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This article discusses the decomposition of methane in the temperature range 550–800 °C on low-percentage   monometallic (Ni/g-Al2O3, Co/g-Al2O3) and bimetallic (Ni-Co/g-Al2O3) catalysts. It is shown that the bimetallic catalyst is more active in the decomposition of methane to hydrogen than monometallic ones. At a reaction temperature of 600 °C, the highest methane conversion is 81%, and the highest hydrogen yield of 51% is formed on Ni-Co/g-Al2O3. A complex of physicochemical methods (Scanning Electron Microscope (SEM), X-ray Diffraction (XRD), Temperature Programmed Reduction (TPR-H2), etc.) established that the addition of cobalt oxide to the composition of Ni/g-Al2O3 leads to the formation of surface bimetallic Ni-Co alloys, while the dispersion of particles increases and the reducibility of the catalyst is facilitated, which provides an increase in the concentration of metal particles - active centers, which can be the reason for an increase in the catalytic properties of a bimetallic catalyst in comparison with monometallic ones. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License  (https://creativecommons.org/licenses/by-sa/4.0). 

In this work, the conversion of waste polypropylene to alternative fuels (liquid and gas) was performed through non-catalytic thermal and catalytic hydrocracking over NiMo/Al2O3 and Pt/Al2O3 catalysts. The process was carried out in an autoclave batch reactor at a temperature of 450 °C and a pressure of 20 bar, which were selected based on experimental optimization. The spent catalyst was also successfully regenerated at 700 °C under a hot airflow. Experiments were conducted to determine the optimum conditions to completely separate the deactivated catalyst from the solid residue easily. The regenerated catalyst was reused to facilitate the economic cost reduction of the process. The reactivated catalysts have almost the same catalytic properties as the fresh catalysts; this was confirmed by several characterization techniques, such as TGA, XRD, SEM, EDX, BET and FTIR. The produced liquids/gases were quantified and classified into their fractions by the number of carbon atoms and gasoline to diesel ratio using GC/MS. The viscosity, density, API gravity, pour point and flash point of oil cuts were also investigated to evaluate the quality of the resulting liquid from the reactions. The NiMo/Al2O3 catalyst gave the highest liquid hydrocarbons yield of 86 wt%, while the highest weight products of gasoline range hydrocarbon fractions of 49.85 wt% were found over the Pt/Al2O3 catalyst. Almost the same catalytic behavior was found with the regenerated catalysts compared to the fresh catalysts. However, the highest gaseous products at 20.8 wt% were found in the non-catalytic thermal products with an increase in the diesel fuel range of 80.83 wt%. The kinetic model was implemented using six lumps and fifteen reactions, and the apparent activation energies for the gasoline and diesel fractions were calculated. In general, all primary and secondary reactions show greater activation energy values on the Pt/Al2O3 catalyst than on the NiMo/Al2O3 catalyst.

The study investigates the impact of Phase Change Material (PCM) and nano Phase Change Materials (NPCM) on solar still performance. PCM and a blend of NPCM are placed within 12 copper tubes submerged in 1 mm of water to enhance productivity. Thermal performance is assessed across four major scenarios with a fixed water level of 1 mm in the basin. These scenarios include the conventional still, equipped with 12 empty copper rods and 142 g of PCM in each tube, as well as stills with NPCM Samples 1 and 2. Sample 1 contains 0.75% nanoparticle concentration plus 142 g of PCM in the first 6 tubes, while Sample 2 features 2% nanoparticle concentration plus 142 g of PCM in the subsequent 6 tubes. Aluminum oxide (Al2O3) nanoparticles ranging in size from 20 to 30 nm are utilized, with paraffin wax (PW) serving as the latent heat storage (LHS) medium due to its 62 °C melting temperature. The experiments are conducted under the local weather conditions of Vaddeswaram, Vijayawada, India (Latitude-80.6480 °E, Longitude-16.5062 °N). A differential scanning calorimeter (DSC) is utilized to examine the thermal properties, including the melting point and latent heat fusion, of the NPCM compositions. Results demonstrate that the addition of nanoparticles enhances both the specific heat capacity and latent heat of fusion (LHF) in PCM through several mechanisms, including facilitating nucleation, improving energy absorption during phase change, and modifying crystallization behavior within the phase change material. Productivity and efficiency measurements reveal significant improvements: case 1 achieves 2.66 units of daily production and 46.23% efficiency, while cases 2, 3, and 4 yield 3.17, 3.58, and 4.27 units of daily production, respectively. Notably, the utilization of NPCM results in a 60.37% increase overall productivity and a 68.29% improvement in overall efficiency.

