Preparation, Characterization, and Application of Magnetic Fe-SBA-15 Mesoporous Silica Molecular Sieves

Magnetic Fe-SBA-15 mesoporous silica molecular sieves were prepared, characterized, and used for magnetic separation. Wet impregnation, drying, and calcination steps led to iron inclusion within the mesopores. Iron oxide was reduced to the metal form with hydrogen, and the magnetic Fe-SBA-15 was obtained. Fourier-transform infrared spectroscopy confirmed the preparation process from the oxide to metal forms. The structure of magnetic materials was confirmed by Mössbauer spectra. Powder X-ray diffraction data indicated that the structure of Fe-SBA-15 retained the host SBA-15 structure. Brunauer-Emmett-Teller analysis revealed a decrease in surface area and pore size, indicating Fe-SBA-15 coating on the inner surfaces. Scanning electron micrographs confirmed the decrease in size for modified SBA-15 particles. From scanning electron micrographs, it was found that the size of the modified SBA-15 particles decreased. Transmission electron micrographs also confirmed that modified SBA-15 retained the structure of the parent SBA-15 silica. Fe-SBA-15 exhibited strong magnetic properties, with a magnetization value of 8.8 emu g−1. The iron content in Fe-SBA-15 was determined by atom adsorption spectroscopy. Fe-SBA-15 was successfully used for the magnetic separation of three aromatic compounds in water. Our results suggest wide applicability of Fe-SBA-15 magnetic materials for the rapid and efficient separation of various compounds

Tanyptera (Tanyptera) hebeiensis Yang et Yang (Diptera: Tipulidae) newly recorded from Shandong, China: sequencing and phylogenetic analysis of the mitochondrial genome

The genus Tanyptera Latreille, is recorded from Shandong Province, China for the first time with T. (T.) hebeiensis Yang et Yang, found in Mount Kunyu, Shandong. In this study, we report the complete mitochondrial genome sequence of T. (T.) hebeiensis, representing the first mitochondrial genome of the subfamily Ctenophorinae (Diptera: Tipulidae), which is a circular molecule of 15,888 bp with an AT content of 77.6%. The mitochondrial genome contains 13 protein-coding genes (PCGs), 22 transfer RNA genes (tRNAs), two ribosomal RNA genes (rRNAs), and a non-coding region. Gene overlaps are found at nine gene junctions, ranging from 1 to 8 bp in length. The canonical mitochondrial start codons for invertebrate mitochondrial genomes are found in 12 PCGs, except for COI which uses the uncanonical start codons TCG. Stop codons of 10 PCGs are invariably complete TAA and TAG, while COII, ND4, and ND5 end with a single thymine stop codon. Phylogenetic analysis reveals that the Pediciidae is a sister group to the remaining Tipuloidea, the Cylindrotomidae has a sister-group relationship with the Tipulidae, and the Limoniidae is not a monophyletic clade

The complete mitochondrial genome and phylogenetic analysis of Tipula (Yamatotipula) nova Walker, 1848 (Diptera, Tipulidae) from Qingdao, Shandong, China

The genus Tipula Linnaeus, is a large group of crane flies with more than 2400 known species from 41 subgenera. In this study, we report the first complete mitochondrial (mt) genome sequence of the subgenus Tipula (Yamatotipula), which is a circular molecule of 15,668 bp with an AT content of 77.2%. The mt genome contains 13 protein-coding genes, 22 tRNA genes, 2 rRNA genes, and a long non-coding region. Three conserved overlapping regions, 8 bp between tRNATrp and tRNACys, 7 bp between ATP8 and ATP6, and 7 bp between ND4 and ND4L, are found. Phylogenetic analysis reveals that the Tipulomorpha includes the family Trichoceridae and the Trichoceridae is sister-group to the remaining Tipulomorpha

A molten carbonate shell modified perovskite redox catalyst for anaerobic oxidative dehydrogenation of ethane

Acceptor-doped, redox-active perovskite oxides such as La0.8Sr0.2FeO3 (LSF) are active for ethane oxidation to CO X but show poor selectivity to ethylene. This article reports molten Li2CO3 as an effective "promoter" to modify LSF for chemical looping-oxidative dehydrogenation (CL-ODH) of ethane. Under the working state, the redox catalyst is composed of a molten Li2CO3 layer covering the solid LSF substrate. The molten layer facilitates the transport of active peroxide (O-2(2-)) species formed on LSF while blocking the nonselective sites. Spectroscopy measurements and density functional theory calculations indicate that Fe4+ -> Fe3+ transition is responsible for the peroxide formation, which results in both exothermic ODH and air reoxidation steps. With >90% ethylene selectivity, up to 59% ethylene yield, and favorable heat of reactions, the core-shell redox catalyst has an excellent potential to be effective for intensified ethane conversion. The mechanistic findings also provide a generalized approach for designing CL-ODH redox catalysts

Lithium carbonate-promoted mixed rare earth oxides as a generalized strategy for oxidative coupling of methane with exceptional yields

Abstract The oxidative coupling of methane to higher hydrocarbons offers a promising autothermal approach for direct methane conversion, but its progress has been hindered by yield limitations, high temperature requirements, and performance penalties at practical methane partial pressures (~1 atm). In this study, we report a class of Li2CO3-coated mixed rare earth oxides as highly effective redox catalysts for oxidative coupling of methane under a chemical looping scheme. This catalyst achieves a single-pass C2+ yield up to 30.6%, demonstrating stable performance at 700 °C and methane partial pressures up to 1.4 atm. In-situ characterizations and quantum chemistry calculations provide insights into the distinct roles of the mixed oxide core and Li2CO3 shell, as well as the interplay between the Pr oxidation state and active peroxide formation upon Li2CO3 coating. Furthermore, we establish a generalized correlation between Pr4+ content in the mixed lanthanide oxide and hydrocarbons yield, offering a valuable optimization strategy for this class of oxidative coupling of methane redox catalysts