Search Results (6)

The purpose of this study is to reveal the characteristics of a Pd/Cu membrane and Ni/Cr catalyst adopted in a biogas dry reforming (BDR) membrane reactor by the numerical simulation procedure. The commercial software COMSOL Multiphysics ver. 6.2 was adopted in the numerical simulation. COMSOL is one type of commercial software that can solve multiphysics phenomena, i.e., chemical reaction, fluid dynamics, heat transfer, etc. The impact of the initial reaction temperature and the thickness of the Pd/Cu membrane on the performance of the BDR membrane reactor using an Ni/Cr catalyst is also investigated. The initial reaction temperatures adopted were 400 °C, 500 °C, and 600 °C, and the thicknesses of the Pd/Cu membrane were varied at 20 μm, 40 μm, and 60 μm. It was discovered that when the initial reaction temperature was raised, the molar concentration of H₂ increased while the molar concentrations of CH₄ and CO₂ decreased. Because the penetration resistance of the Pd/Cu membrane decreased with the decrease in the thickness of the Pd/Cu membrane, the molar concentrations of H₂ remaining in the Pd/Cu membrane and sweep chamber rose with the decrease in the thickness of the Pd/Cu membrane. Full article

The aim of the present study was to clarify the influence of the thickness of the Pd/Cu membrane on the characteristics of biogas dry reforming (BDR) with aNi/Cr/Ru catalyst. We also clarified the impact of the reaction temperature, the molar ratio of CH₄:CO₂, the differential pressure between the reaction and sweep chambers, and the introduction of a sweep gas on the characteristics of a BDR reactor with a Pd/Cu membrane and a Ni/Cr/Ru catalyst. Through this study’s results, we clarify that the concentration of H₂ in the reaction chamber and the sweep chamber increases with the increase in the reaction temperature. In addition, this study clarifies that the highest concentration of H₂ in the reaction chamber and the sweep chamber can be obtained with a molar ratio of CH₄:CO₂ = 1.5:1. This study also clarifies that the highest concentration of H₂ can be obtained with a thickness of 40 μm, a molar ratio of CH₄:CO₂ = 1.5:1, and a differential pressure between the reaction chamber and the sweep chamber of 0 MPa without a sweep gas, which was 4890 ppmV in the reaction chamber and 38 ppmV in the sweep chamber. Under these conditions, CH₄ conversion, H₂ yield, and thermal efficiency were 75.0%, 0.214%, and 2.92%, respectively. Full article

Hydrogen purification is a critical industrial process, and there are ongoing efforts to develop low-cost alternatives to palladium foil membranes. Titanium nitride (TiN) is studied as an interdiffusion barrier to enable hydrogen permeation in composite palladium–vanadium membranes. TiN was deposited via reactive sputtering, and films with the desired (200) orientation were obtained in the metallic regime at 400 °C under a 200 V bias to the substrate. The permeability of thin-film TiN was determined with palladium-based sandwich structures. TiN layers up to 10 nm resulted in a minimal decrease in flux (~20%) relative to a freestanding PdCu foil, which was attributed to the interfacial resistance. At greater thicknesses, the TiN layer was rate-limiting, and it was found that the effective permeability of the sputtered TiN thin films was ~6 × 10⁻¹² mol s⁻¹ m⁻¹ Pa^−0.5. Composite Pd|TiN|V|TiN|Pd membranes exhibited permeability values up to three times greater than pure palladium, exhibiting stability at 450 °C for over 100 h, with the lack of intermetallic diffusion and alloy formation being confirmed with XRD. The membranes were unstable at 500 °C, which was attributed to the instability of the thin Pd layer and loss of catalytic activity. Full article

In this study, we used Principal Component Analysis (PCA) to evaluate the physical and operational properties of palladium (Pd)-based membrane composites, focusing on variables like temperature, differential pressure (ΔP), thickness, hydrogen (H₂) permeability, and H₂ flux. The analysis revealed that the first two principal components explained 53.16% of the total variance, indicating moderate explanatory power. Interdependencies were observed among temperature, thickness, H₂ flux, and H₂ permeability, while ΔP functioned independently. This study found similarities among membranes, such as eco-friendly chitosan-based membranes, which performed comparably to conventional options like Pd–PSS and Pd–Cu/αAl₂O₃. Overall, PCA proved to be an invaluable tool for uncovering hidden patterns, optimizing experimental processes, and deepening the understanding of Pd-based membranes. The findings underscore PCA’s potential to enhance material performance and promote sustainable alternatives, with practical benefits for advancing hydrogen separation technologies. This study illustrates how data-driven approaches can refine material analysis and drive innovation in membrane design. Full article

The present study pays attention to biogas dry reforming for the purpose of producing H₂. It is known that biogas contains approximately 40 vol% CO₂, causing a decrease in the efficiency of power generation due to its lower heating value compared to natural gas, i.e., CH₄. We suggest a hybrid system composed of a biogas dry reforming membrane reactor and a high-temperature fuel cell, i.e., a solid oxide fuel cell (SOFC). Since biogas dry reforming is an endothermic reaction, we adopt a membrane reactor, controlled by providing a non-equilibrium state via H₂ separation from the reaction site. The purpose of the present study is to understand the effect of the thickness of the Pd/Cu membrane on the performance of the biogas dry reforming membrane reactor with a Pd/Cu membrane as well as a Ni/Cr catalyst. The impact of the reaction temperature, the molar ratio of CH₄:CO₂ and the differential pressure between the reaction chamber and the sweep chamber on the performance of the biogas dry reforming membrane reactor with the Pd/Cu membrane as well as the Ni/Cr catalyst was investigated by changing the thickness of the Pd/Cu membrane. It was revealed that we can obtain the highest concentration of H₂, of 122,711 ppmV, for CH₄:CO₂ = 1:1 at a reaction temperature of 600 °C and a differential pressure of 0 MPa and using a Pd/Cu membrane with a thickness of 40 μm. Under these conditions, it can be concluded that the differential pressure of 0 MPa provides benefits for practical applications, especially since no power for H₂ separation is necessary. Therefore, the thermal efficiency is improved, and additional equipment, e.g., a pump, is not necessary for practical applications. Full article

A thin Pd-based H₂-permeable membrane is required to produce high-purity H₂ with high efficiency. In this study, a porous Ni-supported Pd₆₀Cu₄₀ composite H₂-permeable membrane was developed using a reverse build-up method to produce economical H₂ purification. The thickness of the Pd₆₀Cu₄₀ alloy layer produced by the improved membrane production process reached 1.0 μm; it was thinner than the layer obtained in a previous study (3.7 μm). The membrane was characterized by scanning electron microscope, inductively coupled plasma optical emission spectrometer, H₂ permeation test, and Auger microprobe analysis. The permeation tests were performed at 300–320 °C and 50–100 kPa with H₂ introduced from the primary side. The H₂ permeation flux was stable up to ~320 °C. The n-value was determined to be 1.0. The H₂ permeance of the membrane was 2.70 × 10⁻⁶ mol m⁻² s⁻¹ Pa^−1.0 at 320 °C, after 30 h, similar to those of other 2.2-µm-thick and 3.7-µm-thick Pd₆₀Cu₄₀ composite membranes, suggesting that the adsorption and dissociation reaction processes on the PdCu alloy surface were rate-limiting. The Pd cost of the membrane was estimated to be ~1/30 of the Pd cost of the pure Pd₆₀Cu₄₀ membrane. Full article