Indonesia, one of the world's largest producers of crude palm oil (CPO), is aiming to achieve a renewable energy mix target of 23% by 2025 through the implementation of a B35 policy, blending diesel with fatty acid methyl ester (FAME) derived from CPO transesterification. Traditionally, homogeneous catalysts are used in this process, but their sensitivity to free fatty acids reduces biodiesel yield. Therefore, heterogeneous catalysts are being developed to overcome this issue, contributing to sustainable biodiesel production. However, certain heterogeneous catalysts require high temperature, more methanol, longer reaction times, necessitating the exploration of more optimal catalyst options. This study introduces an approach by exploring the use of heterogeneous K2O/g-Al2O3 catalysts in biodiesel production from RBDPO under low-temperature conditions (40 °C), a significant reduction from the commonly operated temperature of near the boiling point of methanol at 60 °C. Utilizing KI and KNO3 as precursors, the effect on different catalyst precursor, temperatures and reaction time were examined. It was found that temperature has the highest effect on conversion. The transesterification process yielded biodiesel with FAME levels ranging from 95.84% to 98.17%, meeting the Indonesian National Standard (SNI 7182:2015) for biodiesel quality. The findings indicate that both KI and KNO3 precursors result in highly active K2O/g-Al2O3 catalysts, achieving high conversion at 40 °C within a 1-hour reaction time, thus demonstrating their effectiveness in low-temperature biodiesel synthesis. This low-temperature process has the potential to significantly reduce energy consumption in industrial biodiesel production. Copyright © 2025 by Authors, Published by BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

This work investigates the effect of high-energy mechanical milling on the activation and phase transformation of synthetic pseudoboehmite powders. The approach aims to provide a clean, solvent-free route with potential industrial relevance for alumina production. Mechanical processing proved effective in inducing the transition from pseudoboehmite to χ-Al2O3 solely through milling. The process yielded nanometric particles with low levels of contamination. The subsequent conversion to α-Al2O3 was achieved through controlled heat treatments, while phase evolution was monitored by differential scanning calorimetry (DSC). A reduction of approximately 110 °C in the α-Al2O3 formation temperature was observed after 30 h of milling. This shift was accompanied by a marked decrease in the activation energy, from 526 kJ·mol−1 for the raw powder to 347 kJ·mol−1 for the milled sample. These results demonstrate the strong mechanochemical activation of pseudoboehmite, highlighting mechanical milling as an effective and scalable route for energy-efficient processing of alumina phases.

To improve the corrosion resistance and wear resistance of electroless nickel-phosphorus (Ni-P) coating on magnesium (Mg) alloy. Ni-P-Al 2 O 3 coatings were produced on Mg alloy from a composite plating bath. The optimum Al 2 O 3 concentration was determined by the properties of plating bath and coatings. Morphology growth evolution of Ni-P-Al 2 O 3 composite coatings at different times was observed by using a scanning electronic microscope (SEM). The results show that nano-Al 2 O 3 particles may slow down the replacement reaction of Mg and Ni 2+ in the early stage of the deposition process, but it has almost no effect on the rate of Ni-P auto-catalytic reduction process. The anti-corrosion and micro-hardness tests of coatings reveal that the Ni-P-Al 2 O 3 composite coatings exhibit better performance compared with Ni-P coating owing to more appropriate crystal plane spacing and grain size of Ni-P-Al 2 O 3 coatings. Thermal shock test indicates that the Al 2 O 3 particles have no effect on the adhesion of coatings. In addition, the service life of composite plating bath is 4.2 metal turnover, suggesting it has potential application in the field of magnesium alloy.

PdO/γ-Al2O3 catalysts are one of the most active catalytic components for the complete oxidation of methane. Under reaction conditions, especially in a wet feed, the catalysts suffer severe performance degradation. This study establishes a series of testing protocols to systematically investigate the causes of catalyst deactivation under methane oxidation reaction conditions. Four distinct catalyst deactivation modes are identified. Two of the deactivation modes are directly related to H2O, either from the feed gas or as a part of the reaction products, with one (Mode 2) being attributed to the formation of surface hydroxyl groups and the other (Mode 3) to the competitive adsorption of H2O on the catalysts. The impact of the two deactivation modes is acute and severe but reversible. In contrast, the other two deactivation modes are gradual and persistent but irreversible. Both modes are induced by CH4 oxidation reaction, with the impact of a wet feed (Mode 4) being substantially more severe than that of a dry feed (Mode 1). The major cause of the irreversible catalyst deactivation is attributed to surface reconstruction of PdO nanoparticles, which behaves as a passivation layer lowering the number of coordinately unsaturated Pd sites for CH4 activation. Although the passivation layer is relatively stable against thermal or hydrothermal treatment, it is not completely inert. Formation and partial regeneration of the passivation layer is a highly dynamic process and heavily depends on the reaction temperature: a lower reaction temperature (≤ 450 ℃) can lead to quicker catalyst deactivation; but a higher reaction temperature (between 500 – 550 ℃) can result in a greater extent of catalyst deactivation.

