The production of formaldehyde (FA) and clean hydrogen gas via the non-oxidative dehydrogenation of methanol is seen to be a promising approach where the anhydrous formaldehyde is an ideal for using in the subsequent manufacture of oxygenated synthetic fuels. In this investigation, NiMoO₄ with nanoaggregates morphology was synthesized by hydrothermal method in presence of triethylamine (TEA) as a surfactant and tested for the non-oxidative catalytic dehydrogenation of methanol into formaldehyde at relatively low temperature. Structural, morphological and textural properties were characterized by TGA, DSC, XPS, XRD, FT-IR, HR-TEM, pyridine-TPD and N₂-sorption assessments. Results of XRD verified the coexistence of mixed phases of both α and β-NiMoO₄. The catalysts' texture, structure, acidity and catalytic activity were greatly influenced by the introduction and the molar ratio of TEA. The variation of catalytic activity is strongly associated to the variation in S_BET and acidity. Activity results revealed that catalyst with Ni:TEA ratio of 1:1 (N₁T₁) was the most active catalyst with methanol conversion of 96% and selectivity to FA of 95% at reaction temperature of 325°C. The outstanding catalytic performance of this catalyst is due to the presence of weak and intermediate strength Brønsted acidic sites on its surface. This catalyst showed remarkable stability for the synthesis of anhydrous formaldehyde over a 160 h period while maintaining the same conversion and selectivity.

In Egypt, the distribution of black sand in various coastal regions has been readily apparent by thorough research. Unfortunately, these investigations did not measure radioactivity in black sand, particularly in the vicinity of the Red Sea. Gamma-ray spectroscopy was used to detect the naturally occurring radioactivity from ²³⁸U, ²³²Th, ⁴⁰K, and ²²⁶Ra in black sand samples from eight locations along the Red Sea coast: Ras Elbehar, Gemsa, Hurghada Elahiaa, Hurghada Titanic, Safaga, Qusier Elsharm Alqbly, Gabal Alrosass, and Marsa Alam. The resultant data were interpolated to represent the spatial distribution. Additionally, the potential rocks sources of radionuclides were geologically mapped to elucidate the relationship between rock components and radioactivity. The results showed that ²²⁶Ra, ²³²Th and²³⁸U were higher at samples collected from Ras Elbehar, Hurghada Elahiaa and Hurghada Titanic compared to the other sites. On the other hand, ⁴⁰K showed the lowest mean value (75.3 ± 3.8 Bq/kg) in Hurghada Titanic samples, while it peaked (563 ± 28 Bq/kg) in Qusier Elsharm Alqbly samples. The interpolated results show notable differences in radioactive amounts between the north and south, which are indicative of several environmental conditions and human activities. Alkaline syenite, syenogranite, older granites (tonalite and granodiorite), and minor acidic volcanic/metavolcanic rocks make up the upstream area of the basin area draining into, for example, the Ras Elbehar locality (highest activity concentrations for ²³⁸U (1596 ± 80 Bq/kg) and ²²⁶Ra (886 ± 44 Bq/kg)), while alkali-feldspar granite, schist, and shale rocks make up the mid-stream area. The findings provide a basis for scientific forecasting on the impact of synthetic or naturally occurring radioactive isotopes introduced into aquatic environments.

Interest in sustainable nitrogen fertilizer production using plasma technology is rapidly growing, and this method is a promising way to decentralize fertilizer synthesis and achieve carbon-free production. However, improving efficiency remains a major challenge for the industrial application of this technology. Herein, we present comprehensive experiments using spark discharge to pinpoint the key factors affecting the efficiency of this process and provide technical approaches to improve the energy usage. We found that applying a bipolar voltage at high frequencies greatly benefited the NO_x yield and its efficiency via the utilization of residual species. Measurements using active cooling for the reactor and electrodes revealed that the chemical loss process was not significant, but the energy loss during the heating of the electrode was the dominant loss process, particularly at high frequencies (>20 kHz) where an anchor state of the spark was reached. However, the beneficial effects of higher frequencies compensated for and mitigated the higher power loss resulting in slowing the increase of the energy cost with the energy density. Moreover, enlarging the plasma zone (reaction channel) by increasing the electrode gap was an effective approach for enhancing the energy usage for the desired reaction. Further, the limitations of enlarging the gap were resolved by inserting a floating electrode in the large gap, yielding higher NO_x production (1.8%–3.0%) at a lower energy cost (1.9–4.4 MJ/mol), and further enhancements could be achieved by optimizing the reactor configuration. Therefore, the results provide an important basis for the further development and optimization of plasma reactors for efficient chemical reactions.

Plasma-based NOx synthesis from ambient air is a promising sustainable technology for producing value-added chemicals, such as nitrogen fertilizer and medication. The relatively low efficiency and product selectivity are major concerns that hinder the commercialization of this technology. Despite advancements in reducing energy costs, limited attention has been paid to improving and controlling selectivity, which significantly contributes to the overall cost. Thus, the present study aimed to gain insights into the efficient pathways and key factors for highly selective NOx synthesis in a recently developed high-frequency spark discharge (HFSD) reactor. The thorough investigations conducted proved that the higher energy efficiency of HFSD is due to higher vibrational and rotational excitations and their efficient utilization. However, the significant impact of higher temperatures on reactions led to poor selectivity of NO and NO2. Therefore, the role of influential factors, such as O2 and H2O contents, as well as residence time, on reactions, were analyzed and optimized. It is found that controlling the oxygen content remarkably improved product selectivity but negatively affected the energy cost. Moreover, water vapor triggered the so-called extended Zeldovich mechanism, which was evident in N2/H2O, affecting NOx formation and selectivity. Interestingly, tuning the gas flow rate effectively controlled selectivity without sacrificing the energy cost. A high NO selectivity of 95% was achieved at an energy cost of 2.1 MJ/mol when a relatively high flow rate of 4 L/min was used.