only on the monolith geometrical features and not on the flow rate. A model for this phenomenon is proposed. The model accurately predicted the flow fraction passing through each region of the monolith for all the cases analyzed.

A Review of the CFD Modeling of Hydrogen Production in Catalytic Steam Reforming Reactors

Global demand for alternative renewable energy sources is increasing due to the consumption of fossil fuels and the increase in greenhouse gas emissions. Hydrogen (H₂) from biomass gasification is a green energy segment among the alternative options, as it is environmentally friendly, renewable, and sustainable. Accordingly, researchers focus on conducting experiments and modeling the reforming reactions in conventional and membrane reactors. The construction of computational fluid dynamics (CFD) models is an essential tool used by researchers to study the performance of reforming and membrane reactors for hydrogen production and the effect of operating parameters on the methane stream, improving processes for reforming untreated biogas in a catalyst-fixed bed and membrane reactors. This review article aims to provide a good CFD model overview of recent progress in catalyzing hydrogen production through various reactors, sustainable steam reforming systems, and carbon dioxide utilization. This article discusses some of the issues, challenges, and conceivable arrangements to aid the efficient generation of hydrogen from steam reforming catalytic reactions and membrane reactors of bioproducts and fossil fuels.

Mo-Doped Cu2S Multilayer Nanosheets Grown In Situ on Copper Foam for Efficient Hydrogen Evolution Reaction

Metal sulfide electrocatalyst is developed as a cost-effective and promising candidate for hydrogen evolution reaction (HER). In this work, we report a novel Mo-doped Cu₂S self-supported electrocatalyst grown in situ on three-dimensional copper foam via a facile sulfurization treatment method. Interestingly, Mo-Cu₂S nanosheet structure increases the electrochemically active area, and the large fleecy multilayer flower structure assembled by small nanosheet facilitates the flow of electrolyte in and out. More broadly, the introduction of Mo can adjust the electronic structure, significantly increase the volmer step rate, and accelerate the reaction kinetics. As compared to the pure Cu₂S self-supported electrocatalyst, the Mo-Cu₂S/CF show much better alkaline HER performance with lower overpotential (18 mV at 10 mA cm⁻², 322 mV at 100 mA cm⁻²) and long-term durability. Our work constructs a novel copper based in-situ metal sulfide electrocatalysts and provides a new idea to adjust the morphology and electronic structure by doping for promoting HER performance.