Aluminum metal matrix composites are valued for their lightweight nature, high performance, and favorable thermal expansion characteristics, preparing them to be suitable for aerospace, defense, automotive, athletic training equipment, and electronics applications. Al-7175 alloy, widely employed in aerospace for advancing structural components, is selected in this pilot study as a base material. reinforcements included varying weight percentages of Al2O3 (2, 4, 6, and 8%), SiC (three levels), and palm kernel shell ash (PKSA) as a sustainable waste-based additive. The composite are fabricated by stir casting method, and test specimens are prepared in accordance with international standards to evaluate stiffness, tensile strength, impact resistance, and wear behavior. The results revealed that incorporating Al₂O₃, SiC, and PKSA enhanced stiffnesses per the additives added in MMCsby1%, 1.5%, 1.6%, and 1.7% (as per the wt.%) and tensile strengthby8%, 10%, and 40, impact resistance by7%, 34%, 25%, and 42%, reduced wear by 2.4%, 22%, and 7.2%due to the synergistic effect of these reinforcements. An L9 orthogonal array and design of experiments (DOE) approach are employed to optimize Wire Electrical Discharge Machining (WEDM) parameters, for minimal surface roughness and optimal material removal rate (MRR). MRR reduction is linked to a higher Ton, voltage, wire feed rate, and Toff settings, with long-range producing higher MRR at minimum reinforcements level but increases in surface roughness. Optimal WEDM parameters are determined as Ton = 5, Toff = 5, voltage = 75, and wire feed = 6, enabling efficient and precise production ofAl-7175 hybrid metal matrix composites (HMMCs) reinforced with Al2O3, SiC, and PKSA across different weight fractions.

Control of the electron spin as well as its charge is predicted to lead to efficient electronic devices, with potentially new functionalities. Injecting and manipulating spin-polarized carriers in silicon is a natural step towards integrating spintronics with current technology. This Review describes the first encouraging results as well as the open questions and challenges that still remain. Worldwide efforts are underway to integrate semiconductors and magnetic materials, aiming to create a revolutionary and energy-efficient information technology in which digital data are encoded in the spin of electrons. Implementing spin functionality in silicon, the mainstream semiconductor, is vital to establish a spin-based electronics with potential to change information technology beyond imagination. Can silicon spintronics live up to the expectation? Remarkable advances in the creation and control of spin polarization in silicon suggest so. Here, I review the key developments and achievements, and describe the building blocks of silicon spintronics. Unexpected and puzzling results are discussed, and open issues and challenges identified. More surprises lie ahead as silicon spintronics comes of age.

In this study, the effects of micro-Al2O3 (MA) and nano-Al2O3 (NA) on the mechanical properties and durability performance of a mortar containing fly ash (FA) were investigated. In the first step, MA and NA were added to the mortar (as a cement replacement) at dosages of 0%, 5%, 10% and 15% by weight. The flowability of the mixture containing NA and MA showed a dosage-dependent behavior, and the addition of MA resulted in a higher flow spread compared with NA. The flow spread increased at 5% (for both NA and MA), and a further increase in the particle content to 10% and 15% decreased the flow spread value. Although the presence of MA and NA contributed to increasing the compressive strength as the particle content increased, the addition of NA resulted in a greater increase in compressive strength (40% increase when adding 15% of NA). The highest splitting tensile strength was obtained when 10% NA was used, and a further increase in the particle content decreased the splitting tensile strength. In the optimization step, the effect of a binder replacement with FA (10, 20 and 30%) in the presence of 10% NA as the optimum level of additive was investigated. Generally, the addition of FA decreased the compressive strength. The highest drop in compressive strength was noticed at early ages, and there was no significant difference in strength development from 14 days to 28 days. A decreasing trend in the splitting tensile strength was observed with the addition of FA content.