Background Developing cost-reduced Pd-based membranes and understanding their integration into membrane reactors for hydrogen production remain important challenges. Although Pd and Pd-Ag membranes have been widely studied for methanol steam reforming, their high cost limits application. Pd-Ni membranes have attracted attention as a lower-palladium-content option for hydrogen separation due to their reduced noble metal content; however, their performance in membrane reactor configurations has not been reported. This study integrates, for the first time, an organic-inorganic activation-fabricated Pd-Ni composite membrane into a membrane reactor for methanol steam reforming, enabling evaluation of membrane behavior and hydrogen separation performance under a reactive environment containing steam, methanol, and reforming products. Methods A dense tubular Pd-Ni membrane (similar to 2 mu m selective layer) was prepared via organic-inorganic activation combined with electroless plating. Hydrogen permeation was evaluated at 200-350 degrees C and 10-50 kPa using pure gases and binary mixtures containing steam or methanol. The membrane was implemented in a membrane reactor packed with a Cu/ZnO/Al2O3 catalyst under identical operating condition (H2O/CH3OH = 1:1; gas hourly space velocity = 2000 h(-)& sup1;) and compared with a conventional reactor. Significant findings The membrane exhibited infinite H-2/N-2 selectivity and a hydrogen flux of 2.55 & times; 10(-)& sup2; mol m(-)& sup2; s(-)& sup1; at 350 degrees C and 50 kPa. Steam and methanol reversibly inhibited hydrogen permeation, stronger for methanol. Methanol conversion reached 46.5% at 350 degrees C and 100 kPa-twice that of the conventional reactor-while hydrogen recovery reached 91%, demonstrating the capability of Pd-Ni membranes to enhance hydrogen separation and improve methanol conversion in MSR membrane reactors.
Introduction and Objectives: Functionally graded materials are an advanced class of composites which their microstructure change continuously in a specific direction. The main purpose of this paper is to study the microstructure of the Al-13.8 wt.% Mg2Si eutectic alloy produced by centrifugal and gravity casting methods and comparison the effect of addition of Al-5Zr inoculant on the changes in their casting microstructure. Materials and methods: In this research, with gravity and centrifugal casting of Al-13.8wt.% Mg2Si alloy and adding an appropriate amount of Al-5Zr inoculant, microstructural changes in the radial direction of the casting cylinder were compared with gravity casting samples. The chemical composition and microstructural characteristics of the samples were studied using energy-dispersive X-ray spectroscopy and optical microscopy, respectively. Results: The microstructure of the centrifugally cast Al-5Zr inoculant-free cylinder exhibited columnar Al/Mg2Si eutectic cells along the radial direction, accompanied with an accumulation of primary Mg2Si particles in the inner layer of the cylinder. Upon the addition of Al-5Zr inoculant, the morphology of Mg2Si secondary phases changed from cubic to Chinese script shape. However, the microstructure of the conventional gravity casting sample containing and without zirconium showed Al/Mg2Si eutectic cells without a specific targeted distribution, an accumulation of primary and light Mg2Si particles in the upper layer of the casting cylinder, which is due to the separation of these particles against the upward direction of gravity. Conclusion: The microstructure of the cast cylinder processed by centrifugal casting containing Al-5Zr inoculant showed a targeted distribution of Al/Mg2Si eutectic cells and aggregation and reduction in the size of Mg2Si particles in the inner radial layer of the cast cylinder.
Ultrasonic welding of titanium to steel is important in medical and aerospace applications, but remains challenging due to the significant differences in their physical properties. In this study, ultrasonic welding was used to join 0.3 mm-thick titanium and St12 steel sheets, with aluminum interlayers of 10, 50, and 100 μm. After preparation, the microstructure of the weld interface was analyzed by optical microscopy, while mechanical properties were evaluated through shear-tensile and microhardness tests. Reducing the interlayer thickness from 100 to 10 μm decreased heat dissipation, raised the interface temperature, and consequently increased the grain size, with the steel grain size rising from 7 to 19.5 μm. As a result, the weld line density increased from 62
Blasting is one of the most critical stages in open-pit mining operations, directly affecting mine productivity, extraction costs, and the control of fines generation. This study focuses on optimizing blasting operations in the Rahmanlu quarry to reduce fines production and enhance overall mining efficiency. Initially, three blasts were examined using image analysis techniques to identify an appropriate blasting pattern. Subsequently, three mathematical models SVEDEFO, Kuz-Ram and modified Kuz-Ram were employed to predict fragmentation resulting from blasting. The model predictions were compared with image analysis results from the actual blasts, with the modified Kuz-Ram model showing the closest agreement to real conditions. A calibration equation was then fitted to further improve the alignment between the modified Kuz-Ram model and actual blast results. Next, eighteen different blasting patterns were developed based on empirical methods, and the optimal pattern was selected according to fragmentation size distribution and economic parameters. Implementation of the optimized pattern resulted in approximately a 10
Due to a large specific surface area, high porosity, and adjustable internal surface properties, metal–organic frameworks (MOFs) have exhibited unmatched versatility in optical sensing applications. Their unique structures, combining inorganic metal ions or cluster nodes with organic linkers, enable the creation of “multiple photonic units” that offer diverse luminescence options suitable for customized sensing applications. Moreover, MOFs achieve ratiometric and multiplexing, and multimodality measurement capabilities by encapsulating luminescent guest molecules within their porous structures, which allows for greater adaptability and functionality in optical measurements. In this review, we have discussed a variety of MOF types, their structures, synthesis properties, mechanisms, and sensing applications. In contrast to previous reviews that overly rely on describing the general luminescent features or sensing capabilities of MOFs, this work is more holistic, covering multi-emission MOFs and extending its focus towards the entire spectrum of MOF-based sensors. This review highlights the versatility of sensing emission tunability achieved by single-, dual-, and multi-emission MOFs by meticulously analyzing their synthesis approaches and functional characteristics. In addition, it brings a new perspective by integrating comprehensive mechanisms of fluorescence enhancement and quenching with food contamination detection applications, where ratiometric sensing becomes pivotal. The addition of wearable sensing, SERS-active MOF nanosensors, and bio-labeling strategies expands the scope beyond conventional sensing platforms and traditional approaches, advancing this review as a prospective resource towards designing multifunctional sensors with integrated detection capabilities based on MOFs.
