Mineral acid-activated sugarcane bagasse ash as solid acid catalyst for the liquid phase esterification of acetic acid with n-amyl, benzyl, and n-butyl alcohols

Potential application of zirconium molybdate as a novel catalyst for the selective dehydrogenation of methanol to anhydrous formaldehyde

The non-oxidative dehydrogenation of methanol is considered a promising method for producing formaldehyde (FA), where the resulting anhydrous formaldehyde is perfect for the use in the subsequent generation of oxygenated synthetic fuels. In the current investigation, a series of Zr(MoO4)2 nanoaggregates, as a novel solid acid catalyst, were hydrothermally fabricated at different temperatures in the presence of triethylamine (TEA) as a surfactant. The original and calcined catalysts were characterized by TGA, DSC, XRD, FT-IR, XPS, HR-TEM, acidity and nitrogen sorption. Analyses revealed that the addition of TEA to the preparation procedures significantly enhanced the textural, acidic, and the catalytic performance of these catalysts. Acidity measurements reflected that the surface of these catalysts possessed Brønsted type of acidic sites of weak and intermediate strength. Catalytic activity results demonstrated that, Zr(MoO4)2 catalyst with Zr: TEA molar ratio of 1:1 (Z1T1) annealed at 400°C exhibited the maximum methanol conversion of 99% and 95% selectivity to formaldehyde at reaction temperature of 325°C. The remarkable catalytic performance was well correlated to the variation in acidity of the catalyst. This catalyst offered a long-term stability towards the production of formaldehyde for a period of time of 160 h with the same activity and selectivity. Also, this catalyst could be re-used for five time giving almost the same performance. The reason for this extreme catalytic activity and selectivity towards formaldehyde synthesis is the presence of weak and moderate strengthened Brønsted acid sites. In light of this, this work has produced an active, stable, and selective catalyst for the conversion of methanol to formaldehyde that is competitive with the most effective conventional and recently discovered catalysts.

Occurrence, distribution, and composition of black sand along the Red Sea, Egypt

Black sand along the Red Sea is often composed of volcanic minerals and heavy minerals. The Red Sea region is known for its unique geological features, and black sand beaches can be found in various areas along its shores. The study presents a comprehensive semi-quantitative chemical analysis of black sand samples collected from various locations along the red sea, revealing significant variations in their elemental compositions. The main oxides were identified in each sample, determined through X-ray diffraction (XRD) and X-ray fluorescence (XRF) analyses, indicate diverse mineralogical compositions. The spatial distribution of minerals at each site is depicted through mapping. Additionally, Fourier-transform infrared (FTIR) spectra offer information on the functional groups present in the samples, revealing the existence of hydroxyl groups, aliphatic compounds, and adsorbed water molecules. For Qusier-Elsharm Alqbly, Safaga, Marsa Alam, Gabal Alrosass, Hurghada Titanic, Hurghada Elahiaa, Gemsa, and Ras Elbehar samples, the results highlight the presence of various minerals, such as Quartz, Calcite, Titanium Dioxide, Magnetite, Hematite, Aluminum Oxide, Zirconium Dioxide, Chromium (III) Oxide, and others, providing insights into the geological characteristics of each location. The differences in mineral content among the examined sites are linked to the geological and mineralogical makeup of the source rocks upstream and midstream in the basins that discharge into the surveyed regions. So, variations in black sand concentrations among different locations offer insights into the geological and mineralogical diversity of the studied areas along the Red Sea coast. This study addresses the existing knowledge gap by focusing on the preliminary exploration and description of the occurrence, distribution, and composition of black sand along the Red Sea in Egypt. whereas the results provide valuable insights into the geological diversity of black sand deposits in the surveyed areas, underscoring the need for additional research and interpretation of these variations. Therefore, the in-depth examination of mineralogical composition and crystal structures establishes a foundation for future investigations in the field of geology and earth sciences.

Modified natural kaolin clay as an active, selective, and stable catalyst for methanol dehydration to dimethyl ether

In this work, the production of dimethyl ether (DME) from methanol over natural kaolin clay modified through impregnation with various percentages of H₂SO₄, WO₃, or ZrO₂ catalysts was investigated. The prepared catalysts were characterized via X-ray fluorescence, X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and N₂-sorption analysis. The acidity of these catalysts was determined through the dehydration of isopropyl alcohol and the chemisorption of pyridine. The catalytic activity performance revealed that the addition of modifiers into kaolin enhanced the latter’s activity toward DME production. In addition, the kaolin clay modified with 10 wt% ZrO₂ exhibited excellent activity of 98% conversion with 100% selectivity at 275 °C. Moreover, this catalyst could proceed the reaction for a long time (6 days) without any noticeable deactivation. The remarkable improvement in the catalytic performance achievement was well correlated with the acidity and the structure of the catalysts.